Efficiency of manganese absorption in chicks fed corn-soy and casein diets

Experiments were conducted with young chicks to quantify the absorption efficiency of manganese (Mn) using tibia Mn uptake as the response criterion. Chicks in experiment 1 were fed a corn-soybean meal diet and either injected intraperitoneally or crop intubated twice daily with three levels of inorganic Mn provided as MnSO4 X H2O. After 14 d, chicks were killed, and intact tibias were removed to facilitate calculation of bone Mn concentration. Excellent straight-line fits (bone Mn concentration as a function of Mn administered) allowed estimation of gut absorption efficiency of Mn by slope-ratio methodology. Absorption efficiency of Mn was calculated to be 1.71% for chicks fed the corn-soy diet. Identical methodology was employed in experiment 2 wherein chicks were fed a phytate- and fiber-free casein-dextrose diet. An absorption efficiency of 2.40% was estimated for chicks fed this diet. Hence, absorption efficiency of inorganic Mn was 40% greater in chicks fed the purified diet than in those fed the conventional corn-soy diet.