Semen characteristics and testosterone profiles of Yankasa rams fed graded levels of dietary protein using cotton seed and palm kernel cakes

The increasing demand of the feed market for protein has necessitated the need to look for and use other sources of this nutrient. Cottonseed cake and palm kernel cakes are used extensively for supplementing ruminant rations to increase their productivity. The efficiency of sperm production, libido and quality of spermatozoa tend to remain uniform throughout the reproductive life of an animal but may be significantly altered by nutrition. The aim of this study was to assess the effects of graded levels of protein on semen characteristics, and serum testosterone profile in Yankasa rams. Fifteen rams aged between 18–24 months and weighing 15–25 kg with good body condition scores (3.5) were used in this study. They were divided into three treatment groups (A, B and C) according to the dietary protein level. Group A (n = 5) received 10 %, group B (n = 5) received 15 % while group C (n = 5) received 20 % combined crude protein of cotton seed and palm kernel cakes, respectively. Semen samples were collected weekly using battery-controlled electro ejaculator. Serum samples were harvested using a Pasteur pipette into serum vials and stored at −20 °C for analysis. These samples were from a representative animal in each group for determination of testosterone profiles using ELISA technique at weeks 1, 6 and 12. Data collected were expressed as means and standard error of the mean (± SEM). Significance of differences between treatments means were estimated at P ≤ 0.05 with Tukey-Kramer multiple comparison test of repeated measures analysis of variance (ANOVA). From this study, it was concluded that rams fed concentrate of 15 % crude protein using cotton seed and palm kernel cakes combined had improved semen characteristics in terms of semen concentration, motility, live sperm cells and morphology, but the crude protein levels had no effects on testosterone concentrations.