Coefficients of total tract apparent digestibility of some feedstuffs for Tambaqui (Colossoma macropomum)

This research aimed at evaluating the coefficients of total tract apparent digestibility (CTTAD) of dry matter (DM), gross energy (GE) and crude protein (CP) for conventional products (whole ground corn, wheat middlings, soybean oil, broken rice and whole ground sorghum) and alternative by-products (cassava root meal, mesquite pod meal and copra meal) by tambaqui (Colossoma macropomum). A semi-purified reference diet containing 345 g kg−1 CP and 13.44 MJ DE kg diet−1 was used and test diets were produced by incorporation of test ingredients in a 7:3 ratio (700 g kg−1 reference diet and 300 g kg−1 test ingredient). Chromic oxide was used as an indigestible inert marker at 1 g kg−1 and feces were collected following a modified Guelph procedure. CTTAD of DM ranged from 0.426 to 0.838 among the feedstuffs. CTTADs of GE showed trend similar to DM, ranging from 0.449 to 0.927. Soybean oil, cassava root meal and broken rice had the highest CTTAD of GE while whole ground sorghum and mesquite pod meal showed the lowest values. The CTTAD of crude protein of the feedstuffs evaluated ranged from 0.714 to 0.875. These results indicate that copra meal and cassava root meal have great potential to replace commonly used ingredients in diets for tambaqui and further research to determine their level of inclusion is needed. Additionally, further research is necessary to determine if the fiber digestibility is influenced by dietary fat content in tambaqui diets. The CTTAD of protein above 0.700 observed in this study indicated that tambaqui is able to efficiently digest protein in several types of ingredients.