酵母培养物对山羊亚急性瘤胃酸中毒体外发酵模型的调控作用

Regulating Effects of Yeast Culture on Subacute Ruminal Acidosis Fermentation Model in Vitro in Goats

本试验旨在探究酵母培养物(YC)对山羊亚急性瘤胃酸中毒外发酵模型的调控作用。采用体外批次培养法,在不同非纤维性碳水化合物(NFC)/中性洗涤纤维(NDF)[1.19(常规底物)和2.30(高NFC底物)]的底物中分别添加6个水平[0(对照)、0.5%、1.0%、1.5%、2.0%和2.5%]的YC,探究其对瘤胃发酵参数的影响,并用多项指标综合指数(MFAEI)进行评定,筛选出在不同NFC/NDF条件下最适YC添加水平。结果表明:1)在高NFC底物条件下,发酵液pH低于5.8时长超过3 h,体外亚急性瘤胃酸中毒模型建立成功;且添加YC能够稳定9~12 h的pH,显著降低12和24 h乳酸含量(P<0.05),显著降低9和12 h氨态氮(NH3 N)含量(P<0.05),显著提高12 h微生物蛋白(MCP)含量(P<0.05),显著提高3、6、12、24 h乙酸百分比(P<0.05),显著提高24 h总挥发性脂肪酸(TVFA)含量(P<0.05)。2)在常规底物条件下,YC能稳定瘤胃发酵液24 h的pH,显著降低12 h乳酸含量(P<0.05),显著提高9 h的NH3 N含量、6和12 h MCP含量及3~24 h TVFA含量(P<0.05)。3)MFAEI结果表明,常规底物条件下,以1.5%的YC添加水平对体外发酵作用效果最佳;高NFC底物条件下,以2.0%的YC添加水平对亚急性瘤胃酸中毒的缓解作用最佳。因此,在高NFC底物条件下添加YC的作用效果更好,能通过降低发酵液中乳酸含量达到调控瘤胃发酵液pH的效果,具有缓解亚急性瘤胃酸中毒的潜力。

The aim of this experiment was to investigate the regulating effects of yeast culture(YC)on suba cute ruminal acidosis(SARA)fermentation model in vitro in goats.Six different levels of YC[0(control),0.5%,1.0%,1.5%,2.0%and 2.5%]were supplemented into substrate with different non fibrous carbohy drates(NFC)/neutral detergent fiber(NDF)at 1.19(conventional substrate)and 2.30(high NFC sub strate),respectively.Rumen fermentation parameters were determined,and moreover,the multi index com posite index(MFAEI)was evaluated.The results showed as follows:1)under high NFC substrate condition,the duration of pH lower than 5.8 was longer than 3 h,which indicated that the SARA model was established successfully in vitro.The pH during 9 to 12 h was stabilized with YC supplementation.In addition,the content of lactate at 12 and 24 h significantly decreased(P<0.05),the content of ammoniacal nitrogen(NH3 N)at 9 and 12 h significantly decreased(P<0.05),the content of microbial protein(MCP)at 12 h significantly in creased(P<0.05),the percentage of propionic acid at 3,6,12 and 24 h significantly increased(P<0.05),and the content of total volatile fatty acids(TVFA)at 24 h significantly increased(P<0.05).2)Under con ventional substrate condition,the pH at 24 h in rumen fermentation fluid was also stabilized with YC supple mentation.At 12 h,the content of lactate significantly decreased(P<0.05);at 9 h,the content of NH3 N sig nificantly increased(P<0.05);at 6 and 9 h,the content of MCP significantly increased(P<0.05);during 3 to 24 h,the content of TVFA significantly increased(P<0.05).3)The MFAET results showed that 1.5%YC could stabilize in vitro rumen fermentation under conventional substance condition;2.0%YC supplementation could relive SARA under high NFC substance condition.In conclusion,YC supplementation has the best effect under high NFC substance condition,and relive SARA by improving the pH and reducing the content of lactic acid in rumen fermentation fluid,which indicate that YC has the potential to alleviate SARA.