| The purpose of this study was to investigate the effects of rumen-protected arginine(RP-Arg)supplementation during pregnancy on lambing performance and the content of arginine(Arg)metabolites in plasma of Duolang ewes,the changes in lactation and milk composition content of Duolang ewes and effects of early supplementation on lamb growth,it provides scientific reference basis for efficient feeding of Duolang ewes and lambs.Experiment Ⅰ: Fifty-one Duolang ewes with body weight of 48.04±9.28 kg were selected and conducted simultaneous estrus and artificial breeding.They were randomly divided into control group,Arg group and RP-Arg group,with 17 ewes in each group.On the 90 th day of pregnancy,the ewes in the control group were supplemented with 0 g/kg BW,in the Arg group were supplemented with 0.25 g/kg BW Arginine and in the RP-Arg group were supplemented with 0.5 g/kg BW rumen-protected arginine per day,and the supplementing ended at the time of deliver.The results showed that lambing rate and live lambing rate in RP-Arg group were lower than those in control group and Arg group,the birth weight of lamb in RP-Arg group was 4.60% and 8.20% higher than that in control group and Arg group,respectively,but there was no significant difference(P>0.05).On the 120 th day of pregnancy,the plasma nitric oxide content and urea content in RP-Arg group were 26.77%(P<0.05)and 36.40%(P<0.01)higher than that in control group,and the spermine content was 20.69% and 20.69% lower than control group and Arg group,respectively(P<0.01),The activity of superoxide dismutase was 23.45% higher than that of Arg group(P<0.01),and the activity of catalase was 20.78% and 16.95% higher than that of control group and Arg group,respectively(P<0.01),the content of estradiol was 15.38% higher than that of control group(P<0.01),and the content of progesterone was 45.75% and 32.05% higher than that of control group and Arg group,respectively(P<0.01);At the 12 th hours after delivery,the activity of superoxide dismutase in the plasma of RP-Arg group was 14.46% higher than that of Arg group(P<0.01),the activity of glutathione peroxidase was 9.04%(P<0.01)and 6.41%(P<0.05)higher than that of control group and Arg groups,respectively,the content of estradiol was 13.52% higher than that of Arg group(P<0.05),and the content of progesterone was 50.25% and 41.12% higher than that of control group and Arg group,respectively(P<0.01),The content of prolactin was 37.53% higher than that of control group(P<0.05).In conclusion,the rumen-protected arginine supplementation during pregnancy can promote the metabolism of arginine in the ewes,thereby increasing the birth weight of lambs,and has a positive effect on promoting the urea cycle,improving the antioxidant capacity and increasing the content of reproductive hormones.Experiment Ⅱ: Fifty postpartum Duolang ewes with body weigh of 59.42±6.10 kg were selected to determine the milk yield of the ewes at the 11 th to 30 th day after delivery and the changes in milk composition at the 1st,3rd,7th and 14 th day.Twenty 7-days-old Dubo×Duolang hybrid male lambs with body weight of 7.76±1.00 kg were randomly divided into control group and supplementary feeding group.Lambs in the supplementary feeding group were suckled with ewes from birth to 6 days of age and supplemented with lambs pellets from 7 days of age to 49 days of age,and lambs in the control group were suckled freely with ewes the beginning to the end of the experiment.The result showed as followers: The total lactation of ewes from 11 to 30 days postpartum was 14.92±2.26 kg,and the average daily lactation was 0.75±0.11 kg.The lactation volume increased continuously on postpartum day 11 to15,reached the highest level on postpartum day 16 to 20 and 21 to 25 and tended to be stable,reached the highest level on postpartum day 25,and gradually decreases on postpartum day 26 to 30.The percentage of milk fat,non-fat solids,milk protein,lactose and the content of ash of ewes on postpartum day 1 were significantly higher than those on postpartum day 3,7,and 14(P<0.01),the milk fat percentage on postpartum day 3 significantly was higher than that on the 7 and 14(P<0.01).The pellet feed supplementation from 7 days of age had significant effects on the body weight gain of lambs at 35 to 42 days of age(P<0.01)and 7 to 49 days of age(P<0.05).In addition,The milk yield changes of Duolang ewes from 11 to 30 days postpartum showed a change pattern that first increased to a peak and then gradually decreased,the content of various nutrients in the milk of ewes on the first day of postpartum is the highest,and their content gradually decreases with the extension of lactation,and supplementary pellet feed can increase the body weight of lambs. |
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