摘要 : Data on 393 Sahiwal dairy cows in Haryana, India, over 25 years (1980-2004) were analysed to study the effects of calving season, calving period and parity on body weight. It was shown that calves born in winter had a higher birth... 展开 Data on 393 Sahiwal dairy cows in Haryana, India, over 25 years (1980-2004) were analysed to study the effects of calving season, calving period and parity on body weight. It was shown that calves born in winter had a higher birth weight, while body weight at 12 and 18 was months significantly higher in the wet and winter seasons, respectively. The highest body weights at 6, 12, 18, 24 and 30 months were observed during 1980-1982, 1986-1988, 1986-1988, 1983-1985 and 1983-1985, respectively. Parity only affected birth weight but the differences between 1->5 parity were not significant. Body weight at 6, 12, 18 and 24 months had high heritabilities, while birth weight and body weight at 30 months had low heritabilities. There was also a significantly high phenotypic correlation of body weight at higher ages and poor genotypic correlation and high heritability at lower ages (birth, 6-month and 12-month body weights). It is suggested that selection can be done early on the basis of birth weight and 6- and 12-month body weights. Better management of dams in advanced pregnancy and calves in early stages may result in early maturity. 收起