Nutrition of the broiler chicken around the period of compensatory growth.

Three experiments were conducted with cage-reared broilers to 21 d following nutrient restriction from 6 to 12 d age. In Experiment 1, birds were full-fed from 6 to 11 or given 50% of ad libitum intake on a daily basis, or 100% of ad libitum intake on a daily basis when the diet was diluted 50% with oat hulls. Birds were not able to fully recover body weight depression by 21 d, although birds previously restricted, by whatever method, were more efficient (P < 0.01) in overall energy intake:body weight gain. Prior feed restriction had no effect on ability to metabolize diet energy (P > 0.05), although these birds did exhibit increased nitrogen retention compared to birds full-fed from 6 to 11 d. In a second experiment, birds were fed diets with 1.25, 1.38, 1.51, 1.63, 1.76, or 1.88% lysine in the realimentation diet from 12 to 21 d. Lysine level had no effect on growth rate or feed efficiency (P > 0.05) for full-fed birds; however there was a linear (P < 0.05) decline in growth rate from 12 to 21 d in response to extra dietary lysine for the birds previously feed restricted from 6 to 12 d. In a third experiment, birds were fed diets varying in energy (3,000 to 3,300 kcal/kg) or protein (22 to 29% CP) from 12 to 21 d following ad libitum vs 50% feed restriction from 6 to 11 d age. Protein level of the diet had little effect on performance traits to 21 d, although there was an indication of improved growth in response to the higher energy concentration. Birds full-fed from 6 to 11 d showed increased liver size at 21 d when fed more protein, although the converse was true for the restricted birds (P < 0.05). The growth response to diet energy was associated with increased carcass fatness. In general, there does not seem to be any advantage to manipulating diet formulation during realimentation of birds previously nutrient-restricted.