Effects of age and eggshell thickness on the hatching results of stored broiler breeder eggs

The present study was conducted to determine the effects of breeder age and eggshell thickness on the hatching results of broiler breeders. A total of 3000 eggs were collected from three flocks at different ages, viz., 27 (young), 48 (middle-aged) and 65 (old) weeks. Eggs were individually weighed and eggshell thicknesses were determined using an ultrasound gauge. The eggs of each age group were classified as thin-, medium- or thick-shelled and stored for 7 days at 18 degrees C and 60% relative humidity prior to incubation. Total egg weight loss during storage and incubation was higher in middle-aged (48 weeks old) flock eggs (11.46%) than in young (10.14%) and old (10.37%) flock eggs. Hatchability was significantly lower in the eggs of the old flock than of the other flocks. The highest hatchability (70.6%) was observed in the young flock. Eggs with thick shells better tolerated the detrimental effects of storage and more eggs remained fertile than amongst the medium- and thin-shelled eggs. The overall hatchability of the old flock was 38.0%, whilst hatchability of set eggs in the thick-shelled group of old flock eggs was 58.3%.