VN April 2021

Vetnuus | April 2021 36 Recent Clinically Relevant Research from Around theWorld FARMANIMALS Scrotal circumference at weaning in beef bulls and subsequent ability to pass a breeding soundness examination as a yearling The objective of this study by Tara Fountain and co-workers was to evaluate the effect of weaning scrotal circumference and other factors collected at the time of weaning on the likelihood of passing a breeding soundness examination as a yearling. Identifying bulls at weaning withhigher likelihoodof passingabreeding soundness examinationas yearlingsmay improvemanagement options tooptimiseproduction efficiency. Data, at both weaning and time of breeding soundness examination, were collected from 1 operation (n = 466 bulls). A logistic regression model was used to evaluate the potential associations of relevant factors (actual weaning scrotal circumference, adjusted weaning scrotal circumference, weight per day of age at weaning, scrotal circumference per day of age at weaning, weaning weight, and breed) on the probability of passing a breeding soundness examination as a yearling. Overall, 92.3% of bulls passed the yearling breeding soundness examination on first evaluation.Weaning scrotal circumference was the only factor of those evaluated associated (P < 0.01) with the probability of passing the breeding soundness examination. No significant differences were found between the categories of weaning scrotal circumference. In the future, more research needs to evaluate predictive model development for weaning scrotal circumference and ability to pass breeding soundness examination. v The primary objective of this study by Miles Theurer and co-workers was to compare different gamithromycin post-treatment intervals (PTI) on clinical health outcomes in cattle naturally affected with bovine respiratory disease (BRD). Eight hundred cattle identified with BRD by pen riders, rectal temperature ≥ 104.0°F (≥ 40°C), and no previous treatments were randomized in a 1:1:1:1 ratio to 3-, 6-, 9-, or 12-day PTI within each lot. Cattle treated for BRD were returned to their home pen, and followed Comparison of gamithromycin post- treatment intervals for beef cattle naturally affected with bovine respiratory disease (Source: Bovine Practitioner) for 60 days (d) to monitor subsequent health outcomes. Cattle were categorised by type (dairy-beef or native). General and generalised linear mixedmodels were used for statistical analyses. First treatment success (P = 0.012) and BRD case fatality risk (P = 0.032) were different among PTI groups. The 9-d PTI group had the greatest first treatment success, which was different (P = 0.008) than the 3-d PTI. The 12-d PTI group had the poorest BRD case fatality risk, which was different (P = 0.071) than the 9-d PTI group. There were no significant differences between the 6- and the 9-d PTI groups. Dairy-beef cattle had an approximately 2-fold higher BRD case fatality risk (P = 0.012) than natives. Results will help practitioners to optimally use gamithromycin in the field. v