Dietary Collagen Peptide Chelated Trace Elements Improved Reproductive Performance Of Breeder Hens And Intestinal Health Of Chick Offspring

Our present study was conducted to examine the effect of dietary collagen peptide chelated trace elements(PTE)on the reproductive performance of Qi Ling breeder hens(the main trace element components are iron,zinc and manganese).We further investigated the effect of maternal PTE nutrition on the intestinal development and lipopolysaccharide(LPS)-induced intestinal inflammatory response in chick offspring.This study provides a theoretical basis for an in-depth study of the effects of maternal PTE nutrition on the regulation of offspring intestinal health.The main contents are as follows:Experiment Ⅰ: Effect of PTE on reproductive performance and egg quality of breeder hensThe aim of this experiment was to investigate the effect of PTE on the reproductive performance of breeder hens.The experiment was conducted using 270 Qi Ling breeding hens(64 weeks old),which were randomly divided into three treatments: the control group(corn-soybean meal based diet),the L-PTE(low dose PTE)group and the H-PTE(high dose PTE)group,with 500 mg/kg and 1000 mg/kg of PTE added to the basal diet for the L-PTE and H-PTE groups,respectively.The treatments last for 8 weeks.The results showed that LPTE treatment significantly increased the egg production rate of breeding hens at 6 and 8weeks,reduced the feed-to-egg ratio,and elevated the serum estrogen and progesterone levels(P < 0.05).However,no significant effect on the deposition of trace elements was observed.The H-PTE treatment significantly increased the egg production rate of breeder hens at the 6and 8 weeks,reduced the feed-to-egg ratio(P < 0.05),increased the deposition of trace elements Fe,Zn and Mn in the yolk(P < 0.05),as well as the serum estrogen levels(P < 0.05)and T-AOC in ovarian tissue(P < 0.05).Both H-PTE and L-PTE treated groups tended to improve yolk color,shell strength,shell thickness and reproductive organ indices of breeding hens compared with the control group(P < 0.1).In conclusion,dietary PTE could increase the antioxidant capacity of ovarian tissues,improve the laying performance and eggshell quality of breeder hens.Experiment Ⅱ: Effect of maternal PTE on intestinal development in chick offspringThe purpose of this experiment was to investigate the role of maternal PTE nutrition in regulating intestinal development of chick offspring.In this study,20 breeder eggs were randomly collected from each group at the end 8th week of experiment and incubated routinely in incubators.Samples were collected at 19 embryonic age for investigation.The results showed that maternal L-PTE treatment significantly increased the embryonic weight(P < 0.05)and the villus height(P < 0.05).Both L-PTE and H-PTE treatments significantly increased the body length of the chick embryo(P < 0.05).Our studies revealed that maternal L-PTE treatment increased the m RNA expression level of Lgr5 in the intestine(P < 0.05),and tended to increase the m RNA expression of β-catenin(P = 0.092)and decrease the m RNA expression of Axin2(P = 0.096).Thus,maternal PTE nutrition might promote the embryonic development through the upregulation of intestinal Lgr5 expression.To further investigate the mechanism of maternal PTE nutrition on the intestinal development of the broiler stage,60 breeder eggs were randomly collected from each group for hatching.After hatching,healthy male chicks were selected according to the maternal treatment and fed on a basal diet.The results showed that maternal L-PTE treatment significantly increased the body weight of chick offspring at 1,14 and 28 days old(P < 0.05).Meanwhile,maternal H-PTE treatment significantly increased the serum IGF-1,T3 and T4 levels in 1-day-old chick offspring(P < 0.05).Both L-PTE and H-PTE treatments significantly increased the ratio of ileal villus height to depth of crypt in 1-and 14-day-old chick offspring(P < 0.05).RT-PCR analysis showed that the maternal L-PTE group significantly up-regulated the m RNA expression of Claudin3,E-cadherin,and Occludin in the ileum of 1-day-old chick offspring(P < 0.05);PTE treatment had no effect on the expression of β-catenin,Axin2 and APC genes,but significantly increased the expression of Lgr5 in 1-day-old chick offspring(P < 0.05).Thus,maternal PTE nutrition could upregulate the expression of genes related to intestinal tight junctions in chick offspring and promote intestinal development.Experiment Ⅲ: Molecular mechanism of maternal PTE nutrition on the alleviation of lipopolysaccharide-induced ileal inflammatory response in chick offspringIn this experiment,an intestinal immune stress model was established by intraperitoneal injection of E.coli-derived LPS into the 14-day-old chick offspring to investigate the modulating effect of maternal PTE treatment on the ileal inflammatory response.The results showed that LPS treatment significantly reduced the villus height and the ratio of villus height to crypt depth in the chick offspring(P < 0.05).Further studies revealed that L-PTE treatment significantly reduced the m RNA expression of NF-κB,TLR4 and IL-1β in the ileum(P <0.05),and maternal PTE treatment tended to reduce the m RNA expression of the inflammatory factor IL-6.Thus,maternal L-PTE nutrition was able to alleviate the LPSinduced inflammatory response by down-regulating the expression of intestinal inflammatory-related factors through the TLR4/ NF-κB signaling pathway in the chick offspring.In summary,the addition of PTE to breeder hens’ diets can improve the laying performance and eggshell quality of breeder hens;promote the intestinal development of chick offspring;reduce the gene expression of TLR4/ NF-κB signaling pathway to alleviate LPS-induced inflammatory response in the ileum of chick offspring.