Visual locomotion scoring in the first seventy days in milk: impact on pregnancy and survival.
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 > or =3 during the first 70 d in milk, and if at least 1 VLS was > or =4 for the same period they were considered lame. Lameness (VLS > or =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 > or =3) vs. nonlame cows; hence, lame cows were at a 15% lower risk of pregnancy than nonlame cows. When lameness was redefined as VLS > or =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 > or =3 and VLS > or =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.
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Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. rcb28@cornell.edu
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D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000145:classification / Q000473:pathology*; D015331:Cohort Studies; D003612:Dairying / Q000379:methods; D005260:Female; D005306:Fertilization / Q000502:physiology; D007774:Lactation; D007794:Lameness, Animal / Q000145:classification / Q000473:pathology*; D008124:Locomotion; D008892:Milk / Q000378:metabolism*; D011247:Pregnancy; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012720:Severity of Illness Index; D016019:Survival Analysis; D013997:Time Factors