Local agro-industrial by-products offer feasible options to supplement breeding rams in mixed farming systems of Ethiopia

This study assessed the supplemental effect of flushing Menz breeding rams with local agro-industrial by-products on their reproductive performance and semen quality. In a completely randomized design, rams (n = 49) with an initial weight of 25.69+2.8 kg and average age of 18.79±3.9 months were allocated to seven treatments with seven replicates. Supplementation consisted of varying combinations of metabolizable energy (7.02, 8.14, 9.91 MJ ME/kg DM) and crude protein (CP) (8.17 and 12.5 %) levels above the basal diet (pasture grazing). The experimental treatments were control, T0 (8 h of free grazing in natural pasture and fallow lands providing 4.7 MJ/Kg metabolizable energy and 6.65 CP) supplemented with T1 (500 g oats grain), T2 (500 g maize bran), T3 (500 g wheat bran), T4 (300 g oat grain +150 g broken lentil grain), T5 (300 g maize bran + 150 g broken lentil grain), T6 (400 g wheat bran). Supplementation significantly (P < 0.05) improve body condition score, scrotal circumference, semen ejaculation volume, spermatozoa concentration, and predictive potential of rams to serve ewes. Notably, all variables within the supplemented groups showed no significant differences (P > 0.05), except for scrotal circumference, where T1 and T3 showed a greater increase (P < 0.05) compared to other treatments. High and positive correlations (r = 0.89) between scrotal circumference and volume of semen were observed. Semen volume and concentration correlated positively (r = 0.7 and r = 0.9 respectively) with the rams’ potential to serve ewes. It is concluded that the reproductive activity of Menz rams is influenced by their nutritional state. Agro-industrial by-products can supply adequate protein and energy levels to enhance reproductive potential of rams. The studied agro-industrial by-products are relatively inexpensive and easily accessible compared to commercial concentrates. Hence, based on the cost-effectiveness of supplementary feed used; it is recommended that T3 and T6 wheat bran-based supplementation strategies be employed to enhance the reproductive performance, semen quality, and the potential of Menz rams to serve ewes. Further research is needed to evaluate how different seasons affect the levels of protein and energy supplementation required for ram flushing.