Feed intake response to the dilution of high-protein and high-energy diets under self-selection feeding

ABSTRACT Two experiments were conducted to examine the temporal response of hens to the simultaneous dilution of high-protein (HP) and high-energy (HE) diets under self-selection feeding. In the initial experiment, the HE and HP diets consisted primarily of cornstarch and isolated soy-bean protein, respectively. In the second experiment, corn and soybean meal (49%) were used as the principal feed ingredients. The diluted diets consisted of a mixture of 80 % of the HP and HE diets and 20 % wood pulp. In both experiments, the hens initially consumed less of the diluted than of the nondiluted diets. After about 6 days, increased intakes of both the diluted HP and HE diets occurred. In the first experiment, compensation in protein and energy intakes in response to diet dilution resulted in intakes of these nutrients similar to those observed with the feeding of nondiluted diets. Com-pensations were similar in the second experiment, except that protein and caloric intakes remained below the levels obtained with the nondiluted diets. Differences in body weight and egg produc-tion between the birds fed the diluted and nondiluted diets were not significant in the first experi-ment. In the second experiment, the feeding of the diluted diets resulted in significant decreases in body weight and egg output. Irrespective of these differences, trends in the intakes of the diluted HP and HE diets were remarkably similar. It was concluded that the ability of chickens to balance protein intake was acquired in the same temporal framework as was the ability to balance caloric intake. (Key words: feed intake, diet dilution, diet selection, protein intake, caloric intake