Results The basic premise of this study was that birds would selectively choose between two different diets when offered a choice. When birds were offered the same feed in two different feeders (Normal), they consumed approximately equal amounts from either feeder (Table 2). This indicates that there was no innate selectivity as to which feeder that the birds might choose from. Therefore, when offered the choice of two different feeds it would further suggest that any deviation from equal amounts of feed consumed would be due to some desire of the bird to meet its nutritional needs. When offered the choice between diets with 15 and 24% CP, both the Growth strain and the Yield strain consumed more feed from the feeder with 15% CP than from the feeder with 24% CP; however this was significantly different only with the Growth strain and only during the period of 10-22 d. When offered the choice between diets with 15 and 32% CP, however, there was a greater degree of difference in choice between the two feeders. Both the Growth strain and the Yield strain consumed a significantly greater amount of feed from the feeder with 15% CP than from the feeder with 32% CP over all age periods. These data indicate that the birds in fact selectively chose from the two different feeds when offered a choice. The effects of the different feeding systems on body weight of two strains of male broilers are shown in Table 3. The Growth strain had significantly greater body weight than did the Yield strain at all age periods except for 42-49 d of age. Body weight gains at all intervals after ten days of age were not significantly influenced by the dietary treatment or by an interaction between dietary treatment and strain. This indicates that the birds of either strain were able to select between the diets with different crude protein levels sufficiently to meet their needs for growth.