Study Of Energy And Protein Requirements For Pregnancy Of Polled Dorset × Small Tailed Han Sheep Crossbred Ewes

24 healthy and similar body condition Polled Dorset × Small Tailed Han Sheep crossbred ewes with reproduction experience were randomly divided into 3 groups(ad libitum feeding, 80% feed restriction, 60% feed restriction) and diets were designed by the NRC raising standard. The metabolism and respiratory calorimetry were measured respectively on 60 days and 120 days of the gestation period. The result showed that(1)The average daily gain of crossbred ewes was decreased with the decreasing of feeding level during pregnancy. In the early and late pregnancy, ad libitum feeding group can reach 250.06 and 253.87 g/d. The rate of feed remuneration of pregnant ewes was decreased with the decreasing of feeding level.(2)The digestibility of nutrients of pregnancy crossbred ewes was effected by the feeding level remarkable. With the decreasing of feeding level, the feed intake reduced and the digestibility of matter increased. The feed intake and the digestibility of matter were showed significant difference between ad libitum feeding and 60% feed restriction during the early pregnancy(P<0.05). With the decreasing of feeding level, the intake and fecal nitrogen, the nitrogen retention and nitrogen retention/nitrogen intake reduced, the nitrogen digestibility rate increased. The intake and fecal nitrogen, the nitrogen digestibility rate were showed significant difference between ad libitum feeding and 60% feed restriction during the early pregnancy(P<0.05). With the decreasing of feeding level, the fecal energy, urine energy and methane energy reduced, the total energy digestion rate, total energy metabolic rate and digestible energy metabolic rate were all increased. The fecal energy was showed significant difference between ad libitum feeding and 60% feed restriction during the early pregnancy(P<0.05), but the rest was showed no significantly difference between the three groups(P>0.05). With the decreasing of feeding level, the fecal carbon, urine carbon, methane carbon and CO2-C reduced, the carbon digestion rate increased. The fecal carbon was showed significant difference between ad libitum feeding and 60% feed restriction during the early pregnancy(P<0.05).(3)In the early and late pregnancy, the net nitrogen maintain requirements were 294.4 and 358.8 mg/kg W0.75?d, and the net protein maintain requirements were 1.840 and 2.242 g/kg W0.75?d. In the early and late pregnancy, the net protein growth requirements were 47.4299BW0.2005g/d and 11.1110BW0.5982g/d under different weight.(4)In the early and late pregnancy, the net energy maintain requirements were208.64 and 258.58 k J/kg W0.75?d, and the metabolic energy maintain requirements were367.66 and 497.70 k J/kg W0.75?d. The maintain efficiency of metabolic energy were 0.567 and 0.519. In the early and late pregnancy, under different weight the net energy growth requirements were 10-3.5616×BW2.2479 and 10-2.6841×BW1.9523, and the metabolic energy growth requirements were10-3.4056×BW2.2479 and 10-2.5098×BW1.9523. The growth efficiency of metabolic energy were 0.6983 and 0.6694.