This study investigated the effects of hormonal status; metabolic changes of restricted ewes during late pregnancy on the ovine fetus growth; development. One hundred Mongolian ewes, synchronized for oestrus; mated, were divided into three groups; offered 0.175 MJME·kgw[0.75]·d[1] (Restricted Group 1, RG1), 0.33 MJME·kgw[0.75]·d[1] (Restricted Group 2, RG2); ad libitum access to feed (Control Group, CG) during their late pregnancy respectively. The results suggested that with the supply of exogenous energy decreasing during late pregnancy, maternal body weight; net body weight loss in RG2; RG1 were lower than those of CG (Ps0.01). The insulin; IGF-1 concentrations of ewes in RG2; RG1 tended to be lower than those of CG (P>0.05), but the GH concentrations in RG2; RG1 were enhanced; there was significant difference between RG1; CG on d 120 of gestation (P<0.05). The glucose concentration of ewes in RG2; RG1 was decreased throughout the feed restriction period,; the differences were observed between RG1; CG on d 120 of gestation (P<0.05). In addition, the nonesterified fatty acid (NEFA); total amino acid (TAA) concentrations of ewes in RG2 tended to increase, but there was no significant difference (P>0.05). However, the NEFA; FAA concentrations of ewes in RG1 were reduced from d 90 to d 120 of gestation, then enhanced from d 120 to d 140 of gestation. During the late pregnancy, with the supply of nutrition decreasing, the negatively physiological; biochemical maternal reactions to restriction became worse, which significantly reduced the average lamb birth weight; daily growth rate of fetus in RG2 (P<0.05); RG1 (P<0.01).
GAO Feng1, HOU XianZhi1 & LIU YingChun2 1 College of Animal Science and Animal Medicine, Inner Mongolia Agricultural University, Huhhot 010018, China
