Canola meal as feeding for Nile tilapia (Oreochromis niloticus L.) during sexual reversion period

The effects of inclusion of canola meal (CM) in rations for Nile tilapia (Oreochromis niloticus L.) during sexual reversion period, were evaluated. One thousand and two hundred fries with 12.05 +/- 1.03 mp of initial average weight and 9.79 +/- 0.52 mm total of average length were distributed in a completely randomized design, with six treatments (.00; 7.0; 14.0; 21.0; 28.0 and 35.0% of CM inclusion), replacing .0; 12.74; 38.21; 50.94 and 63.68% of protein from soybean meal (SM), respectively, and four replicates, with 50 animals per experimental unit. The rations, isocaloric, isofibrous, isoaminoacidic (for lysine and methionine + cystine), isocalcic and isophosphoric were fed for a period of 28 days. Quadratic effects on weight gain (WG), total length (TL), feed/ gain retio (FC), protein efficiency rate (PER) and ration cost per kilogram of weight gain (R$/kg) were observed, and the best levels of inclusion of CM replacing SM were 22.53; 20.74; 19.70; 19.70 and 25.36, respectively. No effect of the levels of CM inclusion on survival (S) was observed. The worst results of FC, PER, S and R$/kg occurred with animals which received control diet, when compared to animals fed CM independent of their inclusion level. The animals fed levels of CM showed better values of WG and TL in relation to animal fed control diet, except for the 7.0 and 14.0% levels of CM inclusion. The best level of CM inclusion in rations for Nile tilapia during sexual reversion period was 19.70% or 35.89% of soybean meal protein replaced by canola meal protein.