Effects of cage density and diet energy concentration on the performance of growing Leghorn pullets subjected to early induced maturity.

Leghorn pullets of a commercial strain were cage-reared at densities of 293 or 586 cm2/bird. Diet treatments consisted of a control step-down protein program, a reverse-protein program, and two treatments involving 18% crude protein throughout rearing with modification of texture and energy concentration according to bird age. Thus, one treatment involved a crumbled low-energy diet to 10 weeks, followed by a crumbled high-energy diet to 16 weeks, while the alternate series involved a mash low-energy diet to 10 weeks followed by the crumbled high-energy diet to 16 weeks. Birds were weighed periodically throughout rearing and, when they were subsequently moved to laying cages, light was immediately increased from 8 to 14 hr. Irrespective of diet treatment, the more liberal density of 586 cm2/bird resulted in a 5 to 8% increase in feed intake (P less than .01). However, this increased intake was not associated with increased body weight (P greater than .05), and as confirmed by carcass analysis, it is assumed that this increased nutrient intake relates to increased maintenance requirement associated with bird activity. Birds offered the crumbled vs. mash high-energy diet to 10 weeks of age, consumed more feed (P less than .01), although change of diet texture from mash to crumble at 10 weeks failed to stimulate appetite. Also, birds reared on either the step-up energy programs were similar in weight to control-reared birds at 16 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)