Egg Quality and Poult Production in Turkeys: 2. Inheritance and Relationship among Traits

Abstract

Heritability of several reproductive traits in turkeys was estimated. Based on the variance of full sib families the heritability estimates of female body weight at fifty percent producton, and egg weight were high (larger than .40) while egg production, days from lighting to first egg, number of broody periods, percent fertility and number of poults per hen had moderate heritabilities (.20 to .40). The heritability estimate of hatchability of fertile eggs was .17 ± .15.Egg production, fertility, hatchability of fertile eggs and number of poults per hen were closely associated genetically. Egg weight, days from lighting to first egg and number of broody periods were negatively correlated with egg production.Fifteen percent of the phenotypic variation in fertility could be accounted for by variation in nine egg traits. Likewise, 25 and 26 percent of the variation in hatchability fertile eggs and number of poults per hen, respectively, were explained by variation in the nine traits. Percent yolk and incubation weight loss had a major effect on fertility and hatchability of fertile eggs. Shell weight contributed significantly to the variation in fertility. Percent shell had a major influence on hatchability. Variation in percent albumen contributed 3.5 percent of the variation in number of poults produced per hen.Shell traits were generally related genetically to hatchability and number of poults produced per hen late in the laying season and also usually had the highest heritability at this time. The reverse was evident for yolk traits.