Classification of the potential breeding ability of range beef bulls based on semen quality parameters in samples collected by transrectal massage--a comparison of the Swedish and Canadian systems.

ABSTRACT

This experiment was conducted to compare the accepted Field system of bull breeding soundness evaluation (BBSE) utilized by veterinarians in Canada with the centralized Swedish (Lab) system. To be classified as a satisfactory potential breeder, both systems require that bulls must have ≥70% morphologically normal sperm; however, minimum progressively motile sperm (≥60% - Field; ≥30% - Lab) and maximum sperm class abnormalities proportions differ (<20% - Field; <15% - Lab). Semen was collected by transrectal massage (TM) from 54 sexually mature beef bulls. The percent progressively motile sperm was determined within minutes of collection and these data were shared. Sperm morphology was evaluated independently utilizing slide staining and microscopic assessment techniques typically used for the evaluation of bull semen within the respective countries. Mean progressively motile sperm was 45% (±23.8%). The mean proportion of normal sperm recorded in the Field (83.6±12.1%) was greater than the Lab (71.1±18.2%) (P<0.001) with more sperm head abnormalities recorded in the Lab (13.6±11.4) than the Field (2.4±2.8) (P<0.01). The number of bulls exceeding the ≥70% morphologically normal sperm was 51 (94.4%) in the Field versus 36 (66.7%) in the Lab (kappa=0.21). Only 13 bulls were classified as satisfactory potential breeders by both systems (kappa=0.15). Efforts to improve and standardize the evaluation of bull sperm morphology are needed, and the use of ≥30% progressively motile sperm threshold for TM-derived samples is recommended.