A study involving 3,120 broilers was used to evaluate the effects of feed form and source of soybean meal (SBM) of the diet on growth performance. From 1 to 21 d of age, there were 12 dietary treatments arranged factorially with three feed forms (mash, crumbles, and pellets) and four commercial sources of SBM that differed in the crude protein content [48.1 and 46.2% crude protein for the USA (USA-1 and USA-2), 47.6% crude protein for Brazil (BRA) and 46.3% crude protein for Argentine (ARG) meals]. From 21 to 42 d of age, diets were fed as pellets, exclusively. Diets were formulated assuming that all SBM and feeds had similar amino acid content per unit of protein.

For the entire experimental period, broilers that were fed crumbles or pellets from 1 to 21 d of age had higher (P < 0.001) body weight gains compared to broilers that were fed mash. Broilers fed pellets had better (P < 0.05) feed conversion than broilers fed mash or crumbles. The broilers fed USA-2 meal had higher (P < 0.01) body weight gains compared to broilers fed BRA or ARG meals, with broilers fed USA-1 meal being intermediate. Also, feed conversion tended (P = 0.06) to be poorer in broilers fed the BRA meal. No interactions between SBM source and feed form were detected for any of the growth performance traits studied

The results indicate that pelleting improved growth performance from 1 to 42 days of age with effects being less evident at 42 days compared to 21 day of age. Source of SBM affected growth performance, indicating the need for a better control of the chemical composition and quality of this ingredient before its use in poultry diets.