Effect of Age and Breed on Semen Quality and Breeding Soundness Evaluation of Pre-Service Young Bulls

This study was conducted at the National Artificial Insemination Center, Ethiopia with an objective of evaluating breeding soundness, effect of age and breed on semen quality and fertility of bulls. The evaluation involved 45bulls (36 breeding and 11 pre-service young bulls) consisting of Holstein Friesian, Jersey, Borana and Cross breeds (Borana X Holstein Frisian). Semen was collected using artificial vagina and the raw ejaculates were evaluated for gross and microscopic parameters. The overall mean (±SD) of libido, volume, concentration, mass motility, preand post freezing motilities of the breeding bulls were 3±0.0, 7.71±2.4ml, 1.03±0.3bill/ml, 3.47±0.5, 78.35±4.2% and 55.98±5.9%, respectively. Borana bulls produced small volume but highly concentrated semen with the highest mass motility of sperm (p<0.001) whereas Holstein Friesian bulls produced the largest volume. Pre-freeze motility of sperm was lowest in crosses (p<0.05) than other breeds. The mean (±SD) scrotal circumference was 34.5±1.7cm with a relatively higher percentage of dead sperm (34.2±19.5%) in the pre-service young bulls. Both breed and age were known to be important factors influencing semen parameters. A rigorous selection of pre-service bulls for artificial insemination program will do away age related defects in the semen while breed attributes can be used to individualize semen evaluation procedures.