中文摘要：

本研究对北京地区中国荷斯坦牛群不同淘汰原因进行归类并对奶牛长寿性的影响因素进行分析,旨在为奶业实践中提高奶牛长寿性提供依据。试验收集了北京地区1996—2014年的奶牛离群记录（51 361条）,将淘汰原因归为11大类。针对在群时间（从出生至淘汰的总天数）,使用SAS MIXED过程,以场、出生年和月、淘汰类型作为固定效应,父亲、场年互作、年月互作为随机效应,分析各因素的影响。结果表明：繁殖障碍与消化类疾病是造成奶牛淘汰的最主要因素,约占40%;奶牛平均在群时间不足5年,平均胎次2.86胎;场、出生年、出生月、淘汰类型均对在群时间有显著影响,父亲效应方差组分约占总方差的1%。北京地区中国荷斯坦牛使用年限较短,被动淘汰比例高,其长寿性受遗传与环境因素共同影响。本研究结果可为中国荷斯坦牛群生产寿命遗传评估建模及实施平衡育种奠定基础。

英文摘要：

The research was conducted to provide foundation knowledge for improving the longevity in dairy practice, through sorting culling reasons and analyzing the influence factors affec tingherd life. Totally 51361 culling records in Beijing area during 1996 to 2014 were collected and culling reasons were grouped into 11 categories. Herd life is defined as number of days from date of birth to date of culling. A linear mixed model was adopted to assess difference effects using MIXED procedure of SAS software, including herd, birth year, birth month, culling type as fixed effects and sire, herd-birth year, birth year-birth month as random effects. The results showed that reproductive disorders and digestive diseases were the reasons causingthe largest proportion of culling, totally reached about 40%. The average of herd life was less than 5 years and average lactation when cows culled was about 2.86. All of the fixed effects had significant effects on herd life and the variance component of sire was about 1% of the total variance. It is concluded that the Chinese Holstein population had relatively short herd life and more likely to be culled due to involuntary reasons. Herd life was jointly determined by genetic and environmental factors. Current study can provide a strong base for establishing the model for genetic evaluation of longevity and implementing balanced breeding strategy.