Repeatability estimates of egg weight and egg-shell weight under various production periods for Bovan Nera Black laying chicken

The present research was designed to examine the repeatability estimates of egg weight and egg shell weight of exotic layers at 25, 51, 72 weeks and overall ages of the bird. For this purpose, thirty birds were selected from the flock of layers in the Babcock University Teaching and Research Farm. A total of thirty (30) eggs were collected daily from the birds continuously for five (5) days of egg production, at each age 25, 51 and 72 weeks. The total number of eggs collected at each age was 150 and 450 for the total of three age periods. Data were collected on egg production traits for egg weight and egg shell weight. The mean values of the egg quality traits revealed an apparent increase for egg weight 55.02-63.29 g and egg shell weight 6.36-7.81 g with a corresponding mean combined data of bird of 60.17 g for egg weight and 7.26 g for egg shell weight. A significant positive genetic correlation was obtained among traits with linear regression equations at different age groups. General linear model procedure of statistical analytical system was used to obtain the variance components for the estimation of repeatability. High repeatability estimates were obtained when the age variance was included in the computation and low to moderate estimates were registered when the age variance was excluded from the computation. Since repeatability estimates from various production periods of egg weight and egg shell weight were low to moderate, these traits can be improved by mass selection there culminating in egg production with optimal quality.