Hormonal, Nutritional, and Immunological Interactions Associated with Efficient Dairy Cattle Reproduction

Efficient reproduction is important for optimal profitability on dairy operations. Unfortunately, most dairy farms do not attain optimal reproduction due to many factors related to management, health, and physiology of high-producing dairy cows. The physiology issues involved in reproduction of lactating dairy cows are complex but increasingly, the interactions between nutrition, the hormonal systems, and altered reproduction in dairy cattle have been elucidated (see reviews Chagas et al., 2007; Lucy, 2001; Wiltbank et al. 2006). The role of health and the immune system on efficient reproduction has also been extensively discussed (Hansen et al., 2004; LeBlanc, 2008; Sheldon et al., 2008). In an attempt to provide some perspective in understanding these complex interactions, this article will briefly update the role of progesterone (P4) within the complex interaction of the immune system, nutrition, and reproduction in the lactating dairy cow.