Seasonal Variation in Hatchability and Its Relation to an Unidentified Dietary Factor

THE subject of the relationship of diet to hatchability has been reviewed by Titus (1939), Cruickshank (1941) and Landauer (1941). However, irrespective of constancy of diet throughout the year, several investigators have reported seasonal variations in hatchability. Smith (1933) reported higher hatchability in the spring and summer than in the winter. This effect was much greater when the only protein supplement was fish meal than when it was dried buttermilk. Byerly, Titus, Ellis and Nestler (1937) showed that hens fed soybean meal as the only protein supplement exhibited higher hatchability in the spring and summer than in winter. The seasonal variation was independent of sunlight since a pen of birds exposed to artificial lighting behaved similarly to a comparable pen exposed to sunlight. On the other hand, no effect of season or of light was noted among hens fed a high quality beef scrap containing 10 percent of liver. Christiansen, . . .