INFLUENCE OF DIETS VARYING IN NUTRIENT DENSITY ON THE DEVELOPMENT AND REPRODUCTIVE-PERFORMANCE OF WHITE LEGHORN PULLETS

At 16 wk of age White Leghorn pullets were fed either a 17% protein com and soybean meal laying diet, the same diet diluted with 15% oat hulls, or a similar diet with major nutrients increased by approximately 15%. Little difference in age at sexual maturity or reproductive performance was noted between any of the diet treatments. In a second experiment pullets fed diets containing similar levels of energy but with either 20 or 14% protein (from hatching to 16 wk of age) showed a decreased spread in body weights beyond 8 wk of age. Pullets appeared to exhibit an appetite for protein up to 8 wk of age, but after 8 wk feed intake was reduced with the lower protein diet. At 16 wk of age the pullets were placed on laying diets containing either 17 or 13% protein and 2,600 versus 2,900 kcal of ME/kg of diet, set up in a factorial arrangement. There were no carryover effects of grower diet to 16 wk of age on subsequent laying performance. However, hens to 55 wk of age produced a similar number but heavier eggs when fed a 17 versus a 13% protein diet, whereas no difference in production or egg size was noted with diets containing 2,600 versus 2,900 kcal of ME/kg of diet. The present data confirm that wide differences in growing programs can produce similar hen house performance providing a ''mature'' pullet weight is attained before the onset of production. Dietary energy, not protein, is the main factor controlling the feed intake of pullets and laying hens. However, there is a period just prior to peak egg production during which hens are not very precise in eating to a particular energy appetite. Also, during this early production period, variations in diet density appear to have a limited influence on rate of production or egg weight.