Effects Of Thiamin On The Rumen Microbial Fermentation And Parameters In Holstein Dairy Cows

In this experiment, with the method of combining in vitro and in vivo, two Holstein dairy cows equipped with rumen cannula were used for providing rumen fluid. In vitro, the study was used to investigate influence of thiamin on the rumen fermentation and parameters under different dietary type adding thiamin; in vivo, four cows were induced subacute ruminal acidosis (SARA) by feeding concentrate daily in gradually increasing feeding regime. In this process, cows were fed thiamin into diets and to investigate influence of thiamin on the internal environment and metabolism of rumen. The main proposal wae to search the reasonable amount of thiamine additives and provide a theoretical reference for the current high intensity of the cows fed. And the dissertation was described in the following3sections.Experiment one:The objective of this part was to determine the effects of thiamin on the rumen fermentation parameters under the condition of regular diet. The in vitro culture was conducted using pectins、xylan、wheat starches、soluble starches、milled filter paper、 carboxymethyl cellulose and casein as substrates, by adding thiamin of20mg/kg、40mg/kg、60mg/kg、80mg/kg in culture medium respectively, and without thiamin as control group. The concentrate/forage ratio is4:6. The results show that there were no significant differences in pH among five treatments of thiamin but there was a rasing tendency. With the addition of thiamin increasing, NH3-N concentration in culture fluid was ascendant; the concentrations of acetate and TVFA were decreased. It was found that thiamin increased the concentrations of propionate、 butyrate. Additionlly, thiamin could increase bacterial protein production and decrease protozoa protein production.Experiment two:the effect of thiamin on the rumen fermentation parameters under high-concentrate diet was investigated in vitro. The in vitro culture was same as in part one. and the concentrate/forage ratio is6:4. The experimental results show that pH in culture fluid increased in case high-concentrate diet when adding thiamin; NH3-N concentration in culture fluid decreased when adding thiamin; Thiamin decreased ruminal protozoal protein yield whereas the yield of ruminal bacterial protein was increased, the concentrations of propionate and butyrate was increased, the concentrations of acetate and TVFA were decreased. as well as the lactate decreased when adding thiamin. Effect of fermentation is the optimum corresponding with180mg/kg thiamin addition.Experiment three:A study was conducted to determine the effect of thiamin on rumen fermentation parameters in the process of inducing subacute ruminal acidosis in dairy cows. Four latating cows with permanent ruminal cannulas were fed suecessively four kind of diets with different concentrate/forage ratio,4:6、5:5、6:4and7:3during the40-day meansurement period, respectively. In this block experiment, cows were randomLy divided into two groups, animals were fed with the thiamin additive of180mg/kg in test group and fed without additive in control group. The results showed that thiamin increased pH during the whole process. Compared to the control group, the concentrations of lactate、acetate、butyrate and TVFA were decreased, the concentrations of propionate was increased. To a certain extent,adding the level of thiamine of180mg/kg can suppress subacute ruminal acidosis.