The objective ofthis trial was to investigate the effects of oxytocin on milk yield and compositionand 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 ofthe following two treatments: hand milking plus an intravenous injection of3 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 14hours until weaning; lambs were weaned at 60 days of age and ewes still milkedonce a day until the end of lactation. Milk samples were collected for analysisof fat, total solids, and solids non-fat. Lactation length averaged 225±27.24and 210±38.77 for control and oxytocin-treated ewes, respectively. Ewesreceiving oxytocin yielded more milk (141.63±51.52 kg) than those onthe control group (89.39±16.65 kg) until 133 days of lactation; however,total milk yield on the entire lactation did not differ significantly comparingoxyitocin-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), totalsolids (17.40±0.42 and 16.18±0.57) and solids non-fat (11.57±0.15and 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 ejectionon ewes not adapted to the milking routine. Yields of cheese (L of milk/kg ofcheese) averaged 4.80, 8.29 and 5.99 L/kg for azeitão, pecorino, androquefort cheeses, respectively.
