Int.J.Curr.Microbiol.App.Sci (2018) 7(7): 970-977 970 Review Article https://doi.org/10.20546/ijcmas.2018.707.117 Neurohormonal Control of Lactation and Milk Let-down in Dairy Animals A. Bhimte 1* , N.S. Thakur 1 , V.P. Maurya 2 and G. Singh 2 1 Division of Animal Physiology, National Dairy Research Institute, Karnal-132001, Haryana, India 2 Division of Physiology and Climatology ICAR-Indian Veterinary Research Institute, Izzatnagar-243122, U.P., India *Corresponding author ABSTRACT Introduction Lactogenesis is the process of differentiation where by the mammary alveolar cell acquires ability to secrete the milk. Once initiated, secretion of milk by alveolar epithelial cells is a continuous process but secretion does not occur at a constant rate over time. Maintenance of secretion throughout an individual lactation cycle requires regular removal of milk from the gland (Alexandrova et al., 1980). Rate of milk secretion depends on available storage capacity within the gland. Rate of milk secretion is fastest immediately after milk removal via suckling or milking and slows dramatically by 10–12 hours. Implementing a shorter interval between subsequent bouts of milk removal can increase milk production capacity. Approximately 35 hours after the most recent milk removal, milk secretion essentially stops. Control of milk secretion is achieved through both physical and chemical interactions (Bisset et al., 1970). Physical interactions Physical limitations are achieved through the build‐ up of pressure within the alveoli, International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 07 (2018) Journal homepa ge: http://www.ijcmas.com Lactation starts with active contraction of the myoepithelial cells surrounding the alveoli, this process is termed milk ejection, or milk let down. These myoepithelial cells contract when stimulated by oxytocin, a hormone released from the neurohypophysis of the pituitary as a result of a neuro-endocrine reflex. The afferent side of the reflex consists of sensory nerves from the mammary glands, particularly the nipples or teats. Afferent information reaches the hypothalamus, which regulates the release of oxytocin from the neurohypophysis. The milk ejection reflex can be stimulated by suckling, concentrate feeding, barn noises, and the sight of the calf. It can also be inhibited by emotionally disturbing stimuli, such as dog barking, outer loud and unusual noises, excess muscular activity, and pain. Stressful stimuli increase the activity of the sympathetic nervous system (epinephrine and norepinephrin) which can inhibit the milk ejection reflex. Keywords Lactation, Milk ejection, Neuroendocrine reflex, Intammary pressure (IMM), Hypothalamus Accepted: 08 June 2018 Available Online: 10 July 2018 Article Info