Use of oxytocin to measure milk output in Merino ewes and its effect on fat content

Abstract

We examined the influence of the dose of oxytocin i n measurement of milk production in Merino ewes and its effect on fat content. Eight ewes were milked after an intra-venous injection of 2.0 International Units (I.U.) of oxytocin, then milked again after a further intra-venous injection of 0, 0.5, 1.0 and 5.0 I.U. of oxytocin, with the treatments allocated to a double Latin square design. The milk yielded at each treatment was recorded and samples of the milk were analysed for fat content. All oxytocin treatments significantly increased the amount of milk extracted (P<0.01), but did not affect the fat content of the milk. The dose-response curve showed a plateau at the 1 I.U. level. It was therefore concluded that 1 I.U. is the most suitable dose for measuring milk output in Merino ewes and that, within the range of doses tested, oxytocin does not affect the fat content of the milk withdrawn.