True metabolizable energy, standardized amino acid digestibility, phosphorus digestibility, and phosphorus bioavailability of fermented soybean meal and fermented full-fat soybeans fed to chickens.

The objective was to evaluate the nutritional value of conventional soybean meal (SBM-CV), fermented SBM-CV (FSBM), full-fat soybeans (FFSB), and fermented FFSB (FFFSB). In Experiments 1 and 2, two precision-fed rooster assays were conducted to determine nitrogen-corrected true metabolizable energy (TME) and standardized amino acid digestibility (SAAD) among the test ingredients using conventional and cecectomized roosters, respectively. Fermentation increased TME in SBM-CV, whereas fermentation reduced TME in FFSB (interaction, P < 0.05). Fermentation did not affect SAAD in SBM-CV or FFSB, but fermentation reduced digestibility of Lys in both SBM-CV and FFSB (P < 0.05). In Experiment 3, an ad libitum-fed broiler chicken assay was conducted to determine apparent ileal digestibility (AID) and total tract retention (TTR) of P at 2 Ca levels among the test ingredients in diets containing either 0.2 or 0.75 % Ca. Greater AID of P was observed at the low Ca level than at the high Ca levels, whereas at the high Ca level, fermentation increased AID and TTR of P for both conventional and full-fat ingredients (interaction, P < 0.05). In Experiments 4 and 5, two 17 d chick trials were conducted to determine P bioavailability for the test ingredients relative to KHPO using crossbred chicks (Experiment 4) and another similar trial using SBM-CV and FSBM in commercial broiler chicks (Experiment 5). Multiple regression analysis of bone ash in mg/tibia and % on supplemental P intake yielded slope-ratio relative bioavailability values (RBV) of P from 23 % to 48 %. Fermentation did not affect RBV of P in SBM-CV but increased the RBV in FFSB in crossbred chicks. In commercial broiler chicks, fermentation did not affect RBV of P in SBM-CV. In summary, fermentation increased TME in SBM-CV and generally had no significant effect on SAAD. Fermentation had a positive effect on AID and TTR of P for both SBM-CV and FFSB when diets contained 0.75 % Ca, and increased RBV of P for FFSB in crossbred chicks.