不同浓度黄芩苷对奶牛瘤胃体外发酵参数和养分降解率的影响

Effects of Different Concentrations of Baicalin on in Vitro Rumen Fermentation Parameters and Nutrient Digestibility of Dairy Cows

试验旨在通过体外瘤胃发酵法研究不同的黄芩苷添加剂量对奶牛瘤胃体外产气量、发酵参数、养分降解率的影响。选取3头体重为650±50 kg、安装永久瘘管的荷斯坦奶牛作为瘤胃液的供体动物,试验共分4组(每个时间点各3个重复),黄芩苷的添加浓度分别为0(对照组A)、0.1(试验组B)、1(试验组C)、2 g·kg^(-1)(试验组D),体外发酵2 h、6 h、12 h、24 h、48 h后分别测定产气量、挥发性脂肪酸(VFA)、氨态氮(NH_(3)-N)、pH、干物质(DM)降解率、中性洗涤纤维(NDF)降解率、酸性洗涤纤维(ADF)降解率。结果表明:(1)随着发酵时间的增加,各组产气量呈上升趋势,各试验组各时间点产气量均显著低于对照组A(P<0.05)。(2)添加黄芩苷后,2 h、48 h各试验组发酵底物的干物质降解率显著高于对照组A(P<0.05);6 h、12 h各试验组中性洗涤纤维降解率高于对照组A(P<0.05);2~24 h各试验组发酵底物的酸性洗涤纤维降解率高于对照组A(P>0.05),其中1 g·kg^(-1)浓度的效果最好。(3)在整个发酵周期内各试验组各时间点的pH均高于或与对照组A相近,随着黄芩苷浓度的增加pH有先升高后降低的趋势;发酵12 h试验组C、试验组D的乙酸、TVFA含量均显著高于对照组A(P<0.05),在发酵2 h、12 h试验组B、试验组C的丁酸含量高于对照组A(P<0.05)。(4)发酵48 h内各试验组的NH 3-N含量均低于对照组A(P>0.05)。综上所述,通过各项指标分析比较,在本试验条件下,奶牛体外瘤胃发酵中适宜的黄芩苷添加浓度为1 g·kg^(-1)。

This experiment was conducted to investigate the effects of baicalin concentration on gas production,fermentation parameters and nutrient digestibility of dairy cows by extracorporeal rumen fermentation method.Three Holstein dairy cows(650±50 kg)with permanent fistulas were used as rumen fluid donors.The experiment was divided into 4 groups(3 replicates at every time point),and the supplemental concentrations of baicalin were 0 g·kg^(-1)(control A),0.1 g·kg^(-1)(group B),1 g·kg^(-1)(group C)and 2 g·kg^(-1)(group D),respectively.Gas production,volatile fatty acid(VFA),ammoniacal nitrogen(NH_(3)-N),pH,dry matter(DM)digestibility,neutral detergent fiber(NDF)digestibility and acid detergent fiber(ADF)digestibility were determined after extracorporeal fermentation for 2 h,6 h,12 h,24 h and 48 h,respectively.The results showed as follows:(1)with the increase of fermentation time,the gas production of each group showed an upward trend,and the gas production of each experimental group at each time point was significantly lower than that of the control group A(P<0.05).(2)After adding baicalin,the dry matter degradation rate of fermentation substrate in each test group at 2 h and 48 h was significantly higher than that in control group A(P<0.05);the degradation rate of neutral detergent fiber in each test group at 6 h and 12 h was higher than that of control group A(P<0.05);the degradation rate of acid detergent fiber in each test group was higher than that of control group A(P>0.05)from 2 h to 24 h,with the effect of 1 g·kg^(-1) concentration the most effective.(3)During the whole fermentation cycle,the pH of each experimental group at each time point was higher than or similar to that of the control group A,and with the increase of baicalin concentration,the pH increased first and then decreased.The contents of acetic acid and TVFA in test group C and D were significantly higher than those in control group A(P<0.05),and the content of butyric acid in test group B and C were higher than those in control group A at 2 h and 12 h of fermentation(P<0.05).(4)The NH_(3)-N content of each test group was lower than that of control group A within 48 h of fermentation(P>0.05).In conclusion,based on the above analysis,the optimum supplemental concentration of baicalin in vitro rumen fermentation of dairy cows is 1 g·kg^(-1) under the conditions of this experiment.