The Effect of Protein Intake on Body Weight, Scrotal Circumference and Semen Production of Bunaji Bulls and their Friesian Crosses in Nigeria

Abstract Scrotal circumference, body weight and semen production traits of Bunaji (BJ) and Friesian X Bunaji (FR X BJ) bull calves fed isocaloric diets of low and high protein levels were investigated for 16 months. The isocaloric rations (2.40 Mcal ME/kg DM) contained crude protein levels of 14.45% (high protein) and 8.51% (low protein). The bulls were electroejaculated biweekly and, on each occasion, body and scrotal measurements and body condition score were taken. The level of protein was found to have a significant influence on physical body growth and semen production traits. Bulls on high protein rations had significantly larger scrotal circumference, greater body weight, higher average daily gains, and higher body condition score than those on low protein diets. Volume of semen, sperm motility, semen concentration and total spermatozoa were significantly ( P The FR X BJ achieved higher average daily gains, higher body weights, larger scrotal circumference, higher sperm concentration and total spermatozoa than BJ. There were no significant breed differences in condition score, volume of semen and sperm motility. Body and scrotal size and semen production traits increased significantly with age. Adequate protein intake and good management of young selected sires at breeding centres are essential for optimum sperm cell production.