Effects Of Rumen-protected Tryptophan And Calcium Folinate Supplementation On The Content Of Plasma Tryptophan,Kynurenine And Melatonin In Sheep

This article aimed to study the effects of tryptophan,rumen protected tryptophan（experiment one）and rumen-protected tryptophan,different doses of calcium folinate（experiment two）supplementation on the content of plasma tryptophan and partial of it’s related metabolites in sheep,and to explored ways to increase the content of plasma melatonin in ruminants.Experiment Ⅰ:Fifteen Suffolk sheep aged 3±0.5 years,with average body weight 53.49±2.41 kg were divided into 3 groups（five in each group）which was control group,trail group I and trial group II.All sheep were fed with 10 g/kg BW powder concentrate,1.8 kg corn silage,and allowed free choice continuous access to mixed hay.Animals of trail group I and trial group II was fed with tryptophan 150mg/kg BW,rumen-protected tryptophan 333 mg/kg BW each day,respectively.The results showed as follows:1)Compared with control group,the content of plasma total tryptophan and free tryptophan in the trial group I were significantly increased at 2 hours after feeding（P<0.01）,and the content of kynurenine was significantly increased（P<0.05）.The content of total tryptophan and free tryptophan in the trial group II was significantly higher than that in control group and trial group I at 6 hours after feeding in the morning（P<0.05）.Plasma free tryptophan in trial groups were considerably higher than that of the control group at4 hours after feeding in the afternoon（P<0.05）.2)The plasma 5-HT of the trial group II was significantly higher than that of control group and trial group I（P<0.05）at 10 hours after feeding in the morning and 8hours after feeding in the afternoon.At 6 and 8 hours after feeding in the morning,the plasma levels of melatonin in trial groups were significantly higher than those in the control group（P<0.01）,and there was no significant differences between the trial groups（P>0.05）.At 4 and 8 hours after feeding in the afternoon,melatonin in trial group II was significantly higher than that in control group（P<0.05）.3)During the daytime,the level of plasma free fatty acids in the control group was significantly higher than that in trial groups at 2 h after feeding in the afternoon（P<0.01）.There was no significant difference in plasma albumin between control and trial groups（P>0.05）.4)Compared with the control group,the trial group II significantly increased the plasma total antioxidant capacity and glutathione peroxidase（GSH-PX）activity and significantly reduced the content of malonaldehyde（MDA）（P<0.01）.The plasma of GSH-PX activity and the MDA content in trail group I were significantly increased（P<0.01）.Therefore,Experiment Ⅱ:Fifteen Suffolk sheep aged 3.0±0.5 years,with average body weight 64.45±2.41 kg were divided into 3 groups（five in each group）which was control group,trail group I and trial group II.All sheep were fed with 12 g of body weight of concentrate,1.8 kg corn silage,222.2 mg of body weight of rumen-protected tryptophan and allowed free choice continuous access to mixed hay.On the basis of this,animals of trail group I and trial group II was added calcium folate 50 mg/sheep,100 mg/sheep each day,respectively.The results showed as follows:1)There was no significant difference of plasma tryptophan and kynurenine between groups during 0 to 12 hours after feeding in the morning（P>0.05）,but plasma tryptophan content in trial groups reduced at 6 and 8 hours after feeding in the morning（P=0.0872,P=0.0531）.Plasma kynurenine content in the plasma of trial groups reduced too at 4.5,6,8 and 10 hours after feeding in the morning（P=0.0948,P=0.0667,P=0.0909,P=0.0542）.2)At 4.5 and 8 hours after feeding in the morning,plasma 5-hydroxytryptamin content in trail groups increased compared with the control group（P=0.0807,P=0.0541）.At 10 hours,plasma 5-hydroxytryptamin content in trail groups significantly increased（P=0.0057）.At 6 and 8 hours after feeding in the morning,plasma melatonin content in trail groups also increased（P=0.0890,P=0.0704）,and it was significantly higher at 10 hours than that in the control group（P=0.0002）.3)Compared with the control group,the plasma total antioxidant capacity and glutathione peroxidase activity in trail group II were significantly increased（P<0.05）,but malonaldehyde concentration was significantly decreased（P<0.05）,total antioxidant capacity in trail group I was also significantly improved（P<0.05）.In conclusion,supplement with tryptophan can rapidly increase the content of total tryptophan,free tryptophan and kynurenine in sheep after feeding,while the above effects were more moderate when feeding rumen protected tryptophan.Supplemented with tryptophan or rumen-protected tryptophan has no significant effect on plasma albumin,free fatty acids and 5-hydroxytryptamine,concentration,but it can increase the content of plasma melatonin between 4～8 hours during daytime,and rumen-protected tryptophan can maintain the melatonin at high level in sheep during nighttime.The plasma antioxidant capacity is improved by feeding with tryptophan or rumen-protected tryptophan.Supplementation with 50or 100 mg·sheep^-1·d-¹calcium folate in sheep fed with rumen-protected tryptophan（222.2 mg/kg BW）has the tendency of reducing plasma kynurenine content from 4.5 h to 10 h post feeding,but has no significant effect on plasma tryptophan,5-hydroxytryptamine and melatonin content during daytime,but can improve the plasma oxidation capacity of sheep.