Wang B, Jiang L S, Liu J X
Beijing Key Laboratory for Dairy Cow Nutrition, College of Animal Science and Technology, Beijing University of Agriculture, Beijing, China.
MoE Key Laboratory of Molecular Animal Nutrition, Institute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou, China.
J Anim Physiol Anim Nutr (Berl). 2018 Jun;102(3):601-610. doi: 10.1111/jpn.12789. Epub 2017 Oct 6.
Optimizing the amino acid (AA) profile of rumen undegradable protein (RUP) can positively affect the amount of milk protein. This study was conducted to improve knowledge regarding the AA profile of rumen undegradable protein from corn stover, rice straw and alfalfa hay as well as the total mixed ratio diets (TMR) based on one of them as forage source [forage-to-concentrate ratio of 45:55 (30% of corn stover (CS), 30% of rice straw (RS), 23% of alfalfa hay (AH) and dry matter basis)]. The other ingredients in the three TMR diets were similar. The RUP of all the forages and diets was estimated by incubation for 16 hr in the rumen of three ruminally cannulated lactating cows. All residues were corrected for microbial colonization, which was necessary in determining the AA composition of RUP from feed samples using in situ method. Compared with their original AA composition, the AA pattern of forages and forage-based diets changed drastically after rumen exposure. In addition, the extent of ruminal degradation of analysed AA was not constant among the forages. The greatest individual AA degradability of alfalfa hay and corn stover was Pro, but was His of rice straw. A remarkable difference was observed between microbial attachment corrected and uncorrected AA profiles of RUP, except for alfalfa hay and His in the three forages and TMR diets. The ruminal AA degradability of cereal straws was altered compared with alfalfa hay but not for the TMR diets. In summary, the AA composition of forages and TMR-based diets changed significantly after ruminal exposure, indicating that the original AA profiles of the feed cannot represent its AA composition of RUP. The AA profile of RUP and ruminal AA degradability for corn stover and rice straw contributed to missing information in the field.
优化瘤胃不可降解蛋白（RUP）的氨基酸（AA）组成可对乳蛋白含量产生积极影响。本研究旨在增进对玉米秸秆、稻草和苜蓿干草瘤胃不可降解蛋白的氨基酸组成以及以其中一种作为饲料来源的全混合日粮（TMR）[饲料与精料比例为45:55（玉米秸秆占30%（CS），稻草占30%（RS），苜蓿干草占23%（AH），以干物质计）]的了解。三种TMR日粮中的其他成分相似。通过在三头安装有瘤胃瘘管的泌乳奶牛的瘤胃中孵育16小时来估计所有饲料和日粮的RUP。对所有残留物进行微生物定植校正，这在使用原位法测定饲料样品中RUP的氨基酸组成时是必要的。与它们原来的氨基酸组成相比，饲料和以饲料为基础的日粮在瘤胃暴露后的氨基酸模式发生了巨大变化。此外，所分析氨基酸的瘤胃降解程度在不同饲料之间并不恒定。苜蓿干草和玉米秸秆中单个氨基酸最大降解率是脯氨酸（Pro），但稻草中是组氨酸（His）。除了苜蓿干草以及三种饲料和TMR日粮中的组氨酸外，在微生物附着校正和未校正的RUP氨基酸谱之间观察到显著差异。与苜蓿干草相比，谷物秸秆的瘤胃氨基酸降解率发生了改变，但TMR日粮没有变化。总之，饲料和以TMR为基础的日粮在瘤胃暴露后氨基酸组成发生了显著变化，这表明饲料原来的氨基酸谱不能代表其RUP的氨基酸组成。玉米秸秆和稻草的RUP氨基酸谱以及瘤胃氨基酸降解率为该领域提供了缺失的信息。
