Visual Locomotion Scoring in the First Seventy Days in Milk: Impact on Pregnancy and Survival

Abstract 

Our hypotheses were that cows classified as lame during the first 70 d in milk have more days from calving to conception and a greater hazard of dying or being culled compared with cows that were not classified as lame. Our objective was to estimate the detrimental effects of lameness on calving-to-conception interval and hazard of dying or being culled in lactating Holstein cows. Data were collected from 5 dairy farms located in upstate New York from November 2004 to June 2006. The design was a prospective observational cohort study. Cows were assigned a visual locomotion score (VLS) using a 5-point scale: 1=normal, 2=presence of a slightly asymmetric gait, 3=the cow clearly favored 1 or more limbs (moderately lame), 4=severely lame, to 5=extremely lame (nonweight-bearing lame). In total 1,799 cows were enrolled. In 2 alternative categorizations, cows were considered lame if at least 1 VLS was ≥3 during the first 70 d in milk, and if at least 1 VLS was ≥4 for the same period they were considered lame. Lameness (VLS ≥3) was detected at least once in 26.5, 54.2, 33.9, 51.8, and 39.3% of all cows in farms 1 to 5, respectively. The hazard ratio of being detected pregnant was 0.85 for lame cows (VLS ≥3) vs. nonlame cows; hence, lame cows were at a 15% lower risk of pregnancy than nonlame cows. When lameness was redefined as VLS ≥4, the hazard ratio of been detected pregnant was 0.76 for lame cows vs. cows with VLS <4. Lameness increased the hazard ratio of culling/death, 1.45 and 1.74 for VLS ≥3 and VLS ≥4, respectively, vs. cows with VLS <3 and VLS <4, respectively. In summary, lameness significantly decreased the hazard of pregnancy and increased the hazard of culling/death. The detrimental effects were amplified when considering only severely lame and non-weight-bearing cows.

Key words: lameness, culling, reproduction, dairy cow