Effects Of Dietary Deficiency Of Selenium And Iodine To Laying Duck Breeders On Antioxidant Capacity And Bone Quality In Breeders And Their Offspring

Both selenium(Se)and iodine(I)are essential trace elements for animals.Se is involved in the synthesis of a variety of proteins in the body,participating in biological functions such as growth,anti-oxidation,immunity and bone metabolism.I plays an important role in thyroid hormone function and animal growth.Up to now,the effects of selenium and I on reproductive performance of breeders and their offspring has not been estimated yet.Therefore,by employing laying duck breeders were used as animal models,the objective of present study was to evaluate the effects of dietary deficiency of Se and I on the antioxidant capacity and bone quality of laying ducks and their offspring.This study provided theoretical basis for the application of trace element nutrition in poultry production.A total of 288 140-day-old Longyan laying duck breeders were randomly allocated into four treatments,with 6 replicate of 12 each.The birds were caged individually and fed with basal diet with or without supplementation of 0.24 mg/kg Se or 0.4 mg/kg I.This experiment lasted for 200 days.Since the experimental day of190,insemination was performed on breeders twice a week with interval of 3 days,and eggs were collected and incubated according to the management instruction established in this lab.After hatching,48 ducklings were selected from each groups and assigned to 6 replicate pens with 8 ducks per pen.The ducklings were fed with diet containing sufficient Se and I until 7 weeks of age.The results showed as following:(1)Effects of dietary Se and I deficiency to female duck breeders on reproductive performance,antioxidant function and bone quality.Dietary deficiency of Se or I had no effects on daily feed intake,egg production,egg weight and feed /egg rate of breeders(P > 0.05).Dietary deficiency of Se had no impact on egg quality,while I deficiency significantly decreased albumen height,haugh unit(P < 0.05),and increased egg-shape index.There were no effects of dietary Se or I on eggs fertility,hatchability,embryo mortality,or healthy ducklings rates(P >0.05).Dietary Se deficiency decreased the activity of glutathione peroxidase(GSH-Px)both in the plasma and liver of breeders(P < 0.01)and increased hepatic malondialdehyde(MDA)levels(P < 0.05).Besides,I deficiency in breeders caused a decrease of total-superoxide dismutase(T-SOD)activity in plasma(P < 0.05),as well as an increase in the plasma content of MDA and oxidized low-density lipoprotein(Ox-LDL)(P < 0.05).Se sufficiency didn’t affected the weight,length,bone mineral density(BMD)and bone mineral content(BMC)of tibia in breeders(P > 0.05),but I deficiency caused a reduction in length of tibia in duck breeders(P < 0.05).(2)Effects of dietary deficiency of Se and I to female duck breeders on antioxidant function and bone growth in the offspringDietary Se deficiency had no effects on feed intake,weight gain,FCR of 1-7 wk old ducks(P > 0.05),however,I deficiency seems to decrease the weight of female ducks of 7 weeks age(P=0.06).Se deficiency in breeders resulted in lower activity of GSH-Px(P<0.01)and a higher concentration of MDA both in plasma and liver(P<0.05)in 1-d-old ducklings.In addition,I deficiency in breeders reduced the activity of T-SOD(P<0.05)and tended to increase the Ox-LDL level(P=0.07)in plasma of 1-d-old ducklings.Moreover,there was an interaction effect of Se and I on plasma GSH-Px activity in 1-d-old ducklings(P<0.01).Interestingly,there were on significant difference in antioxidant enzyme or lipid peroxidation products in plasma and liver in the ducks of 7 wk of age(P > 0.05)after fed diets supplemented with Se and I.Dietary Se deficiency to breeders had no effects on tibia development of1-d-old ducklings(P > 0.05),but I deficiency led to the retardation of tibia development in 1-d-old ducklings,as reflected in the reduction in tibia length,tibia weight,tubular diameter of articular cartilage,and frontal diameter of articular cartilage(P < 0.01).Besides,I deficiency in breeders reduced the expression of X collagen(Col X)in growth plate cartilage in tibia of 1-d-old ducklings,but I deficiency didn’t affect the expression of parathyroid associated proteins(PTHr P).After feeding diets with supplementation of Se or I for 7 weeks,there were no significant differences in tibial quality indexes such as weight,length,tibial circumference,bone density and bone mineral content among groups(P > 0.05).A lower level of IGF-1 in serum was observed in 1-d-old ducklings from I-deficient breeders(P < 0.01),there were no difference in T3 and T4 concentration in plasma of1-d-old ducklings among the treatments(P>0.05).In summary,dietary deficiency of Se or I to in laying duck breeders decreased the antioxidant capacity of their offspring and caused oxidative damage,while I deficiency in breeders could restrain the development of tibia of offspring,however,dietary supplementation of Se and I to hatched ducks could reverse the negative effects.