Availability of minerals in rendered meat and bone meal for Nile tilapia: Preliminary observations

A digestibility trial was conducted with 180 Nile tilapia (32.65 +/- 4.52 g) fed a reference diet containing 350 g/kg crude protein and 4,500 kcal/kg gross energy. Five different meat and bone meals (MBMs) were evaluated. The test diets compound by 70% of reference diet and 30% of each MBM were elaborated and classified according to ash content: MBM-430, MBM-400, MBM-370, MBM-340 and MBM-310. The apparent availability coefficient (AAC) of minerals and the apparent digestibility coefficient (ADC) of dry matter (DM) were subjected to one-way analysis of variance (p < .05). Differences among ADC and AAC were determined by Tukey's multiple range test (p < .05). When appropriate, a polynomial regression analysis was performed. Linear correlation analyses between MBM chemical composition and the AAC and ADC were performed (p < .01). Higher values of ADC(DM), AAC(Ca) and AAC(P) were observed in MBM-310, while low values were observed in MBM-430. Quadratic effects of ash, P and Ca contents on AAC(Ca), AAC(P) and ADC(DM) were observed. The AAC(Ca), AAC(P) and ADC(DM) indicated a negative correlation with ash, P and Ca contents. MBM-310 exhibited the highest mineral AAC, which could be used as a mineral source for Nile tilapia.