Revealing concealed genetic variation in the egg laying pattern of the domestic hen

The purpose of our study was to investigate the possibility of revealing hitherto concealed genetic variation in the laying capacity of the domestic hen. Usually, a laying hen has an oviposition period slightly longer than 24 h (Fraps, 1970; Yoo et al., 1979), although some birds are capable of laying more often than once every day (Yoo et al., 1979; Foster, 1981). In normal circumstances, hens are synchronized by the driving light‐dark cycle and are inhibited from exhibiting fully their innate capacity of ovulation and oviposition. With a short enough cycle the potential for possible rapid layers could be realized. We therefore screened hens for their ability to adapt their ovipositions to a 231/2‐h cycle. The results showed a considerable variation in laying patterns and exposed hens having a faster than 24‐h ovulation/laying interval. Our method gives a more accurate ranking of hens having a superior ovulation rate, and is thus of value in selection for egg production.