Comparison effects of different selenium sources in cottonseed rich diets on digestibility of the diet, performance and hematological parameters of lactating dairy cows

This study was conducted to investigate the effects of different selenium sources on performance, hematological parameters and nutrient digestibility in the diets supplemented with whole cottonseed in Holstein dairy cows. Twelve Holstein dairy cows with average milk production of 40±4kg were used in merged incomplete latin squares design with 4 treatments and 3 repeat for each treat were used. The experiment was conducted in 3 periods of 28 days and 4 treatments including; 1 (basal diet containing 20% cottonseed, without selenium supplement), 2 (basal diet+ 0.3 ppm inorganic selenium, as sodium selenite), 3 (basal diet+0.3 ppm organic selenium, as selenised yeast) and 4 (basal diet+0.3 ppm Nano selenium). In the first and the last days of each period weight, body condition score, feed intake were determined and milk, feed, faces and blood samples were collected. The results showed that however different selenium sources supplementation did not effect on dry mater intake, the final body weight, weight changes, body condition score, blood hematologic parameters and crude protein digestibility (P>0.05), but in contrast Nano and organic selenium significantly increased the digestibility of other nutrients, milk production, 4% fat corrected milk and amount and percentage of milk fat and protein and SSC (P<0.05). Overall, the current results showed that supplementation with 0.3 ppm selenium, especially from organic and nano sources, to the diet containing high levels of unsaturated fat sources increased nutrients digestibility and consequently milk production.