中文摘要：

旨在研究牛场、胎次、公牛家系和泌乳阶段等4个固定效应对中国荷斯坦牛乳脂肪酸组分含量的影响。该研究以816头北京地区中国荷斯坦牛为试验对象，采用气相色谱法对个体牛奶中不同乳脂肪酸组分进行测定，共计包括豆蔻酸（C14：O）、棕榈酸（C16：O）、硬脂酸（C18：O）、油酸（C18：1）和亚油酸（C18：2）等27种性状，采用固定效应模型和SAS9．1软件的GLM过程进行统计分析。结果表明，中国荷斯坦牛乳脂肪酸组分主要以C16：0、C18：In9c、C18：0、C14：0和C18：2为主，C16：0含量为最高达32．65％；SFA：UFA=1．70：1；牛场和泌乳阶段效应对牛乳脂肪酸组分含量影响极显著（P〈O．001），公牛家系效应对主要脂肪酸组分影响显著（P〈O．05），胎次效应对脂肪酸组分影响较小。研究结果显示，中国荷斯坦牛乳中不同脂肪酸组分含量性状主要受到牛场、公牛和泌乳阶段3种效应影响，为进行牛乳脂肪酸含量性状的全基因组关联分析及基因定位研究提供了理论基础，为牛乳营养品质改善提供了指导意义。

英文摘要：

The aim of the present study was to analyze the effect of fixed effects, including herd, parity, sire and clays in milk, on fatty acids traits in Chinese Holstein cattle. Totally 816 Chinese Holstein cows from Beijing were selected as experimental population. By the General Linear Model （GLM） procedure of software SAS 9.1 fixed effect model, the effects of the 4 factors on 27 fatty acids traits（myristic acid （C14： 0）, palmitic acid （C16： 0）, stearic acid （C18： 0）, oleic acid （C18：1）, linoleic acid （C18：2）＇, and so on） were estimated. The phenotypes of 27 traits were measured by using gas chromatography. The results showed that C16.0, C18：1n9c, C18：0, C14.0 and C18：2 were the main components of milk. Of them, the proportion of C16：0 was the highest（32.65%）, SFA ： UFA=1. 70 ： 1. The effects of herd and days in milk on all fatty acids traits were significant （P〈0. 001）, and the effect of sire on main fatty acids traits reached signifi- cant level （P〈0.05）. However, no signifcant effect of parity on fatty acids traits was found （P〉 0.05）. The result indicate that 3 factors, including herd, sire and days in milk, showed significant effects on milk fatty acids traits in Chinese Holstein. The results provide basis for genome- wide association study and gene mapping for milk fatty aeids traits ingful for milk nutrition improvement.