HATCHERY WASTE AND HATCHABILITY OF TURKEY EGGS

The objective of this study was to determine the type and quantity of hatchery waste and egg hatchability during the first laying season of heavy-type turkey hens. The hatchability of 4536 eggs as well as the weight, type and quantity of waste material produced during nine control incubation cycles were monitored in turkey hens aged from 33 to 57 weeks, at three-week intervals. The day of embryo death was indicated and the percentage of embryos that died on successive days and during three incubation stages was calculated. The optimum egg weight was recorded in hens aged up to 45 weeks, and in older hens the average egg weight was higher than 95 g. Infertile eggs accounted for 2.0 to 8.3% hatchery waste. Embryo mortality reached 4.6 to 17.2% before puncture, and 1.4 to 5.8% after puncture. Loss due to the delay in hatching ranged from 0.8 to 6.1% fertile eggs. The highest number of newly hatched birds classified as unsuitable for rearing was noted in hens aged 57 weeks (5.2%), while in the remaining weeks of the laying period the number of such poults was substantially lower. The first and second mortality peak accounted for 13.0–28.0% and 13.0–23.0% of the total loss during incubation, respectively. Another embryo mortality peak (13%) was observed in turkey hens aged 42 weeks. The highest hatchability rate, at 93.1%, was reported in week 42. Over the period of best hatchability, embryo mortality reached 43% : 15% : 42% at three consecutive incubation stages. It was found, based on the type and quantity of hatchery waste and hatch rates, that turkey hens aged between 36 and 48 weeks were characterized by the highest reproductive efficiency. The results of this study may be used as reference values while estimating the total loss during incubation due to hen age in heavy-type turkeys.