Center for Animal and Human Health in Appalachia, Lincoln Memorial University, Harrogate, TN 37752.
Center for Outcomes Research and Epidemiology, Kansas State University, Manhattan, KS 66506.
Am J Vet Res. 2021 Aug;82(8):644-652. doi: 10.2460/ajvr.82.8.644.
To evaluate associations between weather conditions and management factors with the incidence of death attributable to bovine respiratory disease complex (BRDC) in high-risk auction-sourced beef calves.
Cohorts (n = 3,339) of male beef calves (545,866) purchased by 1 large cattle feeding operation from 216 locations and transported to 1 of 89 feeding locations (backgrounding location or feedlot) with similar management protocols.
Associations between weather conditions and management factors on the day of purchase (day P) and during the first week at the feeding location and cumulative BRDC mortality incidence within the first 60 days on feed were estimated in a mixed-effects negative binomial regression model.
Significant factors in the final model were weaning status; degree of commingling; body weight; transport distance; season; precipitation, mean wind speed, and maximum environmental temperature on day P; environmental temperature range in the first week after arrival at the feeding location; and interactions between distance and wind speed and between body weight and maximum environmental temperature. Precipitation and wind speed on day P were associated with lower cumulative BRDC mortality incidence, but wind speed was associated only among calves transported long distances (≥ 1,082.4 km). Higher mean maximum temperature on day P increased the incidence of cumulative mortality among calves with low body weights (< 275.5 kg).
Several weather conditions on day P and during the first week after arrival were associated with incidence of BRDC mortality. The results may have implications for health- and economic-risk management, especially for high-risk calves and calves that are transported long distances.
评估天气条件和管理因素与高危拍卖源肉牛犊牛呼吸疾病复合症（BRDC）死亡率的相关性。
来自 1 个大型肉牛饲养场的 216 个地点购买的雄性肉牛犊牛（545866 头）的队列（n = 3339），并运输到 89 个饲养地点（育肥地点或饲养场）中的 1 个，这些地点具有相似的管理方案。
在购买日（P 日）和在饲养地点的第一周内，以及在饲养的头 60 天内累积 BRDC 死亡率发生率之间，使用混合效应负二项式回归模型评估天气条件和管理因素之间的相关性。
最终模型中的显著因素包括断奶状态、混合程度、体重、运输距离、季节、P 日的降水量、平均风速和最高环境温度、到达饲养地点后第一周的环境温度范围以及距离和风速之间以及体重和最高环境温度之间的相互作用。P 日的降水量和风速与较低的累积 BRDC 死亡率发生率相关，但风速仅与长途运输的牛犊相关（≥1082.4 公里）。P 日的最高平均温度升高会增加体重较轻（<275.5 公斤）的牛犊累积死亡率的发生率。
P 日和到达后的第一周内的几种天气条件与 BRDC 死亡率的发生有关。结果可能对健康和经济风险的管理具有重要意义，特别是对高危牛犊和长途运输的牛犊。
