Abstract #272

# 272
Evaluating the relationship between hoof lesions and culling of dairy cows.
Bobwealth O. Omontese*1, Roger Bellet-Elias1, Almudena Molinero1, Giovana Catandi1, Renan Casagrande1, Zelmar Rodriguez1, Rafael S. Bisinotto2, Gerard Cramer1, 1Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN,, 2Department of Large Animal Clinical Sciences, University of Florida, Gainesville, FL.

Objective of this study was to evaluate the relationship between hoof lesions (HL) and culling in lactating dairy cows. Jersey cows were enrolled at 20 ± 3 DIM (d20). At d20, cows were evaluated for body condition score (BCS; high ≥3.50, moderate = 2.75 to 3.25, low ≤2.50) and were examined for presence of claw horn HL (sole ulcers, toe ulcer, white line disease), sole hemorrhage (SH), infectious HL (digital dermatitis, foot rot), and injury. At 120 ± 3 DIM (d120), cows were reevaluated for presence of HL and BCS. Culling data (died or sold) were collected until 250 DIM and cows that left the herd were right censored. To evaluate the relationship between HL present in early lactation and culling, lesion status at d20 was categorized into (1) no HL (noHL; n = 1,197) or with HL (wHL; n = 442) and (2) HL category as claw horn (CLW; n = 113), SH (n = 280), infectious (INF; n = 36), and injury (INJ; n = 13). To assess the relationship between development of new HL and culling, cows were classified as healthy (no HL at d20 and d120; n = 308), cured HL (presence of any HL at d20 and no HL at d120; n = 72), new HL (no HL at d20 and presence of any HL at d120; n = 597), or chronic HL (presence of any HL at d20 and d120; n = 226). Association between HL and culling was assessed using Kaplan Meier curves and Cox’s proportional hazard regression. Overall, 13.4% cows (n = 221) were culled and there was no relationship between HL at d20 and culling (HR: 1.21; 95% CI: 0.91 to 1.61). Of all the lesion categories assessed in this study, cows with CLW had a greater culling hazard compared with healthy cows (HR: 1.52; 95% CI: 1.01 to 2.27; P < 0.01). Furthermore, cows with INF lesions tended to have greater culling hazard compared with healthy counterparts (HR: 1.72; 95% CI: 0.94 to 3.12; P = 0.07). Overall, 93% of new HL was SH. Cows that developed new HL had a smaller culling hazard compared with healthy cows (HR: 0.42; 95% CI: 0.22 to 0.78; P < 0.01). In conclusion, preexisting CLW and INF lesions at d20 were associated with increased hazard of culling whereas development of new HL between 20 and 120 DIM was associated with a reduction in hazard of leaving the herd.

Key Words: herd exit, hoof trimming, lameness