干旱区生态环境知识资源中心

The effect of water restriction was assessed in Barbarine ewes raised under extremely dry conditions. In Experiment 1, 24 adult ewes were divided into two groups balanced for age and weight. Control ewes (C) had free access to water while deprived ewes (D) were ad libitum watered every 3 days during the last 10 days of pregnancy and the first 60 days of suckling. Accumulated colostrum at birth and rate of secretion between 0-2, 2-15 and 15-24 h were not affected. C ewes yielded more milk than D ewes on days 30 and 60 postpartum (1,487.38 +/- 436.44 vs. 1,096.6 +/- 282.85 g/24 h and 983.42 +/- 228.80 vs. 639.19 +/- 256.92 g/24 h respectively; P<0.01). At birth, lamb's live weight was similar (3.4 kg) for lambs born to C and D ewes (P>0.05). Daily growth rates were 184.67 +/- 55.98 and 162 +/- 43.50 g between d 10 and d 30, and 190.60 +/- 53.47 and 173.8 +/- 45.75 g between d 30 and d 60 for respectively C and D lambs (P>0.05). In Experiment 2, 24 adult ewes were allotted to treatments C and D as above except that for D ewes, water restriction started from 50 days before lambing up to 60 days postpartum. Accumulated colostrum at birth and rate of secretion between 0-2, 2-15 and 15-24 h were not affected. However, milk production was highly affected (P<0.01) by the regime being significantly lower for D ewes at 10, 30 and 45 days postpartum. Despite differences in milk production, there was no effect of access to water of the dams on the weights and growth rates of their offspring's. At birth, C and D lambs weighed 3.4 and 3.3 kg respectively, and at day 60 corresponding figures were 11.2 and 10.3 kg. Both experiments showed an effect of water deprivation only on milk production which is not reflected in lamb weights at birth even when the ewes are deprived during the last third of pregnancy. Lamb growth after birth was also not modified. These results stress the adaptive traits of the Barbarine and should be considered while managing watering of flocks under desert conditions.