title: Effect of step-down and step-up protein-energy feeding systems on egg-type pullet growth and laying performance.
abstract: Four egg-type pullet feeding systems were compared for the production of egg-type pullets. The dietary regimens consisted of either a step-down protein, high energy feeding program; a step-down protein, low energy program; a step-up protein, high energy program; or a step-up protein, low energy program. At 150 days of age all pullets were housed 2 birds per 25.4 X 45.7 cm laying cage and fed a standard layer diet (16% protein). The experiment utilized 2880 birds grown on the floor in a conventional growing house. At 140 days of age, birds subjected to the step-up protein feeding programs were 82 g smaller in mean body weight, had higher mortality, and consumed less feed than the birds on the step-down protein feeding programs. Body weights at 140 days of age were 1.17 and 1.09 kg for the step-down and step-up feeding programs, respectively. Energy levels fed had no significant effect on pullet weight, feed consumed, or mortality to 140 days of age. During the laying phase, hens that had been on the step-down protein feeding program reached 50% production 2.0 days earlier than birds subjected to the step-up protein feeding program. Hen-day production for the step-down and step-up pullet feeding systems based on 308 days' records was 76.09 and 76.86%, respectively. Feed efficiency and mature body weight were not significantly affected by grower feeding programs. The largest egg size and highest laying house mortality were noted in hens grown on the step-down protein feeding program.
mesh_terms: D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004531:Eggs; D005260:Female; D010058:Oviposition
chemical_list: D004044:Dietary Proteins