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Weighting familiar and individual information in animal models and BLUP: 1. Genetic group models, 2. uncertain paternity models

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Authors: M. Ballent, H.G. Landi, G. Bilbao, A. Dick
Issue: 99A-2 (130-138)
Topic: Animal Production
Keywords: Heifers, dairy cattle, review

The present article is a review about precocity, liveweight and body development in dairy heifers of different biotypes. The onset of puberty and body development are factors that contribute in the maintenance of the system. The onset of puberty is determined by the liveweight and the age of the heifers, noticing variations among breeds and even within the same bred. It has been established liveweight targets in heifers based on the mature liveweight, from what rate of growing that would let them reach the 30% of the mature liveweight at the age of 6 months, 60% of the mature liveweight at the age of 15 months (the age ready for the mating) and 90% of the mature liveweight at the age of 24 months (the age ready for the first calving). The liveweight was used to be the only characteristic to determine the body development, has been observed that body measurements such as the heart girth, wither height, hip width and body length allow a better interpretation of the body development. The effect produced by diets with high nutritional levels on mammary development, and as a consequence, on the future milk production, depends on the animal biotype (heavy or light biotype). In heavy biotypes, high rates of weight gain have not produced excessive fat deposition in the mammary tissue.

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