Major factors affecting milk yield are the ability to supply the mammary gland with nutrients
and the gland to produce milk.
Achieving body size targets at first calving is critical:
- Loss of 300 kg of milk (1st lact) per -50kg body weight (BW) at calving, loss of 720 kg of
milk (3 lact) per -50kg BW at calving - Optimal BW is 50% mature BW at 12 months and 85% mature BW after calving or at 21
months - Heifers are failing to achieve recommended live weight target, with 73% of heifers at 22
months being more than 5% below live weight target.
Nutrition of the prepubertal heifer:
- High-energy diets decrease mammogenesis. The prebuteral period (3-12 months) is a
critical phase for udder formation. - High energy intake from 3 to 9 months promotes growth but not mammogenesis.
- Excessive energy increases fat within the udder and impairs mammary development
- High energy diets increase leptin, which inhibits growth of mammary parenchyma via
negatively affecting IGF-I. - Greater protein content during the first year can benefit mammary development.
- Monitoring growth is key to success! Monitor weight, height, and condition of several
heifers at weaning, breeding and freshening.
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