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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.

This study is designed to determine the inheritance pattern of egg weight and egg shell weight of exotic laying chickens at 25, 51, 72 weeks and overall mean ages of the birds. For this purpose, thirty eggs were collected daily from the birds continuously for five days of egg production, at each ages 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. The mean values of egg weight and egg shell weight revealed an apparent increase from 25-72 weeks of age with their corresponding overall mean values. The least square means of egg shell weight at different age groups are significantly different at (P<0.01) while egg weight was significantly the same since egg shell weight depends on age variance for adequate performance. Statistical analytical system was used to obtain the variance components for the estimation of heritability. High and moderate heritability estimates were obtained when the age variance were included in the computation at different age groups for both traits while high, moderate and low estimates were obtained when the age variances were excluded. The heritability estimates from different egg quality traits were low to high. Since egg weight yielded high estimates at various age groups, the low and moderate heritability estimates recorded for egg shell weight imply that collection of additional records and improvement of non-genetic factors influencing the trait will improve the accuracy of characterizing the inherent ability of the birds.

The global poultry industry has experienced significant changes in the methods used to harvest and process the fresh egg over the past century. Applications of animal genetics and breeding have significantly increased in line speed for poultry operation. In this study aims at reviewing production factors that influence egg quality traits across the globe. The production factors so far utilized were classified into three main categories and presented based on their influencing capacity. For this purpose, two types of search criteria to find publications relevant to the scope of this review were employed. The first type was an automatic search performed on the following publishers' databases: ScienceDirect, Google's scholar, researcher gates, academia. The second type was a manual search on conferences, recent theses and dissertation that have not been published in journals from numerous Babcock University. Generally, 23 publications were reported for the breed; 17 for housing, and 19 for age of the breed after excluding studies that do not focus explicitly on breed, housing and age of the bird as production factors that influenced egg quality traits out of 183 potential relevant articles identified from