Effects Of Vitamin B6 And Protein On Intestinal Function And Amino Acid Metabolism Of Weaned Piglets

As quality life improves,people increasingly consume high protein foods.Many studies have shown that vitamin B6(Vit B6),as a coenzyme factor,could regulate many metabolic processes in the body,especially for protein and amino acid.Crude protein(CP)is one of the most important and conventional nutrients in the diet for piglets.An excess or lack of CP will have adverse effects on the piglets’ health.However,fewer experiments have been conducted on the effects of dietary protein and Vit B6,as well as their interactions on the intestinal function and amino acid metabolism of weaned piglets.The objective of this study was to investigate the effects of dietary Vit B6 and its interaction with protein on the growth performance,intestinal function and amino acid metabolism of weaned piglets using a weaning piglet model,which will provide a reference for the application of Vit B6 in weaned piglets and people that are fed a high-protein diet.The experiment was conducted in the 2×3 two-factors [CP(18% and 22%)and Vit B6(0,4,and 7 mg/kg)] design.Thirty-six 21-day of age weaned [(Yorkshire × Landrace)× Duroc] piglets(7.03 ± 0.15 kg BW)were randomly assigned into six dietary treatments with six replicate pens for a 14-d experimental period.During the experimental period,the initial and final body weight were measured.The feed intake and diarrhea were recorded every day.Samples of blood,liver,intestine,intestinal mucosa and its contents were collected for analysis.The data were statistically processed and analyzed using SPSS 20.0 software after sorted by Excel.The main research results are as follows:1.Dietary Vit B6 had no significant effect on the growth performance of weaned piglets(P > 0.05).Compared with LP,dietary HP significantly reduced the average daily feed intake of weaned piglets(P < 0.05).Dietary Vit B6 and protein had significant interactional effects on ileal villus height,villus width,villus area and the number of Ki67 positive cells(P < 0.01).Compared with LP,dietary HP significantly up-regulated the m RNA expression of COX2,TNF-α and TGF-β in ileum(P < 0.05).Compared with LB6,dietary HB6 significantly downregulated the m RNA expression of IL-10 in jejunum(P < 0.05),and up-regulated the m RNA expression of TNF-α,COX2,IL-1β and TGF-β in ileum(P < 0.05).Dietary Vit B6 and protein had significant interactional effects on the m RNA expression of COX2,IL-10,TNF-α,TGF-β in jejunum and TGF-β,TNF-α,COX2 in ileum(P < 0.05).2.Compared with LP,dietary HP significantly increased the content of serum urea nitrogen,free isoleucine,valine,phenylalanine,histidine,tyrosine,leucine,arginine,and total essential amino acid content(P < 0.05)and decreased serum alanine,lysine,serine,glycine and total non-essential amino acids(P < 0.05).Compared with LB6,dietary HB6 significantly increased serum valine and threonine(P < 0.05),as well as increased the serum proline in MB6(P < 0.01).Compared with LB6,dietary HB6 significantly decreased all hydrolyzed amino acids content except for proline in liver(P < 0.05).Dietary Vit B6 and protein had a significant interactional effect on the hydrolyzed tyrosine content in the liver(P = 0.01).Compared with LP,dietary HP significantly reduced the content of hydrolyzed leucine,phenylalanine,proline,serine,glutamic acid,glycine,alanine,total non-essential amino acids and total amino acids(P < 0.05)in ileum.Compared with LB6,dietary HB6 significantly decreased all hydrolyzed amino acids content except for tyrosine(P < 0.05)and MB6 significantly increased the hydrolyzed tyrosine in ileum(P < 0.01).Dietary Vit B6 and protein had a significant interactional effect on the content of hydrolyzed phenylalanine in ileum(P < 0.05).Compared with LP,dietary HP significantly increased the m RNA expression of jejunal SLC6A20(P < 0.05).Compared with LB6,dietary HB6 significantly decreased the m RNA expression of jejunal SLC36A1 and SLC38A2(P < 0.01),and increased the m RNA expression of jejunal SLC38A5 and ileal SLC7A7(P < 0.05).Dietary MB6 significantly decreased the m RNA expression of ileal SLC6A20,SLC7A6 and SLC38A5(P < 0.05).Compared with MB6,dietary HB6 significantly up-regulated the m RNA expression of SLC36A1 and SLC38A2 in ileum(P < 0.05).Dietary Vit B6 and protein had a significant interactional effect on the m RNA expression of SLC38A5,SLC6A20,SLC7A6 and SLC36A1 in ileum(P < 0.05).3.In the ileum,the dominant microorganisms at the phylum level were Firmicutes and Proteobacteria,and the most dominant genus were Clostridium＿sensu＿stricto＿1,Actinobacillus,Romboutsia,Turicibacter and Lactobacillus.Compared with LB6,dietary MB6 significantly increased Chao1 and ACE index(P < 0.05)and the relative abundance of Actinobacteria and Spirochaetes(P < 0.05).In the colon,the dominant microorganisms at the phylum level were Bacteroidetes and Firmicutes,and the most dominant genus were Faecalibacterium,Prevotella-1/2/9,Lactobacillus and Ruminococcaceae＿UCG-002/005.Compared with LB6,dietary MB6 significantly reduced the shannon index(P < 0.05)and the abundance of Actinobacteria and Ruminococcaceae＿UCG-005(P < 0.05).Compared with LP,dietary HP significantly reduced the abundance of Megasphaera(P < 0.01)and increased the content of isobutyric acid(P < 0.05).4.The high-throughput sequencing results showed that 1777 differentially expressed genes were found between HP-LB6 and HP-HB6 and those DEGs relating to cell proliferation mainly enriched in cell division,nucleic acid metabolism and enzyme activity regulation respectively for cell composition,molecular function and biological processes.In summary,Vitamin B6 supplementation in high-protein diet improved the ileal morphology and function of weaned piglets.Dietary Vit B6 and protein had significant interactional effects on the ileal morphology,cell proliferation,intestinal function and metabolism of amino acids of weaned piglets.It indicated that Vit B6 are provided to people with a high-protein diet to improve intestinal function,and better digest and absorb protein.