Effects of housing and two forage diets on the development of claw horn lesions in dairy cows at first calving and in first lactation

This paper describes a systematic study of the development of lesions of th e claw horn (CHL, sole and white Line) in heifers calving for the first tim e, housed either in cubicles or a straw yard and fed either a low- or high- dry-matter forage diet. The feet of all animals were inspected on five occa sions, at approximately four weeks before and four, eight, 16 and 24 weeks post calving.. Haemorrhagic lesions of the sole and white line were describ ed according to a geometric lesion score for severity and a cumulative lesi on score based on the product of (severity x area) for each lesion. Geometr ic and cumulative lesion scores increased in all groups of cattle in the fi rst eight weeks after calving. However, the severity and persistence of the lesions were significantly greater in cattle housed in cubicle yards. Wet feeding increased the severity of CHL in the cubicle yard only. There were no associations between lesion scores and body weight, body condition or fo ot conformation. The heels of the cattle in straw yards tended to be thick but many showed pitting erosions. In cubicles the heels were smooth but thi n. This may have contributed to CHL by increasing concussive forces within the hoof. There was a highly significant (but relatively low) correlation b etween scores for sole lesions and lameness in individual animals. These ob servations are consistent with the hypothesis that systemic events associat ed with calving and the onset of lactation may set in motion the chain of e vents that lead to the lesions of CHL the extent and severity of these lesi ons being then determined by the externally imposed conditions of housing a nd feeding. (C) 2001 Harcourt Publishers Ltd.