|Akers, R - VIRGINIA POLYTECHNIC INST|
Submitted to: Encyclopedia of Dairy Science
Publication Type: Book / Chapter
Publication Acceptance Date: February 16, 2009
Publication Date: January 1, 2011
Citation: Capuco, A.V., Akers, R.M. 2011. Galactopoiesis/Effects of hormones and growth factors. In: Fuquay, J.W., Fox, P.F., McSweeney, P.L.H, editors. Encyclopedia of Dairy Science. 2nd edition. San Diego, CA: Academic Press. p. 26-31. Technical Abstract: The term galactopoiesis was originally coined to describe the enhancement of an established lactation. In this sense, only exogenous somatotropin and thyroid hormones are clearly demonstrated galactopoietic agents in dairy animals. However, in a more inclusive sense, galactopoiesis has been used to describe the maintenance of lactation. A number of hormones and factors are involved in the maintenance of milk production in dairy animals and these will be described in this review. Galactopoietic hormones, growth factors, and regular milk removal are essential for regulation and maintenance of lactation. Although there clearly are species differences, endocrine organ ablation/replacement studies, have shown that prolactin, somatotropin, glucocorticoids and thyroid hormones are typically required for the full maintenance of lactation. Still, additional hormones and growth factors are probably important for the normal physiological maintenance of lactation. In addition to regulatory factors that actively support synthesis of milk components, frequent emptying of the mammary gland supported by the milking-induced release of oxytocin is critical. Other factors that can affect the maintenance of lactation are those that impinge upon maintenance of the secretory cell population by decreasing cell loss or by increasing cell proliferation. These factors do not impact the secretory capacity of existing cells but impact the secretory capacity of the mammary gland, the shape, and length of the lactation curve.