Effects of Cage Density and Diet Energy Concentration on the Performance of Growing Leghorn Pullets Subjected to Early Induced Maturity

Abstract

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<.01). However, this increased intake was not associated with increased body weight (P>.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<.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. Birds fed the reverse-protein diets were smaller in size at 16 weeks and subsequently produced fewer eggs that were of a smaller size (P<.05), suggesting that the program is not suitable where early induced maturity is practiced. Birds reared at 293 cm2 subsequently produced larger eggs (P<.01) than did birds reared at 586 cm2, although the latter birds produced more eggs while consuming more feed (P<.01).It is concluded that reduced stocking density during rearing cannot be used as a means of stimulating growth of early maturing Leghorn pullets.