Effects Of Organic Selenium On Milk Performance And Nutrient Digestion And Blood Biochemical Indicators Of Dairy Cow

This experiment was conducted to study the effects of organic selenium on milk performance and nutritient digestion and blood biochemical indicators of dairy cows, and furthermore, to study influence mechanism of organic selenium on milk performance and to. provide theoretical basis and technical guidance for scientific applications of organic selenium in dairy production.The experiment was divided into 3 parts. 28 healthy Holstein cows in mid lactation were selected according to similar age,weight,lactation period,milk yield and physiological status,and these cows were randomly blocked into four groups with 7 replicates in each treatment in trials 1 to 3. In group 1 as control group, based in diets add 0.3 mg/Kg (DM) diet is the inorganic selenium (se source for sodium selenite), 2, 3, 4 groups for organic selenium respectively of group 1, organic selenium two groups and organic selenium 3 groups, namely in the basic diet add 0.3, 0.6 and 0.9 mg/Kg (DM) diet is the and the ratio of concentration to forage was 48:52. Pre-trial period was 15 d and the experimental period was 60 d. These trails were conducted to study the effects of organic selenium on milk performance and nutrition digestion and blood biochemical indicators of dairy cows. Under the present experimental conditions,the results showed as follows:1. The dietary organic selenium influenced the milk products in quadratical dose-dependent manner(P < 0.05).2. There were no significant differences in milk products and milk ingredients between organic selenium group and inorganic selenium group (P > 0.05), but organic selenium group had a intendence to be increased in milk production compared with the inorganic selenium group There were no significant differences in milk ingredients among organic selenium groups of cows (P > 0.05).3. Organic Se could obviously increase milk selenium and blood se-content compared with inorganic Se (P < 0.0001),and with the addition of dietary organic selenium, milk selenium and blood se-contents were increased in a significant linear or quadratical dose-dependent manner(P<0.05).There was a significant and strong positive correlation.between milk selenium content and blood selenium content (P = 0.9847, r = 0.9594).4. Organic selenium compared with inorganic selenium, could significantly impove the digestibility of EE (P < 0.0001), and also slightly improve digestibility in NDF, CP, Ca, P and selenium (P > 0.05). With the supplementation of dietary organic selenium, nutrient digesttibility of dairy cows enhanced in quadratical dose-dependent manner(P<0.05). According to many indexes, the addition of 0.6 mg/Kg (DM) organic selenium to the diet had the best effect, and the addition of 0.9 mg/Kg (DM) organic selenium to the diet had the worst effect.5. Organic selenium compared with inorganic selenium,had a increase tendency in serum GH, IGF - 1, T3,and T4, PRL and INS ,NEFA and G concentrations, but no significant differences existed(P > 0.05). All of these indicators increased in quadratical increase dose-dependent manner(P<0.05) with the addition of organic selenium to the diets of dairy cows.6. According to the many indicators, adding 0.6 mg/kg(DM) organic selenium to the diet would have better effect.