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Digestible and metabolizable energy concentrations in soybean meal, fermented soybean meal, and soy protein concentrate fed to nursery pigs

Song, Y., and B. Kim

Accurate information of energy concentrations in protein supplements is critical in formulating diets for nursery pigs. Soybean products are widely used in nursery pig diets due to the high crude protein (CP) concentrations. The objective of the present study was to determine the digestible (DE) and metabolizable energy (ME) in soybean meal (SBM, 48.5% CP), 3 sources of fermented SBM (FSBM-A, FSBM-B, and FSBM-C; 52.6% CP, 55.1% CP, and 49.8% CP, respectively), and soy protein concentrate (SPC, 58.4% CP) fed to nursery pigs. Twelve barrows with an initial body weight of 8.7 kg (standard deviation = 0.5) were individually housed in metabolism crates. A replicated 6 × 4 incomplete Latin square design with 12 animals, 6 experimental diets, and 4 periods was employed. A basal diet contained 96.9% corn as the sole source of energy. The experimental diets were prepared by replacing the basal diet with SBM at 31%, FSBM-A at 27%, FSBM-B at 26%, FSBM-C at 29%, and SPC at 24%. Each period consisted of a 4-d adaptation period and a 4-d collection period. The marker-to-marker procedure was used for the quantitative collection of feces. Urine was collected for 96 h. The difference procedure was employed to calculate the DE and ME values of the soybean ingredients. Additionally, a 3-step in vitro assay was conducted to determine in vitro total tract disappearance of nutrients in the ingredients. The DE concentrations in FSBM-A (4,171 kcal/kg as-fed), FSBM-B (4,111 kcal/kg as-fed), FSBM-C (4,027 kcal/kg as-fed) and SPC (3,999 kcal/kg as-fed) were greater (P < 0.05) than that in SBM (3,724 kcal/kg as-fed). The ME concentrations in FSBM-A (3,883 kcal/kg as-fed) and FSBM-B (3,841 kcal/kg as-fed) were greater (P < 0.05) than that in SBM (3,528 kcal/kg as-fed) but did not differ from those in FSBM-C (3,728 kcal/kg as-fed) or SPC (3,767 kcal/kg as-fed). The DE:gross energy (GE) was greatest (P < 0.05) in FSBM-B but lowest (P < 0.05) in SBM with intermediate ratios for other 3 ingredients whereas the ME:GE and ME:DE were not different among the 5 ingredients. The in vitro total tract disappearance of dry matter and organic matter in SPC was less (P < 0.05) than that in other ingredients.

In conclusion, fermented soybean meal and soy protein concentrate contain greater energy concentrations compared with soybean meal.