添加不同水平单宁酸对绵羊体外发酵参数和甲烷产量的影响

Effects of Adding Different Levels of Tannic Acid on Rumen Fermentation Parametersand Methane Production of Sheep in Vitro Method

本试验以精料、青干草和单宁酸作为发酵底物,研究添加不同水平单宁酸对绵羊体外发酵参数和甲烷产量、干物质和粗蛋白质降解率的影响,以期为体内试验筛选适宜的单宁酸浓度,为富含单宁的粗饲料资源应用于反刍动物日粮配制及减少反刍动物养殖过程种甲烷排放提供科学依据。采用体外批次培养法开展研究,发酵底物为精料、青干草和单宁酸,设置底物的精粗比为3∶7。根据单宁酸添加量分为6组,单宁酸添加量分别为0、0.5%、1.0%、1.5%、2.0%、3.0%,发酵时间设置为3、6、12和24 h,每个处理3个重复,测定各培养时间pH、氨氮(NH3-N)浓度、挥发性脂肪酸(VFA)浓度、总产气量、甲烷产量、干物质和粗蛋白质降解率。结果显示,培养至3 h时,1.0%和2.0%单宁酸添加组pH显著高于对照组(P<0.05),其他时间点各组pH无显著差异(P>0.05);1.0%、2.0%和3.0%单宁酸添加组NH3-N浓度显著低于对照组(P<0.05);培养至6和24 h时,各处理组NH3-N浓度均显著低于对照组(P<0.05)。培养至6 h时,2.0%单宁酸添加组乙酸、丙酸、丁酸和总VFA浓度均显著低于对照组(P<0.05);培养至24 h时,1.0%、1.5%和3.0%单宁酸添加组的丙酸、丁酸和总VFA浓度均显著低于对照组(P<0.05);各单宁酸添加组4个时间点丙酸、丁酸、总VFA浓度的平均值均显著低于对照组(P<0.05)。培养至12、24 h时,各处理组总产气量与对照组差异不显著(P>0.05);培养至12 h时,2.0%组甲烷产量显著低于对照组、0.5%组和1.0%组(P<0.05);培养至24 h时,2.0%和3.0%组的甲烷产量显著低于对照组(P<0.05)。因此,添加单宁酸会显著降低体外发酵的NH3-N浓度,抑制VFA的产量,添加1.5%、2.0%的单宁酸能够显著降低瘤胃发酵甲烷产量,添加单宁酸的处理组粗蛋白质降解率显著低于对照组。

In this experiment,concentrate,hay and tannic acid were used as fermentation substrates to investigate the effects of different levels of tannic acid on in vitro fermentation parameters,methane production,the degradation rate of dry matter and crude protein in sheep,in order to screen out the optimal concentration of tannic acid,and as a theoretical basis for untilization of tannic acid-rich roughage resources apply to dietary formulation and reducing methane emission in the process of ruminate farming.Batch culture in vitro was used for this study,the fermentation substrate was concentrate,hay and tannic acid,and the ratio of concentrate to roughage was 3∶7.The supplertation level of tannic acid was 0,0.5%,1.0%,1.5%,2.0%and 3.0%,respectively,the fermentation time was set at 3,6,12 and 24 h,three replicates were set for each treatment.The pH,the concentration of ammonia nitrogen(NH3-N)and volatile fatty acid(VFA),total gas production,methane production and the degradation rate of dry matter and crude protein were determined.The results showed that pH in 1.0%and 2.0%tannic acid groups was significantly higher than that in control group at 3 h(P<0.05),and there was no significant difference between all groups at other time points(P>0.05).The concentration of NH3-N in 1.0%,2.0%and 3.0%tannic acid groups was significantly lower than that in control group at 3 h(P<0.05),more over the concentration of NH3-H in each treatment group was significantly lower than that in control group at 6 and 24 h(P<0.05).The concentration of acetic acid,propionic acid,butyric acid and total VFA in 2.0%tannic acid group was significantly lower than that in control group at 6 h(P<0.05),the concentration of propionic acid,butyric acid and total VFA in 1.0%,1.5%and 3.0%tannic acid groups were significantly lower than that in control group at 24 h(P<0.05),the average concentration of propionic acid,butyric acid and total VFA in each tannic acid adding group was significantly lower than that in control group at 3,6,12 and 24 h(P<0.05).There was no significant difference in total gas production among each group at 12 and 24 h(P>0.05).The methane production in 2.0%tannic acid group was significantly lower than that in control,0.5%and 1.0%tannic acid groups at 12 h(P<0.05).The methane production in 2.0%and 3.0%tannic acid groups were significantly lower than that in control group at 24 h(P<0.05).In conclusion,the addition of tannic acid could significantly reduce the concentration of NH3-N in vitro fermentation and inhibit the production of VFA,the addition of 1.5%and 2.0%tannic acid could significantly reduce the rumen methane production in vitro,the degradation rate of crude protein in the treatment group with tannic acid was significantly lower than that in control group.