Exogenous melatonin: effects on lactation and colostrogenesis in small ruminant livestock

Abstract

Melatonin is a neuroendocrine hormone that is involved in numerous functions in animals, most studies have focused on the ability to control reproduction in species that are sensitive to photoperiodicity. Recently, however, the number of studies on the effects of melatonin on productive aspects of small ruminant livestock has increased. This review summarizes recent published studies on the effects of exogenous melatonin on lactation and colostrogenesis in small ruminants. The melatonin membrane receptors MT1 and MT2 are in the epithelial cells of the mammary glands, which suggests that melatonin might influence milk yield and composition. Furthermore, melatonin exhibits anti-inflammatory, antibacterial, and immune properties, might regulate udder health. Research has shown that melatonin influences the immune system by affecting the synthesis of IgG; however, the precise pathway through which melatonin influences lactation and colostrogenesis in small ruminants is not fully understood. Variability in the effects of exogenous melatonin on lactation and colostrogenesis occurs because of differences in administration routes, dosing protocols, and environmental conditions.