Effects of Selection for Growth and Selection Diet on Eggshell Quality and Embryonic Development in Japanese Quail

Abstract

Decreased hatchability in Japanese quail following selection for growth and relative improvements in hatchability following selection during goitrogen treatment were investigated. An unselected quail line (Line C) and lines selected for high 4-wk body weight while being fed diets containing either 20% CP and .2% thiouracil (TU) (Line T), or 28% CP and no TU (Lines P and H-CD) were used. Egg weight loss between 0 and 4, and 0 and 14 days of incubation, hatchability, and developmental stage of embryonic mortalities were determined in Experiment 1. Length of the incubation period, and percentages of body water and dry body weight were determined for 10- and 14-day embryos and 18-day-old chicks in Experiment 2. Eggshell quality was determined in Experiment 3.Hatchability was lower in selected than in unselected quail due to increased early and late embryonic mortality. Egg weight loss during incubation was greater in Line P than in Line C eggs. Weight loss, measured across lines, was lower in eggs that hatched than in those in which embryos died early. Percentage body water was higher in Line C than in Lines P and T at 14 and 18 days of incubation; however, percentage body water in Line T was lower than Line P at 14 days. Percentage of dry body weight was greater in Lines P and T than in Line C at 14 and 18 days. Eggshell thickness was greater in Line H-CD when compared with Line C.Increases in eggshell permeability occurring during selection for growth were associated with increased embryonic mortality and decreased hatchability. In selected birds, .2% dietary TU did not affect embryonic growth but decreased percentage embryonic body water. Dietary TU may impede the detrimental effects of growth selection on eggshell permeability.