Production and Carcass Characteristics of White Leghorn Pullets Fed Conventional or Step-Up Protein Diets

Day-old Single Comb White Leghorn pullets of a commercial strain were reared to maturity on a conventional dietary program or a step-up protein regime. (12% CP 0 to 12 weeks, 16% 12 to 16 weeks, 19% 16 to 20 weeks). For each treatment, body weight and feed intake were obtained at 14 day intervals for five replicate cages of 10 birds each. At these times, five birds housed in adjacent cages were killed and numerous carcass and visceral characteristics recorded. At 19 weeks of age, all birds were moved to laying cages and offered a single laying diet. Observations were continued to 30 weeks of age, together with records of egg production and egg weight. All carcass and offal samples were analyzed for moisture, crude protein, and ether extractable fat. Birds reared on step-up protein diets were smaller in body size at point-of-lay and this effect was associated with reduced absolute and proportional quantities of fat and protein deposition, with this difference being maintained through early egg production to around 24 weeks of age. The data were presented as a base for investigators involved in systems production and related modeling techniques.