玉米蛋白水解物对奶牛瘤胃体外发酵及纤维素酶活的影响

摘要

为研究全混合日粮(TMR)中添加玉米蛋白水解物(CPH)对奶牛瘤胃体外发酵及纤维素酶活的影响,试验选用3头体重(600±25)kg,安装永久性瘤胃瘘管的健康荷斯坦奶牛作为瘤胃液供体,培养底物为TMR.试验设Ⅰ、Ⅱ、Ⅲ和Ⅳ4个处理组,分别添加0、0.06、0.12、0.24 g/L CPH(干物质基础),每个处理设3个重复.测定体外发酵24 h内发酵液的pH、体外干物质消失率、纤维素酶活、菌体蛋白、氨态氮(NH3-N)和挥发性脂肪酸(VFA)浓度.结果显示:(1)添加不同水平CPH处理产气量、慢速产气部分、潜在产气部分和有效产气速率升高均达到显著水平(P<0.05),其中试验组Ⅱ、Ⅲ和Ⅳ产气量分别较对照组升高5.32%、7.45%和10.64%;(2)与对照组相比,试验组Ⅱ、Ⅲ和ⅣpH分别降低0.60%、0.75%和1.35%(P<0.05),NH3-N浓度分别升高3.05%、4.67%和11.42%(P<0.01),总挥发酸、乙酸、丙酸和丁酸浓度显著升高(P<0.05),其中试验组Ⅱ、Ⅲ和Ⅳ总挥发酸浓度分别升高16.81%、19.97%和23.57%;(3)与对照组相比,添加不同水平CPH处理发酵液纤维素酶活性显著提高(P<0.05).试验组Ⅱ、Ⅲ和Ⅳ菌体蛋白浓度分别升高12.48%、30.37%和24.95%(P<0.05),体外干物质消失率升高1.42%、8.74%和12.31%(P<0.05).由此可见,TMR中添加CPH可以改善瘤胃发酵,提高瘤胃内纤维素酶活性,从而提高饲料利用率,其中以添加0.24 g/L为宜.%The present study was conducted to investigate the effects of corn protein hydrolysate (CPH)on in vitro rumen fermentation and cellulose activity.The rumen fluid was collected from three ruminally cannulated Holstein cows with average body weight(600 ±25)kg.The substrate was total mixed ration(TMR).The test was divided into Ⅰ,Ⅱ,Ⅲ and Ⅳ four groups.CPH(dry matter basis)was added to buffered rumen fluid with concentrations of 0,0.06,0.12 g/L and 0.24 g/L,respectively.Each group had three replications.Gas production was recorded within 24 h of incubation.Moreover,the pH,dry matter disappearance,cellulase activity,ammonia-N,volatile fatty acids and bacterial protein concentration of fermentation liquor were determined within 24 h of incubation.The results showed as follows:(1)The addition of different levels of CPH significantly improved the gas production,gas production from the insoluble fraction,potential extent of gas production and effective gas production rate from the cultures(P <0.05),and the gas production of the treatment Ⅱ,Ⅲ and Ⅳ were 5.32%,7.45% and 10.64% higher than that of the control group,respectively;(2)Compared with control group,the pH of the treatment Ⅱ,Ⅲ andⅣ decreased 0.60%,0.75% and 1.35%(P < 0.05)and ammonia-N increased 3.05%,4.67% and 11.42% (P < 0.01),respectively.The content of total volatile fatty acids,acetate,propionate and butyrate improved significantly(P < 0.05),and the total volatile fatty acids of the treatment Ⅱ,Ⅲ and Ⅳ increased 16.81%,19.97% and 23.57%,respectively;(3)Compared with control group,the addition of different levels of CPH significantly increased the content of cellulose(P < 0.05).The bacterial protein of treatment Ⅱ,Ⅲ and Ⅳincreased 12.48%,30.37% and 24.95%(P < 0.05)and dry matter disappearance increased 1.42%,8.74% and 12.31%(P < 0.05).It followed that addition of CPH could improve rumen fermentation,cellulose activity,and feed utilization rate.The optimum dose was 0.24 g/L.