酵母多糖对哺乳犊牛瘤胃发酵的影响

Effects of Yeast Polysaccharide on Rumen Fermentation of Pre-weaning Calves

试验旨在研究日粮中添加不同剂量的酵母多糖对哺乳犊牛瘤胃发酵参数的影响。选用56头新生荷斯坦犊牛随机分为4组,每组14头(其中母犊6头、公犊8头)。试验Ⅰ组(对照组)饲喂基础日粮,试验Ⅱ、Ⅲ、Ⅳ组在基础日粮中分别添加1、2、3g/(头·d)的酵母多糖,试验期60d,分别在20和60日龄时每组各屠宰4头犊牛,采集瘤胃液测定挥发性脂肪酸(VFA)、pH、氨态氮(NH3-N)及微生物蛋白(MCP)产量。结果表明:(1)在整个生长期内,各处理组犊牛瘤胃液pH及丁酸浓度、乙酸/丙酸差异均不显著(P>0.05);(2)20日龄时,试验Ⅲ组犊牛瘤胃乙酸浓度极显著高于试验Ⅰ组(P<0.01),试验Ⅱ组丙酸浓度显著高于试验Ⅰ组(P<0.05),总挥发性脂肪酸(TVFA)浓度在各组间差异不显著(P>0.05),60日龄时,试验Ⅲ组犊牛瘤胃乙酸浓度极显著高于试验Ⅰ组(P<0.01),各组之间丙酸浓度差异不显著(P>0.05),试验Ⅱ、Ⅲ、Ⅳ组TVFA浓度显著高于试验Ⅰ组(P<0.05),其中试验Ⅲ组最高;(3)20日龄时,试验Ⅲ组犊牛瘤胃NH3-N浓度显著低于试验Ⅰ组(P<0.05),试验Ⅱ组MCP产量显著高于其他各组(P<0.05),60日龄时各组之间NH3-N浓度差异不显著(P>0.05),试验Ⅲ组MCP产量显著高于其他各组(P<0.05)。综合上述结果,在犊牛日粮中添加2g/(头·d)的酵母多糖降低了瘤胃液NH3-N浓度,提高了MCP产量及TVFA浓度,增强了瘤胃内氨和蛋白质的利用,有利于犊牛瘤胃发酵状态的稳定。本试验条件下酵母多糖在0~60日龄犊牛日粮中的适宜添加量为2g/(头·d)。

This experiment was designed to investigate the effects of different dosage of yeast polysaccharide on rumen fermentation of pre-weaning calves.56 Holstein calves with similar body weight and birthday were selected and allotted randomly to four groups with 14 calves（6 heifers and 8 bulls）each group.Calves in groupⅠ（control group）were fed the basis diet,and groupsⅡ,ⅢandⅣ were fed the basis diet supplemented with yeast polysaccharide at the dosage of 1,2 and3 g/d per head,respectively.The experiment lasted for 60 d.At the age of 20 and 60 days,4 calveswere slaughtered in every group.Volatile fatty acid（VFA）,pH,ammoniacal nitrogen（NH3-N）and microbial protein（MCP）contents of rumen liquid were measuered.The results showed as follows：（1） During the whole growth period,there was no significant difference in rumen fluid pH,butyric acid concentration and acetate propionate ratio among the treatment groups（P〈0.05）.（2） At the age of 20 days,the concentration of acetic acid in groupⅢ was extremely significantly higher than that in control group（P〈0.01）,the concentration of propionic acid in groupⅡ was significantly higher than that in control group（P〈0.05）,and the differences of TVFA concentration among all the treatments were not significant（P〈0.05）.At the age of 60 days,the acetic acid concentration of groupⅢ was extremely significantly higher than that in control group（P〈0.01）,and there was no significant difference for the concentration of propionic acid among the four groups（P〈0.05）.The TVFA concentration in groupsⅡ,Ⅲ and Ⅳ were significantly higher than that in control group（P〈0.05）,and the groupⅢ had the highest TVFA concentration.（3） At the age of 20 days,the concentration of NH3-N in group Ⅲ was significantly lower than that in group Ⅰ（P〈0.05）,and the yield of MCP in group Ⅱ was significantly higher than that in other groups（P〈0.05）.At the age of 60 days,the NH3-N concentration had no significant difference among the four groups（P〈0.05）,and the yield of MCP in group Ⅲ was significantly higher than that in other groups（P〈0.05）.These results suggested that adding 2 g/d per head yeast polysaccharide in calves＇ s diets could decrease ruminal NH3-N concentration,increase MCP and TVFA concentrations,which was helpful to enhance the utilization of ammonia and protein in rumen and promote the stability of rumen fermentation in calves.In conclusion,It could be suggested that the appropriate adding amount of calves 0 to 60 days old was 2 g/d per head.