Oxytocin Release and Milk Removal in Ruminants

¹ Institute of Animal Breeding, University of Berne, 3012 Berne, Switzerland

Before milking, less than 20% of the milk yielded by dairy cows is stored within the cistern, where it is immediately available for removal. Most of the milk is available for the milking machine only after milk ejection, which occurs in response to tactile teat stimulation and oxytocin release. For complete milk removal, milk ejection is necessary throughout the entire milking process. The continuation of stimulatory effect of the milking machine until the end of milking is, therefore, essential. Premilking teat stimulation causes induction of alveolar milk ejection before the start of milking. Thus, bimodal milk flow curves (i.e., interruption of milk flow after removal of the cisternal milk) are avoided. Continual ejection of milk is dependent on the presence of elevated oxytocin concentrations during the entire milking. Any interruption of the milk ejection process can disturb milk removal.

Disruption of milk removal can be caused by peripheral inhibition of oxytocin effects on the mammary gland or by inhibition of oxytocin release by the central nervous system. Peripheral inhibition is induced by elevated concentrations of catecholamines through stimulation of -adrenergic receptors in the mammary gland, likely via changes in ductal resistance. Inhibition of oxytocin release by the central nervous system has been observed in primiparous cows immediately after parturition, during peak estrus, and during milking in unfamiliar surroundings; concentrations of ß-endorphin and cortisol are elevated in this situation. However, the role of endogenous opioid peptides in the inhibition of oxytocin release in cows remains unclear. In conclusion, during machine-milking, the physiological requirements of the cows need to be considered, and, most importantly, stressors must be minimized.

Key Words: oxytocin • milk ejection • disturbed milk ejection

Submitted on September 29, 1996
Accepted on October 14, 1997

This article has been cited by other articles:

				A. M. de Passille, P.-G. Marnet, H. Lapierre, and J. Rushen Effects of Twice-Daily Nursing on Milk Ejection and Milk Yield During Nursing and Milking in Dairy Cows J Dairy Sci, April 1, 2008; 91(4): 1416 - 1422. [Abstract] [Full Text] [PDF]

				R. M. Bruckmaier and O. Wellnitz Induction of milk ejection and milk removal in different production systems J Anim Sci, March 1, 2008; 86(13_suppl): 15 - 20. [Abstract] [Full Text] [PDF]

				K. M. Svennersten-Sjaunja and G. Pettersson Pros and cons of automatic milking in Europe J Anim Sci, March 1, 2008; 86(13_suppl): 37 - 46. [Abstract] [Full Text] [PDF]

				V. Tancin, A. H. Ipema, and P. Hogewerf Interaction of Somatic Cell Count and Quarter Milk Flow Patterns J Dairy Sci, May 1, 2007; 90(5): 2223 - 2228. [Abstract] [Full Text] [PDF]

				M. Rovai, M. T. Kollmann, and R. M. Bruckmaier Incontinentia Lactis: Physiology and Anatomy Conducive to Milk Leakage in Dairy Cows J Dairy Sci, February 1, 2007; 90(2): 682 - 690. [Abstract] [Full Text] [PDF]

				L. Gygax and D. Nosal Short communication: contribution of vibration and noise during milking to the somatic cell count of milk. J Dairy Sci, July 1, 2006; 89(7): 2499 - 2502. [Abstract] [Full Text] [PDF]

				I. C. Klaas, C. Enevoldsen, A. K. Ersboll, and U. Tolle Cow-Related Risk Factors for Milk Leakage J Dairy Sci, January 1, 2005; 88(1): 128 - 136. [Abstract] [Full Text] [PDF]

				D. Weiss and R. M. Bruckmaier Optimization of Individual Prestimulation in Dairy Cows J Dairy Sci, January 1, 2005; 88(1): 137 - 147. [Abstract] [Full Text] [PDF]

				G. Caja, M. Ayadi, and C. H. Knight Changes in Cisternal Compartment Based on Stage of Lactation and Time Since Milk Ejection in the Udder of Dairy Cows J Dairy Sci, August 1, 2004; 87(8): 2409 - 2415. [Abstract] [Full Text] [PDF]

				J. Macuhova, V. Tancin, and R. M. Bruckmaier Effects of Oxytocin Administration on Oxytocin Release and Milk Ejection J Dairy Sci, May 1, 2004; 87(5): 1236 - 1244. [Abstract] [Full Text] [PDF]

				D. Weiss, S. Helmreich, E. Mostl, A. Dzidic, and R. M. Bruckmaier Coping capacity of dairy cows during the change from conventional to automatic milking J Anim Sci, February 1, 2004; 82(2): 563 - 570. [Abstract] [Full Text] [PDF]

				C. E. Ontsouka, R. M. Bruckmaier, and J. W. Blum Fractionized Milk Composition During Removal of Colostrum and Mature Milk J Dairy Sci, June 1, 2003; 86(6): 2005 - 2011. [Abstract] [Full Text] [PDF]

				C. G. Van Reenen, J. T. N. Van der Werf, R. M. Bruckmaier, H. Hopster, B. Engel, J. P. T. M. Noordhuizen, and H. J. Blokhuis Individual Differences in Behavioral and Physiological Responsiveness of Primiparous Dairy Cows to Machine Milking J Dairy Sci, October 1, 2002; 85(10): 2551 - 2561. [Abstract] [Full Text] [PDF]

				B. C. McKusick, D. L. Thomas, Y. M. Berger, and P. G. Marnet Effect of Milking Interval on Alveolar Versus Cisternal Milk Accumulation and Milk Production and Composition in Dairy Ewes J Dairy Sci, September 1, 2002; 85(9): 2197 - 2206. [Abstract] [Full Text] [PDF]