[Milk fatty acid profile from Holstein x Gyr cows fed corn silage and concentrate containing or not crude glycerin]

ABSTRACT The objective of this study was to evaluate the milk fatty acid (FA) composition of cows fed corn silage-based diets containing 0% and 8.9% of crude glycerin (GB) on a dry matter (DM) basis. Eighteen Holstein x Gyr cows with 48±18 days in milk and producing 19.8±4.9kg milk/day were used in the study. The experimental design was a randomized block with nine cows per treatment and two repeated measures. Results were analyzed using mixed models. The milk fat contents of myristic, palmitic, rumenic, vaccenic, estearic, oleic, linoleic, α-linolenic, and trans-10 cis-12 CLA were similar between diets. Dietary inclusion of GB decreased elaidic and trans-10 C18:1, and increased lauric acid and odd linear-chain FA contents in milk fat. Both atherogenicity and trombogenicity indices were unaffected by GB inclusion. It was concluded that GB inclusion in corn silage-based diets had no effect on the nutritional quality of milk fat from Holstein x Gyr dairy cows.

摘要 本研究旨在评估以玉米青贮为基础日粮中，添加以干物质（dry matter, DM）为基准计0%与8.9%粗甘油（crude glycerin, GB）时奶牛乳脂肪酸（fatty acid, FA）的组成特征。本试验选用18头荷斯坦×吉尔杂交奶牛，泌乳天数为48±18天，日均产奶量为19.8±4.9kg。试验采用随机区组设计，每个处理组配置9头奶牛，设置2次重复测量，采用混合模型对试验结果进行统计分析。
结果表明，两组日粮对牛乳中肉豆蔻酸、棕榈酸、瘤胃酸（rumenic acid）、反式-11十八碳一烯酸（vaccenic acid）、硬脂酸、油酸、亚油酸、α-亚麻酸以及反-10顺-12共轭亚油酸的乳脂含量无显著差异。日粮添加粗甘油可降低乳脂中反油酸（elaidic acid）与反式-10十八碳一烯酸的含量，同时提升月桂酸与奇数直链脂肪酸的乳脂含量。动脉粥样硬化指数与血栓形成指数均不受粗甘油添加的影响。
综上，在以玉米青贮为基础的日粮中添加粗甘油，对荷斯坦×吉尔杂交泌乳奶牛乳脂的营养品质无显著影响。