EFFECTS OF DAILY EXOGENOUS OXYTOCIN INJECTIONS ON MILK PRODUCTION AND FAT YIELD IN HOLSTEIN COWS

Twenty one Holstein cows milked three times daily in a 3x3 replicated Latin square design were used to determine the effects of daily exogenous oxytocin on 14-d milk production. The cows were assigned to the following treatments: 1) control group, receiving 1.5 ml of saline I min before machine attachment, 2) animals receiving 15 IU (i.m.) of oxytocin I min before machine attachment at each milking and 3) animals receiving 15 IU ofoxytocin 3.5 - 4 min after machine attachment at each milking. Daily milk yield was recorded and milk samples were collected from each cow, biweekly, for milk fat determination. The least square means of milk production were 17.5, 20.1 and 18.8 kg for control group, oxytocin I min before machine attachment and oxytocin injection 3.5-4 min after machine attachment, respectively. Oxytocin significantly increased 4% fat-corrected milk production by 15.1 and 7.3 percent, respectively.