摘要
This study investigated the hypothesis that feeding broilers over-processed meat and bone meal(MBM)would impair gut health in the absence of phytase and in turn,affect inositol phosphate(inositol xphosphate,IPx:IP3,IP4,IP5 and IP6)ester hydrolysis,intestinal permeability,hematology,jejunal gene expression and intestinal morphology during necrotic enteritis(NE).Ross 308 male broilers(n=768)were assigned to one of 8 dietary treatments in a 2×2×2 factorial arrangement,with 6 replicate pens per diet and 16 birds per pen in a completely randomized design.Factors were:NE challenge(no or yes),phytase level(500 or 5,000 FTU/kg)and MBM processing(as-received or over-processed).For the NE challenge,half of the birds were challenged with field strains of Eimeria spp.on d 9 and 108 CFU/mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15.A 3-way challenge,phytase and MBM processing interaction was detected for IP5(P<0.05)and IP6(P<0.05)levels in the ileum.Birds fed low phytase had increased IP5 and IP6 in unchallenged birds only when diets contained over-processed MBM.Challenge with NE increased intestinal permeability as measured by serum fluorescein isothiocyanate dextran(FITC-d;P<0.001),increased white blood cells(WBC;P<0.001),decreased mean corpuscular volume(MCV;P<0.001)and mean corpuscular hemoglobin(MCH;P<0.05),and decreased crypt-tovilli ratio(P<0.05).The over-processed MBM reduced the villi-to-crypt ratio(P<0.05).A 3-way challenge x phytase x MBM processing interaction was detected for mucin 2(MUC-2)expression(P<0.05)where only in unchallenged birds fed over-processed MBM did high phytase reduce MUC-2 expression.A lower expression of aminopeptidase N(APN;P<0.001)and vitamin D receptor(VDR;P<0.001)were recorded in NE challenged birds.In conclusion,NE has a negative impact on the gut and hematology of broilers,but its effect on phytate hydrolysis is minimal.
基金
AB Vista Feed Ingredient,Malborough,UK for funding this research
the University of New England(UNE),Armidale(Australia)is acknowledged for providingthe international postgraduate research award(IPRA)to the lead author
