Effect Of Riboflavin On Reproductive Performance Of Duck Breeders,Growth And Development Of Duck Embryos

In this thesis,three experiments were conducted to investigate the effects of dietary riboflavin on reproductive performance of laying duck breeders,growth and development of duck embryos.Exp.1 Effects of riboflavin on reproductive performance and antioxidant status of duck breeders.Experiment 1 was conducted to investigate the effects of dietary riboflavin levels on reproductive performance,egg quality,riboflavin status,and antioxidant status of laying duck breeders,to estimate the requirement of riboflavin for duck breeders.A dose-response experiment with 5 dietary riboflavin(1.48,3.98,6.48,11.48 and 16.48 mg/kg).A total of 80 female White Pekin duck breeders aged 40 wk were divided into 5 treatment groups with 8 replicates,received 5 experimental diets for 9 wk.The results showed as follow: dietary riboflavin levels did not affect duck breeders weight,feed intake,egg hatchability,egg fertility and egg quality(P>0.05).The duck breeders fed the basal without riboflavin supplementation showed the lowest egg hatchability and blood glucose(P<0.01).Plasma riboflavin,egg yolk riboflavin,egg albumen riboflavin and antioxidant status increased linearly or quadratically as dietary riboflavin increased(P<0.01).According to the broken-line model and broken-line quadratic model,the riboflavin requirements(based on dietary total riboflavin)of laying duck breeders in terms of the egg hatchability,plasma riboflavin,egg yolk riboflavin,egg albumen riboflavin,plasma T-SOD activity and plasma MDA content were 3.19,7.42,3.88,7.44,6.45,8.84 mg/kg and 3.98,10.35,7.05,11.17,8.00,10.65 mg/kg,respectively.Exp.2 Effects of riboflavin deficiency of duck breeders on growth and development of duck embryos.Experiment 2 was conducted to investigate the effect of riboflavin deficiency of duck breeders on organ indexes,body shape indexes,plasma biochemical indexes,antioxidant status and liver structures of duck embryos.A total of 80 White Pekin duck breeders aged 40 wks were allotted to 2 groups,which fed the basal diets without riboflavin(riboflavin deficiency group)and with 16.48 mg/kg riboflavin(control group),with 10 replicates per group and four breeders per replicate.All birds were raised individually for 7 weeks.The results showed as followed: compared with the control group,riboflavin deficiency reduced duck embryo weight and blood glucose at E13,E18,E22 and E26(P<0.05),liver and heart antioxidant status,the expression of antioxidant gene(SOD1,SOD2,GST and GLRX2)reduced significantly(P<0.05).Deficiency group duck embryo liver showed different degree of steatosis,liver cell apoptosis rate and the expression of pro-apoptotic genes(ATF6,CASP3)increased significantly(P<0.05),the expression of anti-apoptotic(Nrf2,HO-1 and GST)reduced significantly(P<0.05).The deficiency group had greater egg sac weight,egg sac index,plasma ALP activity and plasma UA content(P<0.05).And the deficiency group had lower leg length,egg yolk riboflavin,plasma riboflavin and plasma T-CHO(P<0.05).Exp.3 Effect of riboflavin repletion on production performance of duck breeders,growth and development of duck embryos.Experiment 3 was followed by the experiment 2.This experiment was conducted to investigate the effect of riboflavin repletion on egg hatchability,plasma biochemical indexes,tissue riboflavin status,antioxidant status of duck breeders and organ indexes,body shape indexes,blood glucose of duck embryos.A dose-response experiment with 3 treatments,riboflavin deficiency group(basal diets),riboflavin repletion group(fed with 16.48 mg/kg riboflavin at the end of experiment 2),control group(with 16.48 mg/kg riboflavin),with 10 replicates per group and 2 breeders per replicate.All birds were raised individually for 5 weeks.The results showed as followed: compared with the riboflavin deficiency group,riboflavin repletion group egg hatchability and tissue riboflavin increased significantly(P<0.05),duck embryos weight,blood glucose,body length and leg length increased significantly(P<0.05).Repletion group had no difference with control group(P>0.05).In conclusion,duck breeders riboflavin deficiency reduced productive performance,riboflavin status,antioxidant status of duck breeders,and depressed growth and development of duck embryos.According to the broken-line model and broken-line quadratic model,the riboflavin requirements of laying duck breeders in terms of egg hatchability,etc.were 3.92~7.84 mg/kg and 3.98~11.17 mg/kg,respectively.Riboflavin repletion will improve the symptoms of low egg hatchability and slow development of duck embryos which are caused by riboflavin deficiency.