棉籽酶解蛋白对奶牛瘤胃液体外发酵参数及微生物区系的影响

Effects of Enzymatic Hydrolysate of Cottonseed Protein on Rumen Fermentation and Microflora of Dairy Cows in Vitro

本试验旨在通过体外发酵法研究棉籽酶解蛋白对奶牛瘤胃发酵及瘤胃微生物区系的影响。选用体况、泌乳天数相近的4头荷斯坦奶牛作为瘤胃液供体,采用单因子试验设计,将采集的瘤胃液均匀混合后随机分为4组,即对照组(C组)、低浓度组(E组)、中浓度组(F组)和高浓度组(G组),分别添加0(对照)、0.3%、0.5%和0.7%棉籽酶解蛋白(干物质基础)。培养2、4、6、8、12、24、48 h后测定瘤胃发酵参数和瘤胃微生物数量。结果表明:1)与对照组相比,培养2~8 h,各组pH显著降低(P<0.05),但均处于正常范围之内;在整个培养过程中,各组氨态氮(NH 3-N)浓度显著降低,菌体蛋白(MCP)浓度显著升高(P<0.05);C组和G组的总挥发性脂肪酸(TVFA)、乙酸、丙酸、丁酸浓度均显著高于E组和F组(P<0.05),而E组和F组的乙酸/丙酸显著低于C组和G组(P<0.05)。2)与对照组相比,各时间点F组白色瘤胃球菌和黄色瘤胃球菌数量显著增加(P<0.05)。在整个培养过程中,G组反刍兽新月形单胞菌数量显著低于其他组(P<0.05),F组布氏普雷沃氏菌数量显著高于其他组(P<0.05)。培养2~6 h,F组反刍兽新月形单胞菌数量显著高于对照组(P<0.05)。综上所述,棉籽酶解蛋白的添加可改善瘤胃发酵模式,显著提高瘤胃纤维分解菌数量。在本试验条件下,棉籽酶解蛋白的最适添加剂量为0.5%。

The aim of this study was to study the effects of enzymatic hydrolysate of cottonseed protein on rumen fermentation and rumen microflora of dairy cows by in vitro batch fermentation.Four healthy Holstein cows with similar body conditions and lactation days were selected as rumen liquid donors.A single factor design was used in the experiment and rumen fluid were randomly divided into four groups:control group(C group),low concentration group(E group),medium concentration group(F group)and high concentration group(G group),supplementation with 0,0.3%,0.5%and 0.7%enzymatic hydrolysate of cottonseed protein based on dry matter,respectively.The rumen fermentation parameters and the numbers of rumen microorganisms were determined at 2,4,6,8,12,24 and 48 h of incubation time.The results showed as follows:1)compared with control group,enzymatic hydrolysate of cottonseed protein significantly reduced rumen fluid pH at 2 to 8 h,which were not exceed the normal range values.ammoniacal nitrogen(NH 3-N)concentration was significantly decreased and mycoprotein(MCP)concentration was significantly increased during the whole incubation period.The concentrations of total volatile fatty acids(TVFA),acetate,propionate,butyrate and acetate/propionate of C group and G group were significantly higher than those of E group and F group(P<0.05),as well as acetate/propionate of E group and F group was significantly lower than that of C group and G group(P<0.05).2)Compared with control group,the number of Ruminococcus flavefaciens and Ruminococcus albus of F group was significantly increased during the whole incubation period(P<0.05).The number of Selenomonas ruminantium of G group was markedly lower than that of other three groups during the whole incubation period(P<0.05),and the number of Selenomonas ruminantium of F group was markedly higher than that of control group(P<0.05)at 2 to 6 h.The number of Prevotella bryanti of F group was significantly increased compared with control group(P<0.05).In summary,the supplementation of enzymatic hydrolysate of cottonseed protein can improve the pattern of rumen fermentation,which markedly influence the numbers of cellulolytic bacteria flora.Under this experiment condition,0.5%enzymatic hydrolysate of cottonseed protein based on dry matter is proved to be more effective.