Association of origin, performance, and health metrics of beef-on-dairy feedyard cattle with liver abscess at harvest.

Beef-on-dairy cattle (B × D) exhibit a higher prevalence of liver abscesses (LA) at harvest compared to native beef breeds and Holsteins. The objective was to evaluate associations of origin, performance, and health metrics with LA prevalence and severity at harvest in B × D feedyard cattle. Operational data and liver scores were collected from two sources (Dataset 1, n = 330 cohorts; Dataset 2, n = 386 cohorts). For Dataset 1, livers were scored using Elanco's liver scoring system with 4 outcomes of interest: Total LA (All scores; D1TA), Severe LA (Scores A+, A + Adhered, A + Open; D1SA), Severe + LA (A + Adhered and A + Open; D1S + A), and Severe as proportion of Total LA (D1ST). For Dataset 2, livers were scored in 3 non-mutually exclusive categories: Abscessed (D2TA), Condemned (D2CL), and Adhered (D2AdL). Generalized linear mixed models estimated probability of LA outcomes with a beta-binomial distribution to account for overdispersion. Fixed effects included sex, days on feed (DOF), shipping weight, head received, average daily gain (ADG), mortality, railers, average daily feed delivery per head, quarter of arrival/harvest, and region of origin. Feedyard was included as a random effect. Multiple risk factors such as sex, DOF, shipping weight, railers, and origin were associated with D1TA, D1SA, D1S + A, and D1ST. Quarter harvested and ADG were associated with D2TA and D2CL. Shipping weight and origin were also associated with D2TA. Sex was the only risk factor associated with D2AdL. Steer cohorts had higher probability (P ≤ 0.05) of D1TA, D1SA, D1S + A, D1ST, and D2AdL than heifer cohorts. Cohorts on feed > 300 days had higher probability (P ≤ 0.05) of D1TA, D1SA, and D1S + A than cohorts with fewer DOF. Cohorts with shipping weights of 680 to 725 kgs had higher risk (P = 0.03) of D1SA than those > 726 kgs. Average daily gain was associated with (P ≤ 0.02) D2TA and D2CL. Cohorts with < 0.5% railed had a lower probability (P ≤ 0.04) of LA outcomes than those with > 0.5% railed. Cattle harvested in quarter 3 had lower risk (P ≤ 0.03) of D2TA and D2CL. Cohorts originating from region 3 had lower risk (P ≤ 0.05) of D1TA, D1SA, D1S + A, and D1ST than those from regions 1 and 4. These results identify associations among B × D cattle demographics, origin, performance, and health metrics with LA prevalence at harvest. Further research is needed to evaluate management strategies to mitigate LA occurrence.