外源纤维素酶对断奶羔羊瘤胃体外发酵特性的影响

Effects of Exogenous Cellulose on in Vitro Rumen Fermentation Characteristics of Weaner Lambs

本试验旨在研究外源纤维素酶对断奶羔羊瘤胃体外发酵参数及消化酶活性的影响。采用单因素完全随机试验设计,在精料中分别添加0(CON组,作为对照)、280 000(T1组)、300 000(T2组)、320 000 U/kg纤维素酶(T3组),按照精粗比为36.45∶63.55制成基础饲粮作为发酵底物,分别测定在不同发酵时间(0、1、2、4、8、12、24、48和72 h)的干物质降解率、发酵参数及消化酶活性。结果表明:与CON组相比,T2组干物质降解率、微生物蛋白浓度显著升高(P<0.05),氨氮浓度显著降低(P<0.05),但处理和发酵时间对上述指标无显著互作效应(P>0.05)。随着发酵时间的延长,DMD呈现逐渐升高趋势,NH3-N和MCP浓度变化趋势相反,NH3-N浓度在发酵2、8 h时出现峰值,而MCP浓度在发酵2、8 h时出现谷值。处理和发酵时间对各挥发性脂肪酸浓度及乙丙比均无显著影响(P>0.05),但T2组总挥发性脂肪酸浓度显著高于CON组(P<0.05),处理和发酵时间对上述指标均无显著的互作效应(P>0.05)。T2组α-淀粉酶、纤维素酶活性均显著高于CON组(P<0.05),且处理和发酵时间对α-淀粉酶活性有显著的互作效应(P<0.05)。随着发酵时间的延长,各组α-淀粉酶活性呈现波动变化趋势,在发酵4、12 h出现峰值,在发酵2、8、24 h时出现谷值;蛋白酶活性在发酵前4 h呈逐渐降低趋势,之后呈现波动变化趋势;T3组纤维素酶在发酵4 h低于其他组,T2组在发酵8 h高于其他组,T1组在发酵24 h低于其他组。综上所述,精料中添加300 000 U/kg外源纤维素酶能够提高断奶羔羊饲粮体外DMD,促进体外瘤胃发酵,增强MCP的合成,提高NH3-N的利用率,并能提高纤维素酶、α-淀粉酶活性,但对蛋白酶活性无显著影响。

This study aimed to observe the effects of exogenous cellulose on in vitro rumen fermentation param⁃eters and digestive enzyme activities of weaner lambs.A single⁃factor experimental design was used in this study.Exogenous cellulose was supplemented in concentrate at the levels of 0(CON group,as control),280000(T1 group),300000(T2 group)and 320000 U/kg(T3 group),respectively.According to the forage⁃concentrate ratio of 36.45∶63.55,basal diets were formulated and used as fermentation substrates,and the dry matter degradability(DMD),fermentation parameters and digestive enzyme activities were measured after fermented different time(0,1,2,4,8,12,24,48 and 72 h).The results showed as follows:com⁃pared with the CON group,the DMD,microprotein(MCP)concentration of T2 group was significantly in⁃creased(P<0.05),and the ammonia nitrogen(NH3⁃N)concentration was significantly decreased(P<0.05),but the treatment and fermentation time had no significant interaction on above indices(P>0.05).With the fer⁃mentation time extension,the DMD was gradually increased,the change tendency of NH3⁃N and MCP concen⁃trations was opposite,NH3⁃N concentration reached peak values at 2 and 8 h after fermentation,but MCP con⁃centration reached valley values at 2 and 8 h after fermentation.Treatment and fermentation time had no signifi⁃cant effects on each volatile fatty acid(VFA)concentration and acetate/propionate(A/P),but total VFA concentration of T2 group was significantly higher than that of CON group(P<0.05),moreover,the treat⁃ment and fermentation time had no significant interaction on above indices(P>0.05).Theα⁃amylase and cel⁃lulose activities of T2 group were significantly higher than those of CON group(P<0.05),and the interaction of treatment and fermentation time onα⁃amylase activity was significant(P<0.05).With the fermentation time extension,theα⁃amylase activity of each group showed a fluctuation change tendency,it reached peak values at 4 and 12 h and valley values at 2,8 and 24 h after fermentation.The protease activity was gradually de⁃creased at 0 to 4 h after fermentation,and then it fluctuated.For cellulose activity,T3 group was lower than other groups at 4 h after fermentation,T2 group was higher than other groups at 8 h after fermentation,T1 group was higher than other groups at 24 h after fermentation.In summary,supplementation of 300000 U/kg exogenous cellulose in the concentrate can improve the in vitro DMD of diet,enhance the synthesis of MCP,increase the utilization of NH3⁃N,and increase the activities ofα⁃amylase and cellulose,but do not affect the protease activity of weaner lambs.[Chinese Journal of Animal Nutrition,2020,32(6):2911⁃2920]