Effects Of High-fiber Diets During Growing Season On Growth Performance,Gut Health And Meat Quality In Growing-finishing Pigs

Dietary fiber has received increasing attention in the field of swine nutrition,and fiber-rich feeds have been widely used in swine diets.This is not only due to lower feed costs,but also from the continuing discovery of the nutritional value of dietary fiber.We hypothesized that appropriate dietary fiber levels would positively affect the gut microbiota of growing-finishing pigs,resulting in high fiber tolerance and,in turn,improved ability to digest fiber.Therefore,in this experiment,wheat bran was added to the growing diet to explore whether it produces fiber tolerance,and to explore its effects on growth performance,intestinal microbial composition and intestinal barrier function in growing-finishing pigsThe experiment was carried out in the Luochuan pig breeding demonstration base in Yan’an City,Shaanxi Province."Du Dachang" ternary pigs with a body weight of 48.83 ±0.49 kg were selected;the 12-week feeding experiment required 4 pens per diet treatment and 9 pens per pen.Pigs;during the growing period of pigs,the control group was fed a common basal diet,the treatment group was fed a high-fiber diet with a wheat bran content of 15%,and a high-fiber diet was fed uniformly in the later period(after six weeks).Immunofluorescence,RT-qPCR,Western blot and 16s high-throughput sequencing were used to detect the gut villus height,crypt depth,tight junction protein mRNA,and the distribution of gut microbes.SPSS 23.0 software was used for data analysis.The following results are obtained:1.Effects of high-fiber diets in growing season on growth performance of growing-finishing pigs.Compared with the high fiber group,the control group showed higher BW,daily gain and lower feed to meat ratio on the 21st day,and it was significant(P<0.05).However,from the 42nd day,compared with the control group,the BW and ADG of the high-fiber group on the 63rd and 84th days were significantly increased(P<0.05)and the ratio of feed to meat(F:G)was significantly decreased(P<0.05).The above results indicate that the high-fiber feeding in the early stage adapts the intestine to the high-fiber diet,promotes the digestion of crude fiber and nutrients,and improves the growth performance of finishing pigs.2.Effects of high-fiber diets in growing season on intestinal tissue morphology and physical barrier function in finishing pigs.Compared with the control group,the height of intestinal villi in the high fiber group was significantly increased(P<0.01),and the v/c value was significantly increased(P<0.01).In addition,the high-fiber group significantly increased the mRNA expression level of Claudin protein at the transcriptional level(P<0.05).The above results indicated that dietary fiber improved the ileal tissue morphology and physical barrier function of finishing pigs.3.Effects of high-fiber diets in the growing period on the intestinal chemical barrier function of finishing pigs.The high-fiber group had more intestinal epithelial goblet cells than the control group(P<0.05),and significantly up-regulated the expression level of mucin-2 mRNA(P<0.05).These results indicated that dietary fiber improved the chemical barrier function of the ileum in finishing pigs.4.Effects of high-fiber diets on the structure of gut microbiota during the growing period.The high fiber group significantly increased the relative abundance of Firmicutes and Proteobacteria(P<0.05)and decreased the relative abundance of Bacteroidetes(P<0.05).Meanwhile,the concentrations of butyric acid(P<0.05),isovaleric acid(P<0.01)and valeric acid(P<0.05)in the cecal contents of the high-fiber group were significantly increased.The high fiber group significantly decreased the relative abundance of Helicobacter colon(P<0.01).These results suggest that high-fiber diets alter the composition of cecal and colonic microbiota and improve gut health in finishing pigs.5.Effects of high-fiber diets in growing season on the quality of growing-finishing pork.The high-fiber diet in the growing period significantly increased the pH24h of finishing pigs,and had no adverse effect on the conventional meat quality of finishing pigs;in addition,it reduced the cross-sectional area of muscle fibers and promoted the expression and transformation of muscle fiber types to improve the meat quality of finishing pigs.In conclusion,adding wheat bran to growing-finishing pigs’ diets during the growing period increases dietary fiber levels and can adapt the gut to high-fiber diets.It can improve the growth performance of fattening pigs,improve the composition and barrier function of intestinal microflora and meat quality,which is beneficial to the health of the body and can reduce the cost of feeding.