摘要
This review aims to give an overview of the efficacy of yeast supplementation on growth performance, rumen pH, rumen microbiota, and their relationship to meat and milk quality in ruminants. The practice of feeding high grain diets to ruminants in an effort to increase growth rate and weight gain usually results in excess deposition of saturated fatty acids in animal products and increased incidence of rumen acidosis. The supplementation of yeast at the right dose and viability level could counteract the acidotic effects of these high grain diets in the rumen and positively modify the fatty acid composition of animal products. Yeast exerts its actions by competing with lactate-producing (Streptococcus bovis and Lactobacillus) bacteria for available sugar and encouraging the growth of lactate-utilising bacteria (Megasphaera elsdenii). M. elsdenii is known to convert lactate into butyrate and propionate leading to a decrease in the accumulation of lactate thereby resulting in higher rumen pH. Interestingly, this creates a conducive environment for the proliferation of vaccenic acid-producing bacteria (Butyrivibrio fibrisolvens) and ciliate protozoa, both of which have been reported to increase the ruminal concentration of trans-11 and cis-9, trans-11-conjugated linoleic acid (CLA) at a pH range between 5.6 and 6.3. The addition of yeast into the diet of ruminants has also been reported to positively modify rumen biohydrogenation pathway to synthesise more of the beneficial biohydrogenation intermediates (trans-11 and cis-9, trans-11). This implies that more dietary sources of linoleic acid, linolenic acid, and oleic acid along with beneficial biohydrogenation intermediates (cis-9, trans-11-CLA, and trans-11) would escape complete biohydrogenation in the rumen to be absorbed into milk and meat. However, further studies are required to substantiate our claim. Therefore, techniques like transcriptomics should be employed to identify the mRNA transcript expression levels of genes like stearoyl-CoA desaturase, fatty acid synthase, and elongase of very long chain fatty acids 6 in the muscle. Different strains of yeast need to be tested at different doses and viability levels on the fatty acid profile of animal products as well as its vaccenic acid and rumenic acid composition.
摘要译文
该审查旨在概述酵母补充对增长性能，瘤胃pH，瘤胃微生物群的疗效及其与反刍动物肉类和牛奶品质的关系。将高粒饮食喂养对反刍动物的实践，以提高生长速率和体重增加通常导致动物产品中饱和脂肪酸的过度沉积和瘤胃中酸中毒的发病率增加。在右剂量和活力水平上补充酵母可以抵消这些高颗粒饮食在瘤胃中的酸性效应，并积极地改变动物产品的脂肪酸组成。酵母通过伴随着可用糖的乳酸盐（Streptococcus Bovis和Lactobacillus）细菌来竞争其行为，并鼓励利用细菌的生长（Megasphaera Elsdenii）。众所周知，Elsdenii将乳酸转化为丁酸盐，丙酸盐导致乳酸积聚的降低，从而导致瘤胃较高。有趣的是，这为产生疫苗酸的细菌（抑制纤维纤维纤维）和Ciiliate原生动物的增殖产生了有利环境，这两者都据报道，增加反式11和CIS-9，反式-11缀合的亚油酸的瘤胃浓度酸（CLA）在5.6和6.3之间的pH范围内。据报道，添加酵母进入反刍动物的饮食中，以积极地改变瘤胃生物氢化途径，以合成更多有益的生物氢化中间体（Trans-11和CIS-9，Trans-11）。这意味着更多的亚油酸，亚麻酸和油酸的膳食来源以及有益的生物氢化中间体（CIS-9，Trans-11-Cla和Trans-11）将在瘤胃中逃逸完全生物中的生物中吸收成牛奶和肉。但是，需要进一步的研究来证实我们的索赔。因此，应使用转录组织的技术，以鉴定肌肉中的硬脂酰基酸阳离子，脂肪酸合成酶，脂肪酸合酶6等基因的mRNA转录物表达水平。需要在不同剂量和可活性水平上测试不同的酵母菌株对动物产品的脂肪酸谱以及其疫苗酸和官酸组合物。
Abdulmumini B.Amin[a][b]. Influence of yeast on rumen fermentation, growth performance and quality of products in ruminants: A review[J]. Animal Nutrition, 2021,7(1)