A MODEL RELATING EGG WEIGHT AND DISTRIBUTION TO AGE OF HEN AND SEASON

Economic models for table egg layer flocks require determination of eg g value, which is a function of mean egg weight, distribution of indiv idual egg weights, and egg prices for weight categories. Age of flock and season of lay, two major factors affecting egg size and egg weight distribution, were examined in this study of 112 commercial flocks. I ndividual egg weights for 100-egg samples were obtained at 24, 30, 40, 50, 60, 80, and 100 wk of age. Mean egg weight, excluding outliers, w as significantly related to age of hen, season of sexual maturity, and season eggs were laid. The standard deviation of egg weight, excludin g outliers, had a significant curvilinear relationship to mean egg wei ght. Equations were also obtained for mean weights and percentages of under- and oversized eggs (outliers). These equations and integration of the normal distribution can be used to calculate the percentage of eggs in various weight classes over the life of a particular flock.