Effect of overcrowding on claw health in first-calved Friesian heifers.

In two studies on overcrowding and foot lesion development, claw health was monitored monthly, and behavioural activities such as lying/standing observed every 15 min for 5 consecutive days and nights each month of the housing season. In the first experiment, 35 autumn-calving heifers were housed at a 2:1 heifer to cubicle ratio immediately after calving. In the second study, 40 spring-calving heifers were housed at a 2:1 ratio for 2 months before calving and with one cubicle each after calving. Lying time was reduced to 5 h per 24 h in some of the autumn-calving animals and these animals had significantly worse foot lesion scores and clinical lameness than animals lying for 7 or 10 h per 24 h. The spring-calving animals did not show such a severe reduction in lying time and no significant correlation between haemorrhage score and lying time was detected. It is concluded that reduced lying time acts as an exacerbating factor in the development of claw lesions.