Abstract
The apparent digestibility coefficients of dry matter (ADC DM), protein (ADCp), essential amino acids (ADC EAA), and energy (ADCe) for Nile tilapia of a selected range of animal and plant feed ingredients found in Western European and North American markets were determined. The investigation was able to provide useful data and information as a prelude for effective diet formulation for this fish species. A reference diet was used for the basis of assessing hydrolyzed fish protein concentrate (CPSP), full-fat soybean meal (FFSBM), solvent-extracted soybean meal (SESBM), maize gluten meal (MGM), poultry meat meal (PMM), hydrolyzed feather meal (HFM), and spray-dried hemoglobin meal (SDHM) by substitution. For each major commercial test ingredient, the ADC were as follows: for plant proteins - FFSBM (ADCp 86.99% and ADCe 74.84%), SESBM (ADCp 93.46% and ADCe 82.16), and MGM which was also utilized well by Nile tilapia (ADCp 83.03% and ADCe 82.36%); for animal proteins - PMM (ADCp 69.30% and ADCe 73.47%), HFM (ADCp 45.53% and ADCe 49.11%), and SDHM was highly digested (ADCp 85.79% and ADCe 75.96%). The ADC EAA reflected the same trends as ADCp, and these varied from > 87% on average for the EEA in fish meal, > 88% for CPSP, > 84% for FFSBM, > 63% for SESBM, > 83% for MGM, and only 61% for PMM, > 63% for HFM, and > 77% for SDHM. Highest ADC were obtained with SDHM and SESBM among the animal and plant by-products tested, respectively. These are discussed in the context of practical diets for tilapia.