Impact of different processing of full-fat soybeans on broiler performance

The response of broilers to various conditions of expander processing of full-fat soybeans (FFSB) was studied in an experiment involving 5040 birds allocated to 10 dietary treatments with six replicates. In treatments 1-8, the proportions of FFSB in starter, grower, and finisher diets were 40, 39‒43, and 34‒37%, respectively. Diets for treatments 9 and 10 contained commercial soybean meal (SBM) as a main protein source. All diets were isocaloric and were formulated to contain standardized ileally digestible amino acids at levels corresponding to 95% (treatments 1-7 and 10) or 100% (treatments 8 and 9) of requirement. In treatment 1, raw FFSB was used while diets for treatments 2-8 contained FFSB processed by various combinations of times and temperatures used during conditioning and expanding. Urease activity, protein dispersibility index, and trypsin inhibitor activity of FFSB decreased as processing time and/or temperature increased while protein solubility remained relatively unchanged. Concurrently, growth performance of chickens improved (P < 0.05) and their relative pancreas weight decreased (P < 0.05). The best results in terms of feed intake, growth rate, feed conversion ratio, and carcass quality of FFSB-fed birds were obtained using expanding for 15 s at 125°C preceded by short-term (1 min, 100°C) and long-term (5 min, 100°C) conditioning. These results were not significantly different from those achieved with SBM-based diets (P > 0.05). Numerically better performance was found in 100% amino acid diets as compared with 95% diets (P > 0.05). Switching the raw FFSB diet to SBM diet caused relative pancreas weight decrease by 31% during 3 days. An opposite switch resulted in a 65% increase in relative pancreas weight during 4 days.