Mathematical modeling for digestible protein in animal feeds for tilapia

The objective of this study was to formulate mathematical models to estimate digestible protein in some animal feeds for tilapia. Literature results of the proximate composition of crude protein, ether extract, and mineral matter, as well as digestible protein obtained in biological assays, were used. The data were subjected to multiple linear stepwise backward regression. Path analysis was performed to measure the direct and indirect effects of each independent variable on the dependent one. To validate the model, the experience used data from independent studies and values obtained from a digestibility trial with juvenile Nile tilapia testing five meat and bone meals, using the Guelph feces collecting system and chromium oxide (III) as an indicator. The obtained model used to estimate digestible protein values (DP) of animal origin is: DP(g kg-1) = -204.15+1.203xCP;R² = 0.953. The path coefficients showed a high direct positive effect (0.900) of crude protein on the digestible protein content. The mineral matter content has an indirect negative effect on protein digestibility (-0.710), reducing the crude protein content and quality.