Effect of nutritional state on semen characteristics, testicular size and serum testosterone concentration in Sanjabi ram lambs during the natural breeding season

This experiment was conducted to investigate the effect of plane of nutrition on body weight, average daily gain, dry mater intake, semen characteristics, serum testosterone concentration and testicular circumference of Sanjabi ram lambs during the natural breeding season. Sanjabi ram lambs (n=20) that were 8 months of age were penned under natural photoperiod at latitude 34°18′N for a period of 9 months. The control group (C, n=10) received a diet consisting of 80% alfalfa and 20% concentrate, providing 2.18Mcal metabolizable energy and 130.0g/kg DM crude protein, whereas, treatment group (T, n=10) was fed with 65% alfalfa and 35% concentrate, providing 2.34Mcal metabolizable energy and 160.0g/kg DM crude protein. Body weight, additive daily gain and feed intake in T group were significantly greater than those obtained in C group. Body weight and testicular circumference increased at a steady rate throughout the experiment. All semen variables (except percentage of abnormal sperm and semen pH), serum testosterone concentration and testicular circumference were positively influenced by nutritional state (P