| To explore the application effect of acidifiers on broilers,this experiment preliminarily explored the antibacterial effects of single acidifiers and composite acidifiers on common pathogenic bacteria through in vitro antibacterial tests;After animal feeding experiments,single acidifiers(benzoic acid,fumaric acid)and composite acidifiers(containing 60%fumaric acid,25% formic acid,0.2% propionic acid)were used as additives,and white feather broilers were used as experimental animals to explore the effects of the acids used in the experiment on the growth performance,intestinal barrier,and intestinal microbiota of white feather broilers,revealing their application effects,and providing guidance and reference for subsequent production and application.Study on the in vitro antibacterial effect of different types of acidifiers on common pathogenic bacteria in Experiment 1In order to evaluate the antibacterial effect of three acidifiers(fumaric acid,benzoic acid,and compound acidifiers)in vitro,the test uses the double dilution method and the coating plate method to determine the minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of three standard bacteria(Escherichia coli,Staphylococcus aureus,and Salmonella),and each sample is set with three replicates.The results showed that the composite acidifier had inhibitory effects on all three pathogenic bacteria,with MIC and MBC of 0.5 mg/ml,respectively.The MIC and MBC of fumaric acid against Escherichia coli and Salmonella are 1 mg/ml,that of Staphylococcus aureus is 2 mg/ml,that of MBC is 4 mg/ml,that of benzoic acid against Staphylococcus aureus and Salmonella is 2 mg/ml,that of MBC is 4 mg/ml,and that of Escherichia coli is 1 mg/ml.Conclusion: Acidifiers can inhibit the growth of Escherichia coli,Staphylococcus aureus and Salmonella in different degrees.Compared with the other two single acids,the composite acidifier has the strongest antibacterial and bactericidal ability,with MIC and MBC of 0.5 mg/ml.The inhibitory effect of fumaric acid on Escherichia coli and Salmonella was higher than that of Staphylococcus aureus,while the inhibitory effect of benzoic acid on Staphylococcus aureus and Salmonella was better.Effect of acidifiers on growth performance,carcass quality,meat quality,and intestinal barrier function of white feather broilers in Experiment 2In this experiment,360 1-day-old healthy white feathered broilers with an initial weight of(44.05 ± 0.02)g were selected and randomly divided into 6 groups based on the principle of similar weight and half male and half female.Each group had 6 replicates,with 10 chickens per replicate.The blank control group was fed with a basic diet.Experiment group 1(T1)added 2000 mg/kg of benzoic acid to the basic diet,Experiment group 2(T2)added 2000 mg/kg of fumaric acid to the basic diet,and Experiment group 3(T3),Experiment group 4(T4),and Experiment group 5(T5)added 1000,2000,and 3000 mg/kg of composite acidifiers to the basic diet,respectively.Free feeding and drinking during the feeding period,feeding for42 days.The results showed that: 1)Compared with the control group,the average daily feed intake(ADFI)of each experimental group from 22 to 42 days significantly increased(P<0.05);The average daily gain(ADG)from day 22-42,ADFI and ADG from day 1-42,and the final weight(FBW)of broilers from day 42 were significantly increased(P<0.05)in the T1 group,and the ADG throughout the entire period was significantly higher than that of the T2 and T5groups(P<0.05).2)Compared with the control group,each experimental group significantly improved the complete and half clean bore rates of broilers(P<0.05);The b *(yellowing)value of the chest muscles of broilers in the T1 and T3 groups significantly decreased at 45minutes(P<0.05).3)There was no significant difference in organ index between the experimental groups and the control group(P>0.05).4)The nutrient digestibility of organic matter and crude protein in T1 group was significantly higher than that in other groups(P<0.01);Compared with the control group and T2 group,the digestibility of crude ash in T1,T3,T4,and T5 groups was significantly increased(P<0.05).5)Compared with the control group,the pH value of the jejunum in the T3 group(complex acidifier 1000 mg/kg)was significantly reduced(P<0.05).6)Compared with the control group,the gene expression of MUC1(mucin-1)in the T3 group was significantly reduced(P<0.05).7)Compared with the control group,the Shannon index and PD index of cecal microbiota in the T3 group were significantly reduced(P<0.05),while the other indices showed no significant difference(P>0.05).Microbial composition of the cecum: At the phylum level,the abundance of Bacteroidetes in the T3 group was significantly increased(P<0.05),while the abundance of Proteobacteria was significantly reduced(P<0.05).At the genus level,compared with the control group,the abundance of Clostridium and Bifidobacterium in the T3 group was significantly increased(P<0.05),while the abundance of Methylobacterium,Escherichia coli,Porphyrin producing bacteria,and Brucella in the Proteobacteria group was significantly reduced(P<0.05).Conclusion: Compound acidifiers can significantly increase the relative abundance of Bacteroidetes and Actinobacteria(Streptomyces,Bifidobacterium)in feces,and significantly reduce the relative abundance of Methylbacteria,Escherichia coli,Porphyrin producing bacteria,and Brucella in Proteobacteria.It has a positive impact on the expression of genes related to the jejunal barrier,while also reducing intestinal pH to a certain extent.The above results indicate that acidifiers can regulate and optimize intestinal microbiota,enhance intestinal barrier function,and maintain intestinal health.As the feed intake and body weight gain of broilers significantly increase,the carcass quality and meat quality are improved,and the nutrient digestion and utilization efficiency of organic matter,crude protein,and crude ash are improved,ultimately leading to improved growth performance.This indicates that adding organic acids to the diet can enhance nutrient absorption and promote growth and weight gain.In this experiment,the composite acidifier with an additive amount of 1000 mg/kg has the best use effect,so it is recommended to be applied in practical production.In summary,under the conditions of this experiment,a compound acidifier with a dosage of1000 mg/kg has similar effects as benzoic acid in regulating intestinal microbiota,reducing intestinal pH,enhancing intestinal barrier function,improving production performance and carcass quality.However,from the perspective of improving economic benefits,benzoic acid is expensive and not the best choice for production application.Therefore,in practical production applications,it is recommended to add and use composite acidifiers. |
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