Effect Of Organic Selenium On Rumen Fermentation, Anti-oxidation And Immune Function Of Dairy Cows

The experiment was conducted to study the effects of organic selenium on rumen fermentation,anti-oxidation and immune function of dairy cows using in vivo rumianl fermentation test and feeding trial in order to confirm the reasonable dose of organic selenium in diets and to provide theoretical basis for application of organic selenium in dairy farming.The experiments were divided into 3 parts. Experiment 1: Sixteen healthy Holstein dairy cows with similar weight, age, lactation and milk performance were divided into 4 treatment groups (GroupⅠ,Ⅱ,ⅢandⅣ) with 4 replicates in each treatment. Control group (Ⅰ) : 0.3mg Se/kg dry matter as sodium selenite; treat groups (GroupⅡ,Ⅲ,Ⅳ):0.30, 0.60 or 0.90mg Se/kg dry matter as organic selenium(Yeast-Se ).The ruminal fluid samples were collected at the time points of 6h, 12h after feeding, in order to study the effect of organic selenium on ruminal fermentation by determining the pH value,the concentrations of NH3-N,BCP,VFA and Se.Experiment 2 and 3: Twenty eight Holstein dairy cows with familiar body weight, age, lactation and milk production were divided into 4 groups (GroupⅠ,Ⅱ,ⅢandⅣ) with 7 replicates in each treatment in a singal factor assignment . Pre-trial period was 15d, and the experimental period was 60d. The trials were conducted to study the effects of organic selenium on anti-oxidation and immune function of dairy cows.The results showed as followed under the present experimental conditions:1. Adding organic selenium to the diets have no significant effects on pH value, the concentration of acetic acid ,butyric acid, TVFA and C2/C3(P>0.05). But at the time points of 12h after feeding,the concentration of NH3-N in rumen was significantly reduced (P﹤0.05), and the concentration of BCP and propionate acid was significantly increased (P﹤0.05). The selenium concentration in rumen was also increased with the increasement of the addition of selenium to the diets. It was concluded that dietary organic selenium could improve rumen fermentation of dairy cows, and that the addition of 0.60mg/kgDM to the diet had the best effect.2. The dietary organic selenium could increase the selenium concentration in serum and improve anti-oxidation functions of dairy cows. The activity of SOD, GSH-Px,CAT and T-AOC,were increased,and the concentration of MAD was decreased . The effect of the groupⅢ(organic selenium 0.60mg/kgDM) was the best.3. The dietary organic selenium could improve immune functions of dairy cows. The concentrations of IgM, IgG, IgA , sCD4+,sCD4+/sCD8+,IL-1, IL-2 and TNF-a in serum were increased(P<0.05),but the dietary selenium levels have no significant effects on the sCD8+(P>0.05).4. The appropriate dose of organic selenium to the diet in dairy cows was 0.6mg/kg (DM).5. The same dose of organic selenium and inorganic selenium,organic selenium is more effective to improve rumen fermentation,antioxidant function and immune function.