Study Of The Effects And Mechanisms Of Fibers On Growth Performance And Intestinal Functions Of Piglets

Three conventional fiber feeds and two unconventional fiber feeds were selected to investigate the fermentation characteristics and product composition in vitro fermentation.Appropriate fiber feeds were selected for animal tests,to explore the effects of fibers on growth performance,apparent digestibility of nutrients,and blood biochemical indexes of piglets.A high-quality fiber was determined and used to study the effects on growth performance,intestinal barrier function,and microorganisms and the possible mechanism of regulating intestinal health.In Exp.1,soybean hull(SBH),kelp powder(KP),oat bran(OB),fermented distiller’s grains(FDG),and sugar beet pulp(SBP)were used as the test groups,starch(ST)was used as the control group,which were inoculated with piglets fecal for 24 h,48h and 72 h in vitro fermentation.The concentration of short chain fatty acids(SCFA)and the differences of microorganisms in the substrate were studied.The results showed that the main products of SCFA in vitro fermentation were acetic acid(AA)and valeric acid(VA),and the concentration of SCFA was proportional to the fermentation time.The sugar in substrate was degraded completely after 48 hours of fermentation.The SBP and KP showed characteristics of rapid fermentation with higher speed and production of SCFA.The SBH,OB,and FDG showed characteristics of slow fermentation with lower speed and production of SCFA.In Exp.2,the effects of 3% SBH,SBP,FDG,and KP on growth performance,diarrhea rate,nutrient digestibility and serum biochemical indexes of piglets were studied.300Duroc×Landrace×Large piglets(12.0±0.3 kg)were divided into 5 treatments with 6repetitions and fed with the control and experimental diets for 21 days.The results showed that diets with different fiber feeds didn’t significantly affect the growth performance and economic benefits of conservation piglets(P>0.05),but reduce the diarrhea index and fecal p H value,and significantly increase the fecal moisture content(P<0.05).The apparent digestibility of dry matter,total energy,and crude protein were significantly decreased(P<0.05).The digestibility of fiber components was increased relatively,the concentration of amino acids such as aspartic acid,threonine,and serine in serum of piglets was significantly affected by fibers(P<0.05).The blood biochemical indexes and health of piglets in 3% SBP group was not significantly affected(P>0.05).The SBP group showed the best effects on promoting the apparent digestibility of nutrients and the concentration of amino acids and derivatives in piglets.Based on the results of Exp.2,the effects of diets with different levels of SBP on growth performance,nutrient digestibility,health,intestinal structure and barrier function,intestinal microorganisms,related gene expression,and other indicators of piglets in Exp.3.60 Duroc×Landrace×Large piglet(10.0±0.3 kg)were divided into 5 treatments with 6repetitions and fed with the experimental diets containing 0%,2%,4%,6% and 8% SBP respectively for 21 days.The results showed that the average daily feed intake(ADFI),average daily weight gain(ADG),and economic benefit of piglets were not significantly affected by SBP(P>0.05).The apparent digestibility of dry matter and total energy were significantly reduced by adding SBP,but the apparent digestibility of ether extract(EE)and calcium(Ca),especially the fiber components(NDF,TDF,IDF,SDF)were increased significantly(P<0.05).The concentration of fiber decomposing enzymes in piglets was significantly promoted(P<0.05).Analysis of the intestinal microogganism of piglets showed the abundance of f＿ruminococcaceae and f＿veillonellaceae was decreased by adding SBP,but the abundance of f＿prevotellaceae and f＿clostridiaceae＿1 was increased at the family level.The digestibility of most nutrients and the concentration of serum amino acids and their derivatives are the highest in 4% SBP group,which was helpful to improve the diversity and abundance of intestinal microorganisms.The levels of triglyceride,potassium ion,ammonia,and urea nitrogen in the serum of piglets were significantly increased(P<0.05),the contents of immune factors and inflammatory factors were increased,but the level of serum alanine aminotransferase was significantly reduced in the 6% SBP group(P<0.05),accompanied by the damage of intestinal morphology and structure.The feed-gain ratio(F/G)and fecal moisture content were significantly increased,and the secretion of fiber degrading enzymes were significantly promoted(P<0.05),the expression of MUC1 and MUC2 was significantly increased(P<0.05),and only the apparent digestibility of crude protein of piglets was significantly reduced in 8% SBP group(P<0.05).Overall,SBP,SBH,FDG,and KP could be used as the potential fiber sources for piglet’diet based on the characteristics of in vitro fermentation.Based on the utilization of nutrient metabolism,the effects of SBP in piglets’ diets are better than SBH,FDG,and KP.4%～6%SBP(1.8-2.3% SDF)is recomanded in the diet of conservation piglets,which is conducive to improve the intestinal barrier function,increase the concentration of SCFAs,improve the abundance and diversity of intestinal microorganisms and promote the secretion of fiber decomposing enzymes,while diet with more than 6% SBP(more than 2.8% SDF)will affect the intestinal health of piglets.