Estrogen-like Effect Of Quercetin On Performance In Laying Hens

240 of 37-week-old laying hens were randomly divided into 4 groups, with 6 replicates per group and 10 hens per replicate. They were fed basal diet with 0, 0.02%, 0.04% and 0.06% quercetin. The effects of quercetin on performance, reproductive organ, hormone and expression of genes associated with apoptosis in laying hens, and the possibility of quercetin as functional feed additives was explored.The results about performance, reproductive organ, hormone and apoptotic genes showed that:(1)PerformanceCompared with control, laying rate were significantly increased at 0.02% and 0.04% quercetin(P<0.01). Feed-egg ratio were significantly decreased at 0.02% and 0.04% quercetin(P<0.01), and feed-egg ratio were decreased at 0.06% quercetin(P<0.05). No treatment effect was observed in egg weight and feed intake(P>0.05).(2)Reproductive organCompared with control, magnum index and magnum length were significantly increased at 0.04%and 0.06% quercetin(P<0.01). Isthmus index, isthmus length and follicle number were significantly increased at 0.02%, 0.04% and 0.06% quercetin(P<0.01). No treatment effect was observed in weight,ovary index, uterus index and oviduct index(P>0.05).(3)Endocrine hormonesCompared with control, estradiol was significantly increased at 0.04%(P<0.01) and 0.06%quercetin(P<0.05). Progesterone was significantly increased at 0.02%(P<0.01) and 0.04% quercetin(P<0.05). Follicle-stimulating hormone was increased at 0.02% and 0.04% quercetin(P<0.05).Luteiinizing hormone was increased at 0.04% quercetin(P<0.05). Insulin-like growth factors-1 was significantly increased at 0.02%, 0.04% and 0.06% quercetin(P<0.01). Growth hormone was significantly increased at 0.02%(P<0.05) and 0.04% quercetin(P<0.01).(4)Apoptotic genesCompared with control, the expression of Bax m RNA was significantly decreased at 0.02%,0.04%and 0.06% quercetin(P<0.01). The expression of Bcl-2 m RNA was significantly increased at 0.02%and 0.04% quercetin(P<0.01), the expression of Bcl-2 m RNA was significantly decreased at 0.06%quercetin(P<0.01). The expression of caspase-3 m RNAwas decreased at 0.04% quercetin(P<0.05), and it was increased at 0.06% quercetin(P<0.05). The expression of p53 m RNA was significantly decreasedat 0.04% quercetin(P<0.01).In conclusion, appropriate dosage of quercetin improved performance in laying hens via promoting development of reproductive organ, secretion of hormone and expression of genes associated with apoptosis in ovarian. In this study, the optimum level of supplementation for quercetin is 0.032-0.049%.