Effects Of Plant Extracts On Growth Performance, Nutrient Digestibility And Intestinal Health Of Broiler Chickens

This study was divided into two experiments to research effects of differentsupplemented levels of natural plant extracts on growth performance of broiler chicken and itsinfluential mechanism of broiler chicken.The first experiment was designed to study effect of plant extracts on nutrientdigestibility.7242-d-old male ROSS308broiler chicken were individually placed into36cages (replications,2roosters per cage,4replications per treatment). One of the treatmentswas fed basal diet only (control) and the others were fed basal diet added with Avilamycin5mg/kg, Virginiamycin15mg/kg, Enramycin4mg/kg, and plant extracts at levels of50,100,150,200mg/kg of diets.The study showed that supplementation of plant extracts, Avilamycin, Virginiamycin andEnramycin improved GE and DM digestibility of broilers chickens (P <0.05) and had linear(P <0.01) and quadratic (P <0.01) responses of DM and GE digestibility. When birds werefed by plant extracts at50,100,150and200mg/kg, they had improvement of1.45-4.63%apparent digestibility and1.75-4.35%true digestibility for CP,3.05-5.67%apparentdigestibility and2.56-5.54％true digestibility for GE,3.39-6.21%apparent digestibility and3.27-6.00％true digestibility for DM.The second experiment was designed to study the effects of plant extracts on growthperformance, slaughter performance and caecal microflora of broiler chickens.500042-d-oldROSS308broiler chicken (vaccinated obtained from a local commercial hatchery and mixedsex) were randomly allocated into20wire cages (replications,250birds per wire cage,4replications per treatment). One of the treatments was fed basal diet only (control) and theothers were fed basal diet added with Enramycin4mg/kg, and plant extracts at levels of50,100,150mg/kg of diets.The study showed that supplementation of plant extracts and Enramycin increasedADG、ADFI(P <0.01), decreased FCR (P <0.05) and had a linear improvement of ADG,ADFI of FCR (P <0.01). EY (P <0.01) and BMY (P=0.087) of birds were increased whenplant extracts were supplemented by100mg/kg or above, and also had sign trend of EY (P <0.001) and BMY (P=0.049). Spleen index (21d and42d), index of bursa of fabricius (21d)and thymus index (42d) were improved (P <0.01) for addition of plant extracts. All broilers had similar caecal microflora over the entire experimental period but little improvement ofevery microflora. The pH of ileum decreased linearly (P=0.027) by the level of plant extractsincreased. In addition, supplementation of plant extracts increased (P <0.05) VH ofduodenums (42d), jejunums (21d), ileums (21and42d) and VH/CD of duodenums (21d),ileums (21,42d) of birds. Furthermore, there was linear (P <0.01) or quadratic (P <0.01) orboth improved responses as levels of plant extracts supplemented in diets increased from0to150g/kg.All researches above showed that addition of plant extracts and Enramycin couldimprove nutrient digestibility, growth performance, slaughter performance and intestinalhealth of broiler chicken, and also showed plant extracts supplemented at150mg/kg dietsresulting in an optimally result.