Productive and reproductive performances of F1 Holstein x Gir cows in the state of Minas Gerais

ABSTRACT The objective was to evaluate the productive and reproductive performances of F1 Holstein x Gir cows in the state of Minas Gerais. The herd during the summer was managed in a pasture based production system with supplementation of concentrate according to milk production and in the winter it was fed with sugar cane, citrus pulp and concentrate. The characteristics evaluated were: age at first calving, calving to first service interval, service period, calving interval, permanence the cows in the herd, total milk production per lactation, lactation length, average milk daily, productions adjusted to 280 and to 305 days of lactation, milk production per calving interval, and lactation curves. The Incomplete Gamma function was used to estimate the parameters of lactation curves at parturition order, parturition epoch and service period. The other characteristics were analyzed using linear mixed models. The herd showed great performance (6271,56 kg of milk per lactation). F1 Holstein x Gir cows are a good alternative to milk production, as long as good conditions of handling and feeding are guaranteed, and the use of cows derived from breeding programs targeted using genetic improvement criteria.

摘要：本研究旨在评估巴西米纳斯吉拉斯州（Minas Gerais）荷斯坦（Holstein）与吉尔（Gir）杂交F1代奶牛的生产与繁殖性能。夏季牛群采用以牧场为基础的生产管理体系，根据产奶量补饲精饲料；冬季则饲喂甘蔗、柑橘渣与精饲料的混合日粮。本次研究评估的指标包括：初产日龄、产后首次配种间隔、配种期、产犊间隔、奶牛在牛群中的留存时长、泌乳期总产奶量、泌乳时长、日均产奶量、校正至泌乳280天与305天的产奶量、每产犊间隔产奶量以及泌乳曲线。研究采用不完全伽马函数（Incomplete Gamma function）估算不同产次、产犊时期与配种期下的泌乳曲线参数；其余指标则通过线性混合模型（linear mixed models）进行分析。该牛群表现出优异的生产性能，泌乳期总产奶量达6271.56千克。荷斯坦×吉尔杂交F1代奶牛是奶业生产的优良备选品种，只要保障良好的饲养管理与饲喂条件，并采用基于遗传改良标准的育种计划培育的种牛即可。