Uptake and Utilization of Milk Fat and Protein Precursors in the Mammary Gland and Their Regulation in Lactating Dairy Cows
The mammary gland of dairy cows is a bio-factorywhich uses circulating nutrients to synthesize,store,and secrete milk.The mammary epithelial cells,the main site of milk component synthesis,have a remarkable ability to convert circulating nutrients (i.e.milk precursors) to milk components.In order to improve the overall conversion efficiency,it is needed to define the capacity of uptake and utilization ofmilk precursors by the mammary gland,to know the subsequent changes in the composition of individual milk components,and to understand the corresponding regulatory mechanisms of lactation in the mammary gland.This review paper is an overview of recent research advances in uptake and utilization of milk fat and milk protein precursors and their regulation inthe mammary gland of lactating dairy cows.The focus is especially on the quantitative changes in supply of circulating nutrients via mammary artery blood flow and the efficiency of uptake and utilization by mammary gland of lactating dairy cowsfed typical diets which are currently used indairy industry of China.Meanwhile,information is providedabout the key regulatory factors and modes in fatty acid and protein synthesis under various supplies of milk precursors in terms of both quantity and proportions by using biopsy of mammary gland from the trials of different types of diet and the culture of bovine mammary cell lines.The regulatory factors include key enzymes,signal transduction factors,hormones,hormone receptors,and some special substances.Our work and the literature show that some milk protein precursors and special metabolites play bioactive or regulatory roles in lactation.Arginine hasa positive effect on milk protein synthesis,whereas the rumen abnormal metabolite endotoxin (lipopolyssacharide,LPS) exerts a negative effect on milk component synthesis.It is worth mentioning that the amount of glycine released from the mammary gland may be an indicator of the udder health conditions.
dairy cows mammary gland milk fat milk protein arginine glycine lipopolysaccharide
Khas-Erdene Guozhong Dong Changjin Ao Sumei Yan Min Gao Hongrong Wang
College of Animal Science, Inner Mongolia Agricultural University, Huhhot 010018, China College of Animal Science and Technology, Southwest University, Chongqing 400716, China Animal Nutrition Institute, Agriculture and Animal Husbandry Academy, Huhhot 010031, China College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China
国际会议
3rd International Symposium on Dairy Cow Nutrition and Milk Quality(第三届“奶牛营养与牛奶质量国际研讨会)
北京
英文
38-50
2013-05-11（万方平台首次上网日期，不代表论文的发表时间）