不同光照制度对绍兴鸭和高邮鸭生长与相关激素及其基因表达的影响

取33日龄高邮鸭和绍兴鸭公鸭各32只，每品种分为两组，分别给以20h和6h光照，试验期14d。试验前后称重。Nothern杂交法测定垂体GH mRNA和下丘脑SS mRNA表达水平，放免法测定血清中生长激素（GH）、胰岛素生长因子－1（IGF－1）、甲状腺激素（T3、T4）水平。结果表明：高邮鸭20h光照时增重、GH及T4水平显著低于6h光照（P＜0．01）；而绍兴鸭的增重变化则与高邮鸭相比（P＜0．01），血浆GH水平变化与高邮鸭相同，T4水平无显著变化。光照制度的改变未引起两品种鸭IGF－1、T3水平的显著变化。垂体GH mRNA表达水平的变化与增重变化相反。提示光照直接影响鸭生长轴基因的表达以及激素水平，从而显著影响生长速率，但这种影响在不同品种可有完全不同的表现。

Effect of lighting regimen on growth and secretion of related hormones and their gene expression in Shaoxing and Gaoyou ducks

Thirty-three day-old Gaoyou and Shaoxing male ducks were used in the present study.32 birds from each breed were divided into 2 groups each,with one group being exposed to 20 h lighting per day(LL),and another 6 h per day(SL)for 2 weeks.SS mRNA of hypothalama and GH mRNA of pituitaries were quantified by Northern blotting hybridization.GH,IGF-1，T３ and T４ were determined by RIA.The results showed that liveweight gain,GH and T４ of LL treated Gaoyou ducks were significantly lower than those of SL treated （P<0.01)，while liveweight gain of Shaoxing ducks was significantly higher in LL treated than that in SL treated(P<0.01)，the alteration of GH levels appeared the same as in Gaoyou ducks and T４ did not vary significantly.No significant differences of IGF-1 and T３ levels were found between SL and LL groups in both breeds.The effects of light regimen on pituitary GH mRNA expression were opposite to that on liveweight gain in both breeds.This suggests that lighting regimen directly affect hormonal levels and gene expression of somatotropic axis which further influences liveweight gain.The effects of lighting regimen on growth performance as well as gene expression can be totally different in different breeds of ducks.