An evaluation of the changes in distance from the external sole surface to the distal phalanx in heifers in their first lactation

Thin soles are a significant cause of lameness in dairy cattle but in most cases the diagnosis is based on subjective assessment. Ultrasonography has been used to more directly estimate sole thickness, but mostly on a one-off basis or over a short period of time. Data over a longer period of time (such as a lactation period) are lacking and there are no descriptions of the normal changes that occur over time and to show how sole thickness at calving relates to thickness later in lactation. tudy measured the distance between the external sole surface and the distal phalanx (DP) in 25 mixed breed (Jersey cross Friesian and Friesian) heifers on five occasions over their first lactation (approximately 10, 60, 110, 160 and 220 days post calving). There was a significant effect of claw (medial/lateral) and of time after calving on DP. Mean DP was highest on day 10 and was lowest on day 110 at the tip of the distal phalanx (S1) and on day 160 25 mm towards the heel from the tip (S2). DP was greater at S1 in medial claws and S2 in lateral claws. Although mean DP decreased between days 10 and 110, this change was correlated to DP at day 10. At S1 claws with a DP of <7.5 mm tended to increase in thickness between day 10 and 110. Claws which were ⩽8.25 mm at day 10 were 2.43 (95% CI 0.86–6.89) times more likely to be thin (<7.0 mm) at day 110, but of the 12 thin claws at day 110, six had had an adequate DP (>8.25 mm) at day 10. A single measurement of DP at calving was not an effective method for predicting which claws would became thin during lactation.