Yang Zhantao, Zheng Yuhui, Liu Siyuan, Xie Tian, Wang Qianqian, Wang Zhonghan, Li Shengli, Wang Wei
State Key Laboratory of Animal Nutrition and Feeding, Beijing Engineering Technology Research Center of Raw Milk Quality and Safety Control, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Anim Nutr. 2024 Jul 6;18:296-308. doi: 10.1016/j.aninu.2024.06.003. eCollection 2024 Sep.
Dietary fat content can reduce the methane production of dairy cows; however, the relevance fatty acid (FA) composition has towards this inhibitory effect is debatable. Furthermore, in-depth studies elucidating the effects of unsaturated fatty acids (UFA) on rumen function and the mechanism of reducing methane (CH) production are lacking. This study exposed 10 Holstein cows with the same parity, similar milk yield to two total mixed rations: low unsaturated FA (LUFA) and high unsaturated FA (HUFA) with similar fat content. The LUFA group mainly added fat powder (C16:0 > 90%), and the HUFA group mainly replaced fat powder with extruded flaxseed. The experiment lasted 26 d, the last 5 d of which, gas exchange in respiratory chambers was conducted to measure gas emissions. We found that an increase in the UFA in diet did not affect milk production ( > 0.05) and could align the profile of milk FAs more closely with modern human nutritional requirements. Furthermore, we found that increasing the UFA content in the diet lead to a decrease in the abundance of in the rumen (|linear discriminant analysis [LDA] score| > 2 and < 0.05), which resulted in a decrease in the relative abundance of multiple enzymes (EC:1.2.7.12, EC:2.3.1.101, EC:3.5.4.27, EC:1.5.98.1, EC:1.5.98.2, EC:6.2.1.1, EC:2.1.1.86 and EC:2.8.4.1) during methanogenesis ( < 0.05). Compared with the LUFA group, the pathway of CH metabolism was inhibited in the HUFA group (|LDA| > 2 and < 0.05), which ultimately decreased CH production ( < 0.05). Our results illustrated the mechanism involving decreased CH production when fed a UFA diet in dairy cows. We believe that our study provides new evidence to explore CH emission reduction measures for dairy cows.
日粮脂肪含量可降低奶牛的甲烷产量；然而，脂肪酸（FA）组成与这种抑制作用的相关性仍存在争议。此外，目前缺乏深入研究来阐明不饱和脂肪酸（UFA）对瘤胃功能的影响以及降低甲烷（CH）产量的机制。本研究将10头胎次相同、产奶量相近的荷斯坦奶牛分为两组，分别饲喂两种总混合日粮：低不饱和脂肪酸（LUFA）日粮和脂肪含量相近的高不饱和脂肪酸（HUFA）日粮。LUFA组主要添加脂肪粉（C16:0＞90%），HUFA组主要用挤压亚麻籽替代脂肪粉。试验持续26天，在最后5天，在呼吸室内进行气体交换以测量气体排放。我们发现，日粮中UFA的增加对产奶量没有影响（P＞0.05），并且可以使牛奶脂肪酸谱更符合现代人类的营养需求。此外，我们发现增加日粮中UFA的含量会导致瘤胃中某物质丰度降低（线性判别分析[LDA]分数绝对值＞2且P＜0.05），这导致甲烷生成过程中多种酶（EC:1.2.7.12、EC:2.3.1.101、EC:3.5.4.27、EC:1.5.98.1、EC:1.5.98.2、EC:6.2.1.1、EC:2.1.1.86和EC:2.8.4.1）的相对丰度降低（P＜0.05）。与LUFA组相比，HUFA组的CH代谢途径受到抑制（LDA绝对值＞2且P＜0.05），最终导致CH产量降低（P＜0.05）。我们的研究结果阐明了奶牛饲喂UFA日粮时CH产量降低的机制。我们认为，本研究为探索奶牛CH减排措施提供了新的证据。
