Preparation Of Enzymatic Hydrolysate Of Locust Bean Gum And Its Effect On Performance And Intestinal Health Of Broilers

The main component of locust bean gum is galactomannan.Studies have shown that galactomannan can inhibit or adhere to intestinal pathogens and improve intestinal health.However,due to the formation of a relatively viscous glue in the galactomannan,there is a certain negative impact on the digestion and absorption of the animal.In this study,β-mannanase was used to enzymatically hydrolyze locust bean gum,and low-molecular-weight and low-viscosity enzymatic hydrolysis products of locust bean gum were obtained.The ability of the locust bean digestive product to adhere to intestinal pathogens was evaluated in vitro test.Broiler feeding test evaluated the effects of different additive amounts of locust bean lysate on growth performance,serum biochemical index,antioxidant index,nutrient digestibility,intestinal structure and intestinal flora of broilers.The suitable addition amount of the enzymatic hydrolysate of locust bean gum in broiler diet was screened,which provided a theoretical basis for its application as a new feed additive in poultry broiler breeding industry.The paper consists of three parts:Experiment 1:Preparation and detection of in vitro depolymerization activity of locust bean gum hydrolysate.Theβ-mannanase was used to digest 10%of locust bean gum to obtain the enzymatic hydrolysate of locust bean gum.The enzymatic hydrolysis conditions were as follows:substrate concentration was 10%,enzyme dosage was 10000 U/ml,enzymatic hydrolysis temperature was 37°C,pH was 7.0,and enzymatic hydrolysis time was 12 h.S.cerevisiae was used as an adherent object of S.pullorum and E.coli to mimic the adhesion of pathogenic bacteria to intestinal cells.The depolymerization activity of the enzymatic hydrolysate of locust bean gum was evaluated by microscopic observation and spectrophotometer OD value measurement.The results showed that:1)The percentages of galactomannan,galactomannan oligosaccharide and mannose in the enzymatic hydrolysate of locust bean gum were 50.0%,47.35%and 2.65%,respectively.2)It was found by microscopy that the enzymatic hydrolysate of locust bean gum can eliminate the adhesion of S.pullorum and E.coli to yeast cells and has good depolymerization activity.The optimal aggregation ratio of S.pullorum to yeast cells was determined by spectrophotometer OD measurement:V_Yeast:V_S.=5.5:1 at a concentration of OD₆₀₀=2.0.The depolymerization activity of the enzymatic hydrolysate of locust bean gum was evaluated under the conditions,and the results obtained were consistent with those observed by microscopy.E.coli has a weak ability to aggregate yeast cells and is not suitable for the assay conditions.Experiment 2:The objective of this study was to investigate the effects of enzymatic hydrolysate of locust bean gum on growth performance,serum biochemical indexes and antioxidant indexes of broilers.A total of 768 one-day-old AA broilers were randomly divided into 6 groups with 8 replicates per group and 16 chickens per replicate.Group I was basal diet group;group II was the antibiotic group supplemented with an active ingredient content of 5 mg/kg flavomycin;Group III was locust bean gum group,which supplemented with 0.1%locust bean gum;Group IV,V and VI were enzymatic hydrolysate groups,which supplemented with 0.1%,0.2%and 0.3%locust bean gum enzymatic hydrolysate.The experimental period was 42 days.The results showed that:1)from 1 to 21 days of age,the average daily gain of the 0.3%locust bean enzymatic hydrolysate group was significantly higher than that of the basal diet group and the addition of 0.1%locust bean gum group（P<0.05）.The average daily feed intake of the 0.2%and 0.3%locust bean enzymatic hydrolysate groups was significantly higher than that of the basal diet group（P<0.05）.From 22 to 42 days of age,the average daily gain in the 0.2%locust bean enzymatic hydrolysate group was significantly higher than that in the 0.1%locust bean enzymatic hydrolysate group and the locust bean gum group（P<0.05）.From 1 to 42 days of age,the average daily gain and the average daily feed intake of the 0.2%and 0.3%locust bean enzymatic hydrolysate groups were significantly higher than that of the locust bean gum group（P<0.05）.2)the level of blood glucose increased with the increase of the amount of enzymatic hydrolysate of locust bean gum（0.05<P<0.1）.The 0.3%locust bean enzymatic hydrolysate group had a tendency to reduce the activity of AST and ALT（0.05<P<0.1）.3)the MDA level in the 0.3%locust bean enzymatic hydrolysate group was significantly lower than those in the antibiotic group and the locust bean gum group（P<0.05）.The T-SOD level in the 0.3%locust bean enzymatic hydrolysate group was significantly higher than those in the basal diet group and the locust bean gum group（P<0.05）.Experiment 3:The objective of this study was to investigate the effects of enzymatic hydrolysate of locust bean gum on digestibility,intestinal structure and intestinal microflora in broilers.Test animals and test treatments were the same as test two.The results showed that:1)At 21 days of age,the digestibility of crude fat,crude protein and dry matter in group of the 0.3%locust bean enzymatic hydrolysate was significantly higher than those in groups of the basal diet group and the locust bean gum（P<0.05）.At 42 days of age,the digestibility of crude protein in group of the 0.3%locust bean enzymatic hydrolysate was significantly higher than that in group of the locust bean gum（P<0.05）.2)At 42 days of age,the duodenal villus height and villus height/crypt depth in group of the 0.3%locust bean enzymatic hydrolysate were significantly higher than those in groups of the basal diet,the antibiotic and the locust bean gum（P<0.05）.The jejunum height in groups of the 0.2%and 0.3%locust bean enzymatic hydrolysate was significantly higher than that in the basal diet group（P<0.05）.3)At 42days of age,the number of cecal E.coli in groups of the 0.2%and 0.3%locust bean enzymatic hydrolysate was significantly lower than that in group of the basal diet（P<0.05）.The number of cecal lactobacilli in group of the 0.3%locust bean gum enzymatic hydrolysate was significantly higher than those in groups of the basal diet,the antibiotic and the 0.1%locust bean enzymatic hydrolysate（P<0.05）.In summary,the enzymatic hydrolysate of locust bean gum can release the adhesion of Salmonella and Escherichia coli to yeast cells and has good depolymerization activity.In the animal experiment,the addition of 0.3%locust bean gum enzymatic hydrolysate group and the addition of 5 mg/kg of flavomycin group had the same promoting effect on the growth performance of 1-21 day old broilers.The addition of 0.3%locust bean gum enzymatic hydrolysate can improve the antioxidant performance of 42-day-old broiler chickens,increase the intestinal villus surface area and the number of beneficial bacteria in the intestine,inhibit the colonization of intestinal pathogens,and improve the utilization of nutrients.Therefore,in the range of 0.1%to 0.3%of the test,the optimum amount of the enzymatic hydrolysate of locust bean gum in the broiler diet was 0.3%.