Impact of lean growth genotype, dietary amino acid regimen and level of chronic immune system activation on sow lactational performance

Abstract

The functional mammary gland is one of the most metabolically active tissues in the body. The maximally secreting ruminant mammary gland is responsible for 80% of whole body glucose flux (Davis and Bauman, 1974), while the energy requirement for milk production in noiunminants can be four to five times the energy needs for maintenance (Collier, 1985). The events associated with mammary gland function can be divided into three phases: colostrogenesis, lactogenesis and galactopoiesis. Colostrogenesis Colostrogenesis is the accumulation of colostrum which occurs, in general, over the last trimester of gestation. In the sow, it appears that large quantities of colostrum accumulate only in the last days before parturition (Kensinger et al., 1982). Klobasa et al. (1987) analyzed sow colostrum and milk samples at 0, 6, 12, 18, 24, 48 and 72 hours after parturition and each seven days through day 42 of lactation. Milk composition was found to stabilize by 48 hours following the birth of the last pig. More than 90% of the protein in colostrum was found to be composed of immunoglobulin and other serum proteins. Changes in mammary secretion through 48 hours postpartum are illustrated in Table 1.