Effects of gradual differences in trypsin inhibitor activity on the estimation of digestible amino acids in soybean expellers for broiler chickens

Apparent metabolizable energy and ileal amino acid digestibility of commercial soybean meals of different origins in broilers

We studied the chemical composition and the in vivo AMEn content and apparent (AID) and standardized (SID) ileal digestibility of CP and amino acids (AA) of 27 samples of soybean meals (SBM) from Argentina (ARG), Brazil (BRA), and USA, collected in Spain. On 88% DM basis, the BRA meals had more CP (46.9 vs. 46.0 and 45.9%; P < 0.05) and less sucrose (5.21 vs. 6.28 and 6.47%; P < 0.001) and stachyose (4.20 vs. 4.66 and 4.78%; P < 0.05) than the USA and ARG meals. Urease activity, protein dispersibility index, KOH protein solubility, and trypsin inhibitor activity values, were higher for the USA meals than for the South American meals (P < 0.05). In the in vivo trial, broilers received a common crumble diet from 0 to 16 d of age and then, their respective experimental diets (53% of a N-free diet and 47% of each of the 27 SBM tested) in mash form, for 5 d. The AMEn (2,334 vs. 2,282 and 2,277 kcal/kg; P = 0.062) and the AID (87.3 vs. 86.7 and 86.4%; P = 0.054) and SID (91.9 vs. 91.2 and 90.8%; P < 0.05) of the protein, were greater for the USA meals than for the ARG and BRA meals. In fact, the SID of Lys (93.5 vs. 93.0 and 92.1%; P < 0.001) and of the sum of Lys, Met, Thr, Trp, and Cys (91.4 vs. 91.0 and 90.2%; P < 0.05) were greater for the USA meals than for the ARG and BRA meals. In summary, the chemical composition, protein quality indicators, AMEn content, and ileal digestibility of the CP and the AA of the SBM, varied with the country of origin of the soybeans. In order to increase the accuracy of the feed formulation process, the composition and nutrient content of commercial batches of SBM, by country of origin should be controlled and periodically updated.

Effects of expeller soybean on growth performance, amino acid digestibility and intestinal integrity

Expeller soybean (ESB) is a widely used protein source in broiler diets due to its high amino acid digestibility. However, improper heat processing of ESB can negatively affect nutrient digestion, absorption, and metabolism leading to decreased growth performance. The study aimed to investigate the impact of varying processing temperatures on growth performance, amino acid digestibility (AID), and intestinal integrity using 3 different commercial batches of ESB processed at distinct temperatures. These temperatures were 182°C (normal-control), 199°C (overcooked), and 154°C (undercooked). 1,860 off-sex male Cobb 500 broilers were allocated randomly to these treatments, with 10 replicate floor pens (62 birds/pen) from 1 to 35 d of age. Birds consuming the overcooked ESB exhibited significantly lower body weight gain (BWG) and feed intake (FI) on d 14, 28, and 35. They also showed higher feed conversion ratio (FCR) and smaller relative right pectoralis major (RPM) weights at d 35. Meanwhile, birds fed undercooked ESB demonstrated reduced BWG at d 14. Serum fluorescein isothiocyanate-dextran (FITC-d; 4 kD) concentrations on d 16 were notably elevated in birds fed overcooked ESB, indicating increased gut permeability. Overcooked ESB reduced the AID coefficients of several amino acids on d 14 and 28, with Lys experiencing the highest reduction (8%). Undercooked ESB, however, mainly affected the AID of Val, and Phe at d 28. In conclusion, overcooked ESB decreased amino acid digestibility, impaired gut barrier function, and led to diminished growth performance. Conversely, undercooked ESB primarily affected the digestibility of Val and Phe and resulted in reduced BWG at d 14. These findings underscore the critical role of proper heat processing in preserving the nutritional quality of ESB in broiler diets, influencing optimal growth performance, and maintaining intestinal health.

Amino acid digestibility and metabolizable energy of soybean meal of different origins in cecectomized laying hens

This study investigated the variation in amino acid (AA) digestibility and MEn of 18 samples of solvent-extracted soybean meal (SBM; 6 European, 7 Brazilian, 2 Argentinian, 2 North American, 1 Indian) in cecectomized laying hens. The experimental diets contained either 300 g/kg of cornstarch or one of the SBM samples. Pelleted diets were fed to 10 hens in two 5 × 10 row-column designs so that 5 replicates were obtained from each diet during 5 periods. A regression approach and the difference method were used to determine AA digestibility and MEn, respectively. The variation in the digestibility of SBM differed among AA with ranges in digestibility of 6 to 12%-units for most AA. Among the first-limiting AA, the digestibility was 87 to 93%, 63 to 86%, 85 to 92%, 79 to 89%, and 84 to 95% for Met, Cys, Lys, Thr, and Val, respectively. The range of MEn for the SBM samples was 7.5 to 10.5 MJ/kg DM. Indicators of SBM quality (including trypsin inhibitor activity, KOH solubility, urease activity, and in vitro N solubility) and analyzed SBM constituents were significantly correlated (P ≤ 0.05) with AA digestibility or MEn only in a few cases. No differences were observed in AA digestibility and MEn between countries of origins, except low digestibility of some AA and MEn for the 2 Argentinian SBM samples. These results suggest that the precision of feed formulation benefits from considering the variations in AA digestibility and MEn. Often used indicators for SBM quality and analyzed constituents were not suitable to explain variations in AA digestibility and MEn, suggesting that AA digestibility and MEn are determined by other factors.