EFFECT OF FOOT LESIONS ON MILK-PRODUCTION BY DAIRY-COWS

Individual curves for milk production of 428 cows affected by foot les ions were compared with control curves drawn from data of healthy lact ating cows. First, differences were classified into patterns of milk l oss, and their distribution was analyzed among the patterns with regar d to breed, season, parity, stage of lactation, and milk production. T hen, individual milk losses were estimated and analyzed according to t he same factors. During early lactation, as during mid to late lactati on, no marked modifications of the lactation curves occurred for about one-half of the cases. In 25% of the cases, milk production was affec ted for an expanded period (medians were 17 wk for early lactation and 12 wk for mid to late lactation). Corresponding median milk losses we re 440 and 270 kg, respectively. Summer foot lesions were more severe than winter lesions, regardless of stage of lactation. Milk production at foot lesion onset was a determining factor of the amount and patte rn of milk loss only for cases occurring during mid to late lactation.