Age-dependent changes in oviposition pattern and egg production traits in the domestic hen.

Effects of aging on oviposition pattern and egg production traits were studied based on records made between age at first egg and 130 wk of age in 479 hens from three selection lines. During the 1st laying yr (age at first egg to 71 wk of age), all three lines produced equal amounts of egg mass. A significant (P < or = .05) difference in total egg mass production (age at first egg to 130 wk of age) was found between a White Leghorn line selected for egg mass and a Rhode Island Red line selected for egg mass and feed consumption. The mean intrasequence oviposition interval increased significantly (P < or = .001) with age. The early mean intrasequence oviposition interval was not considered to be a good predictor of egg production traits later in life. Three explanations for decreased production with increasing age were found: 1) Oviposition intervals within sequences increased, resulting in shorter sequences and more frequent pause days; 2) the frequency of missing eggs within sequences increased; and 3) more than 1 pause day occurred between sequences.