| The effects of maternal Daidzein on newly hatched ducklings were investigated, in addition, the serum levels of growth-related hormones and tissue expression of relavant genes were determined by RIA and RT-PCR respectively to study the neuroendocrinological mechanism involved.The research includes two parts as follows.1. Effect of Daidzein feeding to laying duck breeders on the early growth and serum levels of growth-related hormones and tissue expression of relavant genes of their offspringsThe laying Shaoxing duck breeders were divided into treatment and control group.The treatment group was supplemented with 5 ppm daidzein in their basal diet.The body weights were recorded and serum concentrations of growth-related hormones and tissue expression of GHR,IGF-IR,GH,SS,ER- (3 and GnRHmRNA were measured .The results showde that:1) Compared to the control , the hatch weight was decreased significantly(p<0.05) ,while the growth rate was increased by 4.7% during the 4 weeks after hatchingso that no differceces were observed between two groups by the age of 4 weeks .It suggeststhat Daidzein feeding to laying duck breeders can suppresse the embryo development,butimprove their early posthatch growth2).At hatch, serum levels of GH and T/( in daidzein-treated group were decreased by 35.8% (p<0.01) and 37.6% (p<0.01) respectively, wherease serum glucagon level was 14.3% higher (p<0.05) than control, furthermore, there were sex differences in serum GH and Glucagon concentration.Serum TS and insulin concentration remain unaffected(p>0.05).At the age of 4 weeks,the serum T4 concentration in Da group was increased by 25.9% (p<0.05) and insulin of male ducks rose by 51.8% (p<0.05), there was also sex differences in serum T4 and insulin concentration. No significant changes of serumTS and Glucagon concentrations were observed at this age(p>0.05).3).At hatch,the relative abundances of liver GHRJGF-IR mRNA and pituitary GH mRNA in daidzein-treated group were reduced by 12.3% (p<0.05), 32.2% (p<0.05) and 23.2% (p<0.05) respectively,while hypothalamic SSJGF-IR and liver ER- & mRNA were not significantly affected by treatment(p>0.05).By the age of 4 weeks,however,the differences in gene expression diminished,which is in accord with their growth.These results display a significant effect of maternal expousure to daidzein on the endocrine system and expression of growth-related genes to regulate the growth of their offsprings.2. Effects of Daidzein treated in ovo on the early growth, hormone secretion and gene expression of Shaoxing ducklingsOn day 7(d 7) of incubation,embryonated eggs of Shaoxing ducks were injected with 100 mg/ml daidzein.At the 25th day after hatching , the green ducks were killed and the blood ,tissue samples were collected.The results showed thatthe daidzein treatment in ovo induced the increases in body weights of ducks by 8.34 (p<0.05), the average daily weight gain by 9.5%,growth rate by 4.8%,serum glucagon concentration by 64.5% (p<0.01), but a fall in serum Tj by 18.0% (p<0.05) .Serum insulin and GH were affected differently with different sex by treatment, GH levels in treated female ducks were 45.8% lower than control,while in male this was not the case.Insulin concentration in treated male ducks were increased by 83.2% (p<0.05) .Daidzein treatment in ovo markedly increased the level of GHR mRNA in the liver by 29.1% (p<0.05) and an up-regulation of ER- P mRNA was found in liver, while had no significant effects on the level of pituitary GH mRNA, hypothalamic SS, IGF-IR mRNA.The results demonstrate that Daidzein treated in ovo influences ducks growth associated with higher GHR gene expression in liver and some changes in growth-related hormones.
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