Study On The Effects Of 5-Hydroxytryptophan On Rumen Function,Growth Performance,Rumen And Blood Metabolites In Sheep

5-Hydroxytryptophan（5-HTP）is a substance extracted from the seed of the African legume shrub plant Griffonia,which has various biological effects such as antidepressant and antioxidant.His research has focused on rats and mice,but has rarely been reported in ruminant applications.In this study,the effects of5-hydroxytryptophan on rumen function,growth performance,rumen and blood metabolites in sheep were explored by in vitro and in vivo experiments,16S r DNA high-throughput sequencing technology and metabolomics technology,and the mechanism of action of 5-hydroxytryptophan on sheep body was revealed,which provided a theoretical basis for its utilization in ruminant nutrition.Test 1:Effects of different doses of 5-hydroxytryptophan（5-HTP）on rumen fermentation,rumen microorganisms and metabolites in sheepIn this study,the effects of adding different doses of 5-HTP on rumen fermentation parameters,microbial community composition and metabolite group of sheep were explored through in vitro tests,and the appropriate dose of 5-HTP feeding in vivo was screened.Three male small-tailed cold sheep（200±10）days old equipped with rumen fistula were selected;Weight（30±2.5）kg was the test subject,using two factors experimental design,factor one is different doses of 5-HTP（0mg/kg DM,2mg/kg DM,4mg/kg DM,8mg/kg DM,10mg/kg DM）,that is,the control group containing only the culture substrate,4 different doses of 5-HTP groups on the basis of the culture substrate,each group has 12 replicates.The second factor is different in vitro culture times（0,3,6,12,24,48h）.The results showed that the addition of5-HTP group with 8mg/kg DM dose could improve feed dry matter utilization and promote the production of rumen volatile fatty acids（VFA）and ammonia nitrogen（NH₃-N）in vitro.5-HTP had a significant effect on rumen microbial community composition（P<0.05）.The total abundance of the top 10 genera was higher in the high-dose group（8 mg/kg DM and 10 mg/kg DM）than in the low-dose group（2mg/kg DM and 4 mg/kg DM）at 12 h and 48 h,and the abundance of Succinivibrio in the high-dose group was significantly higher than in the low-dose group（P<0.05）.There were significant differences in the effect of different amounts of5-HTP on the rumen metabolite group（P<0.05）,and we screened a total of 15differential metabolites that may affect rumen function,among which the addition of low and high doses of 5-HTP caused the proportion of four metabolites in the rumen to be up-regulated by norvaline,2cycloleucine 2,methylmalonic acid and octanal 2,and the addition of high doses of 5-HTP to uridine 2 The proportions of the three differential metabolites of Lignoceric acid and N-methyltryptophan were down-adjusted,and low-dose 5-HTP was added to screen for panthenol 2,lipoic acid,beta-Sitosterol,gluconic acid 1,N,N-dimethylarginine,Cholesterol-2,2,3,4,4,6-d6Downregulation of 6 differential metabolites and upregulation of 2 differential metabolites of Lyxose 2 and 3-hydroxypyruvate.It also screened out 11 metabolic pathways involved in Biosynthesis of unsaturated fatty acids and Methane metabolism.Both Pearson correlation analysis and ASV Spearman correlation analysis results showed that there was a positive correlation between 1-hydroxy-2-naphthoic acid and Succinivibrio,proving that 5-HTP addition may cause an increase in the differential metabolite of 1-hydroxy-2-naphthoic acid in sheep rumen,which in turn causes an increase in the abundance of Vibrio succinate,and ultimately affects the rumen function of sheep.Test 2:Effects of 5-Hydroxytryptophan（5-HTP）on growth performance,nutrient digestion,blood indexes and blood metabolites in sheepIn this study,the effects of 5-HTP on sheep growth performance,nutrient digestion,blood indexes and blood metabolites were explored through in vivo tests,and the mechanism of action of 5-HTP in sheep was further revealed.In this study,a univariate experimental design was adopted,and 10 small-tailed rams（70-85）days old with good body condition,similar weight（20±1.5）kg and good body condition were selected as the study subjects,and randomly divided into two treatment groups,namely the control group and the 5-HTP group（8 mg/kg DM）,5 replicates in each treatment group,1 sheep per replicate,the control group was fed only the basal diet,and the 5-HTP group added 8mg/kg DM dose of 5-HTP to the basal diet.The test period was 60 days,and the growth performance,starch apparent digestibility,blood indexes and blood metabolite group of sheep were determined.The test results The average weight gain of 60 days in the 5-HTP group was 1.2kg more than that in the control group,and the average daily weight gain in the 5-HTP group in the 0-60 days was 0.02kg more than that in the control group,indicating that 5-HTP had a promoting effect on sheep weight and daily weight gain.During the trial period,5-HTP had no significant effect on the apparent digestibility of sheep starch（P>0.05）.5-HTP significantly reduces the total protein and globulin levels（P<0.05）in sheep blood and increases growth hormone levels.During the trial period,the blood content of 5-HTP,serotonin（5-HT）and melatonin（MT）in sheep increased first and then decreased.The results of the blood metabolite group showed that 43 differential metabolites,such as 5-hydroxytryptophan（5-HTP）,S-methylmethionine,Flavidulol A,5-Methoxytryptophan,5-HEPE,Cholic acid,Nutriacholic acid,Agrocybin,and2-Methylhippuric were screened in the 5-HTP group and the control group acid,DL-Tyrosine,L-Methionine,PC,etc.,and screened out that these differential metabolites were mainly involved in 8 metabolic pathways such as Tryptophan metabolism,protein digestion and absorption,so it was inferred that sheep fed 5-HTP can enter the blood to participate in tryptophan metabolism and protein digestion and absorption in sheep.The overall test results showed that the addition of 5-HTP to 8mg/kg DM had the best effect on rumen fermentation function compared with the 0,2,4 and 10mg/kg DM dose groups,and 5-HTP had significant effects on rumen microbial community composition and rumen metabolites（P<0.05）.Feeding 8mg/kg DM 5-HTP has a certain effect on the growth performance of sheep,and proves that sheep feeding5-HTP will not be completely degraded by the rumen,and part of it will enter the sheep blood to participate in tryptophan metabolism and other pathways.In this study,the effects of 5-HTP on rumen function,growth performance,rumen and blood metabolites in sheep were systematically explored through in vitro and in vivo experiments,which provided a theoretical basis for the research and development of functional feed additives and was of great significance in animal husbandry production.