Effects Of Compound Acidifiers On Growth Performance,Immunity And Intestinal Flora And Metabolites Of Piglets

The feeding stage of piglets is considered to be one of the most important steps in the pig industry.A series of problems often occur during the growth of piglets,such as high incidence of diarrhea,reduced feed intake,low immunity and decreased growth performance.However,both the heavy use of antibiotics and the development of resistant bacteria are associated with the spread of antibiotic resistance.Following the European Union,China banned the use of antibiotic additives in animal feed products in 2020.Therefore,effective alternatives to antibiotics are urgently needed to promote the healthy growth of animals.Some researchers have proposed that organic acids can improve the growth performance of piglets and reduce diarrhea by reducing the p H value of digestive juice and maintaining the balance of microflora,which has a very broad application prospect in production.Single acidifier has its own advantages in practical application according to different product effects,but it also has drawbacks such as single function,large addition measurement,poor palatability and strong corrosion.Therefore,people try to explore the use of compound acidifiers.Compound acidifiers can make different product combinations according to the functional requirements of actual production,and can also overcome various shortcomings of single acidifiers.The surface of action is wider and has greater advantages.The aim of this study was to evaluate the effects of compound acidifiers on growth,immunity,intestinal flora and metabolites of piglets.A total of 180 42-day-old "Duroc × Landrace × Landrace" three-way crossbred piglets were randomly divided into 3 groups with 6 replicates per group and 10 pigs per replicate: control group(antibiotic),benzoic acid group(single acidifier)and compound acid group(compound acidifier).The experiment lasted for 28 days.At the end of the experiment,10 piglets with similar body weight were randomly selected from each group for sampling,and the changes of compound acidifier on growth performance,serum immune indexes,intestinal flora and metabolites of piglets were measured and analyzed.The main test results were as follows:1.Effect of compound acidifier on growth performance of piglets: Compared with the control group,compound acid significantly increased the average daily feed intake and average daily gain of piglets(P < 0.05);The compound acidulant significantly reduced the diarrhea rate of piglets during the whole experiment(P < 0.05).2.The effects of acidifiers on serum immune indices of weaned piglets were as follows:compared with the control group,benzoic acid and compound acidifier significantly increased serum Ig A level(P < 0.01),while benzoic acid and compound acid significantly decreased serum IL-1β level(P < 0.05)and compound acid significantly decreased serum TNF-α level(P <0.05).In addition,benzoic acid and compound acid significantly increased the serum β-defensin level of piglets(P < 0.01).3.Effects of compound acidifiers on intestinal metabolites and fecal p H of piglets:Compared with control group,the Alpha diversity(Chao1 index,observed＿categories index)in the compound acid group was significantly higher than that in the control group(P < 0.01,P <0.05).Beta diversity results show that compound acidifier can improve intestinal microflora of weaned piglets more effectively.Adding compound acidulant can increase the number of beneficial bacteria in piglet intestine,and the number of Megasphaera in compound acid group is significantly higher than that in control group(P < 0.05).Lactobacillus and Roseburia in benzoic acid group were significantly higher than those in control group(P < 0.05).4.Effects of compound acidifiers on intestinal microflora of piglets: compared with control group,the Alpha diversity(Chao1 index,Observed＿species index)in compound acid group was significantly higher than that in control group(P < 0.01,P < 0.05).The results of Beta diversity showed that complex acid could improve intestinal microflora of weaned piglets more effectively.The addition of complex acid could increase the number of beneficial bacteria in intestine of piglets,and Megasphaera in complex acid group was significantly higher than that in control group(P < 0.05).The Lactobacillus and Roseburia in benzoate group were significantly higher than those in control group(P < 0.05).Correlation analysis showed that Roseburia was positively correlated with butyric acid in complex acid group(P < 0.05).Prevotella and Roseburia were positively correlated with fecal p H(P < 0.05).The Lactobacillus in benzoic acid group was negatively correlated with Ig A(P < 0.05).Oscillospira was positively correlated with Ig M(P < 0.05).Roseburia was positively correlated with TNF-α in antibiotic control group,while CF231 was negatively correlated with TNF-α(P < 0.05).There was positive correlation between Lactobacillus and β-DF(P < 0.05).Oscillospira and CF231 were negatively correlated with acetic acid(P < 0.05).CF231 was negatively correlated with propionic acid(P < 0.05).In conclusion,antibacterial acidifiers can improve the growth performance and health status of weaned piglets by regulating immunity and intestinal microbiome homeostasis to a certain extent,and the effect of complex acids is better.