Dr. Benny Sharir

Beef cow reproductive management

Benny Sharir DVM

Dr. Benny Sharir

The perfect beef cow

• Reproductive specifications– regular cycle by 15mo– delivers first calf at 24mo– calves in first 3 weeks of calving season– is cyclic again by onset of breeding season– conceives at first breeding opportunity– produces a calf every 365 days

Dr. Benny Sharir

The perfect beef cow

• Maternal specifications– calves unassisted– calf weights are close to breed average– gestation length close to breed average– provides excellent maternal care (colostrum

etc.)– produces sufficient quality milk– has sound udder (teat size, no mastitis etc.)

Dr. Benny Sharir

The perfect beef cow

• Other specifications– temperament is such that she is not a danger to

herself or humans– “easy keeper”– adapted to her environment– has good “disease resistance” (vaccinations)– has high salvage value

Dr. Benny Sharir

Characteristics of Beef cow reproductive cycle

• Prolonged (variable length) PP anestrus (lactational anestrus)

• FSH / follicular development continue during the anestrus period

• low LH pulse frequency and therefore no LH surge possible in anestrus period

Dr. Benny Sharir

Beef cow reproductive physiology

• “suckling effect” and “milk removal” do not solely explain PP anestrus (muzzled calves)

• intact innervation of udder not essential to prolong PP anestrus provided suckle > 2 times per day

• suckling induced hormone changes:prolactin, oxytocin, corticosteroids all

increased

Dr. Benny Sharir

Lactational anestrus

Dr. Benny Sharir

Dr. Benny Sharir

Beef cow reproductive physiology

• PP anestrus appears to be result of a complex interaction of several sensory inputs:– olfactory – visual– auditory– hormonal – metabolic cues (BCS at calving)

Alien calf

Dr. Benny Sharir

Factors affecting PP anestrus in beef cow

• age: heifers versus cows– heifers have longer PP anestrus

• pre-partum nutrition and BCS at calving– profound effect on PP anestrus

• post calving nutrition – may affect CR but less effect on PP anestrus

Dr. Benny Sharir

Dr. Benny Sharir

1=back 2=tail 3=pins4=hooks 5=ribs 6=brisket

Body condition scoring areas

Dr. Benny Sharir

Dr. Benny Sharir

Dr. Benny Sharir

Body condition scores

• accurately reflect metabolic reserves as opposed to just body weight

• varies over the year depending:– on feed availability, – feed quality – metabolic status of the cow

• in general cows that calve thin remain thin

Dr. Benny Sharir

Body condition scores

• accurate predictor of when cyclicity likely to return

• 1 BCS represents about 35Kg BW in medium frame cow

• Equiv. to energy and protein in 125Kg corn

• critical score @ calving:– BCS 5 is min. for cows– BCS 6 is preferred for heifers

Dr. Benny Sharir

Body condition scores and return to cyclicity

percent cycling

BCS (calving) # cows @ 60d @90d

thin (1-4) 272 46 66

mod. (5-6) 364 61 92

good (7-9) 50 91 100

Dr. Benny Sharir

BCS @ pregnancy test. v mean pregnancy rateswithin age group and for the entire cow herd

Parity body condition scores3 4 5 6 7 all

1 40% 50 70 82 83 63 2 43 79 89 100 100 77 3-10 71 86 92 97 95 91 >10 100 92 97 100 100 97 all 54 76 89 94 94 84

note: 1) poor performance of heifers at low BCS v cows2) first calf heifers still 10% less than cows even at higher BCS

Dr. Benny Sharir

Effect of BCS at calving on interval to estrus return and BCS at breeding on PR

BCS post calving interval (days) PR ( %)

3 89 704 70 805 59 946 52 1007 31 100

Dr. Benny Sharir

Heifer management

• calve in min. BCS 6• breed to calve 3wk prior to cow herd

– allows 3 weeks longer to return to cycling

• manage as a separate herd (avoid “social” stress)

• post calving stresses of– growth– lactation

Dr. Benny Sharir

onset calv. end calv. weaning

onset cow breed.end cow breed.

onset heifer breed.

63d

42d

6-8mo

end heiferbreed.

63d

Dr. Benny Sharir

Efficient beef cow reproduction

• calve at 2 yr

• calve every 12mo

• 60% cows conceive first 21d of breeding

• cow breeding season=63d

• 70% heifers conceive first 21d of breeding

• heifer breeding season=42d

Dr. Benny Sharir

Pregnant in the first 21 days

Cows preg. in first 21 days is dependent on:

1) cows cycling first 21 days

2) first service conception ratea) cow fertilityb) bull fertility

Dr. Benny Sharir

The calving pattern

• measures frequency of calvings that occur in each successive 21d period

• goal– 95% of herd in 63d– 60% first 21d

• profound effect on Kgs beef weaned

Dr. Benny Sharir

Prolonged (>60d) breeding season

• prolonged calving season

• uneven line of weaner calves

• inefficient forage use

• retention of late cyclers / non-cyclers– increased late pregnancies– increased open cow

• greatly reduces Kg beef sold

Dr. Benny Sharir

Critical steps in efficient beef production

• Heifer management– raise to breed at 15mo and calve at 24mo– limit breed. season to 42d– begin breed. 3 wk before cow herd– use bulls with low BW EPD’s (Expected Progeny

Difference)– monitor BCS and calve at min. 5 preferably 6– monitor calv. closely, don’t delay intervention– minimize post calving weight loss– separate first lactation cows from cow herd

Dr. Benny Sharir

Critical steps in efficient beef production

• cow herd management– min. BCS 5 at calving– BCS herd 2-3mo before calving season– separate off thins and calculate economic ration

to raise to BCS 5– minimize weight loss post calving– limit breeding season to max. 65d– >60% cows inseminated (bull / AI) in first 3wk

Dr. Benny Sharir

Critical steps in efficient beef production

• cow herd management– bulls semen tested prior to breed. season – preg. check early after breed. season, cull opens– BCS at preg. check / plan for if, when and how

adjustments will be made– check udders, teeth and eyes at preg. check– maintain adequate “clean” calving pastures– monitor vaccine and parasite programs