Document Type : Research Paper
Former M.Sc. Student , Animal Science Department, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran
Associate Professor, Animal Science Department, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran
Assistant Professor, Animal Science Department, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
The present experiment was designed to evaluate the efficiency of the slow-release bolus containing different selenium levels on performance and some blood and milk parameters of Lori Bakhtiari ewes. For this purpose, 45 ewes were divided into three groups (15 in each). Treatments were: 1) control ewes; 2) ewes receiving 0.2 milligrams of selenium per day; and 3) ewes receiving 0.4 mg selenium per day. On the first day of the experiment, all ewes received CIDR and the boluses were fed to the different groups on the same day. During the feeding period the ewes were grazed on the pasture. Blood samples collected from all ewes at 76 days post-mating (mid-gestation) and 30 days postpartum before going to rangeland. The results showed that birth weight, weight at two months of age, average daily gain, milk production, fat content, protein content, non-fat solids content in milk and milk selenium concentration were higher in the groups receiving selenium than the control (P<0.05). Milk production of ewes receiving 0.4 mg selenium per day was higher than those of receiving 0.2 mg selenium per day (P <0.05). Serum selenium and triiodothyronine concentration and blood glutathione peroxidase activity in ewes receiving different levels of selenium were higher than those of control (P<0.05). Overall, both levels of selenium improved the performance of the lambs and some of the blood and milk parameters of the ewes, but the use of 0.40 mg Se/day due to higher milk production is recommended.