Calf rearing is divided into 4 phases based on their nutritional requirements and growth patterns.
- Preweaning
- Postweaning
- Prepubertal
- Post-pubertal
Preweaning Phase
This phase starts right after birth and ends at the age when milk/milk replacer feeding is stopped. It is the most expensive and challenging phase of calf rearing.
During this phase, the liquid diet makes up a major portion of the calf diet, because the calf is born with a non-functional rumen. Milk feeding makes the preweaning phase the most expensive.
Calf immunity is lowest during the first 3 weeks after birth. Of all the 4 phases, calf death is highest during this phase, primarily due to diarrhea and pneumonia.
The success of the preweaning phase depends upon the calf rumen development and prevention of diarrhea and pneumonia.
Key performance Indicators:
Growth rate 500-700 grams/day
Weaning age 40-60 days
Mortality < 5%
Plasma antibodies
Postweaning Phase
This phase starts when milk feeding is stopped and continues till 6 months of age or 150 kg of body weight. Postweaning calf growth highly depends upon the rumen development of the calf during the pre-weaning phase. During this phase, excessive forage feeding can negatively affect calf growth and result in post-bellied calves.
Key performance Indicators:
Growth rate 800-1200 grams/day
Mortality < 2%
Calves should not be pot-bellied.
Prepubertal phase
This phase starts from 6 months of age to 10-12 months of age. During this phase, calf growth should be lean, not fatty. Limit feeding can help in increasing feed efficiency and reducing the rearing cost of calves during the prepubertal phase.
Key performance indicators:
Growth rate 800-1000 grams/day
Lean growth with BCS ≤ 3
Mortality < 2 %
Post pubertal phase
This phase starts from puberty and ends at first calving. During this phase, heifers are bred. Heifers are bred when they attain 65% of their mature body weight. Holstein heifers are bred between 330-350 kg body weight. Heifers’ growth should be continued even after calving.
Key performance indicators:
Mortality < 2%
Lean growth BCS ≤ 3.25
Growth rate 800-1200 grams/ day
Breeding age: 12-15 months of age
Breeding weight: 65% of mature body weight (300-350 kg body weight)
Wither height: 115-125 cm
Calving Weight: 85% of mature body weight, 550-600 kg for Holstein Heifers
Wither Height: 95% of mature height (130-145 cm)
