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Flashcards in beef production lec 7 and 8 Deck (26):

what is PPAI

o post part anoestrus interval


how long does a cycle last and what is the average joining length

o 1 cycle = 21 days
o optimum 6 week joining
 normal 9 week


what is the disadvantage of a longer PPAI

- increased PPAI = later calvers next year
o early joining means early calf so longer time to recover before next calf
o later calvers will conceive later and have less time to rejoin


what is the aims of a tight calving

o tight calving span and concentrated pattern
o 90% weaning rate
o preg rate of 94%
o join most cows in in first cycle
o cull cows worth more, sell them keep heifers


what affects PPAI

o Age of cow – primiparous (heifers) cows have longer PPAI
 CMW, higher demand on body
 have higher PPAI
 pluriparous cows
• don’t need to have as high BCS
o Nutrition / Body condition
 cows with better nutrition have shorter PPAI
 want a BCS of 2.5-3/5 oestrus
 Losing 1/4 BCS in the 90 days post-partum delays the PPAI by about 14 days, compared to no weight loss.
 biggest influence BCS at calving
o Suckling (lactational anoestrus)
 have calf still on them
o Breed differences
o Retained after birth – uterine infection


what BCS is needed for spring vs autumn calving and why

o autumn calving has greater variation in FS
 need in better FS of 3.5-4
 drop in demand over winter
o spring calving
 less variation
 need in FS 2.5-3


what management can be used for joining heifers

o early calving heifers become early calving cows
o The optimal strategy
 Don’t join heifers only on gross conformational faults (<5%)
 retain hiefers sell older cull cows
 Drench retained heifers
o Weigh at weaning
 target CMW, draft off ones that will achieve without help
 preferential feed lighter heifers to get to CMW
o Mate to high fertility “heifer bull”
o Join for 6 weeks only
 ‘Overjoin’ and sell empties
 sell those that didn’t go in calf over first 6 weeks as PTIC
o Join for 10 weeks
 ‘Over-join’ and sell late calvers
 need to be preg tested
• Allows additional flexibility in culling decisions
o higher heifer retention
 increased rate of genetic turnover through increased selection pressure on old cows
 Higher income due to increased value of cull cows over young heifers


what affect does BCS of PPAI

increase BCS = decrease in PPAI


what conception rate does a 2 cycle ( 6 week joining) get

o So two cycles (42 days) should give 96% conception rates


what is the optimal joining rate

o AIM- 95% calving in 63 days


what is the advantage of a short calving interval

o advantage of short joining
 calves at weaning are are higher as had longer time to gain weight
 potentially in 10 month old weaners $80-$160 between calves.
 condensed calving (from 12wks to 6wks)
• 5.9% increase in GM over base system.


why preg diagnose?

o early ID of NIC – cull – feed utilisation
o predicts calving pattern (ages foetuses) late calvers for preferential feeding
o cull late calving heifers - use early calvers as replacements
o ID abnormalities
o drought strategy
o assists economic management of production


what can be used to evaluate bulls?



what is BDE and what is measured

 Scrotal circumference (cm)
 Physical examination
 Semen analysis
 Morphology
 Mating behaviour / mating ability.


what do you look for in a bulls ebvs?

• calving ease, 400 day weight, scrotal circumference, fat


what health measures should be taken before joining a bull?

3 months prior BSE, health check (drench and vaccination)


outline the annual timeline of a beef cow

gestation (9 months) 275-280 days

calve at 275-280 days

lactating PPAI 50 days

lactating and cycling 35 days (JOINING PERIOD)

lactating and preg (weaning) dry and preg (time varies)


when can a calve be weaned?

o goal 90 kg @ 90 days
o as young as 100 days
o generally 8-10 months


what factors influence time of weaning

o availability of feed
o condition and age
o type of production
o heifer calves and CMW


what are the 4 main weaning methods

o creep, over the fence, abrupt into paddock, yard weaning


which is the best waning practise and why

 yard weaning
• needs to be in small area
• good hay
• plenty of human contact
• in preparation of feedlots
o higher gains when enter feedlots
• lower sickness %


what is the difference in carass between a high and low GR?

low GR, protein put on preferentially leaner
high GR, more fat laid down


what is the difference between restriction pre and post weaning

o restricted
 early restriction has severe impact on growth
• <200 kg LW
• don’t grow as much
• higher fat put down, less muscle
• little compensatory growth
 restriction post weaning
• preferentially put on protein to fat
o compensatory growth


what is backgrounding and what impact is there on carcass composition

- back grounding
o from weaning to sale, e.g. for feedlots
o Moderate growth (0.6kg/day) will:
 Increase ADG and FCR in the feedlot
 less fat,
 lower marbling
 more prone to rapid chilling.
o High growth (>1.0kg/day)
 show slower gains in the feedlot
 cost more to feed
 have higher levels of overall fat and marbling.
 less prone to the effects of chilling rate on toughness
 have less connective tissue toughness


what are HGP and what is the advantage of these

o hormonal growth
o increase weight gain
 10-30%
o increase FCE

 5-15%
o increase profit
 $30-80/head
o leaner carcasses
 5-8%
o used in feedlots
 reduces methane as makes feed breakdown more efficient
o natural and sympathetic forms


what are the disadvantages of HGP

decreased fertility, some markets wont accept
want hormone free