Causes of rejection of beef bulls in breeding soundness evaluation

Abstract

-The objective of this study was to analyze the rates of rejection in the different steps of the breeding soundness evaluation of beef bulls in the state of Rio Grande do Sul, Brazil. The breeding soundness of 22,113 young and mature bulls of 14 beef breeds, participating in the Program of Reproductive Evaluation (PARTO) was evaluated in the experiment.Data concerning to the causes of rejection in the four steps of the breeding soundness evaluation (general physical examination, genital tract examination, semen evaluation and sexual behavior assessment) were analyzed by the Chi-square test and univariate regression analysis. According to year, general physical examination, genital tract examination and semen evaluation determined the rejection of 0.9% to 2.5%, 5.1% to 7.7%, 1.8% to 5.3%; and 4.2% to 6.7%, 7.3 to 9.3%, and 2.5% to 5.5% of young and mature bulls, respectively. Mature bulls presented higher chances of rejection than young bulls in the general physical examination in every year evaluated; as to the genital tract examination, their chances of rejection were higher in years I and II, but not in year III. In the semen evaluation, there was no difference between the ages assessed in any of the three years evaluated. Sexual behavior assessment accounted for the rejection of 1.9 to 6.0% of the young bulls and 2.9% to 3.9% of mature bulls, in accordance with the years evaluated; in years I and II, mature bulls presented higher rejection rates than young bulls. These results confirm the importance of performing all steps of the breeding soundness evaluation, including the sexual behavior assessment as a work routine, rather than an additional, optional stage of the evaluation, which should be carried out before the breeding season. The results indicate the relationship between bull age and rejection rate in the breeding soundness evaluation.

An assessment of dairy herd bulls in southern Australia: 1. Management practices and bull breeding soundness evaluations

“…Our observed premating prevalence of high-risk status, 19.5%, fits in to the observed range seen in studies of beef bulls, where 6 to 33% of bulls were classified as high risk or unsatisfactory (Elmore et al, 1975;Bruner et al, 1995;Acuña and Campero, 1999;Chacón et al, 1999;Kennedy, 2002;Waldner et al, 2010;Menegassi et al, 2012). Those studies came from widely varied geographical locations and farming systems, with differences in the guidelines used for classification of breeding soundness.…”

“…As the serving ability component of the BBSE was not performed in our study, it is likely that the premating prevalence of high-risk status would have been even higher had it been undertaken. In one study, 3 to 5% of bulls were rejected based on serving capacity test (Menegassi et al, 2012). McDiarmid (1981) reported that 15% of bulls were poor performers in a serving capacity test due to spiral deviation (46%), flaccid or injured penises (10%), locomotor system abnormalities (10%), and low serving capacity (34%).…”

Reproductive success or failure in four breed groups of beef bulls

“…The failure rates of the breed groups increased with age, as reported by other researchers, even when they considered breeds rather than genetic groups (Blockey, 1984;Acuña and Campero, 1997;Gottschall and Mattos, 1997;Cumming, 2003;Menegassi et al, 2012).…”

An assessment of dairy herd bulls in southern Australia: 2. Analysis of bull- and herd-level risk factors and their associations with pre- and postmating breeding soundness results

“…et al, 1973;Bagshaw and Ladds, 1974), as well as the prevalence of histological degenerative changes in the testes (Humphrey and Ladds, 1975). The effect of age on BBSE results also varies, with studies reporting increasing numbers of rejections with age (McCosker et al, 1989;Menegassi et al, 2012), and no change in BBSE result with age (Chacón et al, 1999;Waldner et al, 2010).…”