Effects of unidentified growth factor sources on feed preference of chicks

The effect on feed preference of various feed ingredients considered to be sources of unidentified growth factors (UGF) was studied with egg-type chicks. In each experiment five or six pens of 20 males were assigned to each treatment. All chicks were fed a corn-soy basal diet with added fat during days 1 to 13. During days 14 to 21 chicks of the test treatment were offered a choice of the basal diet (Feeder 1) or a test diet with one of the UGF sources (Feeder 2). In pens of the control treatment both feeders contained the basal diet. All diets were approximately equal in calculated nutrient composition. The UGF sources, included at 5% of the diet, were meat and bone meal (MBM); fish solubles and meal (FSM); a commercial mixture made from fish, whey, and fermentation products (UGF mix); and distillers dried grains with solubles (DDGS). Each day feed consumption from each of the feeders was measured and their positions were alternated. Chicks showed a significant preference for FSM and UGF mix in two trials, no preference for MBM in one trial, and no preference for DDGS in one trial, and a significant rejection of DDGS in the other. No differences in weight gain were noted. The MBM decreased gain/feed and DDGS increased total feed intake in one of two trials. These studies indicate that some UGF sources improve feed preference in chicks fed practical diets.