| Arginine has a wide range of biological roles.Arginine is easily degraded in ruminant rumens,reducing utilization in the body.The addition of L-citrulline to the diet of single-stomach animals can increase the plasma arginine concentration and improve reproductive performance.L-citrulline does not degrade in ruminant rumens,can some biological role of replenishing arginine be achieved by feeding ruminants L-citrulline? Therefore,this paper studied the effects of L-citrulline feeding on plasma amino acid concentration,reproductive hormone level and reproductive performance after feeding L-citrulline to lake sheep ewes,which provided a scientific basis for the application of L-citrulline in the production of lake sheep ewes.Experiment 1: this experiment adopts the single factor and multi-level test method.Thirty Hu sheep ewes weighing(27.93 ± 1.19 kg)and 8 months old were randomly divided into 5 treatment groups: con group,5 L-Cit group,10 L-Cit group,15 L-Cit group and 20 L-Cit group.There are 6 sheep in each group,and each sheep is fed with 1.19 kg TMR(dry matter)per day.On this basis,the supplementary feeding levels of L-citrulline were 0,5,10,15 and 20 g/d.The experiment lasted for 30 days.The results showed that: 1)the concentrations of citrulline,ornithine and arginine in sheep plasma increased linearly with the level of L-citrulline supplementation(P<0.05),increased the content of plasma NO(P<0.01),decreased the content of blood ammonia(P<0.01),and significantly increased the content of plasma urea in 10 L-Cit group and 20 L-Cit group(P<0.05).2)The contents of gonadotropin releasing hormone,luteinizing hormone and follicle maturation stimulating hormone in each level group were significantly higher than those in con group(P<0.01),and the contents of estradiol in 10 L-Cit group were significantly lower than those in con group and each level group(P<0.01);The content of progesterone in 5 L-Cit group was significantly higher than that in con group and other level groups(P<0.05).3)Supplementation with L-citrulline increased the contents of total antioxidant capacity,catalase,superoxide dismutase and glutathione peroxidase in sheep plasma(P<0.05);Supplementation with L-citrulline reduced the content of malondialdehyde in sheep plasma(P<0.01).Experiment 2: Thirty Hu sheep ewes weighing(41.12 ± 5.73 kg)were randomly divided into two treatment groups: CON group and L-Cit group,with 15 sheep in each group.Each sheep was fed with 1.45 kg TMR per day.On this basis,the supplementary feeding amount of L-citrulline was 0g/d and 10g/d.The experiment lasted for 96 days.The results showed that: 1)the contents of gonadotropin releasing hormone,follicle stimulating hormone,luteinizing hormone,estradiol,progesterone,testosterone and prolactin in the plasma of Hu sheep ewes before estrus had no significant effect among the groups(P>0.05).2)During estrus,the contents of gonadotropin releasing hormone,follicle stimulating hormone,luteinizing hormone,estradiol,progesterone,testosterone and prolactin in plasma of Hu sheep ewes had no significant effect among the groups(P>0.05).3)The weight gain and average daily gain of L-Cit group were significantly higher than those of CON group(P<0.01).4)The conception rate,lambing rate and double lambing rate in L-Cit group were higher than those in CON group.Under the experimental conditions,L-citrulline supplementation could significantly increase the concentration of relevant amino acids in plasma,reproductive hormone level,antioxidant capacity,reproductive performance and body weight gain of Hu sheep ewes,but had no significant effect on the content of reproductive hormone in plasma before and during estrus.Therefore,L-citrulline can be used as a nutritional regulator to promote the transport and absorption of amino acids and improve the antioxidant capacity and reproductive ability of ewes. |
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