Dairy Herd Replacement Programs

Question 1

What is the overall goal of replacement rearing?

Answer 1

to grow a healthy heifer in a cost effective manner that will calve around 24 months of age at 85% of her mature body size (1200 lb post-calving; BCS 3.0-3.5)

Question 2

What are the 5 “C”s of calf rearing?

Answer 2

• Colostrum
• Cleanliness
• Comfort
• Calories
• Consistency

Question 3

What are the recommended volume, quantity, and timing for colostrum feeding?

Answer 3

• Timing: ASAP after birth
• Mass:
  
  • good quality: >50 g/L Ig
  • excellent quality: >70 g/L Ig
  • 5-6 L of good quality colostrum or 4 L or excellent quality colostrum
• 4L in 1st feeding within 2h after birth or 2-3L ASAP after birth and 2-3 L within 4-6 hr of 1st feeding

Question 4

When does gut “closure” occur?

Answer 4

• in a linear fashion beginning at birth
• efficiency of absorption is 25-50% at 0 hrs
• closure complete by 24 hrs

Question 5

How do you measure quality in the field?

Answer 5

• Colostrometer: SG highly correlated w/ colostral IgG concentration
• Refractometer
• single radial immunodiffusion
• ELISA
• zinc sulphate turbidity
• sodium sulphite precipitation
• glutaraldehyte test
• serum total protein

Question 6

What serum total protein concentration is used as a cutoff to determine adequate passive transfer?

Answer 6

TP goal > 5.5 g/dl at 2-8 days of age

Question 7

What are the various types of housing for calves?

Answer 7

Individual housing:

• Hutch: placed in long rows for ease of feeding, etc, >2 hutches apart, can be moved to new locations
• Calf barn: use every other pen, clean as infrequently as possible to reduce aerosolization of pathogens
• Hybrid: hutches under roof - protection from weather

Group housing

• often combined w/ automated feeding systems, milk delivery ad lib or mechanized

Question 8

What’s the recommended daily amount of milk or milk replacer that a calf should be offered and how many times per day should calves be fed?

Answer 8

• Pre-weaning (birth to 4-8wks): 2-2.5 L or 2.5-3 L twice daily, unless ad lib or mechanized feeder
  
  • feed more in cold weather
    *

Question 9

At what ages should grain and water be available to the calf?

Answer 9

• water should be offered day 1
• high quality grain starting at day 2-3

Question 10

When should calves be disbudded? What methods are used in pre-weaned calves?

Answer 10

• 1 day: caustic paste (Na/Ca hydroxide)
• <2 mo: hot iron
• 2-3 mo: hot iron
  
  • once >10 mm, become attached to frontal sinus and have to be amputated
• >3 mo: surgical removal (amputation)
  
  • open (most)
  • closed (cosmetic)

Question 11

What are optimal group sizes for pre-weaning (if in groups) and post-weaning calves?

Answer 11

Pre-weaning:

• < 21 d = < 10-12 calves
• 21-56 d = < 50 calves

Post-weaning:

• stocking rate: <15 calves/pen
• regrouped 1-3 weeks post-weaning

*smaller the group size and age range within a pen, the better health tends to be

Question 12

What is the goal growth rate (pounds per day) ?

Answer 12

for calves: about 1.8 lb/day

for heifers: 1.7-1.8 lb/day

Question 13

What are the criteria you would use for deciding when to breed heifers for the first time?

Answer 13

• >750 lb (>51”) and at least 11 m old when 1st bred
• maintain good reproductive performance growth

Question 14

What are the major goals for management of pregnant heifers?

Answer 14

• maintain good growth and control flies
• observed freq during summer to check for mastitis
• do not allow into wet areas during summer
• biweekly to monthly BCS check
• avoid overfeeding