Feeding Value of Experimental Soybeans

Two experiments were conducted to determine amino acid digestibility and levels of digestible energy (DE) and metabolizable energy (ME) in five sources of soybean meal (SBM). The five soybean meals included hexane-extracted SBM produced from high-protein soybeans (SBM-HP) and conventional soybeans (SBM-CONV), mechanically extruded-expelled SBM produced from high-protein soybeans (EE-SBM-HP), low-oligosaccharide soybeans (EE-SBM-LO), and conventional soybeans (EE-SBM-CONV). Five diets were formulated to compare SBM sources plus a N-free diet. These six treatments were used in the first experiment to determine amino acid digestibility of each meal. Twelve growing barrows (initial BW: 67.7 ± 1.34 kg) were allotted to a replicated 6 x 6 Latin square design with six periods and six diets in each square. Each period lasted seven days and ileal digesta were collected on day six and seven of each period. Results of the experiment showed that the standardized ileal digestibility (SID) of all amino acids, except tryptophan, were similar for SBM-HP and SBM-CONV, but EE-SBM-HP and EE-SBM-LO had greater (P < 0.05) SID of histidine, isoleucine, lysine, threonine and valine than EE-SBM-CONV. The SID of all indispensable amino acids in EE-SBM-HP was greater (P < 0.05) than in SBM-HP. The SID of arginine, isoleucine, leucine, and phenylalanine in EE-SBM-CONV was greater (P < 0.05) than in SBM-CONV, but the SID of tryptophan was also greater (P < 0.05) in SBM-CONV than in EE-SBM-CONV.

Experiment two was conducted to measure DE and ME in the same five sources of SBM as used in experiment one. Forty-eight growing barrows (initial BW: 38.6 ± 3.46 kg) were placed in metabolism cages and randomly allotted to six diets with eight replicates per diet. A corn-based diet and five diets based on a mixture of corn and each source of SBM were formulated. Urine and feces were collected during a five-day collection period, and values for DE and ME in each source of SBM were calculated using the different 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. The researchers concluded that SBM processed from high protein soybeans had a greater feeding value compared to SBM processed from soybean with conventional levels of protein because of greater concentrations of digestible amino acids and ME. They also found that extruded-expanded processed soybean meal using low-oligosaccharide soybeans had a greater concentration of most indispensable amino acids than similarly processed meal from conventional soybeans, but the concentration of ME were similar in these two meals. Results of this experiment also showed that amino acid digestibility values in extruded-expelled SBM were greater than in hexane-extracted SBM.

Baker, K.M. and H. H. Stein. 2009 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. J. Animal Sci.87:2282-2290.