摘要
This study was conducted to determine the effect of necrotic enteritis(NE),phytase level and meat and bone meal(MBM)processing on bone mineralization of broilers and litter quality.Ross 308 male broiler chicks(n=768)were allotted to 48 pens with 16 birds each.There were 8 dietary treatments in a 2×2×2 factorial arrangement.Factors were NE challenge(no or yes),phytase level(500 or 5,000 FTU/kg),and MBM(as-received or over-processed).Half of the birds were challenged with field strains of Eimeria spp.at d 9 and 108 CFU per mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15.The middle toe,tibia and femur of 2 birds per pen were excised at d 16 and 29 for determination of ash,breaking strength(BS)and bone mineralization.At d 42,all were assessed for hock burns and litter was scored and assessed for dry matter(DM).At d 16,challenged birds had lower toe ash(P<0.01),femur ash(P<0.001),tibia ash(P<0.001)and tibial BS(P<0.001)than unchallenged birds.At d 16,challenged birds fed high phytase and over-processed MBM had higher toe Mn than those fed low phytase and as-received MBM.At d 29 unchallenged birds fed high phytase and as-received MBM had a higher toe Mn than those fed over-processed MBM.At d 16,a phytase×MBM interaction was detected for femur Zn concentration(P<0.05),where a higher level of Zn was observed in the high phytase group fed over-processed MBM.At d 16,tibial Ca(P<0.05)and P(P<0.05)were lower in the chal-lenged whereas the femur K(P<0.001),Mn(P<0.01)and Na(P<0.001)were higher in the chal-lenged at d 16.At d 42,challenged birds had higher litter DM(P=0.058)and fewer hock burns than those unchallenged(P<0.05).In conclusion,NE impaired bone traits but high phytase and over-processed MBM increased bone mineral contents.Cases of hock burns may be lower under NE in-cidences due to lower livability of birds reducing litter wetness.
