Phosphorus digestibility and concentration of digestible and metabolizable energy in corn, corn coproducts, and bakery meal fed to growing pigs

Two experiments were conducted to determine the standardized total tract digestibility (STTD) of P and the concentration of DE and ME in corn, hominy feed, bakery meal, distillers dried grains with solubles (DDGS), corn gluten meal, corn gluten feed, and corn germ meal fed to growing pigs. In Exp. 1, 84 barrows (initial BW: 13.7 +/- 2.3 kg) were placed in metabolism cages and allotted to 14 diets with 6 replicate pigs per diet in a randomized complete block design. Seven diets were formulated to contain corn, hominy feed, bakery meal, DDGS, corn gluten meal, corn gluten feed, or corn germ meal as the sole source of P. Seven additional diets were similar to the initial 7 diets with the exception that 600 units of microbial phytase was included in each diet. The STTD of P was greater (P < 0.05) in DDGS, corn gluten meal, and corn gluten feed than in corn, hominy feed, bakery meal, and corn germ meal, and the STTD of P was also greater (P < 0.05) in bakery meal than in corn and hominy feed. Addition of phytase increased (P < 0.05) the STTD of P in corn, hominy feed, bakery meal, and corn germ meal but not in corn gluten meal, corn gluten feed, or DDGS. In Exp. 2, 56 barrows (initial BW: 14.6 +/- 2.2 kg) were placed in metabolism cages and allotted to 7 diets with 8 replicate pigs per diet in a randomized complete block design. A corn-based diet consisting of 97.5% corn and vitamins and minerals was formulated. Four additional diets were formulated by mixing corn and DDGS, corn gluten feed, corn gluten meal, or corn germ meal, and 2 diets were based on hominy feed or bakery meal. The concentration of ME was 3,891, 3,675, 3,655, 3,694, 4,400, 3,169, and 3,150 kcal/kg DM in corn, hominy feed, bakery meal, DDGS, corn gluten meal, corn gluten feed, and corn germ meal, respectively. The ME (DM basis) in corn was greater (P < 0.05) than in hominy feed, bakery meal, corn gluten feed, and corn germ meal, but less (P < 0.05) than in corn gluten meal, and the ME in hominy feed, bakery meal, and DDGS was greater (P < 0.05) than in corn gluten feed and corn germ meal. In conclusion, DDGS, corn gluten meal, and corn gluten feed have a greater STTD of P than corn, hominy feed, bakery meal, and corn germ meal, but phytase can be included in diets containing corn, hominy feed, bakery meal, and corn germ meal to improve P digestibility. The ME in corn gluten meal is greater than in bakery meal, corn, and other corn coproducts.