Effects Of Cysteamine Hydrochloride On Rumen Fermentation, Performance And Blood Biochemical Parameters Of Dairy Cows

In this experiment, in situ technique was used to study the effects of difference doses of cysteamine hydrochloride on rumen fermentation, performance and biochemical parameters of mid-lactation Chinese Holstein dairy cows. Forty mid-lactating Holstein cows with similar milk yield, day in milk and parity were used and divided into 5 treatments with a randomized block design. CS, at doses of 0(control),15,30,75 and 150 g/d were reached in the total mixed ration, respectively. The experiment was conducted over a period of 10 weeks, including 2 weeks for adaptation and 8 weeks for data collection. The results were showed as follows:1. Effects of different cysteamine supplementation on rumen fermentation, microprotein synthesis, and bacterial abundance. The results indicated that, rumen pH (6.30-6.69) and acetate concentration were not affected by treatments (P>0.05). Rumen ammonia-N concentration in 75g/d treatment was greater than CON and 15g/d treatment (P=0.001). However, total volatile fatty acid concentration in 75g/d and 150g/d treatments were lower compared with CON and 15g/d treatments (P=0.007), and their A:P ratio were lower than CON and 15g/d, too. Cows fed 15g/d CS had the lowest proportion of propionate (P=0.026) and the highest acetate:propionate ratio (P=0.004), compared with the other treatments. The concentration of protozoa protein (P=0.018) and total microprotein (P=0.041) in the 75g/d treatment were lower than CON. 30-75g/d CS increased the relative abundances of P. ruminicola (P=0.001) and B. fibrisolvens (P<0.001). However,150g/d CS downregulated F. succinogenes, R. albus and R. flavefaciens abundance (P<0.001).2. Effects of different Cysteamine supplementation on nutrition digestibility, production performance,milk quality and milk amino acid of dairy cows. The results showed as follows: The digestibility of CP, Ca, P, NDF and GE in 15g/d treatment were higher than those in the control group (P>0.05). However, decreased tendencys were found in 75g/d and 150g/d groups, and those in the 150g/d group were the lowest. Average daily feed intake (ADFI), milk yield, 4% FCM yield and feed efficiency were the highest in 75g/d group, those indices were the lowest in 150g/d treatment, and milk yield and 4% FCM in the 150g/d treatment were significantly lower than CON and 15g/d treatment(P<0.05). Milk fat percentage and milk total solids percentage were the highest in 75g group, and there were no significant differences between other experimental groups and control group (P>0.05); milk urea nitrogen concentration was decreased with the increase of CSH supplemental level, and 150g group was the lowest.3. Effects of different Cysteamine hydrochloride supplemetation on serum biochemical, enzyme, hormone, antioxidant and immune Indices of dairy cows. The results showed as follows: Comparing with the 150g group,15g group significantly increased the GLB content (P<0.05). It significantly improved the AST concentration in 150g group comparing with the 15g and 30g treatments (P<0.05). Cows fed 15g/d of CSH had higher serum GH and T4 concentration than did cows in the control group (P<0.05); and fed 30g/d had higher GH and T3 concentration (P<0.05). The SOD level decreased with the adding doses (0.05<P<0.1). Furthemore, it significantly increased the GSH-PX concentration in the 15g group comparing with the control group and the 150g group (P<0.05). The MDA level of the 150g group was significantly higher than that of the 15g treatment (P<0.05). The serum IgA、IgG、IL-6、IL10 and cortisol levels of 15-30g/d treatments were increased compared with CON. IgA concentration of the 15-30g/d groups were significantly greater than CON and 150g/d treatment(P<0.05). Besides, The IgG and IL-10 levels of 15g/d were significantly higher than 75-150g/d treatments(P<0.05), and cortisol level of the 15g/d group was higher than 150g/d(P<0.05).Conclusion:The results of this study indicated that 15-30g/d CS supplement could improve rumen fermentation, nutrient digestibility, immune and antioxidant indices levels, as well as lower serum enzyme. However, add more than 75g/d CSH did some said effects. As a result, the safe dose of CSH in dairy cows’ration is less than 75g/d, and the suitable dose of CSH is 15-30g/d. When in terms of the usage results and cost, the best dose is 15g/d.