酵母对亚急性瘤胃酸中毒绵羊缓解效果及作用机制研究

旨在探究一株酿酒酵母和两株瘤胃源褶皱假丝酵母对亚急性瘤胃酸中毒(subacute ruminal acidosis，SARA)绵羊的缓解作用及其机制，为研制防治SARA微生态制剂提供优良菌株和理论依据。选取60只2月龄同期断奶的杜泊羊(♂)×湖羊(♀)F₁代作为试验动物。通过逐步递增饲粮精粗比成功诱导40只绵羊发生SARA，将SARA绵羊随机分为4组，每组10只，分别为：SARA组、酿酒酵母组(Saccharomyces cerevisiae，SC)、褶皱假丝酵母一组(Diutina rugosa 1，DR1)、褶皱假丝酵母二组(Diutina rugosa 2，DR2)，各组均饲喂精粗比为90∶10的日粮，酵母组于每天晨饲后分别灌服100 mL酿酒酵母ACCC 21162、褶皱假丝酵母N09、褶皱假丝酵母N07。对照组(Control，CON)饲喂50∶50饲粮。分别于第1、3、7、10天测定各组瘤胃液pH，第10天测定瘤胃与血液异常代谢产物、血气指标、瘤胃菌群。结果显示：1)灌服酵母组第3天后瘤胃液pH显著高于SARA组(P<0.05)，灌服酵母可使SARA得有效缓解。2)瘤胃菌群相对丰度发生变化，SC组最优菌属为乳杆菌属，CON组最优菌属为普雷沃氏菌科未确定菌属，SARA、DR1、DR2组最优菌属为瘤胃菌科未确定属；灌服酵母组中，SC组丰富度指数最高，DR2组多样性指数最高。3)灌服酵母组瘤胃液和血液乳酸、瘤胃液组胺显著低于SARA组(P<0.05)。4)SC、DR2组血液pH、全血碱剩余极显著高于SARA组(P<0.01)，灌服酵母组血液二氧化碳分压、二氧化碳总量、实际碳酸氢盐显著高于SARA组(P<0.05)。5)瘤胃液pH与血液实际碳酸氢盐呈现显著正相关(P<0.05)，瘤胃液乳酸与瘤胃菌群Chao 1指标呈现显著负相关(P<0.05)。结果提示，3株酵母均可提升瘤胃菌群丰富度、降低瘤胃液和血液乳酸、减轻瘤胃炎症、缓解机体酸中毒。

Study on Relieving Effect and Mechanism of Yeast on Subacute Ruminal Acidosis in Sheep

This study was designed to explore the alleviating effect and mechanism of a strain of Saccharomyces cerevisiae and two strains of Diutina rugosa from rumen on subacute ruminal acidosis (SARA) in sheep. In order to provide strains and a theoretical basis for developing probiotics to prevent SARA in sheep. Sixty two-month-old weaned Dubo sheep (♂)×Hu sheep (♀) F₁ generations were selected as experimental animals. SARA was successfully induced in forty sheep by gradually increasing the diet concentrate-to-roughage ratio. SARA sheep were divided into 4 groups (n=10):SARA group;Saccharomyces cerevisiae ACCC 21162 (SC) group;Diutina rugosa N09 (DR1)group; Diutina rugosa N07 (DR2)group. All four groups were fed a diet with a concentrate to roughage ratio of 90:10. And SC,DR1 and DR2 groups were respectively gavaged with 100 mL Saccharomyces cerevisiae ACCC 21162,Diutina rugosa N09 and Diutina rugosa N07 after morning feeding.The control group (CON, n=10) was fed 50:50 diet at all times. The ruminal pH was measured on the 1, 3, 7, and 10 d after adding yeasts, respectively. On 10 d after adding yeasts, rumen microflora, abnormal metabolites, and blood gas were measured. The results showed that:1) Ruminal pH in the yeast groups was significantly higher than that in the SARA group on the 3rd day (P<0.05), and SARA was effectively relieved in yeast groups. 2) The optimum bacteria in SC and CON groups were Lactobacillus and unidentified Prevotellaceae, respectively, while in the other groups it was unidentified Ruminococcaceae. In the yeast groups, SC group had the highest richness index and DR2 group had the highest diversity index. 3) The rumen and blood lactic acid and rumen histamine in the yeast groups were significantly lower than those in the SARA group (P<0.05). 4) Blood pH and base excess in SC and DR2 groups were extremely significantly higher than those in the SARA group (P<0.01). The blood carbon dioxide partial pressure, total carbon dioxide, and bicarbonate concentration in the yeast groups were significantly higher than those in the SARA group (P<0.05). 5) There was a significantly positive correlation between ruminal pH and actual bicarbonate in the blood (P<0.05), and a significant negative correlation between rumen lactic acid and Chao 1 index of rumen microflora (P<0.05). These results indicated that three yeasts had the effects on improving the abundance of rumen microflora, reducing rumen and blood lactic acid, alleviating rumen inflammation and body acidosis.