The objective of this trial was to investigate the effects of oxytocin on milk yield and composition and on cheese yield of Santa Inês sheep receiving a diet containing 12% CP and 65% TDN. Animals were maintained in pens and were assigned to one of the following two treatments: hand milking plus an intravenous injection of 3 IU of oxytocin or hand milking without oxytocin injection (control group). Ewes were milked daily and remained with their lambs for a daily period of 14 hours until weaning; lambs were weaned at 60 days of age and ewes still milked once a day until the end of lactation. Milk samples were collected for analysis of fat, total solids, and solids non-fat. Lactation length averaged 225±27.24 and 210±38.77 for control and oxytocin-treated ewes, respectively. Ewes receiving oxytocin yielded more milk (141.63±51.52 kg) than those on the control group (89.39±16.65 kg) until 133 days of lactation; however, total milk yield on the entire lactation did not differ significantly comparing oxyitocin-treated (169.64 ± 71.05) with control (119.72±32.73) animals. Milk contents of fat (5.84±0.44 and 4.96±0.47), total solids (17.40±0.42 and 16.18±0.57) and solids non-fat (11.57±0.15 and 11.22±0.25) differed between both groups of animals, respectively. Results showed improved milk yield and composition on oxytocin-injected ewes; therefore, it is recommended the use of oxytocin to facilitate milk ejection on ewes not adapted to the milking routine. Yields of cheese (L of milk/kg of cheese) averaged 4.80, 8.29 and 5.99 L/kg for azeitão, pecorino, and roquefort cheeses, respectively.
fat; hormone; lactation; sheep
