Genetics and environmental effects upon production traits of holstein herds in the Rio Grande do Sul state, Brazil

Ciência Rural

Rorato, Paulo Roberto Nogara²  Rigon, José Luiz³  Matos, Rosangela Soares¹  Ferreira, Gilka Barbosa² 

[1] Universidade Federal de Santa Maria, Santa Maria;Associação de Criadores de Gado Holandês do Rio Grande do Sul

关键词: dairy cattle;    genetic parameters;    environmental effects;    production traits;   

DOI  :  10.1590/S0103-84781997000300017

学科分类：农业科学（综合）

来源: Universidade Federal de Santa Maria * Centro de Ciencias Rurais

【 摘 要 】

In order to evaluate the impact of environmental and genetics effects upon production traits, information used in this study was obtained from 4085 lactations of Holstein cows, daughters of 172 sires, out of 42 herds, from 1988-1994, whose farms were located in four different geographical regions, in the southern, Brazil. The environmental effects were analysed by the Least square analyses. The statistical model included fixed effects (region, herds by region, lactation order and season of the year) and dependent variables milk yield (MY) and fat yield (FY). Means, standard deviation and variations coefficients for MY and FY were respectively, 5672±1513kg, 27% and 188±57kg, 30%. There was significant effect to all variables studied. The genetic parameters were estimate using the MTDFREML Program (BOLDMAN et al., 1995) in a model using the fixed effects of region, herd, lactation order and year-season and random effects of the animal on milk and fat yield. The heritability estimates for milk yield (MY) and fat yield (FY) ajusted to 305 days of lactation were 0.19 and 0.17, respectively. The genetic correlation coefficient for MY x FY was 0.95.

【 授权许可】

CC BY-NC