Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10979907 | Journal of Dairy Science | 2013 | 12 Pages |
Abstract
Farmers attempting to reduce first-calving age (FCA) need to understand which rearing management factors influence FCA and first-lactation milk production (FLP). Reduced FCA might be associated with lower FLP. This study describes the association between herd FCA, FLP, and several herd-level health and rearing management variables and describes the association between FCA and FLP at the cow level. It uses data from a 2010 survey of 100 Dutch dairy farms about general management, colostrum and milk feeding, housing, cleanliness, healthcare, disease, and breeding. It also used available data on FCA and 305-d FLP at both cow and herd level. The associations between median FCA and median FLP of the herd and herd-level health and rearing management variables were determined using multivariate regression analysis. The median FCA was associated with minimum age of first insemination, feeding of waste milk, and the amount of milk given preweaning. The median FLP was associated with median FCA and vaccination status for bovine respiratory syncytial virus. The association between FCA and FLP (based on 8,454 heifers) was analyzed with a single-effect linear mixed model, where the dependent variable was either FCA or relative FCA (defined as the difference between FCA of the heifer and median FCA of the herd to which they belonged). Heifers having an FCA of 24Â mo produced, on average, 7,164Â kg of milk per 305Â d, and calving 1Â mo earlier gave 143Â kg less milk per 305Â d. When FCA did not deviate from the median herd FCA, heifers produced, on average, 7,272Â kg of milk per 305Â d. From the median FCA of the herd, heifers calving 1Â mo earlier produced 90Â kg of milk per 305Â d less, and heifers calving 1Â mo later produced 86Â kg per 305Â d more. This is the first study that explained FLP using relative FCA. It assumes that heifers raised within the same farm have similar development because they are similarly managed. Similar management is reflected by the median FCA of the herd, with a deviation of the heifer's FCA from median FCA reflecting the heifer's development relative to the herd's average. The advantage of using relative FCA was that it accounts for between-farm differences in rearing management. It showed that earlier insemination without adjusting management to ensure sufficient development lowers FLP. An economic optimum exists between rearing costs, FCA, and FLP and, as a consequence, decisions with regard to young stock management should be made with care.
Keywords
Related Topics
Life Sciences
Agricultural and Biological Sciences
Animal Science and Zoology
Authors
N. Mohd Nor, W. Steeneveld, T. van Werven, M.C.M. Mourits, H. Hogeveen,