Impact of Oxytocin-Milking Method on Lactation Performance and Lactation Length of Sheep

Determination of milk yield potential using an accurate method is essential for assessing nutritional requirements, evaluation of genetic potential, lamb growth and survival, management decisions and improving performance traits of sheep flocks. Exogenous oxytocin injection is applied to estimate milk secretion rate in sheep. Oxytocin is a neurohormone produced in the hypothalamo-neurohypophysial system, which is released into the blood in response to teat stimulation. It has a galactopoietic effect and plays an important role in lactation acting on milk ejection via the secretory activity and contraction of myoepithelial cells. One hundred singleton-bearing and rearing Makui breed ewes were assigned into two treatments: group I (hand milking and stripping following the intramuscular injection of 2.5 IU of oxytocin) and group II (hand milking and stripping). The study aimed to examine the effect of exogenous oxytocin injection on milk yield, milk composition and lactation length of ewes during the entire lactation period. Data were recorded at fortnightly intervals from post-partum day 14 onward. Oxytocin treatment group produced significantly more average daily milk yield (562.3 vs. 301.4 g) and total milk yield (93.6 vs. 38.5 kg) compared with non-treated animals (P