Effect Of Diffent Nutrient Levels On Reproductive Performance Of Tan×Small Tail Han Ewes

The trial was carried out to study the effects of different nutrition levels on reproductive performance of crossbred ewes ( Tan ×Small Tail Han). It was designed as randomized experiment of single factor with three levels. LevelⅠ, Ⅱand Ⅲwere 0.8×—, 0.9×—and 1.0 ×NRC respectively. The 30 ewes in lamb which were from 1.5 to 2 years old and first or second conceive were chose and divided into three groups consisting of ten ewes each level according to the homogeneous pri-nciple. All ewes were housed in individual pen. But 6 , 5 and 7 ewes were used to the statistical analysis respectively corresponding LevelⅠ, Ⅱa nd Ⅲ. Three periods were composed of the late pregnancy period (from 97d to 150d), the lactation length (L.period) (30d) and flush period ( from weaning to the second estrus). The results showed as follows: 1. In the late pregnancy period, LWG of ewes themselves of the level Ⅰ, Ⅱand Ⅲwere -4.38±1.91kg, 2.36±2.78kg and 6.12±3.35kg. The total birth weight of lambs of each ewe were 5.73±1.34kg, 5.40±1.65kg and 7.69±2.24kg respectively ( P>0.05), but litter weight of level Ⅲwas higher than levelⅠand Ⅱ( P=0.086). The average birth weight of lambs each group were 3.82±0.76kg, 3.86±0.58kg and 4.10±0.77kg respectively ( P>0.05), and the average conceptus were 8.55±1.56kg, 8.20±2.34kg and 9.96±4.61kg respectively ( P>0.05). The DMD, OMD, CPD and ADFD of dietⅡwere significantly higher than dietⅠ( P<0.01), the OMD and ADFD were higher than diet Ⅲ(P<0.05,P<0.01) . 2. In the L.period, the average number of lambs nursed by one ewe from each group were 1.75 and 1.40 and 1.70 respectively, total milk yield for 30d was 25.12±4.27kg, 38.43±12.53kg and 52.72±13.50kg respectively, the LWG of the ewes each level were 2.25±3.43kg, -1.45±4.57kg and -1.86±3.89kg ( P>0.05), while LWG of the lambs that each ewe nursed were 6.15±2.62kg, 9.22±2.17kg and 11.90±3.58kg ( level Ⅲwas significantly higher than levelⅠ) respectively. The weaning weight of the lamb ( kg.per lamd) was 7.71±2.26kg, 10.45±1.72kg and 11.19±2.51kg ( levelⅠwas significantly lower than level Ⅲ(P<0.01)and Ⅱ(P<0.05)). The DMD and OMD ( P<0.01) and CPD of diet Ⅲ( P<0.05) were significantly higher than dietⅠ, and no significant difference between LevelⅡa nd LevelⅠ, Ⅲwas observed ( P>0.05) on the above. No significant difference on ADFD among the three diets was found ( P>0.05). 3. In flush and mating period, the heat cycle of ewes for levelⅠ, Ⅱand Ⅲoccurred at 18.60d, 13.25d and 10.71d after weaning when the average LW of three groups ewes were 46.06kg, 46.44kg and 53.71kg, the increment of liveweight compared with that in weaning were 1.35kg, -0.41kg and 2.00kg respectively, the ratio of ewe in estrus were correspond to 83.33%, 80.00% and 100.00%, the fertility rates of ewes were 100%, 100% and 85.71%. After second estrus, ewes of all groups were on massfeeding at 0.9×NRC　level. The lambing percentage of levelⅠa nd Ⅱwere both 200%, while level Ⅲwas 183.33%. The lambing interval of three Levels were 201.8d, 183.5d and 187.7d respectively, two-lambing-one-year was realized in LevelⅡand Ⅲ. The birth weight of LevelⅠ, Ⅱand Ⅲwere 3.34kg, 3.68kg and 3.96kg respectively.