beef production lec 7 and 8

Question 1

what is PPAI

Answer 1

o post part anoestrus interval

Question 2

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

Answer 2

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

Question 3

what is the disadvantage of a longer PPAI

Answer 3

• 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

Question 4

what is the aims of a tight calving

Answer 4

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

Question 5

what affects PPAI

Answer 5

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

Question 6

what BCS is needed for spring vs autumn calving and why

Answer 6

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

Question 7

what management can be used for joining heifers

Answer 7

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

Question 8

what affect does BCS of PPAI

Answer 8

increase BCS = decrease in PPAI

Question 9

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

Answer 9

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

Question 10

what is the optimal joining rate

Answer 10

o AIM- 95% calving in 63 days

Question 11

what is the advantage of a short calving interval

Answer 11

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.

Question 12

why preg diagnose?

Answer 12

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

Question 13

what can be used to evaluate bulls?

Answer 13

BSE
genetics
health

Question 14

what is BDE and what is measured

Answer 14

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

Question 15

what do you look for in a bulls ebvs?

Answer 15

 EBVS

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

Question 16

what health measures should be taken before joining a bull?

Answer 16

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

Question 17

outline the annual timeline of a beef cow

Answer 17

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)
calve

Question 18

when can a calve be weaned?

Answer 18

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

Question 19

what factors influence time of weaning

Answer 19

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

Question 20

what are the 4 main weaning methods

Answer 20

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

Question 21

which is the best waning practise and why

Answer 21

	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 %

Question 22

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

Answer 22

low GR, protein put on preferentially leaner

high GR, more fat laid down

Question 23

what is the difference between restriction pre and post weaning

Answer 23

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

Question 24

what is backgrounding and what impact is there on carcass composition

Answer 24

-	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 


Question 25

what are HGP and what is the advantage of these

Answer 25

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

Question 26

what are the disadvantages of HGP

Answer 26

decreased fertility, some markets wont accept

want hormone free