RESUMEN
Although semen quality is one of the major traits that influence breeding soundness examination outcomes in bulls, field conditions occasionally do not allow for the collection of semen samples by means of an artificial vagina. The aims of the present study were to report the results of a large number of semen collections that were performed via the transrectal massage (TRM) of the accessory sexual glands of Italian yearling beef bulls and compare this semen collection method to the artificial vagina (AV) method in term of breeding soundness examination outcomes; furthermore, we determined whether the breed affected the semen characteristics. In the TRM group (n = 475), the semen samples were collected via TRM of the accessory sexual glands, and in the AV group (n = 502), the AV method was used. In the TRM group, semen samples were obtained from 81.3% of the bulls and penile protrusion was observed in 87.6% of the animals during semen collection. The sperm concentrations (920.5 ± 439.0 vs. 281.0 ± 259.8 × 10(6)/mL) and the percentages of total abnormal spermatozoa (22.8 ± 15.0 vs. 18.8 ± 12.9) were significantly higher in the AV group than those in the TRM group. The percentage of bulls that did not meet the minimum requirement for normal cells (≥70%) was 6.2% higher in the AV group than that in the TRM group (P < 0.05). Moreover, the samples collected from Chianina bulls by TRM exhibited a lower percentage of motile sperm and a higher percentage of abnormal spermatozoa when compared with the other two breeds. The major drawbacks of the TRM technique were the inability to conduct complete evaluation of the libido and mating ability of the yearling bulls, a significant reduction of the number of spermatozoa collected, and an increase in the variability of the semen characteristics due to breed. In conclusion, despite the drawbacks, TRM guarantees that semen evaluation can be conducted in cases in which the semen samples cannot be collected with the AV method.
Asunto(s)
Bovinos/fisiología , Eyaculación/fisiología , Estimulación Física , Recuento de Espermatozoides/veterinaria , Espermatozoides/anomalías , Recolección de Tejidos y Órganos/veterinaria , Animales , Masculino , Cabeza del Espermatozoide , Motilidad Espermática , Espermatozoides/fisiología , Recolección de Tejidos y Órganos/métodosRESUMEN
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.