dairy production lec 10

Question 1

what is the problem with small heifers

Answer 1

• small heifers
  o high repro culling
  o shorter herd life

Question 2

what is the advantage of well grown heiffers

Answer 2

-	well grown heifers
o	tighter calving
o	less induction  
- higher MY over life time
reduced AFC

Question 3

what problems do heifers risk

Answer 3

o	Poor adaptation to changing diets 
o	Starvation or suboptimal nutrition 
	biggest hazard 
	protein and energy 
	increased risk of diseases 
o	Parasitism and infectious disease 
o	acidosis 
	poor transitioning 
o	Reproductive failure 
o	Calving

Question 4

what is the association between LWFC and MY

Answer 4

• mature milk yield depends on LWFC
• higher LWFC can produce more milk
 want MY at first calving to be 80-85% of mature cows production

Question 5

what is the target LW

Answer 5

 target LW depends on mature LW
• at joining should be around 60-65%
• by calving should be 90% of mature weight

Question 6

how much does a heifer need to be growing

Answer 6

 need 0.7kg/day target growth average to reach

Question 7

when should the AFC be

Answer 7

around 2 years

more flexible in a seasonal calving

Question 8

what are the key management hazards in heifer growth

Answer 8

weaning management
disease and parasite management
nutrition
transitioning

Question 9

what is the target weaning rate

Answer 9

varies 65-120 kg

Question 10

what are the disease and parasite managements

Answer 10

drench, vaccinate and plant toxicities

Question 11

how does a ration at weaning compare to first lactation

Answer 11

weaning has higher protein content similar energy 10 MJME

Question 12

how much energy does a weaner need

Answer 12

10ME

Question 13

why do you need to transition feed

Answer 13

 heifers need transition
• Rumen adaptation
• prevention of acidosis and metabolic problems
• Provision of energy and protein for foetus and udder development

Question 14

how long is a transition feed

Answer 14

 >3 weeks on lead feed a risk for milk fever

Question 15

what is happening during 6-12months

Answer 15

skeletal growth

Question 16

what is happening during 12-15 months

Answer 16

puberty

key period for parasite control

Question 17

what is happening during 15-18 months

Answer 17

joining
 target 350-390kg heifer
 maintain growth
• 9.5 MH/kg DM 16-18% CP

Question 18

what is happening during 18-21 months

Answer 18

 early pregnancy
 still target growth
slightly lower protein and energy required

Question 19

what is happening during 21-24 months

Answer 19

late preg

energy requirements increasing

Question 20

what is happening during 23- 25 months

Answer 20

calving and lactation
energy requirements increase
need transition diet

Question 21

what is the benefit of increased LW at first calving

Answer 21

o	Improve milk production 
	23L milk/kg heavier LWFC over 3 lactations 
	heifer eats more-produce more
	bigger size so can compete for feed
o	Improve fertility
	increased LW at mating = increased CR 
•	fewer empties
•	increased CR 
•	tighter calving 
o	Reduce age at first calving (AFC) 
	better economically
•	quicker return 
•	longer milking life 
	high AFC
•	poor fertility/too small
•	delayed joining 
o	Reduce dystocia 
	dystocia can increase calving interval and lactation yield
	smaller heifers most at risk 
o	Reduce wastage (birth to 2nd calving) 
	reduce culling before second lactation 
	loose genetic advancement

Question 22

what is the problem with heifers being too big

Answer 22

o fatty udder syndrome
 high growth on low protein diet prior and during puberty
 reduced feed efficiency
 lay down fat on udder