Effects Of Dietary Supplementation With β-1,3-Glucan On Growth Performance And Intestinal Health Of Broilers Infected With Clostridium Perfringens

Broiler necrotizing enteritis is a common intestinal toxic disease in the poultry industry.Chronic intestinal mucosal damage caused by subclinical NE will cause weakened digestion and absorption,daily weight gain and feed conversion efficiency of chickens.The problem of loss of production performance can also cause broiler flock deaths in severe cases,with a mortality rate of up to 50%.With the arrival of July 1,2020,our country’s animal husbandry will gradually enter the era of non-antibiotic,but the increase in the incidence of necrotizing enteritis in poultry has once again become a problem in front of livestock workers.Therefore,this experiment explored the effect of β-1,3-glucan on the growth performance,intestinal health and cecal microflora of broilers infected with Clostridium perfringens and judge whether β-1,3-glucan is an antibiotic substitute.The test consists of three parts:Exp.1 Effects of dietary supplementation with β-1,3-glucan on the growth performance of broilers infected with Clostridium perfringensThis experiment investigated the effect of adding β-1,3-glucan to corn-soybean meal-based basic diets on the growth performance of broilers infected with Clostridium perfringens.We conducted the trial with 672 one-day-old AA broilers in seven equal groups with six repeats per treatment and each repeat included 16 broilers: 1)Control group: basic diet + non-challenge,2)Challenge group: basic diet + challenge,3)CP125 group: 125 mg/kg β-1,3-glucan + challenge,4)CP250 group: 250 mg/kg β-1,3-glucan + challenge,5)CP375 group: 375 mg/kg β-1,3-glucan + challenge,6)CP500 group: 500 mg/ kg β-1,3-glucan + challenge,7)CP750 group: 750 mg/kg β-1,3-glucan + challenge.The trial lasted 42 days.The test results showed that: 1)In the early stage of the test(1~21 days),the addition of β-1,3-glucan to the diet did not significantly affect the average daily feed intake,average daily weight gain and 21-day-old body weight of broilers(P > 0.05);however,it has a significant effect on FCR(P = 0.062),and when the dose of β-1,3-glucan is 250-500 mg/kg,the effect is relatively good,when the dose is greater than 500 mg/kg,the FCR may increase.In the later period of the experiment(22-42 days),the challenge treatment significantly reduced the 42-day-old body weight,average daily weight gain and feed conversion efficiency of broilers(P < 0.05);β-1,3-glucan could significantly reduce FCR(P < 0.05)and increase body weight of 42-day-old broilers.2)The challenge treatment significantly increased the liver index at 21 days of age(P < 0.05),while β-1,3-glucan can reduce the liver index.3)C.perfringens challenge significantly increased the duodenal and jejunum intestinal pathological scores(P <0.05).Different doses of β-1,3-glucan can reduce the pathological scores,but it’s not significant(P > 0.05).4)The challenge of Clostridium perfringens significantly reduced the ratio of duodenal villi height and crypt depth at 21 days of age(P < 0.05).When the dose of glucan was 250-750 mg/kg,there was no statistical difference between the control group ang treatment groups(P >0.05),indicating that β-1,3-glucan had a better effect in this dose interval;the ileum crypt depth of the 42-day-old challenge group was significantly greater than that of the other treatment groups(P < 0.05).In summary,C.perfringens challenge reduced the growth performance of broilers.Adding 250-500 mg /kg β-1,3-glucan to the diet can improve the growth performance of broilers.Exp.2 Effects of dietary supplementation with β-1,3-glucan on the intestinal health of broilers infected with Clostridium perfringensThis experiment investigated the effect of adding β-1,3-glucan(250 mg/kg)to corn-soybean meal-based basic diets on the intestinal health of broilers infected with Clostridium perfringens.In a 2×2 factorial arrangement,a total 384 one-day-old AA broilers in 4 equal groups with six repeats per treatment and each repeat included 16 broilers: 1)basic diet + non-challenge,2)basic diet + challenge,3)250 mg/kg glucan + non-challenge,4)250 mg/kg glucan + challenge.Using q PCR to detect nutrient transporters(Pep T1,SGLT1,L-FABP),tight junction proteins(Claudin-1,Occludin,ZO-1)and MUC2 in the small intestinal mucosa of broilers.The test results showed that: the main effect analysis showed that β-1,3-glucan significantly upregulated 21-day-old ileum MUC2,42-day-old duodenum Pep T1 and Occludin,jejunum SGLT1 and Claudin-1 m RNA expression level(P < 0.05);significantly reduced the expression of 21-day-old duodenum SGLT1 and Occludin,jejunum Occludin,ileum L-FABP and Occludin,42-day-old ileum MUC2 m RNA expression level(P < 0.05).The challenge of Clostridium perfringens significantly increased the expression of MUC2 in the 21-day-old duodenum(P < 0.05);significantly reduced the 21-day-old jejunum SGLT1,Occludin and Claudin-1,21-day-old ileum Claudin-1 and Occludin,42-day-old jejunum L-FABP m RNA expression levels(P < 0.05).Interaction analysis showed that there were interactions between the two treatment factors on the m RNA expression levels of 21-day-old small intestine MUC2 and ileum Pep T1 and 42-day-old jejunum L-FABP(P < 0.05).In summary,under this test condition,the challenge of Clostridium perfringens will affect the absorption of nutrients in the small intestine of broilers and destroy the barrier function of the small intestine intestinal mucosa.The addition of β-1,3-glucan to the diet can improve the intestinal mucosal damage caused by the challenge of Clostridium perfringens in some degree and maintain the health of the intestine.Exp.3 Effects of dietary supplementation with β-1,3-glucan on the cecum microflora of broilers infected with Clostridium perfringensIn this experiment,samples of cecum contents were collected at 21 and 42 days of age,and 16 S high-throughput sequencing was performed on the variable regions of 16 S r DNA V3~V4 to detect the structure of microbial flora in cecum and explore β-1,3-glucan and Clostridium perfringens challenge treatment on the cecum microbial community in broilers.The test results showed that: 1)C.perfringens challenge can increase the Chao1 index and ACE index of 21-day-old cecum flora.2)Challenge treatment will affect the microflora of the cecum,destroying the structural stability of the flora,and β-1,3-glucan can play a better role in the regulation of the flora,causing the disordered structure of bacteria was more similar to the control group and 250 mg/kg β-1,3-glucan group.3)At 21 days of age,the dominant phyla to all treatment groups are Firmicutes,Tenericutes,Proteobacteria,Cyanobacteria,Actinobacteria and Bacteroidetes and so on;the dominant genus are Faecalibacterium,Unclassified_Ruminococcaceae,Unclassified_Clostridiales,Unclassified_Lachnospiraceae,Oscillospira,[Ruminococcus],Ruminococcus,Blautia,Dorea,Bacteroides.At 42 days of age,the dominant phyla to each treatment group are Firmicutes,Bacteroidetes,Proteobacteria,Cyanobacteria and Actinobacteria.The dominant genus includes Faecalibacterium,Unclassified_Clostridiales,Unclassified_Ruminococcaceae,Unclassified_Rikenellaceae,Unclassified_Lachnospiraceae,Oscillospira,Alistopes,[Ruminococcus],Bacteroides,Parabacteroides.4)At the phyla level,the main effect analysis showed that the challenge treatment significantly increased the relative abundance of 42-day-old Firmicutes(P < 0.05)and significantly reduced the relative abundance of Bacteroidetes(P < 0.05).At the genus level,the main effect analysis showed that the challenge treatment significantly increased the relative abundance of 21-day-old Faecalibacterium(P < 0.05),and could significantly reduce the relative abundance of 21-day-old Unclassified_Ruminococcaceae and 42-day-old Oscillospira and Alisipes;Interaction analysis showed that the two treatment factors had a significant interaction effect on the relative abundance of 21-day-old Faecalibacterium,Unclassified_Ruminococcaceae,Oscillospira,and Blautia(P < 0.05).In summary,the challenge of Clostridium perfringens change the composition and steady state of the cecum microbial flora,and β-1,3-glucan can restore this change to a certain extent,thereby maintaining microecological balance and improving intestinal health.In summary,the addition of β-1,3-glucan to the diet can improve the growth performance and intestinal health of broilers infected with Clostridium perfringens,and can regulate the steady state of the cecum microbial flora of broilers.