BEEF CATTLE RESEARCH ~ POPULATION MEDICINE~

D. O. Rae DVM, MPVM Food Animal Reproduction and Medicine Service Large Animal Clinical Sciences College of Veterinary Medicine University of Florida And many colleagues.

MORBIDITY, MORTALITY, PERFORMANCE

• 1. Calf loss, failure to wean a calf • Pregnancy loss, calf death loss to weaning.

• 2. Johnes Disease • Chronic disease impact on performance

• 3. Tritrichomonas foetus (Trich) • The effect on cow performance • Venereal disease transmission- the bull

Cow-Calf Veterinary Practice ~ We monitor Cow-Calf Health and Production

Calving season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Breeding Season

Weaning How many cows are pregnant?

How many stay pregnant?

How many calves are born alive? How many neonates die?

How many calves die later?

How many calves are weaned?

How do the calves perform?

Beef Unit Mean (13 y) Max Min Sum Cows Exposed 267 288 245 3,476 Cows Pregnant 88.8% 93.2% 82.7%

Cows Died 0.9% 1.4% 0.0%

Abortion 0.9% 2.6% 0.0% Calves Born 87.8% 91.8% 81.7% Calves Died 5.9% 9.3% 4.1%

at birth 3.1% 4.4% 0.8% <10 d 1.3% 2.2% 0.4%

10-30 d 0.6% 1.2% 0.0% >30 d 0.9% 3.8% 0.0%

Early mkt 1.9% 5.6% 0.4%

Alive >30d 82.1% 87.1% 76.1% Weaned 79.7% 85.9% 69.7%

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BRU- Cow Calf Performance

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SFBU- Calf death loss Diedat birth<10 d10-30 d>30 d

A JOHNES DISEASE PATTERN

• Johne’s disease (JD, paratuberculosis) is • an incurable, chronic, infectious disease of ruminants, • caused by Mycobacterium avium subsp. paratuberculosis (MAP) • characterized by progressive weight loss and profuse diarrhea

• Estimates of paratuberculosis prevalence

• between 3% and 9% (Thorne and Hardin, 1997; Roussel et al., 2002; Hill et al., 2003).

• Florida, 7.4% (Keller et al., 2004).

• In dairy cattle: production affected by sub clinical infection. • reduced milk, fat, and protein yields in US Holsteins (Gonda et al., 2007).

• In beef cattle: production affected(?) • studies similar to those in dairy cattle are limited.

‘STUDY OPPORTUNITY’

• Long term genetic study of productivity in multi-breed beef cattle

• Beef Research Unit- University of Florida. • Animal compositions-

• ranged from 100% Angus (A) to 100% Brahman (B).

• ***Under a Johne’s control program since 2001 • Impact of JD on genetic results?

ASSOCIATION BETWEEN COW REPRODUCTION AND CALF PREWEANING GROWTH TRAITS AND ELISA SCORES FOR PARATUBERCULOSIS IN A

MULTI-BREED HERD OF BEEF CATTLE

M.A. Elzo, D.O. Rae, S.E. Lanhart, F.G. Hembry, J.G. Wasdin, D.J. Driver Department of Animal Sciences and Large Animal Clinical Sciences University of Florida

STUDY OBJECTIVES

• To quantify the association between subclinical paratuberculosis (measured by a MAP ELISA score) to • cow reproduction and weight traits, and • calf preweaning growth traits

ANIMAL MANAGEMENT

• Breeding: by both AI and natural service • Calving season: mid-December to mid-March • Cow data: reproductive performance, body condition, weight (6 years) • Calf data: calf preweaning growth (6 years)

• Annual MAP ELISA herd test

• A blood sample collected from all cows annually (6 years). • Measuring the antibodies to MAP present in a sample.

• ELISA scores assigned to each cow

• 0 = negative, [No MAP antibodies detected] • 1 = suspect, [Low level MAP antibodies, below positive range] • 2 = weak positive, [Low levels MAP antibodies, in positive range] • 3 = positive, (and, 4 strong positive) [Moderate to high antibodies levels].

TIME OPEN

• ELISA scores 2 and 3 were • clearly associated with longer TO • subclinical JD affect a cow’s ability to become pregnant. • a longer TO negatively affect cow longevity in the herd.

• Hypothesis:

• Though not showing clinical signs, • these cows have a limited nutrient availability to support reproduction; • thus a delay in attaining pregnancy.

COW WEIGHT LOSS

• Cows ELISA score 3 lost more weight (P < 0.01) than cows with ELISA score 0.

• Hypothesis:

• cows seem to reach an advanced stage of JD before showing weight loss • observationally, cows developing (JD) lose weight precipitously, • a threshold of gut damage may occur before observable signs appear.

CALF BIRTH WEIGHT

• Lower birth weight is seen in calves of non-zero ELISA score cows.

• Hypothesis:

• resources to support intrauterine calf growth may be diverted or unavailable due to JD.

CALF WEANING WEIGHT

• cows with ELISA score 3 had calves • with significantly lower WWT and WW205 • WWT (-15.2 ± 6.8 lb, P < 0.03) • WW205 (-16.3 ± 6.2 lb, P < 0.008) • than calves from negative cows.

• Hypothesis: • there is a negative impact of subclinical JD on milk production, • effects increase with the progression of disease

IMPLICATIONS

• Subclinical JD is associated with • lower cow fertility (longer times from calving to conception), • lower ability of cows to maintain weight, • lower calf birth weights, and • lower calf weaning weights.

• These agree with adverse effects seen in dairy cattle.

• Losses are measurable and could be substantial.

PREVALENCE AND EFFECT OF TRITRICHOMONAS FOETUS IN

BULLS AND COWS IN FLORIDA

TRICHOMONIASIS

• Contagious, venereal, post-breeding disease • Infertility, Pyometra, Abortion

• Cows are transiently infected • Bulls remain infected

• but show no sign of infection

A FLORIDA STATE SURVEY:

• 1984 bulls cultured for T. fetus • 119 bulls culture positive. • 6.0% (3 to 12%, CI)

• Culture positive samples • from 17 of 59 surveyed herds. • 29% (17 to 41%, CI).

A FLORIDA STATE SURVEY:

• Herd prevalence • (How many herds had a least 1 infected bull?)

• Herds <500 head 10% • Herds >500 head 54%.

• Odds for herd size • Herds with >500 breeding females 10.5 x more

likely to have at least one T. foetus positive bull than a herd of <500 breeding females (p<0.001).

A FLORIDA STATE SURVEY:

• Estimates of within herd prevalence • (How many bulls in each herd were infected?)

• Mean 11.9% (range 1.8% to 27%) • North Florida 17.9% • South Florida 11.1%. • Herd size <500 24.4% • Herd size >500 9.2%. • A bull in South Florida was 4x more likely to be

culture positive than a bull in North Florida.

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Bull Age (yr)

Bull Age by T. foetus Infection Status

Non-infected T. foetus Infected

T. FOETUS EFFECT ON COW PERFORMANCE

• For each 1% rise in within herd prevalence cow performance measures decline

• weaning percentage reduced by 0.6% • mean weaning weight per exposed cow reduced 3.5 lb.

Example: Two bulls infected of 10 sires (20% prevalence) • Expect a 12% reduction in weaned calf crop • Expect mean weaning weight to be 70 lb lighter

PRODUCER RECOMMENDATION

• Pregnancy check cows (have a baseline) • Monitor calving

• How many pregnant cows deliver a calf? • How many calves are lost… when and how?

• Monitor performance of cows and calves (BCS, wt) • Especially, calf number weaned, weaning weight, days of age

• Monitor disease problems in the herd. • Track and manage disease that may influence your herd performance.

• Immunize bulls, cows and calves • At appropriate times, with appropriate products • At the direction and under the supervision of your herd veterinarian

• Do a BSE on bulls annually. • Test bulls, especially older bulls, for T. foetus

• Use younger bulls in multi sire groups and cull older bulls (>8 yrs)

THANK YOU Questions?