The effects of step-wise improvement of forage combination in total mixed rations on fatty acid profile in the rumen and milk of Holstein cows

作     者：BAI Sarvvl CAO Zhi-jun JIN Xin WANG Ya-jing YANG Hong-jian LI Sheng-li 

作者机构：State Key Laboratory of Animal Nutrition College of Animal Science and Technology China Agricultural University Beijing Engineering Technology Research Center of Raw Milk Quality and Safety Control College of Animal Science and Technology China Agricultural University 

出 版 物：《Journal of Integrative Agriculture》 (农业科学学报（英文版）)

年 卷 期：2018年第17卷第8期

页      面：1833-1842页

核心收录：

学科分类：0710[理学-生物学] 0832[工学-食品科学与工程（可授工学、农学学位）] 090502[农学-动物营养与饲料科学] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 1004[医学-公共卫生与预防医学(可授医学、理学学位)] 0905[农学-畜牧学] 0906[农学-兽医学] 09[农学] 0901[农学-作物学] 0703[理学-化学] 0902[农学-园艺学] 0713[理学-生态学] 

基　　金：supported by the National Natural Science Foundation of China (31772628) the National Key Basic Research Program of China (2011CB100801) 

主　　题：forage combination lactating cow ruminal fatty acid milk fatty acid 

摘      要：Five lactating Holstein cows in a 5×5 Latin square experiment were fed five high-concentrate total mixed rations(TMRs) to investigate the effects of step-wise improvement of forage combination on ruminal and milk fatty acid profiles. The ratio of concentrate to forage was fixed as 61:39, and the step-wise improvement of forage combination was applied as: TMR1, a ration containing corn stover; TMR2, a ration containing corn stover and ensiled corn stover; TMR3, a ration containing ensiled corn stover and Chinese wild ryegrass hay(Leymus chinensis); TMR4, a ration containing the ryegrass hay and whole corn silage; TMR5, a ration containing the ryegrass hay, whole corn silage and alfalfa hay. The TMRs were offered to the cows twice daily at 0700 and 1900 h. The entire experiment was completed in five periods, and each period lasted for 18 days. Diurnal samples of rumen fluids were collected at 0100, 0700, 1300 and 1900 h(day 16); 0300, 0900, 1500 and 2100 h(day 17); and 0500, 1100, 1700 and 2300 h(day 18). The step-wise improvement of forage combination increased energy and crude protein contents and decreased fibre content. As a result, the step-wise improvement of forage combination increased dry matter intake and milk yield(P0.05). The step-wise improvement increased dietary content of linolenic acid(C18:3 n-3), but did not alter dietary proportions of palmitic acid(C16:0), stearic acid(C18:0), oleic acid(C18:1 cis-9), linoleic acid(C18:2 n-6) and arachidic acid(C20:0). In response to the forage combination, ruminal concentration of C16:0, C18:2 n-6 and C18:3 n-3 linearly increased against their dietary intakes(P0.10). The step-wise improvement increased milk contents of C10:0, C12:0, C14:0, C16:0, C18:2 n-6 and C18:3 n-3(P0.10) and decreased milk contents of C18:0 and C18:1 cis-9(P0.05). Milk yields of C16:0, C18:1 cis-9, C18:2 n-6 and C18:3 n-3 were linearly increased by the increase of these fatty acids in the rumen(R2≥0.79, P0.05), and milk yields of C18:2