Factors affecting fatty acids composition in milk of grazing cows

放牧奶牛乳中脂肪酸组成的影响因素

• 批准号: 16580218
• 负责人: HANADA Masaaki
• 金额: $ 1.22万
• 依托单位: Obihiro University of Agriculture and Veterinary Medicine
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16580218/
• 关键词: grazing cow; milk; fatty acids composition; conjugated linoleic acid; 変動要因; 乳牛

Four trials were conducted to investigate the factors affecting fatty acids composition, especially focused on CLA (conjugated linoleic acid), in milk of grazing cows.In experiment 1,fatty acids composition in milk collected from whole day grazing dairy farms (WG), time restricted grazing farms (TG) and non grazing farms (NG) were measured from April to December. The cows in WG and TG were grazed on temperate pasture from May to October. The cows in NG were offered total mixed ration throughout the season. Across the grazing season, proportions of CLA to total fatty acids in milk of WG,TG and NG were 1.4,0.9 and 0.4 mol%, respectively.In experiment 2,six milking cows were kept under grazing and non-grazing condition to investigate the effect of linoleic and linolenic acids intake on the CLA content in the milk. These results suggested that the increase of CLA in milk under grazing condition was due to the increase of vaccenic acid supply, which was synthesized form linolenic and linoleic acids in the rumen, to mammary glandIn experiment 3,three steers were offered fresh herbage to investigate the fatty acid composition in duodenum digesta. The amount of vaccenic acid flow to the duodenum of steers fed fresh herbage was about ten times more than that of CLA flow, suggesting that the CLA in the milk of grazing cows are mainly synthesized from vaccenic.In experiment 4,cheeses were made from the milk of the grazing cows to test whether the CLA in milk could remain in the cheese. The proportion of CLA to total fatty acids in cheese increased linearly with increase of the proportion of CLA in milk, suggesting that it could be possible to make a cheese containing high level of CLA using the milk produced from grazing cows.

本研究通过4个试验研究了放牧奶牛乳中脂肪酸组成的影响因素，特别是共轭亚油酸（CLA）的影响因素，试验一从4月至12月对全放牧、限牧和非放牧奶牛乳中脂肪酸组成进行了测定。从5月到10月，WG和TG中的奶牛在温带牧场上放牧。NG奶牛在整个季节提供全混合日粮。在整个放牧季节中，WG、TG和NG乳中CLA含量分别占总脂肪酸的1.4mol%、0.9mol%和0.4mol%。这些结果表明，放牧条件下乳中CLA含量的增加是由于瘤胃中亚麻酸和亚油酸合成的异油酸向乳腺的供应量增加所致。结果表明，放牧奶牛乳中CLA主要由异油酸合成，而流到十二指肠的异油酸量是流到十二指肠的CLA量的10倍左右。奶酪中CLA占总脂肪酸的比例随着牛奶中CLA比例的增加而线性增加，这表明可以使用放牧奶牛生产的牛奶来制作含有高水平CLA的奶酪。