不同碘添加水平对牦牛瘤胃体外发酵的影响

本试验旨在研究饲粮中添加碘酸钙对牦牛瘤胃体外发酵的影响。以碘酸钙作为添加形式,以牦牛饲粮为底物进行体外瘤胃发酵,底物碘含量分别为0.1、0.3、0.5、0.7、0.9 mg/kg,发酵48h,测定发酵后的产气量、瘤胃发酵指标及消化酶活力。结果表明:当底物碘含量为0.3mg/kg,NH_3-N浓度、微生物蛋白质(MCP)含量、脂肪酶(LPS)活力、胰蛋白酶(TYS)活力、纤维素酶(CLS)活力达到最大值,分别为14.267 mg/100mL、4.619g/L、0.462U/mL、65.463U/mL、69.527U/mL,碘含量为0.3mg/kg时,乙酸(aceticacid)、丙酸(propionicacid)、总酸(TVFA)浓度达到最高值,分别为:56.142mmol/L、30.877mmol/L、87.460mmol/L,各组之间差异均不显著(P>0.05),乙酸与丙酸的比例达到最小值1.819,显著低于其它所有组乙酸与丙酸的比例(P<0.05);在底物碘含量为0.5mg/kg时,淀粉酶(AMS)活力与纤维素酶(CLS)活力达到最大值分别为1.832U/mL、69.527U/mL;在底物碘含量为0.7mg/kg时,总产气量与甲烷产量达到最大值分别为80.8mL、11.88mL。综合以上结果,在体外条件下,在底物碘含量为0.3～0.7mg/kg时,有利于瘤胃发酵和饲草料降解。

Effects of different Iodine addition level on rumen fermentation in Vitro in yak

This study was to investigate the effect of calcium iodine content in dietary on rumen fermentation in vitro of yaks. Rumen fermentation in vitro was carried out with calcium iodine as additive and yak diet as substrate.. The iodine content of the substrate was 0.1, 0.3, 0.5, 0.7, 0.9 mg/kg respectively, the gas production volume, rumen fermentation index and digestive enzyme activity were determined after 48h. The results showed that while the content of iodine in substrate was 0.3mg/kg,the concentrations of NH 3-N,content of microbial protein (MCP),activity of lipase(LPS),trypsin(TYS),cellulose(CLS) reached the highest,which were14.267mg/100mL,4.619g/L,0.462U/mL,65.463U/mL,69.527U/mL respectively, acetic acid,propionic acid and total volatile fatty acid (TVFA) reached the highest,which were 56.142 mmol/L,30.877 mmol/L,87.460 mmol/L respectively,there was no significant difference between the groups ( P >0.05);The ratio of acetic acid to propionic acid reached the minimum value of 1.819, which was significantly lower than that of all other groups ( P <0.05).When the iodine content was 0.5 mg/kg, the activity of amylase (AMS) and cellulose(CLS) reached the highest,which were 1.832U/mL,69.527U/mL respectively;When the iodine content was 0.7 mg/kg, the total gas production and methane production reached the highest,which were 80.8mL、11.88mL respectively. It was concluded that when the iodine content of Yak fodder is between 0.3 mg/kg and 0.7mg/kg under in vitro condition, which is help to rumen fermentation and forage degradation.