Application Of Compound Acidifier In Broiler Production Based On Response Surface Methodology

Acidifiers play an important role in aquaculture as effective feed additives for antibiotics.Acidifiers can be used in disinfection of aquaculture environment,drinking water and feed for animals.Acidifiers can provide H⁺in the gastrointestinal tract,enhance the activity of pepsin,improve food digestibility,and inhibit the growth and reproduction of harmful bacteria.However,most compound acidifiers can only act on the stomach and cannot play a role in the intestine when they reach the intestine and neutralize with alkaline substances such as bile pancreatic fluid.Therefore,acidifiers with long-term and lasting functions can give full play to their advantages,avoid multiple use under the same conditions,save costs and improve aquaculture efficiency.In this study,response surface method was used for in vitro screening,and the in vitro screening indexes mainly included buffer force,change amount of dietary acid force and bacteriostatic zone of Escherichia coli.Two acidifiers were developed:water-based compound acidifiers and solid-type compound acidifiers.The design idea was to design conjugate acid-base pairs and improve the action time in small intestine by using the properties of the substance and the function of the carrier.It provides a theoretical basis for the development of prolonging the action time of acidifier in the future.In this study,according to the recommendations of the response surface,when the buffer force（Y₁）of in vitro screening of potable compound acidifiers,the change amount of dietary acid force（Y₂）and Escherichia coli inhibitory zone（Y₃）,and the buffer force（Z₁）of in vitro screening of solid compound acidifiers,the change amount of dietary acid force（Z₂）and the Escherichia coli inhibitory zone（Z₃）are all the highest values,The drinking acidifiers were lactic acid 39.96%,propionic acid 19.8%and potassium diformate 4.95%,Y₁=7.82 m L,Y₂=19.35 m L and Y₃=35.74 mm.The solid acidifiers formic acid 9.99%,propionic acid 6.9%,Citric acid 20%and potassium diformate 4.95%,Z₁=6.14 m L,Z₂=11.76 m L and Z₃=36.15 mm.In this study,0-day-old AA broilers（mixed breeding of male and female）with similar body weight and healthy body condition were fed for 21 days.Random Ly divided into 5 groups of 6replicates each,with 10 chickens per replicate,fed in 2 batches.The first batch was an experiment with a water-based acidifier and there were 3 of them,the experimental group,the commercial group and the control group.The concentration of water-based acidifier added to the drinking water of the test group was 0.1%,0.2%and 0.3%respectively.The second batch was solid acidifier test,with 3 and experimental group,commercial group and control group.The concentrations of reinforced acidifier were added to the diets of experimental groups at 0.1%,0.2%and 0.3%.Samples were taken at 21 days of age and the results were as follows:production performance:Compared with the control group,the average daily gain（P<0.01）,the final weight（P<0.01）,and the ratio of feed to gain（P<0.01）were significantly increased in drinking water acidifier test groupⅡ;And the production performance of groupⅡis better than that of commodity group.Compared with the control group,the average daily gain and final weight of solid acidifier test groupⅡwere significantly increased.The ratio of feed to gain was significantly decreased（P<0.01）.And the production performance of groupⅡis better than that of commodity group.Apparent digestibility:the apparent digestibility of crude protein of water-type acidifier groupⅡwas significantly different from that of control group（P<0.05）,and the apparent digestibility of crude protein of water-type acidifier groupⅡwas higher than that of commodity group;The apparent digestibility of ether extract in groupⅠwas significantly different from that in control group（P<0.05）,and the apparent digestibility of ether extract in groupⅡwas higher than that in commodity group.The crude protein digestibility of solid acidifier groupⅠwas significantly different from that of control group（P<0.01）,and the crude protein digestibility of solid acidifier groupⅠwas higher than that of commercial group;The apparent digestibility of dry matter and ether extract was not significant（P>0.05）.Slaughtering performance:the slaughtering rate of water-type acidifier groupⅡwas significantly different from that of control group（P<0.05）,and the slaughtering rate of water-type acidifier groupⅡwas higher than that of commercial group;The chest muscle rate of groupⅠwas significantly different from that of control group（P<0.05）,and the chest muscle rate of water-type acidifier groupⅠwas lower than that of commercial group.The leg muscle percentage of solid type acidifier groupⅡwas significantly different from that of control group（P<0.05）,and the leg muscle percentage of solid type acidifier groupⅡwas higher than that of commercial group;The chest muscle rate of solid type acidifier groupⅢwas significantly different from that of control group（P<0.05）,but the chest muscle rate of solid type acidifier groupⅢwas lower than that of commercial group.Immune organ index:thymus index of water-based compound acidifier groupⅠand groupⅢhad significant differences compared with control group（P<0.05）;Compared with the control group,the thymus index in groupⅠwas increased by 43.41%,and that in groupⅠwas increased by 16.20%compared with the commodity group.There was no significant difference between spleen index and bursa of Fabricius index（P>0.05）.There was significant difference between solid acidifier bursa of Fabricius index groupⅢand control group（P<0.05）.Bursa of Fabricius index groupⅢwas increased by 36.17%compared with control group,and bursa of Fabricius index groupⅢwas increased by 7.5%compared with commercial group.There was no significant difference between thymus index and spleen index（P>0.05）.Intestinal p H value:duodenal p H of water-based acidifier groupsⅡandⅢwas significantly different from that of control group（P<0.05）.Jejunum p H of experimental group was significantly different from that of control group（P<0.05）,ileum p H of groupⅢwas significantly different from that of control group（P<0.01）.Compared with the control group,the duodenum p H of groupⅠwas significantly different（P<0.01）,the jejunum p H of groupⅢwas significantly different（P<0.05）,and the ileum p H of test group was not significantly different（P>0.05）.In terms of the taxonomic composition of intestinal microorganisms,water-based acidifiers significantly reduce the reproduction of opportunistic pathogens such as Enterococcus,and promote the colonization and growth of beneficial bacteria such as Lactobacillus.Erysipelotrichaceae＿Clostridium,Ruminococcus and Blautia were found in the test group and the commercial group.The relative abundance of enterococcus opportunistic pathogens in solid acidifier test group was higher than that in commercial group,and the relative abundance of Lactobacillus in jejuni in groupⅠwas the highest.In the experimental group,Bacteroides and sphingosinomonas had relatively high abundance.In conclusion,the recommended dosage of drinking water acidifier is 2 kg/t;The recommended dosage for solid acidifiers is 1-2 kg/t.