First and second cycle egg production characteristics in commercial table egg flocks

Egg production data for 1,231 first cycle and 887 second cycle commercial table egg layer flocks were studied to determine the shape of the production curve, the relationship between the two cycles, and the effects of strain and season on various measures of egg production. Means for peak egg production were 89.1 and 80.0%. Calculated slopes for the period from peak production to 60 wk of age and 40 wk postmolt were .596 and .671%/wk, and egg production levels at the end of each cycle were 71.2 and 61.7% for the first and second cycles, respectively. Egg production curves proved to be nonlinear with significantly greater slopes during the last 10 wk of each cycle compared with the earlier part of the cycle. This nonlinearity was shown to be associated with winter- and fall-hatched flocks for the first cycle of lay and with second cycle flocks that reached Week 30 in the spring and fall months. Calculated slopes averaged .565%/wk from peak to 50 wk of age compared with .655%/wk from 50 to 60 wk of age. Second cycle flocks had slopes of .590%/wk from peak to 30 wk postmolt compared with .819%/wk from 30 to 40 wk postmolt. Individual White Leghorn strains varied significantly in all measured traits with the exception of the calculated slope from peak egg production to Week 50 in the first cycle and from peak egg production to Week 30 in the second cycle.