| Phytosterol esters(PSE)is the products of esterification of phytosterols.Tributyrin(TB)is a typical short chain fatty acid derivative.Studies on model animals show that TB and PSE are expected to be safe and green feed additives.However,the physiological functions of PSE and TB are different.PSE mainly regulates material metabolism,such as antioxidation,cholesterol reduction,and energy metabolism,whereas TB mainly regulates intestinal morphology,barrier function and intestinal flora diversity.We speculate that PSE and TB have some synergistic effects on improving growth performance,enhancing intestinal function,and regulating intestinal microflora structure of weaned piglets,but further research is needed.Therefore,this paper aims to study the effects of TB and PSE and their combination on growth performance,intestinal flora,intestinal chyme metabolites,and intestinal barrier of weaned piglets.(1)Experiment 1: one hundred and twenty PIC commercial healthy weaned piglets with similar body weight were selected and divided into 5 groups with 8replicates in each group and 3 piglets in each replicate.The piglets in the control group were fed the basic diet,while the piglets in the experimental group were fed the experimental diets supplemented with 150,300,450 and 600 mg/kg PSE in the basic diet,respectively.Before the experiment,7 days were set as the transition period,and the experiment stage was lasted 28 days.The results showed that the average daily feed intake of 150 mg/kg PSE group was significantly higher than that of the control group(P<0.05)in the early stage of the experiment(1-14d),which increased by5.93%.The average daily gain of 300 mg/kg PSE group was significantly higher than that of the control group(P<0.05).The other experimental groups had no significant effect on the average daily feed intake and average daily gain(P>0.05).In the late stage of the experiment(15-28d),PSE had no significant effect on average daily feed intake,average daily gain,and feed/weight of weaned piglets(P>0.05).During the whole experiment period(1-28 d),PSE had no significant effect on average daily feed intake,average daily gain,and feed/weight of weaned piglets(P>0.05).In the early stage of the test(1-14d),the diarrhea index of each level of PSE group was lower than that of the control group,and the diarrhea index of the 300 and 450 mg/kg groups was the lowest.However,the differences in diarrhea index were not significant(P>0.05).In the later stage of the experiment(15-28 days),the diarrhea index of the 300 mg/kg group was lower than that of the other groups.During the whole trial period(1-28days),the piglets fed with the PSE had lower diarrhea index when compared with the control group.In different groups,the 300 mg/kg group had the lowest diarrhea index.However,the differences in diarrhea index were not significant(P>0.05).(2)Experiment 2: ninety-six PIC commercial healthy weaned piglets with similar body weight were selected and divided into 4 groups with 8 replicates in each group and 3 piglets in each replicate.In a 2 * 2 Block trial design,the control group was fed the basic diet,while the experimental group was fed the basic diet supplemented with1500 mg/kg TB、300 mg/kg PSE、1500 mg/kg TB +300 mg/kg PSE,respectively.Before the experiment,7 days were set as the transition period,and the experiment stage was lasted 28 days.The results showed that the ADFI and ADG of weaned piglets were significantly elevated by the TB(P<0.01),while PSE significantly decreased the feed/weight(P<0.05).All of them had no effect on the growth performance of weaned piglets in the late stage(15-28d)and the whole stage(1-28d).TB and PSE had no significant effect on organ index and p H value of intestinal contents of weaned piglets.PSE significantly decreased the content of serum albumin(P<0.05)and increased the level of high density lipoprotein cholesterol(P<0.01)in the early stage of the experiment(1-14days),and had a significant interaction effect with TB on reducing the level of serum triglyceride and increasing the level of high density lipoprotein cholesterol(P<0.05).PSE significantly increased serum insulin,growth hormone,and insulin-like growth factor levels(P<0.05),and the combination of PSE and TB had interaction effect(P<0.05).PSE significantly reduced the level of serum endotoxin(P<0.05).(3)Experiment 3: on the basis of Experiment 2,the effects of PSE,TB and their combination on intestinal health of piglets were further analyzed.The results showed that PSE,TB and their combination had no significant effect on ileal chyme activities of weaned piglets(P>0.05).PSE significantly decreased the levels of IL-8 and TNF-α in ileum mucosa(P<0.01),whereas significantly increased the levels of IL-10 and Ig A(P <0.01).TB significantly increased the level of IL-8 in ileal mucosa of piglets(P< 0.05).PSE and TB significantly increased the ratio of villus height to crypt depth(P< 0.05).PSE and TB significantly promoted the m RNA expression of occludin and claudin 1 genes(P <0.05).(4)Experiment 4: on the basis of Experiment 2,the effects of PSE,TB,and their combination on intestinal microflora,intestinal chyme metabolites and intestinal mucosal transcriptome were studied by omics.At the phylum level,the abundance of Firmicutes in ileum of piglets in each group was the highest,while the proportion of Firmicutes in PSE group was lower than that in the other three groups.The proportion of Actinobacteria in PSE group was the highest and that in TB group was the lowest.The proportion of Proteus in TB group was the highest and that in PSE + TB group was the lowest.The proportion of Bacteroides in TB,PSE and TB + PSE groups was significantly higher than that in the control group,and the proportion of TB + PSE was the highest.Compared with the control group,the abundance of Lactobacillus in TB group was higher,while that in TB + PSE group was lower.The abundance of Streptococcus in PSE and TB + PSE groups was significantly higher than that in the control group and TB group.The octococcus in TB + PSE group was the highest,while that in TB group was the lowest.The Staphylococcus in TB,PSE and TB + PSE groups were significantly lower than those in the control group.A total of 780 metabolites were identified in ileal chyme,159 of which showed differences.KEGG signaling pathway analysis showed that the different metabolites were significantly enriched in isoflavonoid biosynthesis,ether lipid metabolism,tryptophan metabolism,biosynthesis of phenylpropanoids,galactose metabolism,and other signaling pathways.A total of 69426 transcripts were identified from 25346 genes in ileal mucosa of piglets,including 24175 known genes from 49331 transcripts and 1171 newly identified genes from 20095 transcripts.A total of 2713 differentially expressed genes were identified and enriched in immune regulation,vitamin metabolism,enzyme activity regulation,substance transport and carrier activity,and other signaling pathways.In conclusion,In the early stage of the test,300mg/kg PSE can effectively improve the average daily gain of piglets,and dietary supplementation of TB and PSE can improve the growth performance of weaned piglets,help to maintain the dynamic balance of serum biochemical indexes,and improve the health status of the body.They can also effectively enhance the immune regulation ability of piglets’ intestine after weaning,maintain the structural integrity of piglets’ intestine,maintain the intestinal mucosal barrier function,help to increase the intestinal beneficial flora and reduce the harmful flora,improve the intestinal flora structure,and regulate the intestinal microbial balance.PSE and TB can improve the intestinal structure of weaned piglets by improving the level of intestinal metabolites.In general,TB and PSE have a certain synergy. |
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