sperm morphology and fertility of progeny-tested ai dairy bulls in sweden

AÑO 1, NÚMERO 12, AGOSTO 2008

LA TASA DE PREÑEZ

Existen diferentes parámetros para evaluar la fertilidad en el hato lechero y cada parámetro permite identificar problemas diferentes. Así, el porcentaje de concepción se refiere a la proporción de vacas gestantes del total inseminado, mientras que la tasa de preñez representa la proporción de vacas que gestan del total elegible para que presenten estro y que pudieran ser inseminadas durante un periodo equivalente a un ciclo estral (21 días). El porcentaje de concepción permite identificar problemas relacionados con el momento del servicio, la técnica de inseminación y los factores asociados con la muerte embrionaria temprana. La tasa de preñez es un parámetro resultante de dos aspectos: la eficiencia en la detección de estros y el porcentaje de concepción. La tasa de preñez se calcula multiplicando la eficiencia en la detección de estros por el porcentaje de concepción, dividido entre 100. De tal modo que, en un hato con una eficiencia en la detección de estros de 50% y con un porcentaje de concepción de 30, se obtiene una tasa de preñez de 15%. Este número indica que, de las vacas elegibles para que muestren estro y sean inseminadas en un periodo de 21 días, sólo 15% queda gestante. La tasa de preñez permite identificar problemas relacionados con la falla en la concepción y aquellos asociados con la eficiencia en la detección de estros. La mayor aspiración de un productor o del veterinario es lograr que la tasa de preñez sea igual al porcentaje de concepción, esto indicaría que de las vacas elegibles para ser detectadas en estro todas son inseminadas (100% de eficiencia en la detección de estros). En los hatos lecheros nacionales, una meta posible de alcanzar en la tasa de preñez es de 20%, cabe destacar que en los hatos de Estados Unidos la tasa de preñez promedio alcanzada es de 14%. Dado que, el aumento en la fertilidad global del hato mediante un incremento en el porcentaje de concepción, es realmente difícil de lograr, una posibilidad para mejorar la fertilidad ―probablemente la única― es mediante el aumento de la tasa de preñez. Es decir, con la misma proporción de vacas gestantes, después de cada servicio podemos aumentar el número de vacas gestantes por mes, aumentando únicamente el número de vacas inseminadas.

Dr. Joel Hernández Cerón y M.C. Álvaro Ortega León Compiladores

Departamento de Reproducción

http://www.unam.mx

http://www.fmvz.unam.mx

http://www.fmvz.unam.mx/fmvz/departamentos/reproduccion.htm

Noticias de Reproducción Bovina AGOSTO 2008

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Resúmenes

Theriogenology 70 (2008) 682–691

Sperm Morphology and Fertility of Progeny-Tested AI Dairy Bulls in Sweden

A. Al-Makhzoomia, N. Lundeheimb, M. Håårdc, H. Rodríguez-Martíneza

aDivision of Reproduction, Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of

Agricultural Sciences (SLU), Uppsala, Sweden. bDepartment of Animal Breeding and Genetics, Faculty of Veterinary Medicine and Animal

Science, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden. cSvensk Avel ek för, Örnsro, 532 94 Skara, Sweden.

Use of bull semen with high levels of sperm abnormalities, reflecting genital dysfunction, is not recommended for artificial insemination (AI) since it would most likely lead to subfertility. Sperm quality, including sperm morphology, may deteriorate with increasing age of the bull thus becoming a source of concern when using older, progeny-tested AI bull sires. Although a relationship between sperm morphology and fertility after AI in progeny-tested bull sires has been reported, it is yet unclear which sperm abnormalities are most critical. This constituted the core aim of a 22-month long retrospective study in proven (aged 60–84 months at the start of the study) AI sires of the Swedish Red (SR, n = 8) and Swedish Holstein (SLB, n = 4) breeds where their semen (107 freezing batches in total, built by a single ejaculate (n = 3) or pooling two consecutive ejaculates (n = 104) collected at 1–3 months interval), were subjected to detailed morphological examinations on wet- and dry, stained smears. Attention was paid to between and within-bull variations with regard to presence and level of sperm abnormalities. Sperm morphology differed significantly between sires and ejaculates, with 6/12 sires having ejaculates containing >10% of morphologically deviating sperm head shapes, a commonly used threshold for young AI bulls in Sweden. However, with the exception of pear-shaped or narrow-at-the-base anomalies, the mean values for individual defects were always within the limits expected for a normal bull sire, and were therefore considered acceptable. The percentage of morphologically normal spermatozoa was positively related to fertility, whose output differed significantly among bulls. Among sperm abnormalities, the proportion of morphologically deviating sperm head shapes were negatively correlated with fertility, pear-

shaped sperm heads in particular. In conclusion, the relationship between sperm morphology and fertility after AI calls for frequent (2–3 months interval) detailed assessments of sperm morphology in AI stud bull sires.

[email protected]

Animal Reproduction Science 107 (2008) 36–47

Effect of Progesterone (P4) Intravaginal Device (CIDR) to Reduce Embryonic Loss and to Synchronize Return to Oestrus of Previously Timed Inseminated Lactating

Dairy Cows Mufeed A. Alnimer, Wadie F. Lubbadeh

Department of Animal Production, Faculty of Agriculture, University of Jordan, Amman 11942, Jordan.

A study on postpartum dairy cows was done to evaluate the effect of using progesterone intravaginal device (CIDR) to synchronize return to oestrus of previously timed inseminated (TAI) cows and to evaluate embryo survival and pregnancy rate in the return to oestrus cows. All cows were subjected to TAI program. On Day 14 after AI, cows were assigned randomly into two groups: treated group (CTAI; n = 126) and control group (TAI; n = 172). Every cow in the CTAI group received CIDR device for 7 days. Cows were observed for oestrus after CIDR removal in the first period (Days 21–28). Cows, which did not show oestrus, were retreated with CIDR on Day 28 for 7 days and they were observed for oestrus after CIDR removal in the second period (Days 35–42). Pregnancy was diagnosed on Days 28, 45 and 90 after AI. In the first period, more cows in the CTAI group showed oestrus within 2.4 days after CIDR removal compared to cows within 4 days in the control. In the second period, more cows in the CTAI group showed oestrus within 4.5 days compared to cows within 3.7 days in the control. Pregnancy rates on Day 28 were not different between both groups. Pregnancy rates on Days 45 and 90 were higher for cows in the CTAI (42.1±5.3%, P = 0.028 and 38.9±5.2%, P = 0.020) compared to that in the TAI group (35.5±3.9% and 31.9±3.8%). Moreover, pregnancy rates were lower for multiparous cows (34.2±4.1, P = 0.017 and 30.2±3.9%, P = 0.008) compared to primiparous cows (42.7±5.2% and 39.9±5.1%) on Days 45

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and 90, respectively. Pregnancy losses between Days 28–45 and 45–90 tended to be lower for the CTAI group and primiparous cows compared to the TAI group and multiparous cows. Pregnancy rates of first (P = 0.020), second, third and up to fourth AI were higher (P = 0.001) for the CTAI group (38.9±0.05%, 78.6±0.05%, 92.1±0.04%, 93.6±3.71%) compared to that for the TAI group (31.9±0.03%, 54.1±0.04%, 68.0±0.03%, 81.4±2.75%, respectively). Days open for pregnant cows were similar in both groups, but lower (P = 0.025) for primiparous cows (81.6±4 day) compared to multiparous cows (93.8±3 day). Number of services for pregnant cows was lower (P = 0.002) for the CTAI group (1.70±0.10) compared to that for the TAI group (2.14±0.09), whereas it was similar for primiparous and multiparous cows. Results indicate that the CIDR device improved synchronization to return to oestrus and increased pregnancy rate to first, second, third and fourth AI by reducing embryonic and fetal losses.


Kinetics of Fertilization and Development, and Sex Ratio of Bovine Embryos Produced Using the Semen of

Different Bulls M. Alomara,b, H. Tasiauxa, S. Remaclea, F. Georgea, D. Paula, I.

Donnaya aUCL, Institut des Sciences de la Vie, Unité des Sciences vétérinaires,

Place Croix du sud 5 Boîte 10, B-1348 Louvain-la-Neuve, Belgium. bDivision of Animal Production, Department of Agriculture, Atomic

Energy Commission, P.B. Box 6091, Damascus, Syria.

The between bulls variation in in vitro fertility and the shift of sex ratio towards male embryos are two problems affecting the in vitro production (IVP) of bovine embryos. Our objective was to evaluate the kinetics of fertilization, embryo development and the sex ratio of the resulting embryos using the frozen/thawed semen of four different bulls. In a first experiment, the kinetics of pronucleus (PN) formation was evaluated at 8, 12 and 18 h post-insemination (hpi). Based upon the pronuclei sizes and the distance between the two pronuclei, inseminated oocytes were classified in three PN stages. Differences between bulls were observed at each time point, but were more important at 12 hpi. At 8 and 12 hpi bull III showed a significantly faster PN evolution by comparison with the three other bulls (P < 0.05), while at 18 hpi, the proportion of the three PN stages was similar to those of bulls I and IV, bull II being delayed. In a second experiment, the

kinetics of in vitro embryo development was compared using time-lapse cinematography. The analysis of embryos reaching the blastocyst stage revealed significant differences in the mean time of first cleavage (range of 22.7–25.6 h, P < 0.05), while the lengths of the subsequent three cell cycles did not differ between bulls. The early mean time of first cleavage with bull III was associated with an early blastulation and a high blastocyst rate at Day 7, in opposition to what was observed with bull II showing a later timing of first cleavage (first cleavage 22.1 hpi versus 25.5 hpi; blastulation 140.4 hpi versus 152.5 hpi; D7 blastocyst rates: 31.3% versus 21.9%; P < 0.05). In a third experiment, 65–76 Day 8 blastocysts per bull were sexed by PCR. Only blastocysts obtained with bull III showed a shift in sex ratio towards male embryos (76% male embryos; P < 0.05). Such shift was already observed at the 2-cell and morula stages. In conclusion, the bull influences the kinetics of PN formation, of embryo development and the sex ratio of the embryos. Moreover, those parameters might be related.

[email protected]

Animal (2008), 2:8, pp 1158–1167

Expression Profiles of Genes Regulating Dairy Cow Fertility: Recent Findings, Ongoing Activities and Future

Possibilities B. Beerda1, J. Wyszynska-Koko2, M. F. W. te Pas1, A. A. C. de

Wit1 and R. F. Veerkamp1 1Animal Breeding and Genomics Centre, Animal Sciences Group of Wageningen UR, 8200 AB Lelystad, The Netherlands; 2Institute of

Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzebiec, 05-552 Wolka Kosowska, Poland.

Subfertility has negative effects for dairy farm profitability, animal welfare and sustainability of animal production. Increasing herd sizes and economic pressures restrict the amount of time that farmers can spend on counteractive management. Genetic improvement will become increasingly important to restore reproductive performance. Complementary to traditional breeding value estimation procedures, genomic selection based on genome-wide information will become more widely applied. Functional genomics, including transcriptomics (gene expression profiling), produces the information to understand the consequences of selection as it helps to unravel physiological mechanisms underlying female fertility traits. Insight into the latter is needed to develop new effective


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management strategies to combat subfertility. Here, the importance of functional genomics for dairy cow reproduction so far and in the near future is evaluated. Recent gene profiling studies in the field of dairy cow fertility are reviewed and new data are presented on genes that are expressed in the brains of dairy cows and that are involved in dairy cow oestrus (behaviour). Fast-developing new research areas in the field of functional genomics, such as epigenetics, RNA interference, variable copy numbers and nutrigenomics, are discussed including their promising future value for dairy cow fertility.

[email protected]

Reproduction, Fertility and Development, 2008, 20,

784–788 Technical Note

Effect of Density Gradient Centrifugation With Trypsin on the in vivo Fertilising Capability of Bovine

Spermatozoa Brock A. BlevinsA,C, Morne de la ReyB and Naida M. LoskutoffA

AThe Bill and Berniece Grewcock Center for Conservation and Research, Henry Doorly Zoo, Omaha, NB 68107, USA. BEmbrio Plus,

Brits, NorthWest 0250, RSA.

The present study investigated the effect of a novel density gradient centrifugation (DGC) treatment using recombinant trypsin on the in vivo fertilising capability of bovine spermatozoa compared with a standard method. In Trial 1, semen collected from Boran and Ankole (Bos indicus) bulls was treated either with a silane-coated silica particle colloid formulated for humans with a recombinant trypsin or processed using a standard method (dilution in an egg yolk based diluent). Semen processed by the two methods was used to artificially inseminate (AI) superovulated cattle. Day 7 embryos were flushed and assessed for fertilisation rates and embryo quality.Trial 2 used a trypsinised silane-coated silica particle colloid formulated specifically for bovine semen. Trial 1 resulted in significantly higher fertilisation rates using the trypsinised human DGC treatment than cows inseminated using the standard method (75.2% v. 67%, respectively; P <0.01), but the numbers of transferable-quality Day 7 embryos did not differ between the two groups (P >0.05). Results for Trial 2 indicated that cows inseminated with the trypsinised bovine DGC treatment had significantly increased fertilisation rates compared with the standard method (88.4% v. 63.1%, respectively;

P <0.01) and had significantly higher numbers of transferable-quality embryos (70.3% v. 51.8%, respectively; P <0.01). In summary, bovine sperm treatment before AI by DGC and recombinant trypsin increases fertilisation rates and can result in more transferable-quality embryos compared with standard methods.

[email protected]


The Effect of Nutrition on Sexual Development of Bulls A.D. Barth, L.F.C. Brito, J.P. Kastelic

Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon,

Saskatchewan, Canada S7N 5B4.

Most bulls that are managed for sale as yearlings are fed high-energy diets in the post-weaning period to maximize rates of gain in body weight. High-energy diets with adequate protein, vitamins and minerals result in a larger scrotal circumference at 1 y of age, however, part of this increase in size is likely due to scrotal fat. It is unclear whether testis size and spermatogenesis is significantly affected by nutritional intake in the post-weaning period. There are indications of an effect of calfhood nutrition on age at puberty and testis size. Scrotal circumference was smaller in yearling bulls raised by first-parity dams, compared to those raised by older dams. This may have been due to lower milk production by first-parity dams, an in utero effect, or both. The effect of reduced calfhood nutrition may be mediated through gonadotropin secretion. Calves destined to become later maturing bulls with smaller testes had lower amounts of LH secretion during the period of the early gonadotropin rise (8–16 wk of age). Furthermore, augmenting circulating LH concentrations at this time by treating calves with GnRH hastened pubertal development. In addition, FSH treatments in calfhood also increased scrotal circumference and hastened spermatogenesis. In that regard, FSH has been considered a main driver of Sertoli cell proliferation in prepubertal animals. Since Sertoli cell multiplication ceases at 20–25 wk of age in bulls, final testis size in bulls is likely determined in calfhood. Four experiments were done to investigate the effects of calfhood nutrition on pubertal development. These studies confirmed that superior calfhood nutrition augmented gonadotropin secretion (which is probably mediated by metabolic hormones); this resulted in

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larger testes at 1 y of age and an earlier onset of spermatogenesis.

[email protected]


Effect of Progesterone Administration on the Ovarian Response to Superovulatory Treatments in Cattle

S. Callejasa, R. Alberiob, J. Cabodevilaa, J. Allerb, R. Catalanoa, M. Teruela, F. Duloutc

aArea de Reproducción (FISFARVET), Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Campus Universitario, Paraje Arroyo Seco S/N,

B7000GHG Tandil, Buenos Aires, Argentina. bIntituto Nacional de Tecnología Agropecuaria Balcarce, 7620 Balcarce, Buenos Aires,

Argentina. cCIGEBA, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, 1900 La Plata, Argentina.

To evaluate ovarian response in Angus cows previously treated with progesterone (P4), animals were randomly assigned to two groups: T600 group (n = 14), 600 mg of P4/day. P4 was injected from days 3 to 7 of the estrous cycle. On day 7, superovulatory treatments began. The control group (n = 12) was given vehicle only. The superovulatory treatments in the control group began on days 7–9 of the estrous cycle. The superovulatory total treatment dose of 400 mg NIH FSH P1 was given twice a day over a 4-day period. Ultrasonography of the ovaries was conducted 3 days preceding the initiation of superovulatory treatment, every 24 h. In both groups, an additional ultrasonographic evaluation was made at 24 h after the end of superovulatory treatment. Blood samples were collected 4 days preceding the initiation of superovulatory treatment, every 24 h. Additional samples were taken from the P600 group for 12 day after of initiation of superovulatory treatment every 24 h, except on the fifth day after the initiation of superovulatory treatment. In the P600 group, P4 concentrations were greater than in the control group (P < 0.01) and remained over 1 ng/ml up to day 11 after beginning of superovulatory treatment. The diameter of the dominant follicle was larger in the animals of the control group (P < 0.01). Cows of the P600 group had a greater number of Class I (3–4 mm) follicles (P < 0.01). A significant day and treatment effect (P < 0.01) were observed in Class II (5–9 mm) follicles. Effects due to treatment on the number of Class III follicles (P < 0.05) were observed. In the P600 group, no estrous post-superovulatory was observed and there were no ovulations that occurred. Conversely, 100% of the cows of the control group showed estrous. In the P600 group,

there were a greater number of Class III follicles (P < 0.01) and a lesser number of Class II follicles (P < 0.05) at 24 h after the end of superovulatory. In the control group, 66.7% of the cows responded to superovulatory treatments. In conclusion, the daily administration of 600 mg of P4, from days 3 to 7 of the estrous cycle, produces an increase of plasma concentrations of this hormone from day 4, resulting in changes in follicular dynamics (absence of follicles greater than 10mm of diameter and an increase of the population of Class I follicles). As to the ovarian stimulation using Folltropin V® in animals receiving a daily injection of 600 mg of P4 from days 3 to 7 of the estrous cycle, a greater population of follicles≥10mm developed by 24 h after superovulatory treatments were completed.

[email protected]


Bull Breeding Soundness Evaluation: A Practitioner’s Perspective

J.H. Alexander Alexander Veterinary Services, 3135 Buck Reed Road, Edwards, MS

39066, United States.

It is well established that the bull breeding soundness evaluation (BBSE) is an easily performed, relatively inexpensive, and extremely useful tool for the cow–calf operation. However, the BBSE can only achieve its full potential if it is performed properly by the practitioner in the field. A properly performed BBSE should include the use of the standards established by the Society for Theriogenology and a systematic protocol by the practitioner. This paper will review the Society for Theriogenology BBSE standards and the author’s protocol.

[email protected].


The Development of Beef Breeding Bulls T.J. Engelken

Veterinary Diagnostic and Production Animal Medicine, Iowa State University, College of Veterinary Medicine, Ames, IA 50011, United

States.

Management of the bull battery will have a dramatic impact on profitability of the cow/calf enterprise. It is critical that young bulls be selected and developed to maximize longevity and productivity for the eventual buyer. Bulls must be structurally sound, healthy, and have adequate libido in order to service the required number of females. Once bulls complete their first breeding





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season, special care must be taken in order to ensure that they recover and regain needed body condition and pass a bull breeding soundness examination (BBSE). Mature bulls that have reached their genetic potential for growth require less intensive management, but the health program and annual BBSE cannot be overlooked. Mature bulls are also more likely to carry venereal disease and should be screened according to local disease incidence and state regulations. All bulls, regardless of age, should be observed early during the breeding season to ensure that they are physically capable of mounting and servicing females. The establishment of a complete management program, especially for young bulls, is essential to ensure that ranch resources are used efficiently, including maintenance of a high level of reproductive performance of the cow herd.

[email protected].

Animal (2008), 2:8, pp 1104–1111

Why is it Getting More Difficult to Successfully Artificially Inseminate Dairy Cows?

H. Dobson, S. L. Walkera, M. J. Morris, J. E. Routly and R. F. Smith

Department of Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, Wirral CH64 7TE, UK.

Successfully using artificial insemination (AI) is defined as getting cows pregnant when the farmer wants them in-calf and making the best use of appropriate genetic potential. Over the past 30 to 50 years, the percentage of animals in oestrus that stand-tobe-mounted (STBM) has declined from 80% to 50%, and the duration of STBM from 15 h to 5 h; both in parallel with a reduction in first-service-pregnancy-rate from 70% to 40%. Meanwhile, the incidence of lameness and mastitis has not decreased; and it takes more than an extra 40 and 18 days, respectively, to get a lame or mastitic cow in-calf compared to healthy herd-mates. The intensity of oestrus is 50% lower in severely lame cows, and fewer lame cows ovulate. Luteal phase milk progesterone concentrations are also 50% lower in lame cows, and follicular phase oestradiol is also lower in non-ovulating lame cows compared to ovulating animals. Furthermore, lame cows that do not ovulate do not have an LH surge, and the LH pulse frequency in their late follicular phase is lower (0.53 v. 0.76 pulses/h). Thus, we suggest that the stress of lameness reduces LH pulsatility

required to drive oestradiol production by the dominant follicle. The consequent low oestradiol results in less-intense oestrus behaviour and failure to initiate an LH surge; hence there is no ovulation. A series of experimental studies substantiate our hypothesis that events activating the hypothalamus–pituitary–adrenal axis interfere at both the hypothalamus and the pituitary level to disrupt LH and oestradiol secretion, and thus the expression of oestrus behaviour. Our inability to keep stress at a minimum by appropriately feeding and housing high-production cows is leading to a failure to meet genetic potential for yield and fertility. We must provide realistic solutions soon, if we want to successfully use AI to maintain a sustainable dairy industry for the future.

[email protected]

Animal (2008), 2:8, pp 1128–1134

Developmental Programming of Reproduction and Fertility: What is the Evidence?

D. S. Gardner1, R. G. Lea1 and K. D. Sinclair2 1School of Veterinary Medicine and Science, Sutton Bonington

Campus, University of Nottingham, Loughborough LE12 5RA, UK; 2School of Biosciences, Sutton Bonington Campus, University of

Nottingham, Loughborough LE12 5RA, UK.

The concept of the foetal/developmental origins of adult disease has been around for 20 years and from the original epidemiological studies in human populations much more evidence has accumulated from the many studies in animal models. The majority of these have focused upon the role of early dietary intake before conception, through gestation and/or lactation and subsequent interactions with the postnatal environment, e.g. dietary and physical activity exposures. Whilst a number of theoretical models have been proposed to place the experimental data into a biological context, the underlying phenomena remain the same; developmental deficits (of single (micro) nutrients) during critical or sensitive periods of tissue growth alter the developmental pathway to ultimately constrain later functional capacity when the individual is adult. Ageing, without exception, exacerbates any programmed sequelae. Thus, adult phenotypes that have been relatively easy to characterise (e.g. blood pressure, insulin sensitivity, body fat mass) have received most attention in the literature. To date, relatively few studies have considered the effect of differential early environmental exposures on reproductive




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function and fecundity in predominantly mono-ovular species such as the sheep, cow and human. The available evidence suggests that prenatal insults, undernutrition for example, have little effect on lifetime reproductive capacity despite subtle effects on the hypothalamic–pituitary–gonadal axis and gonadal progenitor cell complement. The postnatal environment is clearly important, however, since neonatal/adolescent growth acceleration (itself not independent from prenatal experience) has been shown to significantly influence fecundity in farm animals. The present paper will expand these interesting areas of investigation and review the available evidence regarding developmental programming of reproduction and fertility. However, it appears there is little strong evidence to indicate that offspring fertility and reproductive senescence in the human and in farm animal species are overtly affected by prenatal nutrient exposure. Nevertheless, it is clear that the developing gonad is sensitive to its immediate environment but more detailed investigation is required to specifically test the long-term consequences of nutritional perturbations during pregnancy on adult reproductive well-being. [email protected] or [email protected]


Increased Pre-implantation Development of Cloned Bovine Embryos Treated With 5-aza-20-Deoxycytidine

and Trichostatin A X. Ding, Y. Wang, D. Zhang, Y. Wang, Z. Guo, Y. Zhang

Institute of Bioengineering, Northwest A&F University, Yangling, Shaanxi 712100, China.

Limited success of somatic cell nuclear transfer is attributed to incomplete reprogramming of transferred nuclei. The objective was to determine if 5-aza-20-deoxycytidine (5-aza-dC) and trichostatin A (TSA) promoted reprogramming and improved development. Relative to untreated controls, treatment of donor cells, cloned embryos, and continuous treatment of both donor cells and cloned embryos with a combination of 0.01 µM 5-aza-dC and 0.05 µM TSA significantly increased the blastocyst rate (11.9% vs 31.7%, 12.4% vs 25.6%, and 13.3% vs 38.4%, respectively) and total cell number (73.2 vs 91.1, 75.2 vs 93.7, and 74.6 vs 96.7). Moreover, blastocyst rate and inner cell mass (ICM) cell number of embryos continuously exposed to both reagents were significantly higher than that of a

TSA-treated group (38.4% vs 23.9% and 27.4 vs 18.2). The DNA methylation level of 2-cell embryos was decreased significantly, whereas the histone acetylation level increased dramatically after donor cell treatment and continuous treatment with both reagents. However, these epigenetic features of cloned blastocysts were not significantly different than the untreated control group. Following embryo treatment, DNA methylation and histone acetylation levels of cloned blastocysts were unchanged, except for the group given 0.5 µMTSA (acetylation level was significantly increased, but development potential was reduced). In conclusion, development of cloned bovine embryos was enhanced by 5-aza-dC and TSA; furthermore, the combination was more effective than either one alone.

[email protected]; [email protected]

Journal of Dairy Science 91:3025–3033, 2008

Pregnancy Incidence in Norwegian Red Cows Using Nonreturn to Estrus, Rectal Palpation, Pregnancy-

Associated Glycoproteins, and Progesterone R. T. Garmo,* A. O. Refsdal,† K. Karlberg,* E. Ropstad,* A.

Waldmann,‡ J. F. Beckers,§ and O. Reksen* *Department of Production Animal Clinical Sciences, Norwegian

School of Veterinary Science, PO Box 8146, NO-0033 Oslo, Norway. †Geno Breeding and AI Association, Holsetgata 22, 2326 Hamar,

Norway. ‡Estonian University of Life Sciences, 62 Kreutzwaldi Street, 51014 Tartu, Estonia. §University of Liege, Faculty of Veterinary

Medicine, B 4000 Sart-Tilman, Belgium.

The objectives of the study were to estimate pregnancy incidence and calving rate after first artificial insemination (AI) in Norwegian Red cows undergoing spontaneous estrus, to assess the relationship between pregnancy and management factors at herd or cow level, to evaluate differences between 60-d nonreturn rate (NRR60d) and pregnancy incidence, and to compare the accuracy of pregnancy diagnosis by rectal palpation and plasma pregnancy-associated glycoproteins (PAG) analysis supported by progesterone measurements. In total, 829 animals (n = 229 heifers, 234 first lactation, 173 second-lactation, and 193 >second-lactation cows) were included. Milk samples for progesterone analysis were collected both at AI and 3 wk later. Cows with progesterone concentrations <3 ng/mL at AI were considered in estrus or having non active ovaries, whereas cows with progesterone concentrations >7 ng/mL 3 wk later were considered pregnant. Blood sampling for PAG analysis and pregnancy diagnosis by


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rectal palpation were conducted 57.6 ± 0.92 d after AI. Pregnancy-associated glycoprotein concentrations equal to 2.5 ng/mL gave the greatest sensitivity (94.3%) and specificity (94.6%) in the assessment of pregnancy. The number of days from calving to first AI was 85.3 ± 1.71. Overall NRR60d after first AI was 72.5%. The corresponding values for heifers, first-lactation, second lactation, and >second-lactation cows were 76.9, 67.1, 69.9, and 76.2%. Overall pregnancy incidence after first AI was 63.7%. The corresponding values for heifers, first-lactation, second-lactation, and >second-lactation cows were 70.0, 58.2, 61.6, and 64.9%. Overall calving rate to first AI was 57.2%. The corresponding values for heifers, first-lactation, second-lactation, and >second lactation cows were 64.9, 54.3, 54.7, and 53.9%. The overall difference between NRR60d and pregnancy incidence was 8.8%, whereas the parity-specific differences were 6.9, 8.9, 8.3, and 11.3% for heifers, first-lactation, second-lactation, and >second-lactation cows, respectively. Eight animals with PAG <2.5ng/mL and classified as pregnant by rectal palpation calved, whereas 5 animals with PAG ≥2.5 ng/mL and classified as nonpregnant by rectal palpation also calved. The study showed that Norwegian Red cows have relatively high reproductive performance. Breeding for fertility traits over 35 yr is probably an important reason for such high fertility.

[email protected]

Animal (2008), 2:8, pp 1144–1152

Integration of Physiological Mechanisms That Influence Fertility in Dairy Cows

P. C. Garnsworthy, K. D. Sinclair and R. Webb University of Nottingham School of Biosciences, Sutton Bonington

Campus, Loughborough LE12 5RD, UK.

Fertility in dairy cows has been declining for the past three decades. Genetic selection for increased milk production has been associated with changes in key metabolic hormones (growth hormone, insulin, IGF and leptin) that regulate metabolism by homoeostasis and homeorhesis. These metabolic hormones, particularly insulin, provide signals to the reproductive system so that regulation of ovarian function is coordinated with changes in metabolic status. Studies have shown, for example, that increasing circulating insulin concentrations during the early post partum period can advance the resumption of oestrous

cycles by enhancing follicular growth. However, high concentrations of insulin can be detrimental to the developmental competence of oocytes, which is also influenced by the supply of fatty acids at the systemic level and at the ovarian level. Insulin status is also associated with the incidence and characteristics of abnormal ovarian cycles. These changes can occur without significant variation in circulating gonadotrophin concentrations. This suggests that additional factors, such as peripheral metabolites, metabolic hormones and locally produced growth factors, may have a modulating role. Recent evidence has demonstrated that ovarian responses to metabolic signals and nutrient profile vary according to the stage of the reproductive cycle. Improved understanding of this multifactorial process enables nutrition to be matched to genotype and milk production, with a positive impact on pregnancy rate.

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Livestock Science 117 (2008) 88–92

Effects of GnRH in Combination With PGF2α on the Dynamics of Follicular and Luteal Cells in Post-pubertal

Holstein Heifers R. Harpera, W.A. Bennettb, E.J. Cuadraa, C.F. Vaughna, N.S.

Whitworthb aAlcorn State University, 1000 ASU Drive, Box 750, Alcorn State, MS 39096, United States. bDepartment of Obstetrics and Gynecology, University Medical Center, 2500 North State Street, Jackson, MS

39216, United States.

Holstein heifers were randomly allotted by weight, age and body condition score to one of three treatments to test the hypothesis that GnRH administration concurrent with PGF2α injection would advance follicle or corpus luteum (CL) development parallel to an induced luteolysis of the pre-existing CL. Heifers in the control group (n=14) received two treatments of PGF2α (25 mg, im) given 10 days apart. Groups 2 (n=14) and 3 (n=14) received an additional treatment of GnRH (100 µg, im) after the first and second PGF2α respectively. Estrus detection began immediately after PGF2α and continued for 80 h. Blood sampling was initiated 7 days prior to the first PGF2α (day −7) and continued on days 0, 7, 10 (prior to the second PGF2α), 17 and 24. Heifers were artificially inseminated after the second PGF2α and pregnancy diagnosed at 60 days. There was a trend (Pb.10) toward a lower estrus response in group 3 when compared to the other groups. Pregnant heifers in group 2 had lower




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progesterone (0.44±0.09 vs. 1.72±0.56 ng/ml) a week after the second PGF2α than the non-pregnant animals in that group (Pb.05). Similar results were observed in the control group but only within the responding heifers (0.61±0.08 vs. 0.93±0.03 ng/ml; Pb.05). Progesterone in heifers in group 2 remained high on day 0, 7, and 10 (1.48±0.37, 1.23±0.39, 1.96±0.36 ng/ml) in spite of the treatment with PGF2α. This data suggest that administration of GnRH following PGF2α alters bovine luteal and/or follicular cell function.

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Infectious Causes of Embryonic and Fetal Mortality M. Daniel Givensa,b, M.S.D. Marleyb

aDepartment of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States. bDepartment of

Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.

The purpose of this review is to summarize bacterial, fungal, protozoan, and viral causes of reproductive dysgenesis in cattle, sheep, goats, pigs, horses, dogs, and cats. The clinical presentations of disease due to reproductive pathogens are emphasized, with a focus on assisting development of complete lists of causes that result in abortion and infertility in these species. Clinicians are encouraged to assess clinical presentation, create complete lists of differential diagnoses, obtain appropriate diagnostic samples, maximize diagnostic laboratory support, and avoid zoonotic infections resulting from reproductive pathogens of animals. The foundation of an accurate diagnosis of reproductive loss due to infectious pathogens facilitates the prudent use of immunization and biosecurity to minimize reproductive losses.

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Pathogens that cause infertility of bulls or transmission via semen

M. Daniel Givensa, M.S.D. Marleyb aDepartments of Pathobiology and Clinical Sciences, College of

Veterinary Medicine, Auburn University, Auburn, AL 36849, United States. bDepartment of Pathobiology, College of Veterinary Medicine,

Auburn University, Auburn, AL 36849, United States.

The purpose of this paper is to review scientific evidence regarding pathogens that cause infertility of bulls or that could be transmitted via bovine semen. Although several pathogens can cause male infertility and potentially be

transmitted via semen, adhering to disease control recommendations provided by Certified Semen Services (CSS) and the World Organization for Animal Health (OIE) can prevent infectious male infertility and ensure that the risk of pathogen transmission via semen is negligible. Regarding bulls to be used for natural breeding, quarantine prior to herd introduction and appropriate diagnostic testing during quarantine will commonly prevent introduction of pathogens that adversely affect reproduction.

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Animal (2008), 2:8, pp 1120–1127

The Consequences of Metabolic Changes in High-Yielding Dairy Cows on Oocyte and Embryo Quality

J. L. M. R. Leroy1, A. Van Soom2, G. Opsomer2 and P. E. J. Bols1

1Laboratory for Veterinary Physiology, Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary

Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium; 2Department of Reproduction, Fertility and Herd Health;

Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.

Unsatisfactory reproductive performance in dairy cows, such as reduced conception rates, in addition to an increased incidence of early embryonic mortality, is reported worldwide and has been associated with a period of negative energy balance (NEB) early post partum. Typically, NEB is associated with biochemical changes such as high non-esterified fatty acid (NEFA), high b-hydroxybutyrate (b-OHB) and low glucose concentrations. The concentrations of these and other metabolites in the follicular fluid (FF) of high-yielding dairy cows during NEB were determined and extensively analyzed, and then were replicated in in vitro maturation models to investigate their effect on oocyte quality. The results showed that typical metabolic changes during NEB are well reflected in the FF of the dominant follicle. However, the oocyte seems to be relatively isolated from extremely elevated NEFA or very low glucose concentrations in the blood. Nevertheless, the in vitro maturation models revealed that NEB-associated high NEFA and low glucose levels in the FF are indeed toxic to the oocyte, resulting in deficient oocyte maturation and developmental competence. Induced apoptosis and necrosis in the cumulus cells was particularly obvious. Furthermore, maturation in saturated free fatty acid-rich media had a carry-over effect on embryo quality, leading





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to reduced cryotolerance of day 7 embryos. Only b-OHB showed an additive toxic effect in moderately hypoglycemic maturation conditions. These in vitro maturation models, based on in vivo observations, suggest that a period of NEB may hamper the fertility of high-yielding dairy cows through increased NEFA and decreased glucose concentrations in the FF directly affecting oocyte quality. In addition to oocyte quality, these results also demonstrate that embryo quality is reduced following an NEB episode. This important observation may be linked to the typical diet provided to stimulate milk yield, or to physiological adaptations sustaining the high milk production. Research into this phenomenon is ongoing.

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Reprod Dom Anim 43, 415–421 (2008)

Immunohistochemical Detection of Receptors for Oestrogen and Progesterone in Endometrial Glands and

Stroma during the Oestrous Cycle in Nelore (Bos taurus indicus) Cows

I Martin1, R Torres Neto2, E Oba1, J Buratini Jr3, M Binelli4, R Laufer-Amorim2 and JCP Ferreira1

1Department of Animal Reproduction and Veterinary Radiology, School of Veterinary Medicine and Animal Science, UNESP;

2Department of Veterinary Clinic, School of Veterinary Medicine and Animal Science, UNESP; 3Department of Physiology, Biosciences

Institute, UNESP, Botucatu; 4Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, USP,

Pirassununga, Brazil.

The aim of the present study was to monitor endometrial distribution and concentrations of oestrogen receptors a (ERa) and progesterone receptors (PR) by immunohistochemistry in Nelore cows (Bos taurus indicus) during the oestrous cycle. Blood samples were collected for progesterone measurement and endometrial samples were taken from the uterine horn contra lateral to the corpus luteum in 16 cows at days 0 (ovulation), 5, 9, 13 and 19 of the oestrous cycle. Immunostaining evaluation for ERa and PR in the glandular epithelium and uterine stroma was performed by two methods: positive nuclei counting and staining intensity of the nuclei. Specific positive staining reactions for both receptors were limited to cell nuclei and they were not identified in the cytoplasm. The proportion of ERa positive nuclei had a temporal variation throughout the oestrous cycle in both cell types evaluated and was higher in uterine stroma than the glandular epithelium (p < 0.05). The greatest

proportion of ERa stained nuclei was observed at oestrus and during the initial and mid luteal phase (days 5, 9 and 13) (p < 0.05) in the glandular epithelium and at days 0, 5 and 9 in the uterine stroma (p < 0.01). The proportion of PR positive nuclei remained constant throughout the entire oestrous cycle for both cell types evaluated (p > 0.05). A higher proportion of PR positive nuclei was measured in the uterine stroma compared with the glandular epithelium (p < 0.05). Intensity of staining for ERa and PR varied throughout the oestrous cycle (p < 0.01). There was a higher staining intensity at days 0 and 5 in the stroma for ERa (p < 0.01) and PR (p < 0.01) and in the glandular epithelium at days 0, 5, 9 and 13 for Era (p < 0.01) and at days 0, 5 and 9 for PR (p < 0.01) when compared with the other evaluated days. These data demonstrate that ERa and PR expression varied throughout the oestrous cycle in Nelore cows, in general with highest concentrations at oestrus and the lowest during the luteal phase. This is similar to patterns observed in Bos taurus taurus.

Reprod Dom Anim 43, 464–472 (2008)

Luteolytic Effect of Prostaglandin F2α on Bovine Corpus Luteum Depends on Cell Composition and Contact

AJ Korzekwa1, JJ Jaroszewski2, I Woclawek-Potocka1, MM Bah1 and DJ Skarzynski1

1Division of Reproductive Endocrinology and Pathophysiology, Institute of Animal Reproduction and Food Research, PAS;

2Department of Pathology and Pharmacology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn,

Poland.

Prostaglandin F2α (PGF2α) is a main luteolytic factor in vivo; however, its direct luteolytic influence on steroidogenic cells of bovine corpus luteum (CL) is controversial and not fully understood. The aim of the study was to clarify PGF2α action on bovine CL in different in vivo and in vitro conditions and to examine whether the contact among all main types of CL cells is necessary for luteolytic PGF2α action. In experiment 1, the bovine CL (day 15 of the oestrous cycle) was perfused using in vivo microdialysis system with dinoprost (an analogue of PGF2α) for 0.5 h. Dinoprost caused a short-time increase in progesterone (P4), whose concentration decreased there after (at 6-, 10-, 12- and 24-h after treatment). In experiment 2, the direct effect of PGF2α on P4 accumulation in CL steroidogenic cells cultured in monolayer (day 15 of the cycle) was determined. PGF2α after 24 h

http://www.blackwell-synergy.com/loi/rda



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of incubation increased P4 accumulation in steroidogenic CL cells. In experiment 3 steroidogenic, endothelial CL and immune cells (day 15 of the cycle) were incubated with PGF2α in cocultures for 24 h in glass tubes and the levels of P4, stable metabolites of nitric oxide (NO) and leukotriene (LT) C4 were determined. Although PGF2α treatment increased P4 secretion in homogeneous steroidogenic CL cell culture, the decrease in P4 secretion in cocultures of all types of CL cells was observed. The secretion of NO and LTC4 increased after the treatment of PGF2α both in pure cultures of CL cells and in cocultures. The interactions between endothelial and immune cells with steroidogenic CL cells are needed for luteolytic PGF2α action within the bovine CL. Our results indicate that the cell coculture model, including the main types of CL cells, is the most approximate to study PGF2α role in vitro.


Developing Replacement Beef Heifers T.J. Engelken

Veterinary Diagnostic and Production Animal Medicine, Iowa State University, College of Veterinary Medicine, Ames, IA 50011, United

States.

The replacement heifer represents the next generation of genetic progress for the cow herd. Producers invest a substantial amount of capital in these females, even if they fail to become pregnant. In order to get a return on this investment, it is imperative that these heifers become pregnant early in the first breeding season, calve with a minimum of dystocia, breed back in a timely fashion, and then continue to be productive for a number of years. Practitioners working with heifer development programs need to emphasize a systemic approach that evaluates these females at critical times. These programs need to address such areas as weaning and nutritional management, genetic selection, prebreeding evaluation, the breeding season, and heifer management from pregnancy examination through the end of their first calving season. This increased level of scrutiny should not end until the heifer weans her first calf and is determined to be pregnant the second time. This type of program will ensure optimal reproductive rates, female longevity, and a positive return on the producer’s investment.

[email protected].

Reprod Dom Anim 43, 477–480 (2008)

Oocyte Recovery by Ovum Pick Up and Embryo Production in River Buffaloes (Bubalus bubalis)

BM Manjunatha2, JP Ravindra1, PSP Gupta1, M Devaraj2 and S Nandi1

1National Institute of Animal Nutrition and Physiology (NIANP), ICAR, Bangalore, India; 2Department of Animal Reproduction, Gynaecology and Obstetrics, Veterinary College, Karnataka Veterinary, Animal and

Fishery Sciences University (KVAFSU), Bangalore, India.

Ovum pick up (OPU) was conducted twice a week for 12 weeks in six cycling, non-descriptive (local breed), Indian buffaloes to study the efficiency of OPU on recovery of oocytes for embryo production. OPU was performed using an ultrasound equipment with a 5-MHz transvaginal transducer, a single-lumen, 18-gauge, 55-cm-long needle and a constant vacuum pressure of 110 mmHg. The number and size of follicles were determined before puncture. The recovered oocytes were graded, washed, matured for 24 h and then fertilized with frozen–thawed semen, followed by embryo culture on the oviductal monolayer. The mean number of follicles observed per animal per session did not differ between animals or between puncture sessions. A mean number of 3.62 ± 0.32 mm follicles were observed, 2.90 ± 0.15 mm follicles were punctured and 1.21 ± 0.07 oocytes were recovered per animal per session, with an average recovery rate of 42%. Of the total oocytes recovered, 64% were suitable for in vitro embryo production (grade A + B) whereas 36% were classified to be of grades C + D. A mean number of 0.25 ± 0.2 transferable embryos was produced in vitro per buffalo per session with a transferable embryo production rate of 32%. In conclusion, this study demonstrated that twice-aweek OPU could be applied repeatedly, without any adverse effects on the follicular growth and oocyte recovery and that recovered oocytes could be used for in vitro embryo production in buffaloes.


Epidemiology and disease control in everyday beef practice

R.L. Larson College of Veterinary Medicine, Kansas State University, 111B Mosier

Hall, Manhattan, KS 66506, USA.

It is important for food animal veterinarians to understand the interaction among animals, pathogens, and the environment, in order to implement herd-specific biosecurity plans. Animal factors such as the number of immunologically





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protected individuals influence the number of individuals that a potential pathogen is able to infect, as well as the speed of spread through a population. Pathogens differ in their virulence and contagiousness. In addition, pathogens have various methods of transmission that impact how they interact with a host population. A cattle population’s environment includes its housing type, animal density, air quality, and exposure to mud or dust and other health antagonists such as parasites and stress; these environmental factors influence the innate immunity of a herd by their impact on immunosuppression. In addition, a herd’s environment also dictates the ‘‘animal flow’’ or contact and mixing patterns of potentially infectious and susceptible animals. Biosecurity is the attempt to keep infectious agents away from a herd, state, or country, and to control the spread of infectious agents within a herd. Infectious agents (bacteria, viruses, or parasites) alone are seldom able to cause disease in cattle without contributing factors from other infectious agents and/or the cattle’s environment. Therefore to develop biosecurity plans for infectious disease in cattle, veterinarians must consider the pathogen, as well as environmental and animal factors.

[email protected].


Effect of Milking Frequency in Early Lactation on Energy Metabolism, Milk Production and Reproductive

Performance of Dairy Cows S. McNamaraa,b, J.J. Murphya, F.P. O'Marab, M. Rathb, J.F.

Meea aTeagasc, Moorepark Dairy Production Research Centre, Fermoy, Co.

Cork, Ireland. bUCD School of Agriculture, Food Science and Veterinary Medicine, Belfield, Dublin 4, Ireland.

The objective of this study was to evaluate the effect of imposing different milking frequencies for the first 4 weeks of lactation on energy balance, blood metabolic profiles and reproductive performance. The milking frequencies imposed were once daily for the first 4 weeks of lactation and twice daily subsequently (X1), twice daily for the entire lactation (X2) and three times daily for the first 4 weeks of lactation and twice daily subsequently (X3). Two weeks prior to the first expected calving date, sixty-three multiparous, Holstein-Friesian cows, were allocated to treatments based on expected calving date, parity (lactation number=2 and lactation numberN2),

BCS and BW. Mean DMI was lower (Pb0.05) on X1 than X2 (15.7 and 17.1 kg/day) over the first 4 weeks of lactation, but DMI on X3 was not different to either. Milk yield was lower (Pb0.05) on X1 than on X2 and X3 (24.1, 31.9 and 31.4 kg/day) from weeks 1 to 4 and at week 10 of lactation (30.9, 33.9 and 33.7 kg/day) but was not different at week 20. Yield of milk constituents followed the same pattern as milk yield. Milking frequency had no significant effect on milk fat or protein concentration but milk lactose concentration was higher (Pb0.05) on X1 than on X2. Cows on X1 experienced less (Pb0.05) negative energy balance than those on X2 and X3 from weeks 1 to 4, with no difference between X2 and X3. Cows on X1 lost less BW (Pb0.05) from weeks 1 to 4 and lost less BCS up to day 73 of lactation than cows on X2 and X3. Plasma NEFA and BHB concentrations tended to be lower and plasma glucose tended to be higher on X1 than on X2 and X3 from weeks 1 to 4, while plasma insulin was higher on X1 than on X2 and X3 for the first 2 weeks of lactation. There was no difference between treatments in any reproductive performance variable measured. These results indicate that reduced milking frequency decreases milk yield and improves energy balance and metabolic status in early lactation.

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Animal (2008), 2:8, pp 1112–1119

Effect of Progesterone on Embryo Survival D. Morris and M. Diskin

Teagasc, Animal Production Research Centre, Mellows Campus, Athenry, Co. Galway, Irelan.

Increased genetic selection over the past 40 years has resulted in a dairy cow with an improved biological efficiency for producing milk but with an associated reduced fertility. Embryo loss is the greatest factor contributing to the failure of a cow to conceive. The extent and timing of embryo loss indicates that 70% to 80% of this loss occurs in the first 2 weeks after artificial insemination (AI). This is the period when a number of critical phases in embryo development occur and where protein accretion, substrate utilization and embryo metabolism increase dramatically. During this time the early embryo is completely dependent on the oviduct and uterine environment for its survival and it is likely that the embryo requires an optimal uterine environment to ensure normal growth and




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viability. There is increasing evidence of an association between the concentration of systemic progesterone and early embryo loss and that progesterone supplementation of cows, particularly those with low progesterone, can reduce this loss. While progesterone is known to affect uterine function and embryo growth, little is known about the uterus during the period of early embryo loss and how this is affected by changes in the concentration of systemic progesterone. The expression of uterine genes encoding the transport protein retinol binding protein (RBP) and the gene for folate binding protein (FBP) appear to be sensitive to changes in systemic progesterone, particularly during the early luteal phase of the cycle. Uterine concentrations of proteins also seem to be regulated by stage of cycle; however, their relationship with the systemic concentration of progesterone is unclear. There is an urgent need to characterize the uterine environment from a functional perspective during the early part of the luteal phase of the cycle, particularly in the high-producing cow, in order to understand the factors contributing to early embryo loss and in order to devise strategies to minimize or reduce this loss.

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Effect of Synchronization Protocols on Follicular Development and Estradiol and Progesterone

Concentrations of Dairy Heifers J. L. Stevenson,* J. C. Dalton,† J. E. P. Santos,‡ R. Sartori,§

A. Ahmadzadeh,# and R. C. Chebel,*1,2 *Caine Veterinary Teaching Center, and †Research and Extension Center, University of Idaho, Moscow 83844. ‡School of Veterinary Medicine, University of California-Davis, Tulare 93274. §Embrapa Recursos Genéticos e Biotecnológicos, Brasília, Distrito Federal,

Brazil. #Animal and Veterinary Science Department, University of Idaho, Moscow 83844.

The objectives were to evaluate the effect of synchronization protocols on follicular development and estradiol 17-β (E2) and progesterone (P4) concentrations in dairy heifers. In experiment 1, 36 heifers were assigned to 1 of 6 synchronization protocols in a 3 × 2 factorial design: presynchronization with GnRH on study d −6 or −9 [study d 0 = initiation of the Cosynch + CIDR (controlled internal drug releasing insert containing P4) protocol] or no presynchronization (control) and one injection of PGF2α or not on study d 0. In experiment 2, 126 heifers were assigned to 1 of 4 synchronization protocols in a 2

× 2 factorial arrangement: presynchronization or not with GnRH on study d −6 and injection of PGF2α or not on study d 0. In experiments 1 and 2, all heifers received a modified Cosynch protocol with CIDR for 7 d starting on study d 0. After the PGF2α of the Cosynch and removal of the CIDR, heifers were detected in estrus and inseminated. Those not inseminated by study d 10 received an injection of GnRH and were timed-inseminated. Ovaries were scanned by ultrasound on d 0, 2, and 5, daily from d 7 to 14, and on d 16. Blood samples collected on d 0, 2, 7, 9, and 16 were analyzed for P4, and the blood sample collected on d 9 was analyzed for E2. Pregnancy was diagnosed at 28 and 40 ± 3 d after artificial insemination. In experiment 1, there was a tendency for the presynchronization protocol to affect the proportion of heifers ovulating in response to the first GnRH injection of the Cosynch + CIDR protocol. In experiment 2, a greater proportion of presynchronized heifers ovulated in response to the first GnRH injection. Although heifers receiving PGF2α had larger ovulatory follicles on d 7 and before ovulation and shorter intervals to estrus and ovulation, these heifers tended to have decreased concentrations of E2 during proestrus. Presynchronization of dairy heifers with GnRH increased ovulation in response to the first GnRH injection, and treatment of heifers with PGF2α at initiation of the Cosynch + CIDR protocol increased the size of the ovulatory follicle and reduced the intervals to estrus and ovulation.


Protein Kinase C (PKC) Role in Bovine Oocyte Maturation and Early Embryo Development R.G. Mondadoria, J.P. Nevesb, P.B.D. Gonçalvesc

aAnimal Reproduction Laboratory, Department of Veterinary Medicine, UPIS Faculdades Integradas, SEPS 712/912, Brasilia, DF 70390-125, Brazil. bAgronomy and Veterinary College, University of

Brasilia, Brasilia, DF 70910-900, Brazil. cDepartment of Large Animals, Federal University of Santa Maria, Santa Maria, RS 97105-

900, Brazil.

The aims of the present study were to determine the role of protein kinase C (PKC) on meiotic resumption and its effects on pronuclear formation and cleavage in the bovine. Oocytes were matured in the presence of 0, 1, 10 and 100 nM of phorbol 12-myristate 13-acetate (PMA), to evaluate the percentage of germinal vesicle breakdown. To study pronuclear formation and




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cleavage, oocytes were randomly distributed in four groups and matured in modified TCM-199 with LH and FSH (negative control); 10% of estrous cow serum (positive control); 100 Nm of PMA (treatment); 100 nM of 4α-PDD (phorbol ester control). Oocytes were also matured in positive control medium, fertilized and transferred to KSOM with increasing concentrations of a PKC inhibitor. The protein profile and the presence of PKC at the end of maturation period were determined by SDS-PAGE followed by Silver Stain and Western blot, respectively. PMA stimulated meiotic resumption in a concentration-dependent manner. PKC stimulation during oocyte maturation caused an increase in pronuclear formation and did not cause parthenogenetic activation. Inhibitor of PKC (MyrPKC) inhibited cleavage in a dose-dependent and irreversible manner. A protein band around 74 kDa was not detected in PMA-treated oocytes and PKC was not detected by Western blot at the end of the maturation period. In conclusion, meiotic resumption was accelerated and the rate of oocytes with two pronuclei was increased when PKC was activated during oocyte maturation. Moreover, cleavage was inhibited in the presence of PMA.

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Effect of Reactive Oxygen Species on Capacitation and Associated Protein Tyrosine Phosphorylation in Buffalo

(Bubalus bubalis) Spermatozoa S.C. Roy, S.K. Atreja

Division of Animal Biochemistry, National Dairy Research Institute, Karnal-132 001, India.

In the present study, the effect of two particular reactive oxygen species (ROS), superoxide anion (O2•−) and hydrogen peroxide (H2O2) on buffalo (Bubalus bubalis) sperm capacitation and associated protein tyrosine phosphorylation was studied. Ejaculated buffalo spermatozoa were suspended in sp-TALP medium at 50×106/mL and incubated at 38.5 ◦C for 6 h with or without heparin (10 (g/mL; a positive control), or xanthine (X; 0.5 mM)-xanthine oxidase (XO; 0.05 U/mL)-catalase (C; 2100 U/mL) system that generates O2•− or NADPH (5 mM) that stimulates the endogenous O2•− production or H2O2 (50_M). The specific effect of O2•−, H2O2 and NADPH on buffalo sperm capacitation and protein tyrosine phosphorylation was assessed by the addition of superoxide dismutase (SOD), catalase and

diphenylene iodonium (DPI), respectively, to the incubation medium. Each of X+XO+C system, NADPH and H2O2 induced a significantly higher percentage (P < 0.05) of capacitation in buffalo spermatozoa compared to control. However, DPI inhibited this NADPH-induced capacitation and protein tyrosine phosphorylation and suggested for existence of an oxidase in buffalo spermatozoa. Using immunoblotting technique, at least seven tyrosine-phosphorylated proteins (20, 32, 38, 45, 49, 78 and 95 kDa) were detected in capacitated buffalo spermatozoa. Out of these, the tyrosine phosphorylation of p95 was induced extensively by both O2•− as well as exogenous source of H2O2 and using specific activators and inhibitors of signaling pathways, it was found this induction was regulated through a cAMP-dependent PKA pathway. Further, immunofluorescent localization study revealed that these ROS-induced tyrosine-phosphorylated proteins are mostly distributed in the midpiece and principal piece regions of the flagellum of capacitated spermatozoa and suggested for increased molecular activity in flagellum during capacitation. Thus, the study revealed that both O2•− and H2O2 promote capacitation and associated protein tyrosine phosphorylation in buffalo spermatozoa and unlike human and bovine, a different subset of sperm proteins were tyrosine-phosphorylated during heparin- and ROS-induced capacitation and regulation of these ROS-induced processes were mediated through a cAMP/PKA signaling pathway.

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Days to Calving in Artificially Inseminated Cattle: Alternative Models and Analyses

D.L. Robinson Beef Industry Centre, NSW Department of Primary Industries, University of New England, Armidale, NSW 2351, Australia.

Investigations by Robinson [Robinson, D.L., 2007. Days to calving in artificially inseminated cattle: comparison of potential traits. Livestock Science 110, 174–180] concluded that the most useful trait for assessing fertility of artificially inseminated (AI) beef cows is AI days to calving (AIDC), a trait that mimics days to calving for naturally mated cows. Various fixed and random effects were fitted to AIDC to determine the best way of modelling lactation status of the cow, the effect of service sire, using smaller contemporary




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groups and lowering the penalty value for non-calvers. Fitting the time interval between calving and the start of mating either as a 10-level factor or a cubic spline function explained considerably more variation than fitting the standard 2- level factor (wet or dry). Estimated permanent environmental effects of the cow were considerably reduced. This suggests that, if a cow calves late in the season (less than 60 days before she is inseminated), her fertility is reduced. Models should therefore account for this effect. If fitted, service sire explained 1.6% of phenotypic variation, compared to a much larger sire×contemporary group interaction (3% of phenotypic variation). It is therefore important to account for sire×contemporary group interactions. When the fertility of service sires is not being evaluated, service sires could be incorporated into the definition of contemporary groups. Ideally, breeders should be encouraged to formally record contemporary (or mating) groups. Reducing the size of contemporary groups (inferred from the data) by limiting the time interval between first and last inseminations from 120 to 60 days had only a marginal effect as did reducing the penalty for non-calvers from 21 to 10 days.

[email protected].


Update on Treatment of Vesiculitis in Bulls H. Rovay, A.D. Barth, M. Chirino-Trejo, M.F. Martínez

Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

Four experiments were done to determine: (1) the effectiveness of early detection and treatment of vesiculitis in bulls; (2) whether antibiotic treatment at recommended dosages will result in adequate vesicular gland tissue concentrations of antibiotics to prevent in vitro bacterial growth; (3) whether intraglandular injection of antibiotics can be a successful alternative to systemic antibiotic treatment; and (4) the effectiveness of tilmicosin versus tulathromycin for treatment of clinical vesiculitis. In Experiment 1, there was a high rate of spontaneous remission from vesiculitis detected at 9–12 mo of age. Furthermore, there was no advantage for early antibiotic treatment versus no treatment for bulls of this age. In Experiment 2, bacteria on agar plates were exposed to fluid extracted from vesicular gland biopsies after antibiotic treatment of normal, healthy bulls. Although inadequate concentrations of antibiotics

were achieved to inhibit bacterial growth when recommended dosages of various antibiotics were administered, doubling the antibiotic dosage increased in vitro bacterial growth inhibition. In Experiment 3, relatively nonirritating antibiotics were injected directly into the glands of bulls with clinical vesiculitis, demonstrating that intraglandular injections of antibiotic could be used as a successful alternative to systemic antibiotic treatment. Experiment 4 was a clinical field trial to compare the efficacy of tilmicosin versus tulathromide at recommended dosages for the treatment of clinical vesiculitis. Although the results favored tulathromycin, both antibiotics resulted in clinical cures of vesiculitis.

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Domestic Animal Endocrinology 35 (2008) 190–197

Role For des-acyl Ghrelin in the Responsiveness of Plasma Hormones and Metabolites to Ghrelin in

Holstein Steers Hnin Thidar Myint, Hideto Kuwayama

Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 1-11, Inada, Obihiro 080-8555, Japan.

Gastric-derived peptide hormone ghrelin is known for its potent growth hormone (GH) stimulatory effects. The acyl-modification on N-terminal Ser3 residue is reported to be important to stimulate the ghrelin receptor, GH secretagogue-receptor type1a (GHSR1a). However, major portion of circulating ghrelin lacks in acylation, and some biological properties of des-acyl ghrelin have been reported in monogastric animals. In the present study, the responsiveness of plasma hormones and metabolites to ghrelin in steers was characterized, and role for des-acyl ghrelin in these changes was investigated. The repeated intravenous administrations of bovine ghrelin (1.0 µg/kg BW) every 2 h for 8 h to Holstein steers significantly increased the plasma acylated ghrelin, total ghrelin, GH, insulin and NEFA levels. The GH responses in peak values and area under the curves (AUCs) were attenuated by repeated injections of ghrelin, however, the responses of plasma total ghrelin were similar. Plasma insulin AUC decreased after fourth injection of ghrelin while plasma NEFA AUCs gradually increased by repeated injections of ghrelin. Pretreatment of des-acyl ghrelin (10.0 µg/kg BW) 5 min prior to the single injection of ghrelin (1.0 µg/kg BW) did not affect the ghrelin-induced hormonal changes. Moreover, the responses of plasma GH to bovine


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and porcine ghrelin, which differ in C-terminal amino acid residues, were similar in calves. These data show that (1) GH release was attenuated by repeated administration of ghrelin, (2) ghrelin regulates glucose and fatty acid metabolism probably via different pathway, and (3) des-acyl ghrelin is unlikely the antagonist for ghrelin to induce endocrine effects in Holstein steers.

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Reprod Dom Anim 43, 457–463 (2008)

Field Trial on Progesterone Cycles, Metabolic Profiles, Body Condition Score and their Relation to Fertility in

Estonian Holstein Dairy Cows J Samarütel1, K Ling1, A Waldmann1,2, H Jaakson1, T Kaart1

and A Leesmäe3 1Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences; 2Institute of General and Molecular

Pathology, University of Tartu, Tartu; 3Piistaoja Experimental Station, Piistaoja, Pärnu County, Estonia.

Resumption of luteal activity postpartum and fertility were investigated in an Estonian Holstein high milk production and good fertility dairy herd. Body condition was scored after every 10 days in 54 multiparous dairy cows (71 lactations) calving inside from December to March during 4-year period. Blood samples were taken 1–14 days before calving and 1–14, 28–42 and 63–77 days after calving: analytes estimated were serum aspartate aminotransferase (AST), glucose, ketone bodies, total cholesterol, non-esterified fatty acids and triglycerides. The general linear mixed model was used to compare the data for cows with different characteristics in luteal activity postpartum based on their milk progesterone profiles. Fortyfive per cent of cases had abnormal profiles; delayed resumption of ovarian cyclicity postpartum (DC) was the most prevalent abnormality. There was no difference in body condition scores between the groups. The DC and prolonged luteal phase groups had higher serum AST activity (p < 0.01) 1–14 days postpartum compared with normal group. The DC group also had higher cholesterol and triglyceride values (p < 0.05) 28–42 days postpartum and higher milk fat/protein ratio (p < 0.01) on the first month of lactation compared with normal profile group. Despite long post-calving anoestrous period (71 ± 5.0 days; mean ± SEM) DC group had 64.7% first service pregnancy rate (normal group 48.6% and PLP group 37.5%). This study did not find any detrimental effect of prolonged anovulatory period postpartum on subsequent fertility.

Reproduction, Fertility and Development, 2008, 20, 741–749

A unique Method to Produce Transgenic Embryos in Ovine, Porcine, Feline, Bovine and Equine Species

F. Pereyra-BonnetA, R. Fernández-MartínA, R. OliveraA, J. JarazoA, G. VicheraA, A. GibbonsB and D. SalamoneA,C

ALaboratorio de Biotecnología Animal, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, C1417 Buenos

Aires, Argentina. BLaboratorio de Reproducción de Rumiantes Menores, Instituto Nacional de Tecnología Agropecuaria, Box 277,

EEA Bariloche, Argentina.

Transgenesis is an essential tool in many biotechnological applications. Intracytoplasmic sperm injection (ICSI)-mediated gene transfer is a powerful technique to obtain transgenic pups; however, most domestic animal embryos do not develop properly after ICSI. An additional step in the protocol, namely assistance by haploid chemical activation, permits the use of ICSI-mediated gene transfer to generate transgenic preimplantation embryos in a wide range of domestic species, including ovine, porcine, feline, equine and bovine. In the present study, spermatozoa from five species were coincubated with pCX-EGFP plasmid and injected into metaphase II oocytes. The chemical activation protocol consisted of ionomycin plus 6-dimethylaminopurine. We detected high proportions of fluorescent EGFP embryos for all five species (23–60%), but with a high frequency of mosaic expression (range 60–85%). To our knowledge, this is the first study to produce exogenous DNA expression in feline and equine embryos. Chemical activation reduces the lag phase of egfp expression in ovine embryos. Our results show that this unique method could be used to obtain ovine, porcine, feline, bovine and equine transgenic preimplantation embryos.

[email protected]


Insemination Factors Related to Timed AI in Cattle R.G. Saacke

Virginia Polytechnic Institute and State University, Department of Dairy Science, Blacksburg, VA 240610315, United States.

Six-day-old bovine ova/embryos were recovered non-surgically and used as biomonitors to evaluate time of artificial insemination. These embryos/ova provided information regarding fertilization status and embryo quality, as well as quantitative and qualitative data regarding associated accessory sperm. Both sperm access to the ovum (addressed by accessory sperm) and fertilization status/embryo quality were important


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in addressing pregnancy rate for specific intervals from the onset of estrus to insemination. Based on these biomonitors, early insemination failed to achieve optimum pregnancy rate due to inadequate access of sperm to the ovum (i.e., low fertilization rate, manifested by low accessory sperm numbers). However, embryo quality was high in early inseminations, which favors pregnancy. Late insemination failed to achieve optimum pregnancy rate (due to reduced embryo quality), however, sperm access to the ovum was highest. Thus, the selection of an insemination time to achieve optimum pregnancy rate appeared to be a compromise between the two extreme intervals. For timed-AI programs, consideration of the time of ovulation (and its variability) becomes important, in addition to conventional considerations, such as semen handling, site of insemination, and bull selection.

[email protected].


Maintenance of Pregnancy in Dairy Cattle After Treatment with Human Chorionic Gonadotropin or

Gonadotropin-Releasing Hormone J. S. Stevenson,* S. M. Tiffany,* and E. K. Inskeep†

*Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201. †Division of Animal and

Nutritional Sciences, West Virginia University, Morgantown 26506-6108.

The objectives were to determine whether a single injection of either human chorionic gonadotropin (hCG) or GnRH would: 1) increase ancillary formation of new luteal structures, 2) increase serum concentrations of progesterone, and 3) increase pregnancy survival in dairy females treated once between 26 and 71 d of pregnancy. A total of 421 cows were enrolled between January and November 2001, with 92, 106, and 223 females (included 68 nulliparous heifers at 1 location) treated at the 3 locations. Upon diagnosis of pregnancy, females were allocated randomly to receive 100 µg of GnRH, 1,000 IU of hCG, or 2 mL of saline. Blood samples were collected at 0, 1, 2, and 4 wk after treatment, and pregnancy status was reassessed at 1, 2, and 4 wk. New luteal structures were formed in 23.8% of cattle, with hCG (50%) and GnRH (26%) being more effective than saline (7%). Treatment had no effect on the proportion of females forming 2 new luteal structures (7.6%), and 36.2% of all induced structures

regressed during the 4- wk study period. Pregnancy losses were unaffected by treatment, stage of pregnancy, or number of induced luteal structures but were nearly 9-fold greater in females in which induced luteal structures regressed. No loss occurred in females having 2 new luteal structures. Pregnancy losses decreased quadratically from 30 to 42 d. Serum progesterone did not differ among treatments, but among females forming new luteal structures, progesterone was greater at 1 (7.2 ± 0.3 vs. 6.3 ± 0.2 ng/mL) and 2 wk (7.0 ± 0.3 vs. 6.1 ± 0.2 ng/mL) after treatment. Progesterone at the first pregnancy diagnosis was predictive of imminent pregnancy loss; the lower the initial progesterone, the sooner subsequent loss was observed. The right ovary was dominant in the location of new luteal structures. Regression of new luteal structures occurred more often on the left ovary and contra-lateral to the corpus luteum of pregnancy (53.2 vs. 22%). In conclusion, treatment of dairy cattle with either GnRH or hCG failed to prevent pregnancy loss, but concentrations of progesterone were predictive of subsequent pregnancy loss.

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Gossypol Disrupts Embryo Development in Heifers M. Villaseñor,* A. C. Coscioni,* K. N. Galvão,* R. C. Chebel,*

and J. E. P. Santos*† *School of Veterinary Medicine, University of California–Davis, Tulare

93274. †Department of Animal Sciences, University of Florida, Gainesville 32611.

Our objectives were to determine the effects of dietary free gossypol (FG) intake on plasma and uterine gossypol concentrations and embryo development and viability before and after culture with gossypol. Fifty postpubertal Holstein heifers weighing (±SD) 406 ± 34.5 kg at 11.5 mo of age were blocked by age and body weight (BW) and randomly assigned to 1 of 3 isocaloric and isonitrogenous diets differing in their FG content: control (0 mg of FG/kg of BW), moderate (17.8 mg of FG/kg of BW), and high (36.8 mg of FG/kg of BW). Heifers were fed the diets for 70 d before superovulation and embryo collection. Superovulated heifers were flushed on d 5 after induction of ovulation, and early morulae were either stained, to determine the number and proportion of live and dead cells, or randomly assigned to an in vitro culture for 96 h in media containing either 0 or 10 µg/mL of gossypol acetic




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acid. Plasma and uterine gossypol concentrations increased with increasing gossypol intake. The number of low-quality embryos-ova was greater for the high than for the moderate and control diets. Embryos collected from the high diet had the least number of cells because of fewer live cells, and were smaller in diameter. Greater dietary gossypol reduced blastocyst development and extended the time to reach the blastocyst stage. Similarly, gossypol concentration at 10 µg/mL compromised in vitro development and increased the proportion of degenerated embryos at 96 h in culture. These findings provide in vivo and in vitro evidence that intake of 36.8 mg of FG/kg of BW per d and gossypol concentrations >7 µg/mL in plasma, in uterine flush, or in vitro compromise early embryo development, which might explain some of the negative effects of gossypol on the fertility of dairy cows.

[email protected]

Animal (2008), 2:8, pp 1153–1157

Effect of Escherichia coli Infection of the Bovine Uterus From the Whole Animal to the Cell

E. J. Williams1, S. Herath1, G. C. W. England2, H. Dobson3, C. E. Bryant4 and I. M. Sheldon1

1Department of Veterinary Clinical Sciences, Royal Veterinary College, Royal College Street, London, NW1 0TU, UK; 2The School of

Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, LE12 5RD, UK;

3Department of Veterinary Clinical Science and Animal Husbandry, Faculty of Veterinary Science, University of Liverpool, Leahurst,

Neston, CH64 7TE, UK; 4Centre for Veterinary Science, Department of Clinical Veterinary Medicine, University of Cambridge, Cambridge,

CB3 0ES, UK.

Following parturition, contamination of the uterine lumen by bacteria is ubiquitous, and uterine health is impaired in cattle because infection persists in 10% to 15% of animals as endometritis. Endometritis causes infertility for the duration of infection, and subfertility persists even after apparent successful resolution of the disease. Escherichia coli is the pathogenic bacterium most frequently isolated from the post partum uterus, and is associated with increased concentrations of peripheral plasma acute phase proteins and fetid vaginal mucus. The presence of E. coli is also associated with slower growth of the first post partum dominant follicle and perturbed oestradiol secretion. Furthermore, in animals that ovulate the first dominant follicle, the corpus luteum is smaller and secretes less progesterone. The endotoxin lipopolysaccharide (LPS), which is released from E. coli, can pass from the uterine

lumen to the peripheral circulation and LPS concentrations are increased in cows with uterine infection. Infusion of E. coli LPS into the uterine lumen suppresses the pre-ovulatory luteinising hormone surge and disrupts ovulation in heifers. In vitro, endometrial explants produce prostaglandins in response to LPS. Addition of LPS or E. coli to stromal or epithelial cells increases cyclooxygenase-2 mRNA expression, and stimulates the production of prostaglandin E2 and prostaglandin F2a. Furthermore, uterine and ovarian cells express mRNA of the molecules required for recognition of LPS, Toll-like receptor-4 and CD14. In summary, E. coli is a common cause of infertility involving the perturbation of the hypothalamus, pituitary and ovary in dairy cows.

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Animal (2008), 2:8, pp 1135–1143

Factors Influencing Heifer Survival and Fertility on Commercial Dairy Farms

D. C. Wathes, J. S. Brickell, N. E. Bourne, A. Swalia and Z. Cheng

Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts AL9 7TA, UK.

The average dairy cow survives only three lactations, reducing the availability of replacement heifers. Prenatal losses occur due to early embryonic mortality (about 40%), later embryo loss (up to 20% in high-yielding herds) or abortion (about 5%). A recent survey of 19 UK herds showed that 7.9% of calves were born dead and 3.4% died within 1 month. During the rearing phase, 6.7% of animals were lost before reaching first service at 15 months due to disease or accident and another 2.3% failed to conceive. Many potential replacements therefore never enter the milking herd. This severely limits opportunities for on-farm selection of breeding cows in addition to presenting a welfare issue and causing economic loss. The most profitable animals once lactation is reached combine good milk production with a regular calving pattern. Some aspects of performance are related to age at first calving (AFC), which in turn is influenced by heifer growth rates. Poorly growing animals required more services to conceive, calved later and subsequently performed badly. Optimum fertility and maximum yield in the first lactation were associated with an AFC of 24 to 25 months. However, heifers calving at 22 to 23 months




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performed best in terms of total milk yield and survival over the first 5 years, partly because good heifer fertility was associated with better fertility later. We have investigated some possible juvenile predictors of future performance. Low-birth-weight calves were more likely to come from either primiparous mothers or older dams (31 lactations) with higher peak milk yields, suggesting that the uterine environment may limit prenatal calf growth due to competition for nutrients with maternal growth or milk production. Linear trait classification scores for frame size show genetic correlations with longevity. The skeletal measures of height and crown rump length in 1-month-old calves was correlated to subsequent stature, and frame size was correlated to weight at 15 months. It may thus be possible to predict performance from simple size measurements as juveniles. Neither endogenous nor stimulated growth hormone (GH) release in 6-month-old calves were related to milk yield in the first three lactations, but size of a stimulated GH peak was positively related to milk energy values in the first lactation. Cows with delayed ovulation (.45 days) in the first lactation had a higher GH pulse amplitude and lower IGF-I as a juvenile. Cows that partition excess energy into milk in their first lactation may suffer reduced longevity.

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Effect of Oestrus Synchronization Methods on Oestrus Behaviour, Timing of Ovulation and Pregnancy Rate

During the Breeding and Low Breeding Seasons in Nili-Ravi Buffaloes

Hassan Mahmood Warriach, Aijaz Ali Channa, Nasim Ahmad Department of Theriogenology, Faculty of Veterinary Science,

University of Veterinary and Animal Sciences, Lahore, Pakistan.

The objective of this study was to determine the effect of oestrous synchronization methods on oestrous behaviour, timing of ovulation and pregnancy rate during the breeding and low breeding seasons in Nili-Ravi buffaloes. In Experiment 1, oestrous behaviour and timing of ovulation were determined from (n = 34) oestruses. The mean (± S.E.M.) time of ovulation after the onset of standing oestrus was greater (P < 0.05) in PGF2α-induced luteolysis (30.6±1.5 h) compared to Ovsynch buffaloes (15.0±0.8 h). In Experiment 2, pregnancy rates were compared between two methods of synchronization (detected oestrus and Ovsynch protocol) during

the breeding and low breeding seasons. Pregnancy rates of buffaloes bred at detected oestrus (62.5%) or by the Ovsynch protocol (36.3%) during the breeding season did not differ significantly (P > 0.05) from those which were inseminated during the low breeding season (55.5%) and (30.4%), respectively. This study demonstrates clearly that (1) timing of ovulation in Nili-Ravi buffalo is about 30 h after the onset of standing oestrus and (2) buffaloes can be successfully synchronized with optimum fertility using either PGF2α alone (detected oestrus) or using (Ovsynch protocol) during low breeding season, to calve during the period when milk availability is short.

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High-Pressure Steam Sterilization of Previously Used CIDR Inserts Enhances the Magnitude of the Acute

Increase in Circulating Progesterone After Insertion in Cows

J.F. Zuluagaa,b, G.L. Williamsa,b aAnimal Reproduction Laboratory, Texas A&M University, Agricultural

Research Station, 3507 Hwy 59E, Beeville, TX 78102-8571, USA. bCenter for Animal Biotechnology and Genomics, Department of

Animal Science, Texas A&M University, College Station, TX 77843, USA.

Objectives were to compare serum concentrations of progesterone (P4) in ovariectomized cows receiving (1) new, (2) re-used disinfected (DIS), and (3) re-used autoclaved (AC) controlled internal drug release (CIDR) inserts. Five ovariectomized (OVX) beef cows were used in a replicated 3×3 Latin square design. Each experimental period was 7 days, with at least 48 h between periods. All re-used CIDR had been inserted previously in beef cows for 7 days. Upon removal, CIDR used for the DIS treatment were washed thoroughly and soaked in a chlorhexidine gluconate solution (0.03%) for 2 h, rinsed thoroughly with water and air-dried. For the AC treatment, CIDR were not soaked in disinfectant but were steam sterilized at 121 ºC and 724mm Hg for 20 min before use. Blood samples were collected at 0, 10, 30, 60, 180, and 480 min relative to time of insertion of CIDR, daily until day 7, and at 30, 60, and 180 min relative to time of removal for radioimmunoassay of P4. Mean serum concentrations (ng/mL) of P4 during the 7-day period of insertion were greater (P < 0.03) for new (3.7±0.2) and AC (3.4±0.3) than for DIS




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CIDR (2.8±0.2). These effects were created primarily by differences occurring during the first 8 h after CIDR insertion. Within this interval, mean concentrations (ng/mL) differed (P < 0.05) among all groups, but values for AC (6.0±0.7) exceeded both new (4.6±0.5) and DIS (2.7±0.3) markedly. Autoclaving may be the best option when re-using CIDR inserts because it creates greater concentrations of P4 immediately after insertion and reduces maximally the risk of disease transmission.

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Pregnancy-Associated Glycoproteins and Pregnancy Wastage in Cattle

B.K. Whitlocka, H.S. Maxwellb aDepartment of Anatomy, Physiology & Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849 USA. bDepartment of Clinical Sciences, College of Veterinary Medicine,

Auburn University, Auburn, AL 36849 USA.

Accurate diagnosis of non-pregnancy and prompt re-enlistment of ‘‘non-pregnant’’ cattle into an appropriate breeding protocol are essential components of successful reproductive programs. Various methods aimed at improving detection of pregnancy and identification of non-pregnant cows earlier and more accurately are the focus of previous review articles and beyond the scope of this manuscript. Recently, the ability to measure pregnancy-associated glycoproteins (PAGs) in cattle has changed how pregnancy and, more importantly, non-pregnancy are detected. This presentation provides an overview of current research on the pregnancy associated glycoprotein family, and how these glycoproteins might be utilized as indicators of pregnancy wastage in cattle.

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Heritable Bovine Fetal Abnormalities B.K. Whitlocka, L. Kaiserc, H.S. Maxwellb

aDepartment of Anatomy, Physiology & Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA. bDepartment of Clinical Sciences, College of Veterinary Medicine,

Auburn University, AL 36849, USA. cDepartment of Medicine, College of Human Medicine, Michigan State University, East Lansing, MI

48824, USA.

The etiologies for congenital bovine fetal anomalies can be divided into heritable, toxic, nutritional, and infectious categories. Although uncommon in most herds, inherited congenital anomalies are probably present in all breeds of

cattle and propagated as a result of specific trait selection that inadvertently results in propagation of the defect. In some herds, the occurrence of inherited anomalies has become frequent, and economically important. Anomalous traits can affect animals in a range of ways, some being lethal or requiring euthanasia on humane grounds, others altering structure, function, or performance of affected animals. Veterinary practitioners should be aware of the potential for inherited defects, and be prepared to investigate and report animals exhibiting abnormal characteristics. This review will discuss the morphologic characteristics, mode of inheritance, breeding lines affected, and the availability of genetic testing for selected heritable bovine fetal abnormalities.

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Characterization of Estrus Detection, Conception and Pregnancy Risk of Holstein Cattle From the Central

Area of Chile P. Melendeza,c, M. Duchensb, A. Perezb, L. Moragab, L.

Archbaldc aCollege of Veterinary Medicine, University of Santo Tomas, Av.

Limonares 190, Vin˜a del Mar, Chile. bCollege of Veterinary Medicine, University of Chile, Av. Sta. Rosa 11735, La Pintana, Santiago, Chile.

cCollege of Veterinary Medicine, University of Florida, PO Box 100136, Gainesville, FL 32610-0136, USA.

The objectives were to characterize the estrus detection risk (HDR), conception risk (CR), and pregnancy rate (PR) of postpartum (pp) Holstein cattle from the central area of Chile. The study used records of 2269 lactations from six dairy farms in central Chile (Mediterranean-type climate) during 2004. Three 21-d periods for estrus detection were considered (50–70, 71–91, and 92–112 d pp). Estrus detection risk, CR, and PR at the first, second, and third periods were analyzed by logistic regression, whereas overall PR at the end of the 63-d study (112 d pp) was assessed with survival analysis. The overall HDR was 51.1%. The HDR, CR, and PR were 48.4, 42.2, and 17.3%, respectively, during the first period; 52.8, 41.8, and 20.5% during the second period; and 52.9, 39.2, and 19.7% during the third period. The HDR was lower during Period 1 than during Periods 2 and 3 (P ≤ 0.05). Conception risks were not different among periods (P > 0.05); however, PR was lower during Period 1 than during Periods 2 and 3 (P ≤ 0.05). Overall PR over time differed among parities, but was not





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significantly different among seasons. There were no significant interactions among parity, season and herd for HDR, CR and PR for the three 21-d periods. Parity 1 had higher CR and PR than Parity 2 and 3+ during Period 3. Overall, survival curves for the risk of non-pregnancy among parities (1, 2, 3 or greater) were different over time (P ≤ 0.05). Cows of Parity 1 became pregnant earlier than cows of Parity 2, and Parity 3 or greater. Survival curves for the risk of non-pregnancy among seasons (summer, fall, winter, and spring) were not different over time (P > 0.05).

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Effect of banding or burdizzo castration on plasma testosterone, acute-phase proteins, scrotal circumference, growth, and health of bulls

W.Y. Panga,b, B. Earleya, V. Gathb, M.A. Croweb aTeagasc, Grange Beef Research Centre, Dunsany, Co. Meath,

Ireland. bSchool of Agriculture, Food Science & Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.

The objective was to assess the effect of banding or burdizzo castration performed on farms on plasma testosterone, acute-phase proteins, scrotal circumferences, growth, and well-being of bulls. 243 Continental bulls (12 months; 399.2±5.72 kg) from three different farms were allocated at random, after stratification on weight within breed type, to one of three treatment groups: banding castration (BAND; n=80), burdizzo castration (BURD; n=83), or controls (CON; n=80). The castration methods were conducted under local anaesthesia, and tetanus toxoid vaccine and antibiotic were also injected at castration. BAND and BURD castrates had lower (Pb0.001) plasma testosterone concentration than control bulls, with no difference between BAND and BURD castrates on 28 d post-castration. From days 0 to 14 post-castration, BAND (P=0.0002) and BURD (Pb0.0001) castrates had lower average daily gain

(ADG) than CON bulls, no difference (P=0.46) was found between BAND and BURD castrates. From days 15 to 28, BAND castrates had lower ADG compared with BURD castrates (P=0.03) and CON bulls (P=0.01), while no difference (P=0.76) was found between BURD and CON. From days 29 to 56, BAND (P=0.01) and BURD (P=0.002) castrates had lower ADG than CON bulls, no difference (P=0.55) was found between BAND and BURD. From days 57 to 84, the ADG of BAND castrates was not different compared with BURD castrates (P=0.12) and CON bulls (P=0.38), while BURD had lower (P=0.02) ADG compared with CON. The integrated ADG from day 0 to 112 of BAND (P=0.0001) and BURD (P=0.02) groups were lower compared with CON, while there was no difference (P=0.09) between BAND and BURD castrates. On d 14 post-castration, BAND castrates had lower scrotal temperature than BURD (Pb0.0001) and CON (Pb0.0001), and BURD castrates had greater (Pb0.006) scrotal temperature than CON; BAND castrates had lower scrotal latitudinal and longitudinal circumferences than BURD castrates (Pb0.001) and CON bulls (Pb0.001), and BURD castrates had greater (Pb0.001) scrotal latitudinal and longitudinal circumferences than CON bulls. BAND (Pb0.0001) and BURD (P=0.01) castrates had greater glucose concentration than CON bulls, and BAND castrates had greater (P=0.04) glucose concentration than BURD. In conclusion, BAND or BURD castration significantly reduced plasma testosterone concentration; reduced average daily weight gain mainly during the first 2 weeks, which was not compensated during the subsequent 16 weeks; increased withdrawal of stored energy and increased plasma protein concentration. BURD showed an advantage over BAND in growth during days 15 to 28 following castration.

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Fuente: Gaceta UNAM


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Próximos eventos

XXI CONGRESO PANAMERICANO DE CIENCIAS VETERINARIAS Y 16 REUNIÓN ANUAL DEL CONASA Asociación Panamericana de Ciencias Veterinarias Consejo Técnico Consultivo Nacional de Sanidad Animal Fecha: 12 al 16 de octubre de 2008 Sede: Guadalajara, Jal Informes: www.panvet2008.com

8º CONGRESO INTERNACIONAL DE MVZ ESPECIALISTAS EN BOVINOS Asociación de Médicos Veterinarios Especialistas en Bovinos de la Laguna Fecha: 6, 7 y 8 de Noviembre de 2008 Sede: Auditorio del Centro Cultural Universitario “Braulio Fernández Aguirre” de la Universidad Autónoma de Coahuila. Torreón, Coah, México Informes: asociació[email protected]

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Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación

http://www.sagarpa.gob.mx

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Federación de Colegios y Asociaciones de Médicos Veterinarios Zootecnistas de México, A.C. www.fedmvz.com

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Organización Panamericana de la Salud. www.cinu.org.mx/onu/estructura/mexico/org/ops.htm

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sperm morphology and fertility of progeny-tested ai dairy bulls in sweden

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