Factors affecting milk ejection and removal during milking and suckling of dairy cows

Abstract

The release of oxytocin and milk ejection occurrence in response to teat stimulation are crucial for fast and complete milk removal during milking or suckling. The milk ejection reflex can be disturbed at central or peripheral level under different experimental and practical conditions. The central disturbance results in the lack or insufficient ejection of the alveolar milk into the cistern due to inhibited oxytocin release from pituitary into the blood circulation. The important role in the pathophysiological regulation of the inhibited release of oxytocin is played by an opioid system. Endogenous opioids have suppressive effects on oxytocin release under the normal conditions of milk removal. However under the conditions of disturbed milk ejection their role in dairy cows was not confirmed. Other possible mechanisms involved in the central inhibition of oxytocin release are discussed. In dairy cows as compared with rats the mechanisms involved in the regulation of oxytocin release at the central level remain unclear. The central inhibition of oxytocin release has often been observed in dairy practice during milking of primiparous cows after parturition, suckling by alien calf, calf removal before milking, milking of cows in the presence of own calf, relocation and milking in an unknown milking place. If sufficient released oxytocin cannot induce the transfer of milk from alveoli to cistern, peripheral mechanisms are involved. Peripheral mechanisms are related to the increased levels of catecholamines and/or activation sympathetic nervous system at the udder level. In conclusion, the release of oxytocin and milk ejection efficiency can be very easily suppressed by many factors. The effect of milking conditions on regulation of milk ejection has to be considered. Thus the physiological requirements of dairy cows have to be respected.

Effects of suckling on milk yield and milk composition of dairy cows in cow–calf contact systems

“…This indicated a negative feed-back effect of these types of cow–calf contact on milk secretion. Machine milked cows secrete lower amounts of oxytocin than cows that are suckled, and cows used to nursing respond to machine milking with a disturbed milk ejection (Tančin and Bruckmaier, 2001). The milk remaining in the udder after an incomplete milking in combination with a constant milk secretion may lead to a return of milk from the udder cistern to the alveolar compartment (Caja et al ., 2004) and a faster udder filling between milking times, both inducing a decline of milk secretion (Albaaj et al ., 2018).…”

Serotonin: A Local Regulator in the Mammary Gland Epithelium

“…Neural signals, transmitted via the mammary nerve, stimulate secretion of both OT and PRL. This suckling reflex for each hormone has been reviewed elsewhere (20)(21)(22). The cycle of filling and emptying of the mammary glands relies on the different time constants of OT and PRL secretion and response.…”

First description of milk flow traits in Tunisian dairy dromedary camels under an intensive farming system

“…Milk within the udder can be divided into two fractions: cisternal milk which is immediately extracted by the machine without oxytocin release; and alveolar milk which can only be removed by the active involvement of the animal, when oxytocin release and milk ejection occurs (Bruckmaier & Blum, 1998). When the animals are physiologically stressed owing to acute events or long-term bad conditions of milking (Tancin & Bruckmaier, 2001), we can record physiological responses such as high levels of cortisol and reduced sensitivity to ACTH (Bruckmaier & Wellnitz, 2007) and catecholamines release (Bruckmaier et al 1997). That leads to a clear partial or total inhibition of milk ejection reflex and a delay in milk ejection and/or reduced milk flow is often described (Wellnitz & Bruckmaier, 2001).…”