Lactation Biology.

The article presents abstracts of various papers related to lactation that were presented during the symposium held on July 27, 2005 in Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science, and the Canadian Society of Animal Science. One of the papers discussed is "Evidence of a Role of Prolactin in Mediating Photoperiodic Effects During the Dry Period," by H.M. Crawford, J.L. Dauderman, D.E. Morin, T.B. McFadden and G.E. Dahi. Short day photoperiod (SDPP) during the dry period increases milk production in the subsequent lactation relative to long day photoperiod (LDPP). In addition we have observed that SDPP improves immune function during the transition compared with LDPP. The hypothesis is that mammary and immune responses under SDPP result from increased prolactin sensitivity. Another paper discussed is "A Proteomic Approach to Evaluate the Effects of Body Weight and Plane of Nutrition on Protein Expression Profiles of Mammary Gland Extracts From Holstein Heifers," by K.M. Daniels, K.B. Webb, M.L. McGilliard, M.J. Meyer, M.E. Van Amburgh and R.M. Akers. Biochemical and cellular mechanisms governing alterations in heifer udder development are poorly understood relative to prepubertal feeding and animal performance. Mammary development in dairy heifers was characterized with the use of proteomics, which is the study of the complete set of translated proteins in a biological sample.