荷斯坦奶牛牛嘴宽度影响因素分析及遗传参数估计

【目的】探究中国荷斯坦奶牛牛嘴宽度的群体规律，并估计其遗传参数。【方法】2021年7月至2021年8月分别在2个规模化奶牛场测定了628头泌乳期荷斯坦奶牛的牛嘴宽度及臀高、体高、体斜长和胸围等体尺性状，同时利用体斜长和胸围估计试验牛体重。利用SPSS 26.0软件分析了牧场、月龄和泌乳阶段等因素对牛嘴宽度的影响，以及牛嘴宽度与各体尺性状之间的相关关系；基于DMU软件采用单性状动物模型估计了牛嘴宽度的方差组分及遗传力。【结果】荷斯坦奶牛牛嘴宽度的群体平均值为17.28 cm，变异系数为5%，变异相对较小；牧场和月龄对牛嘴宽度均有极显著影响（P<0.01），泌乳阶段对牛嘴宽度有显著影响（P<0.05），牛嘴宽度随母牛月龄的增加呈逐渐增加的趋势，泌乳初期牛嘴宽度显著小于其他泌乳阶段（P<0.05）；牛嘴宽度与各体尺性状之间存在极显著正相关（P<0.01）；荷斯坦奶牛牛嘴宽度的遗传力估计值为0.28，为中高遗传力性状。【结论】牧场和月龄对奶牛牛嘴宽度影响极显著，泌乳阶段对奶牛牛嘴宽度影响显著，牛嘴宽度与臀高呈较弱相关。荷斯坦奶牛牛嘴宽度是一个具有中高遗传力的体尺性状。

Influencing Factors Analysis and Genetic Parameters Estimation of Muzzle Width in Holstein Dairy Cows

【Objective】 This study was aimed to reveal the population characteristics, and estimate the genetic parameters of muzzle width in Chinese Holstein dairy cows.【Method】 The muzzle width, rump height, body height, body length and chest girth of 628 Holstein dairy cows was measured in two dairy farms from July 2021 to August 2021.The body weight was estimated by body length and chest girth.SPSS 26.0 software was employed to analyze the impacts of herd, month and lactation stage on muzzle width, and obtain the correlation coefficient between muzzle width and body size traits.The variance components of muzzle width were estimated using single-trait animal model based on DMU software, and its heritability was calculated.【Result】 The muzzle width of Holstein dairy cows was 17.28 cm with a small variation (variation coefficient of 5%).Herd and month had extremely significant effect on muzzle width (P<0.01), lactation stage had significant effect on muzzle width (P<0.05), and muzzle width increased with the increase of month.Muzzle width in early lactation was significantly smaller than that in other lactation stages (P<0.05).The extremely significant and positive correlations between muzzle width and body size traits were found in Holstein dairy cows (P<0.01).The estimated heritability of muzzle width in Holstein dairy cows was 0.28, which was a moderate to high heritability trait.【Conclusion】 The herd and month had an extremely significant effect on muzzle width, and the lactation stage had a significant effect.The muzzle width was weakly correlated with rump height.The muzzle width was a body size trait with moderate to high heritability in Holstein dairy cows.