Screening Of Phytase-producing Lactobacilli And Their Effect On Growth Performance And Phosphrous Excretion Of Broiler Chicken

The aim of this study is to screen a Lactobacillus strain with high phytate-degrading activity from the gastrointestinal tract of chickens,and to evaluate the effect of Lactobacilli on growth performance,slaughter performance,immune organ index,ileal flora and phosphorus excretion amount of broiler chicken.The phosphatase and phytase activities of the strain B₉ were individually assayed.The biological assay indicated B₉ is L.plantarum. The main contents and results are as follows:1.Thirty-nine strains of Lactobacillus were isolated and purificated from the gastrointestinal tract of four healthy chickens by MRS-MOPS medium.There are five strains demonstrated high phytase activity in the select medium and produced a color reaction with ALP.By measuring phytase and phosphatase activity,B₉ was found to have the highest activity.The crude activity of phytase of B₉ was 15.97U/mL at pH5.0 and 16.13U/mL at pH7.2.2.According to the results of traditional morphological characters and molecular biology techniques,B₉ was identified as Lactobacillus plantarum.3.150 one-day-old AA broiler chickens were randomly divided into 5 treatments in 6 replications with 5 birds per replicate The five treatment groups were as follows:Group 1,2,3,feeding diets added with L.plantarum B₉(1.5×10⁹CFU/g) 0.05%,0.1%,0.2% respectively.Group 4 feeding diet added with 600U/Kg phytase.Group 5 was control group feeding with standard diet(corn-soybean diets).The tests lasted for 42 days.Feeding experiment results are as follow:(1) Growth performance:Compared with group 5,the average daily gain(ADG) of group 1,2,3 increased by 8.26%(P＜0.01),9.88%(P＜0.01),7.15%(P＜0.01)respectively. Compared with group 4,the ADG of group 1,2,3 increased by 2.40%(P＞0.05),3.94% (P＜0.05),1.35%(P＞0.05).Compared with group 5,group 4 increased by 5.72% (P＜0.01).Compared with group 5,feed conversion ratio(F/G) of group 1,2,3 decreased by 2.45%(P＜0.01),4.41%(P＜0.01),0.49%(P＜0.01).Compared with group 4,F/G of group 1,2.3 decreased by 1.97%(P＜0.01),3.94%(P＜0.01),0.00%(P＞0.05).Compared with group 5,F/G of group 4 decreased by 0.49%(P＜0.05).In this experiment, Lactobacilli addition(0.1%,1.5×10⁹CFU/g) significantly increased ADG(P＜0.01),and decreased F/G(P＜0.01).(2)Slaughter performance(SP):Compared with group 5,the SP of group 1,2,3 increased,including dressing percentage,bore half the rate of net,net rate of full-bore,leg rate and pectoral rate.Compared with group 4,the SP of this three groups also increased.The SP of group 1,2,3 have the trend of reduce.In this experiment,Lactobacilli addition(0.05%,1.5×10⁹CFU/g) significantly increased the SP(P＜0.01).(3)Immune organ index(IOG):Compared with group 5,the IOG of group 1,2,3 increased,including thymus index,spleen index and bursal index.The IOG of group 1,2,3 showed a increasing trend followed by decreasing.In this study,Lactobacilli addition (0.05%,1.5×10⁹CFU/g) significantly increased the IOG(P＜0.01).(4)Ileal flora(IF):Compared with group 5,amount of floras in ileum of group 1,2,3 was significantly different from each other,except anaerobic bacteria of group1.Amount of Bacillus bifidus,Lactic acid bacteria,Bacteroid and total anaerobe bacteria in the test groups increased,while Enteric bacilli,Enterococci,and total aerobe bacteria of the test groups decreased.The B/E value of Lactobacilli addition(0.2%,1.5×10⁹CFU/g),as an intestinal health indicators,was significantly increased(P＜0.01),indicated that the ecological environment balance between normal flora in ileum has recovered.(5)Phosphorus and Calcium excretion(P-Ca):From 21d to 42d,compared with group 5,the P-Ca of groupl,2,3 significantly(P＜0.05) reduced,and group 3 had the lowest P-Ca. Compared with group 4,the P-Ca of group 3 reduced significant(P＜0.05) on 28d and extreme significant(P＜0.01) on 42d.Lactobacillus addition more than 0.05%in the broiler chicken's diets can effectively reduce P-Ca,and equal to the effect of adding phytase 600U/Kg.In this study,Lactobacilli addition(0.2%,1.5×109CFU/g) significantly reduced P-Ca(P＜0.05).