| The addition and application of dietary fiber in feed can solve the problem of feed resource shortage,and promote the benign development of "efficiency improvement,open source and green" in pig industry to a certain extent.At the same time,the increase of fiber can improve the structure and function of the intestinal flora of the host,and then affect the growth and development traits of the host.As a characteristic local breed,Bamei pig itself has the advantages of tolerance to rough feeding.In order to further reveal the fiber influence on Duroc×Bamei pig growth and development,this study on intestinal flora as the breakthrough point,in-depth study the influence of different fiber adding level of intestinal flora,and further analyzed the flora and the important economic characters,the correlation of Duroc×Bamei pig for appropriate diet fiber added level provides important basis for carrying out the work of this study is to:Twenty-four Duroc ×Bamei pigs were randomly divided into four groups,which were fed basal diet(CK),basal diet+10%(Ⅰ),17%(Ⅱ)and 24%(Ⅲ)silage broad bean straw(dietary fiber levels were 2.4%,4.2%,5.5%and 6.8%)respectively.Growth performance,carcass and meat quality performance were measured after 90 days of experiment.The results showed as follows:(1)with the increase of fiber level,feed to meat ratio in groupⅡ was significantly decreased(P<0.05),lean meat percentage was significantly increased(P<0.05),skin thickness,backfat thickness and fat percentage were significantly decreased(P<0.05);(2)Muscle shear force in group Ⅱ was significantly decreased(P<0.05)and cooked meat rate in group Ⅱ was significantly increased compared with other groups(P<0.05);(3)Organ index results showed that the proportion of large intestine to live body weight was significantly increased with dietary fiber content increasing(P<0.05);(4)Intestinal pH value showed that with the increase of fiber level,cecum pH decreased(P<0.05).Based on the comprehensive analysis slaughter performance and meat quality of hosts,the optimal dietary fiber level was 4.2%.The structure and function of intestinal flora were analyzed by metagenomic sequencing of cecal contents.135 phyla,2726 genera and 20,844 species of bacteria were identified by annotation.α-diversity results showed that the diversity of 5.5%CF bacteria was significantly increased.(3)The results of β-diversity showed that there was significant difference between group Ⅱ and CK(P<0.05);(4)LEfSe results showed that Bacteroidetes,Alistipes,Bacteroidia and Paraprevotella were significantly enriched in group Ⅱ.9 phyla,268 genera and 450 species of fungi were identified by annotation.Compared with the CK,the diversity and abundance of fungal microorganisms in groups Ⅱ and Ⅲ showed an increasing trend.(3)Adonis and PCoA results showed that there were significant differences in cecum bacterial species between group Ⅲ and CK(P<0.05).(4)LEfSe results showed that most of the Epicoccum and Metarhizium,which were related to fiber degradation,were significantly enriched in group Ⅲ with the increase of fiber level,and there was no significant difference in relative abundance among the four groups by One-way ANOVA analysis,but no significant difference at phylum level.At the genus level,Epicoccum and Gymnopilus in the fungal abundance Top200 were significantly different among the four treatment groups.Cecal microbiological function analysis showed that(1)Subdoligraunlum and Erysipelotrichaceae was positively correlated with the bone weight and backfat thickness of the host through the MXCP450(Metabolism of Xenobiotics by Cytochrome P450)and DM-CP450(Drug Metabolism)metabolic pathway,Bacteroides and Paraprevotella were mainly involved in lipid metabolism and polysaccharide degradation pathways,and negatively correlated with backfat thickness and fat weight of the host.Norank_g_Bacteroides and Alloprevotella were significantly positively correlated with GD(Glycosaminoglycan degradation)and GDM(Glyoxylate and dicarboxylate metabolism)metabolic pathways to promote lean meat formation.(2)Epicoccum and Gymnopilus were positively correlated with the metabolic pathway of glycerophospholipid,lean meat rate of hosts,but negatively correlated with phenotypic traits such as fat rate and bone weight.Punctulria and its taxa showed significant positive correlation with amino acid biosynthetic pathway and fat rearrangement.In summary,the conclusions of this study are as follows:dietary fiber supplementation significantly affects the diversity and abundance of intestinal bacteria and fungi,and the structural changes of bacterial community cause significant differences in carbohydrate metabolism,amino acid metabolism,vitamin and cofactor metabolism pathways of Bamei pigs.Through correlation analysis,the change of Bacteroides,Paraprevotella,Epicoccum and Metarhizium resulted in the change of lipid metabolism and carbohydrate metabolism,and affected the formation of lean meat and fat deposition.Through comparison,it is preliminarily determined that 4.2%CF can promote slaughter performance,meat quality of host without affecting growth performance,and 5.5%CF can promote the dynamic balance of intestinal flora and promote the healthy development of intestinal tract,which can obtain good economic benefits.This experiment provided a research basis for the optimization of feeding program and breeding of candidate Bamei pigs. |
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