The digestibility of most indispensable AA in high-protein full-fat soybeans is greater than in conventional full-fat soybeans, but there is no information on the digestibility of AA or on the energy concentration in SBM produced from high-protein soybeans fed to pigs. The objective of the present work was to test the hypothesis that SBM produced from high-protein or low-oligosaccharide soybeans have different digestibilities of AA and energy than SBM produced from conventional soybeans.
Therefore, two experiments were conducted to determine AA digestibility and the concentration of DE and ME in 5 sources of soybean meal (SBM). The 5 sources included hexane-extracted SBM produced from high-protein soybeans (SBM-HP) and conventional soybeans (SBM-CONV), and mechanically extruded-expelled SBM produced from high-protein soybeans (EESBM-HP), low-oligosaccharide soybeans (EE-SBM-LO), and conventional soybeans (EE-SBM-CONV). Five diets that each contained 1 source of SBM and a N-free diet were used in Exp. 1 to determine AA digestibility in each meal. Twelve growing barrows (initial BW: 67.7 ± 1.34 kg) were allotted to a replicated 6 × 6 Latin square design with 6 periods and 6 diets in each square. Each period lasted 7 d, and ileal digesta were collected on d 6 and 7 of each period.
Results of the experiment showed that the standardized ileal digestibility (SID) of all AA except Trp was similar for SBM-HP and SBMCONV, but EE-SBM-HP and EE-SBM-LO had greater (P < 0.05) SID of His, Ile, Lys, Thr, and Val than EE-SBM-CONV. The SID of all indispensable AA in EE-SBM-HP was greater (P < 0.05) than in SBM-HP. The SID of Arg, Ile, Leu, and Phe in EE-SBM-CONV was greater (P < 0.05) than in SBM-CONV, but the SID of Trp was also greater (P < 0.05) in SBM-CONV than in EE-SBM-CONV. Experiment 2 was conducted to measure DE and ME in the same 5 sources of SBM as used in Exp. 1. Forty-eight growing barrows (initial BW: 38.6 ± 3.46 kg) were placed in metabolism cages and randomly allotted to 6 diets with 8 replicates per diet. A corn-based diet and 5 diets based on a mixture of corn and each source of SBM were formulated. Urine and feces were collected during a 5-d collection period, and values for DE and ME in each source of SBM were calculated using the difference procedure. Results showed that the ME in SBM-HP tended to be greater (P = 0.10) than in SBM-CONV (4,074 vs. 3,672 kcal/kg of DM). The ME in EE-SBM-HP also tended to be greater (P = 0.10) than in EE-SBM-CONV and in EE-SBM-LO (4,069 vs. 3,620 and 3,721 kcal/kg of DM), but there was no difference in ME between extracted and extruded-expelled meals.
It is concluded that SBM-HP has a greater feeding value than SBMCONV because of greater concentrations of digestible AA and ME. Likewise, EE-SBM-LO has a greater concentration of most indispensable AA than EE-SBMCONV, but the concentration of ME is similar in these 2 meals.
K. M. Baker and H. H. Stein. Amino acid digestibility and concentration of digestible and metabolizable energy in soybean meal produced from conventional, high-protein, or low-oligosaccharide varieties of soybeans and fed to growing pigs. 2009. Journal of Animal Science, 87:2282-2290. doi:10.2527/jas.2008-1414