Effect of nutrition level on reproductive performance of Tan×Small Tail Han crossbred ewes
Le résumé fourni par la source
The effects of(Ⅰ) 0.8×NRC,(Ⅱ) 0.9×NRC and(Ⅲ) 1.0×NRC levels of metabolic energy(ME) and crude protein(CP) on reproductive performance of ewes during the late period of pregnancy(97-150 d),lactation period(30 d) and flush period(from weaning of lambs to end of the second estrus cycle) were studied.Thirty Tan×Small Tail Han crossbred ewes in lamb at the first or second conceiving stage were randomly divided into three groups(6,5 and 7 ewes in groups Ⅰ,Ⅱ and Ⅲ respectively were used for statistical analysis).All the ewes were individually housed in pens with lamb creep.1) During the late period of pregnancy,the postpartum weight of ewes for group Ⅰ(43.50±7.50 kg) was lower than those of groups Ⅱ and Ⅲ(47.20±2.12 and 54.79±6.72 kg).The average daily gain(ADG) of ewes-selves for group Ⅲ(137.4±59.8 g) was greater than those of groups Ⅰ and Ⅱ(-57.7±39.9 and 34.2±56.2 g).Differences in birth weight of lambs(3.82±0.76,3.86±0.58 and 4.10±0.77 kg respectively) among the three groups were not significant,but litter weight was greater for group Ⅲ(7.69±2.24 kg) than for groups Ⅰ and Ⅱ(5.73±1.34 and 5.40±1.65 kg).2) During the period of lactation,milk yield of ewes(27.08±4.52,40.34±11.90 and 55.48±14.29 kg),body-weight(BW)(13.49±3.82,14.62±3.64 and 19.32±4.45 kg) and body-weight gain(BWG) of litters(7.17±2.71,9.22±2.17 and 12.28±3.15 kg),BW at weaning(7.71±2.26,10.45±1.72 and 11.19±2.51 kg) and BWG of lambs(4.10±1.60,6.59±1.38 and 7.08±2.09 kg) increased with the nutritive levels of ewes.BW of group Ⅰ ewes increased(+0.94±2.053 kg) but for groups Ⅱ and Ⅲ,it decreased(-0.35±2.74 and-1.86±3.89 kg),although there were no significant differences in BWG among all groups.3) For group Ⅰ,Ⅱ and Ⅲ ewes,BWs at the end of nursing were 46.31±7.61,46.85±2.58 and 52.93±4.20 kg respectively.The first estrous cycle occurred at 18.60±12.86,13.25±6.70 and 10.71±4.07 d after cessation of nursing.The ratios of barren ewes at the end of the second estrous cycle were 16.67%,20.00% and 14.29%,and the lambing intervals were 201.8,183.5 and 187.7 d.
Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.