Concentration of digestible and metabolizable energy in L-threonine and L-valine biomass products fed to weanling pigs

An experiment was conducted to test the hypothesis that concentrations of digestible energy (DE) and metabolizable energy (ME) in threonine and valine biomass products are not different from those in fish meal. Two threonine biomass products (i.e., Thr-BM1 and Thr-BM2) and 1 valine biomass product (Val-BM) were obtained from the production of crystalline L-threonine and Lvaline. The biomass products consist of the fermentation biomass that is left after the crystalline amino acids have been harvested at the end of fermentation. Forty weanling barrows (11.25 +/- 0.65 kg) were placed individually in metabolism crates and allotted to a completely randomized design with 5 diets and 8 replicate pigs per diet. A bakery meal-based diet consisting of 973.5 g/kg bakery meal was formulated. Four additional diets containing a mixture of bakery meal and Thr-BM1, Thr-BM2, Val-BM, or fish meal were also formulated. Feces and urine samples were collected for 5 days after a 5-day adaptation period. Results indicated that the apparent total tract digestibility of gross energy was less (P < 0.05) in Val-BM than in Thr-BM1, fish meal, and bakery meal. The concentration of ME in bakery meal, Thr-BM1, Thr-BM2, Val-BM, and fish meal was 15.73, 16.59, 16.98, 17.04, and 16.39 MJ/kg (dry matter basis), respectively, and these values were not different. In conclusion, the concentration of ME in threonine and valine biomass products was not different from the ME in bakery meal or fish meal, which indicates that these ingredients may be used as energy sources in diets fed to weanling pigs.