Effects of age variance on repeatability estimates of egg dimensions of Bovan Nera Black laying chickens

The present research was designed to examine the effects of age variance on repeatability estimates of egg length, egg breadth and egg shape index of Bovan Nera Black laying chickens at 25, 51, 72 weeks and combined ages of the bird. For this purpose thirty birds were selected from the flock of layers in the Babcock University Teaching and Research Farm. They were individually housed in labeled separate battery cage. A total of thirty (30) eggs were collected daily from the birds continuously for five (5) days of egg production, at each age of 25, 51 and 72 weeks. The total number of eggs collected at each age were 150 and 450 for the total of three age periods. Data were collected on egg production traits for egg length, egg breadth and egg shape index. These data were subjected to statistical analysis using Completely Randomized Design. General linear model procedure of statistical analytical system (SAS) was used to obtain the variance components for the estimation of repeatability. Moderate repeatability estimates were obtained when the age variance was included in the computation and low estimates were registered when the age variance was excluded from the computation. The repeatability estimates from different egg quality traits were low to high. Since most of the traits recorded low repeatability values, these traits can be improve by mass selection thereby culminating into egg production with optimal quality.