Determining the apparent ileal digestibility of amino acids for soybean meal from select soybean varieties with varying levels of crude protein

Authors: DUNMIRE, KARA - KANSAS STATE UNIVERSITY; BRAUN, MICHAELA - KANSAS STATE UNIVERSITY; EVANS, CAITLIN - KANSAS STATE UNIVERSITY; STARK, CHARLES - KANSAS STATE UNIVERSITY; PAULK, CHAD - KANSAS STATE UNIVERSITY; Fallen, Benjamin

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2022
Publication Date: 1/13/2023
Citation: Dunmire, K.M., Braun, M.B., Evans, C.E., Stark, C.R., Paulk, C.B., Fallen, B.D. 2023. Determining the apparent ileal digestibility of amino acids for soybean meal from select soybean varieties with varying levels of crude protein. Journal of Applied Poultry Research. 32(2). https://doi.org/10.1016/j.japr.2023.100333.
DOI: https://doi.org/10.1016/j.japr.2023.100333

Interpretive Summary: Soybean meal (SBM) is the primary protein source used in broiler diets. Conventional processing of soybeans into SBM involves several steps including dehulling, solvent extraction, and heat processing to destroy antinutritional factors. Thus, the multi-step processing of getting soybeans to an acceptable feeding quality introduces opportunity for variation in SBM. In addition, optimizing SBM quality will help to improve the economics of broiler production. Therefore, the objective of this study was to determine the apparent ileal digestibility (AID) of amino acids (AA) for SBM varying in solvent extraction method used in processing and crude protein (CP) content when fed to broilers. Dietary treatments consisted of 1 of 4 soybean sources varying in quality determined by CP content and processing method used. One standard meal protein soybean variety was used as a control and was processed using two different solvent extraction methods, the first producing SBM with 44% CP (CON) and the second producing SBM with 50% CP (PCON). Two newly developed high meal protein varieties were both processed using the second extraction method, producing SBM with 52% CP (52SBM) and 56% CP (56SBM), respectively. A total of 240 one-day old male broilers were evaluated for a 15-day study and were allotted to 1 of 4 dietary treatments. In conclusion, we determined the SBM extraction method can influence AID of AA and needs to be considered when formulating diets. In addition, the SBM processed from the high meal protein soybean variety with 56% CP (56SBM) had an increased AA digestibility compared to the control SBM processed with the same procedures and the other 52% CP SBM (52SBM).

Technical Abstract: A total of 240 Ross 308 one-day old male broilers were placed in batteries for a 15-day study to evaluate apparent ileal digestibility (AID) of amino acids (AA) for soybean meal (SBM) processed from two high meal protein soybean experimental lines. There were 10 replicates per treatment with 6 broilers per cage. On day 9, cages were allotted to 1 of 4 dietary treatments. One standard meal protein soybean variety was used as a control and was processed using two different solvent extraction methods, the first producing SBM with 44% CP (CON) and the second producing SBM with 50% CP (PCON). Two newly developed high meal protein varieties were both processed using the second extraction method, producing SBM with 52% CP (52SBM) and 56% CP (56SBM), respectively. Broilers fed CON and 56SBM had an increased (P < 0.003) AID of total AA, Arg, His, Lys, Thr, and Trp compared to those fed PCON and 52SBM. The AID of Ile and Phe increased (P < 0.001) in broilers fed 56SBM compared to CON and 52SBM, with PCON intermediate to CON and 52SBM. Broilers fed 56SBM had an increased (P < 0.001) AID of Leu compared to all other sources. The AID of Met increased (P = 0.007) in broilers fed CON and 56SBM compared to 52SBM. Broilers fed CON and 56SBM had an increased (P < 0.001) AID of Val compared to PCON and 52SBM. In conclusion, we determined the SBM extraction method can influence AID of AA and needs to be considered when formulating diets. The high meal protein soybean variety with 56% CP (56SBM) also had increased AA digestibility compared to the other three dietary treatments, which emphasizes the importance of increasing the meal protein content in soybeans used in poultry diets.