Genetic and environmental aspects on milk yield and calving interval of dairy herds monitored by computerized information systems

Revista Brasileira de Zootecnia

Zambianchi, Ana Rosa²  Pereira, Carmem Silva³  Freitas, Maria Armênia Ramalho de¹ 

[1] IEEZRP;CNPq e CAPES;UFMG

关键词: DAISY system;    fertility;    Holstein cows;    milk production     Introdução A produtividade da pecuária leiteira brasileira;    quando comparada à dos países desenvolvidos;    deixa muito a desejar;    visto que nossos rebanhos apresentam baixa eficiência reprodutiva e produtiva;    reflexo;    entre outras causas;    da não-utilização das tecnologias já disponíveis para o setor leiteiro;   

DOI  :  10.1590/S1516-35981999000600013

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

This study was carried out to analyze the influence of some environmental effects on the milk yield and calving interval and to estimate the genetic parameters at 305-day milk yield (P305), and calving interval (IP). Data from 3044 lactations of 1568 Holstein cows, calved from 1988 to 1995 belonging to dairy herds monitored by DAISY (The Dairy Information System), were used. The Least Squares Method was used to study the environment effects and the Derivative-Free Restricted Maximum Likelihood (REML) algorithm was used to estimate genetic parameters using univariate and bivariate sire model. The estimated means and standard errors were 4634.4+108 kg and 421.7+ 93.5 days for P 305 and IP, respectively. Calving year, herd or production level and age of cow affected all studied traits. The estimated heritabilities ranged from 0.24 to .43 for P305 and .06 to .07 for IP. The genetic, phenotypic and environmental correlation between 305-day milk yield and calving interval were .42, .12 and .11, respectively. There was an additive genetic variation for milk yield and a positive genetic correlation, but undesirable relationship among the traits, sugesting that the selection for high milk yield could increase the calving interval.

【 授权许可】

CC BY-NC