2Sharp P J.Photoperiodic Control of reproduction in the domestic hen[J].PoultryScience,1993,72: 897～905.
3El halawani M E,Silsby J L,Rozenboim I,et al.Increased egg production by activeimmunization against vasoactive intestinal peptide in the turkey (Meleagrisgallopavo)[J].Biology of Reproduction,1995,52:179～183.
5Malpaux B,Robinson J E,Wayne N L,et al.Regulation of the onset of the breedingseason of the ewe:importance of long days and of an endogenous reproductiverhythm[J].Journal of Endocrinology,1989,122:269～278.
