Study On The Regulatory Mechanism Of Dietary Zinc Pectin Oligosaccharides Chelate On Growth Performance In Broiler Chickens

Zinc pectin oligosaccharides chelate(Zn-POS)was a new kind of feed additives,and no report related to it was available in broilers.In present dissertation,3 experiemnts were conducted to investigate the effects of dietary Zn-POS on growth performance,antioxidant capacity,zinc status and intestinal health in broiler chickens,select the optimum supplemental level and study the growthpromoting merchanism of Zn-POS.Exp.1 was conducted to select the optimum supplemental level of Zn-POS in broiler diets.Four hundred and eighty 1-day old healthy broilers were randomly allocated to 5 groups with 6 replicates per group and 16 chicks per replicate.The experimental diets were formulated with the same supplemental Zn level(80 mg diet/kg)and consisted of an unsupplemented control diet based on corn-soybean meal or similar diets supplemented with either 62.5 mg/kg flavomycin,or 300,600,900 mg/kg Zn-POS,respectively.Zn SO4 was used to adjust to the desired amount of Zn(80 mg diet/kg)in the Zn-POS diets.Results showed that supplememtation of Zn-POS in the diets increased the growth performance,immune function,antioxidant capacity,the digestibility of nutrients,and tissue zinc accumulation of broilers.The optimum supplemental level of Zn-POS in broiler diets was 600 mg/kg.Exp.2 was conducted to investigate the effect of dietary pectin oligosaccharides(POS)or Zn-POS on growth and metabolism of broilers.A total of 324 1-day-old Arbor Acres broilers randomly assigned to 3 groups with 6 cages of 18 chicks.Treatments were: 1)Control,80 mg/kg 的 Zn from Zn SO4;2)POS,80 mg/kg Zn from Zn SO4 + 482 mg/kg POS(same amount of POS as treatment 3);and 3)ZnPOS,80 mg/kg zinc from Zn-POS.Both POS and Zn-POS supplementation increased average daily weight(ADG),average body weight(BW),pancreatic metallothionein(MT)concentrations,duodenual villus height(VH),and volatile fatty acids(VFA)concentrations,the operation units and observedspecies in the cecal digesta of broilers.Compared to POS,Zn-POS supplementation increased hepatic copper-zinc superoxide dismutase,glutathione peroxidase and gene expression of nuclear factor E2 related factor,pancreatic m RNA levels of MT,zinc transporter 1,and zinc transporter 2,duodenal villus height to crypt depth ratio,the butyrate concentrations and relative abundance of Para Bacteroides、Lachnospiraceae-UCG-010 in the cecal digesta,decreased crypt depth in the duodenum of broilers.Exp.3 was conducted to study the growth-promoting merchanism of Zn-POS in broilers.A total of 648 one-day old healthy broilers were randomly divided into 6 groups with 6 replicates(18 chicks per replicate).The experimental diets were formulated with the same supplemental Zn level(80 mg diet/kg)and consisted of an unsupplemented control dietbased on corn-soybean meal or similar diets supplemented with either 62.5 mg/kg flavomycin,or 200,400,600,800 mg/kg Zn-POS,respectively.Zn SO4 was used to adjust to the desired amount the Zn(80 mg diet/kg)in the Zn-POS diets.Results showed that dietary Zn-POS supplemntation improved growth performance by increasing ADG and BW,decreasing the mortality of broilers.Additionally,tissue antioxidant capacity were also improved by increasing the activities of total superoxide dismutase,reducing malondialdehyde contents in serum and liver,increasing the hepatic gene expressions of nuclear factor E2 related factor,superoxide dismutase 1,and glutathione peroxidase1.For zinc status,supplementation of Zn-POS increased serum and pancreatic zinc accumulation,hepatic and pancreatic MT concentrations,and gene expressions of MT,zinc transporter 1,and zinc transporter 2 in pancreas.Besides,dietary Zn-POS supplementation increased villus height and villus height to crypt depth ratio in the duodenum and jejunum,the concentrations of VFA and microbiota in the cecal digesta of broilers.In conclusion,our study revealed that dietary Zn-POS supplementation increased growth performance and digestibility of nutrients by enhancing tissue antioxidant capacity,zinc status,and intestinal health in broilers.It’s optimal to supplement 600-800 mg/kg Zn-POS in broiler diets.And the growth-promoting effect of Zn-POS was greater than zinc sulfate or the mixture of zinc sulfate and POS under same zinc supplemental level conditions.