Apparent Protein and Energy Digestibility and Amino Acid Availability of Commercial Meat and Bone Meal for Nile Tilapia, Oreochromis niloticus

Meat and bone meal (MBM) is an excellent source of amino acids (AAs) for fish but its proximate composition varies according to its origin and processing. Apparent digestibility coefficients (ADC) of dry matter, crude protein, and gross energy, and apparent availability coefficients (AAC) of essential and nonessential AAs (EAA and NEAA, respectively) in MBM containing various levels of crude protein (MBM-340, 370, 400, 430, and 460 g/kg) were determined for juvenile Nile tilapia (Oreochromis niloticus, 32.7 +/- 4.5 g). A reference diet containing 351.9 g/kg crude protein and 4541.1 kcal/kg of gross energy and test diets containing a 70: 30 mixture of the reference diet and MBM were used with 5 g/kg Cr2O3 as an external indicator. ADC of dry matter, gross energy, and crude protein in MBM samples were 42.9-76.2%, 71.6-89.1%, and 49.4-86.9%, respectively. MBM-400, 430, and 460 showed higher dry matter, gross energy, and crude protein ADC than that by MBM-340 and 370. All AAs in MBM-460 showed AAC of EAA>90%, while the value for MBM-430 was >85%, except arginine (82.1%) and lysine (84.8%). High ADC of energy, crude protein, and AAC in MBM-430 and 460 indicate good potential as quantitative AA sources. Besides the low AA quality of MBM-340, 370, and 400, their utilization is limited by low digestible energy and high ash, which should be considered in the production of least-cost, well-balanced, and sustainable diets for tilapia.