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