• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Tropical Animal Health and Production >Genetic parameters and trends for calving interval in the first three lactations of Iranian Holsteins
【24h】

Genetic parameters and trends for calving interval in the first three lactations of Iranian Holsteins

机译：伊朗荷斯坦牛前三个泌乳期的产犊间隔的遗传参数和趋势

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Calving records from the Animal Breeding Center of Iran collected from January 1987 to December 2007 and comprising 292,875 calving events of Holsteins from 1,413 dairy herds were analyzed using univariate and bivariate linear animal models to estimate heritabilities and genetic correlations for calving intervals in the first three lactations of Holstein cows. Genetic trends were obtained by regressing yearly mean estimates of breeding values on calving year. Average calving intervals were from 406 to 414 days and decreased over the parities. Heritability estimates for calving intervals varied from 0.03 to 0.04 across the parities. Also, estimates of genetic correlations between calving intervals in different parities were high and ranged from 0.67 to 0.89. The average annual phenotypic trends obtained from fitting linear regression of annual mean calving intervals at parity 1 and 2 were significant (P < 0.01), but the phenotypic trend of calving interval at parity 3 was not significant over the years. On the other hand, there was an increasing genetic trend for calving interval at parity 1, and there were decreasing genetic trends for calving intervals at parity 2 and 3 over the years (P < 0.01). The low estimates of heritability obtained in this study imply that much of the improvement in calving interval traits could be attained by improvement of production environment rather than genetic selection.
机译：使用单变量和双变量线性动物模型分析了从1987年1月至2007年12月从伊朗动物育种中心收集的产犊记录，包括来自1,413个奶牛场的292,875个荷斯坦牛的产犊事件，以评估前三个泌乳期产犊间隔的遗传力和遗传相关性荷斯坦奶牛。遗传趋势是通过对产犊年份的育种值的年均估计值进行回归得到的。平均产犊间隔时间为406天至414天，并且平均产犊时间有所缩短。产犊间隔的遗传力估计值在整个胎次之间从0.03到0.04不等。同样，在不同胎次产犊间隔之间的遗传相关性估计很高，范围在0.67至0.89之间。通过对1和2岁的平均产犊间隔进行线性拟合的线性回归获得的年平均表型趋势是显着的（P <0.01），但多年来在3胎的产犊间隔的表型趋势并不显着。另一方面，随着时间的推移，产犊次数在平胎1处的遗传趋势呈上升趋势，而产犊时间在平胎2和3处的遗传趋势在下降（P <0.01）。在这项研究中获得的遗传力估计值较低，意味着产犊间隔性状的大部分改善都可以通过改善生产环境而不是通过遗传选择来实现。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号