Independent effects of hen age and egg size on incubation and poult characteristics in commercial turkeys.

Nicholas hens from the same flock were studied throughout the growing and laying periods. From 36 to 55 wk of age, 800 eggs were collected at approximately 5-wk intervals. At each age, a subsample of 100 eggs were randomly selected for egg weight, yolk weight, yolk DM, and yolk lipid (DM). The remaining 700 eggs were individually weighed and incubated. All eggs were reweighed at 25 d (transfer) and poults were individually weighted at hatch. At each sampling age, 50 poults were selected for analysis of yolk sac weight, yolk sac DM, and yolk sac lipid (DM). From 33 to 45 wk, mean hen BW decreased 0.9 kg. Across all ages, the relative weight of abdominal fat decreased more than that of the Pectoralis major. Relative yolk weight increased and relative albumen weight decreased with age. Yolk sac weight and lipid content (DM) of the poults at hatch increased markedly with age of hen. Across all ages, eggs were divided into weight classes. Initial egg weight had no effect on proportional moisture loss at 25 d or on relative poult weight at hatch. Egg moisture loss through 25 d was greatest in eggs from 36-wk-old hens compared with hens at 41, 45, 50, or 55 wk. Mean poult weight increased from 62.6 g at 36 wk to 64.9 g at 55 wk. Relative poult weight increased 3% from 36 to 55 wk when corrections for initial egg size were taken into consideration.