Responses of dairy ewes before and after parturition to different nutritional regimes during pregnancy

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Abstract
Some effects of nutritional levels during pregnancy on subsequent lactation were studied in dairy ewes. Three basic (maintenance) rations and 3 steaming-up levels were compared in a factorial experiment. All ewes were fed 0.4 kg of hay daily and pellets ad lib. Ewes entering late pregnancy in heavy body condition due to a high basic ration consumed 21% less feed in early lactation than those that had received the lower rations. Reduced appetite was more marked in single- than in twin-bearing ewes. Steaming-up levels did not have any effect on ad lib feed consumption during lactation. Twin-bearing ewes consumed, on the average, 9.6% more feed than single-bearing ones. There was a negative correlation between body weight change during lactation and weight change during pregnancy. Overfatness of ewes was followed by low milk yields. In ewes which were on constant steaming-up levels during the last 2 mo. of pregnancy, milk production was significantly higher in twin- than with single-bearing ewes. There was no such difference in the ewes whose feed allowance during pregnancy had been gradually raised according to the free fatty acid concentration in their blood plasma. There was no correlation between feed intake and body weight change during lactation or between body weight change and milk production. There were highly significant correlations between feed intake and milk yield. Fat percentage in milk was not affected by feeding level during pregnancy. Average fat level was 6.7 .+-. 0.2% and 7.5 .+-. 0.2% in the milk of twin- and single-bearing ewes, respectively.