Effects of drying-off procedure of ewes' udder in subsequent mammary infection and development of mastitis

Objective of the study was to evaluate effects of the procedure followed for udder drying-off (i.e., progressive or abrupt cessation of lactation) in subsequent mammary infection and development of mastitis. In ewes of group A (n = 19), drying-off took place progressively during a period of 22 days; in ewes of group B (n = 12), udder drying-off took place abruptly. Samples of teat duct material and of milk for bacteriological and cytological examination were collected before start of the drying-off procedure, as well as on two occasions after the subsequent lambing: the first immediately after lambing - before the lambs sucked their dam for the first time (15 ewes: 9 group A and 6 group B) or up to the 1st day after lambing (16 ewes: 10 group A and 6 group B) and the second on the 4th or 5th day after lambing (all ewes). Median time to first teat duct or mammary infection post-partum was 0 days (teat ducts and mammary glands) for group A and 2.25 and 0 days (teat ducts and mammary glands, respectively) for group B (P > 0.38). Of the 33 bacterial isolates obtained, 79% were coagulase-negative staphylococci. No significant differences were observed between the two groups in the post-partum frequency of teat duct infection (P > 0.13), of mammary infection (P > 0.8), of subclinical mastitis (P > 0.78) or of abnormal findings in a mammary gland (P > 0.11). No significant differences were seen between the two groups in the post-partum incidence risk of any of the outcomes studied: teat duct infection (P = 0.545), mammary infection (P = 0.647), subclinical mastitis (P = 0.476) or abnormal findings in a mammary gland (P = 0.259). No significant differences were evident between the two groups in cure rate of abnormal findings in a mammary gland (P = 0.847). The results support a hypothesis that the procedure for udder drying-off (i.e., progressive or abrupt cessation of lactation) does not affect the risk of subsequent mammary infection and development of mastitis. (C) 2012 Elsevier B.V. All rights reserved.