Abstract: The aim of this study was to assess the effects of concentrated feed supplementation in the perinatal period on weight gain, blood physiological and biochemical indices, lactation performance of grazing Mongolian ewes grazed in the Gobi areas and growth performance of their lambs. A total of 20 gestational Mongolian ewes averagely weighted （60±5.54） kg with similar physical condition were selected and randomly assigned into an experimental group （n=10） and a control group （n=10）. The basal diet of the control group was supplemented with 300 g corn per ewe per day, and that of the experimental group was supplemented with 300 g self-prepared concentrated feed per ewe per day. The supplementary feeding experiment had a pre-feeding period of 5 days and a formal feeding period of 60 days. All the tested ewes were weighted at the initial and final stage of the supplementary feeding experiment, and the total weight gain was calculated; at the end of the supplementary feeding experiment, the ewes were sampled for determination of blood routine indices and serum biochemical indices; from 15^th to 85^th day after lambing, the milk yield of the ewes was determined every 10 days by using weight difference method; the birth weight and 90-day-old weight of the lambs were measured, and the daily weight gain of the lambs within the 90 days of age was calculated. The differences in the above indicators between experimental group and control group were statistically assessed.The results showed that during the supplementary feeding experiment, no significant （P>0.05） difference in the total weight gain between experimental group and control group was observed, the weight loss of the ewes in experimental group was 1.71% lower than that of the ewes in control group; there were no significant （P>0.05） differences in blood routine indices and serum biochemical indices between experimental group and control group; during the entire lactation period, the ewes in experimental group had higher milk yield compared to those in control group, and significant （P<0.05 or P<0.01） difference was observed at the 75^th and 85^th day after delivery; compared with the lambs in control group, the 90-day-old weight and the daily weight gain within the 90 days of age of the lambs in experimental group were increased （P>0.05）. In summary, the supplemental feeding with concentrated feed in the perinatal period can increase the milk yield of postpartum grazing Mongolian ewes and improve the daily weight gain of lambs.

Key words: supplementary concentrated feed, Mongolian ewes, milk yield, lambs, daily weight gain