Muscle δ13C change in Nile tilapia (Oreochromis niloticus) fingerlings fed on C3-or C4-cycle plants grain-based diets

The effects of grain-based diets from C3 or C4-cycle plants on muscle δ13C change process in Nile tilapia (Oreochromis niloticus) fingerlings were investigated. Two groups of sex reversal males Nile tilapia fingerlings were fed with isoproteic (32.0% DP) and isocaloric (3200 kcal DE/kg) diets, differing from each other by their δ13C. Muscle samples were collected and the carbon isotopic composition was measured. For C4 diet, the formula for the muscle δ13C change related to the intake time of a new diet was δ13C = − 14.88 − 9.21e−0.0209t and the half-life (T) of the muscle carbon was 33.2 days. For C3 diet, the formula was δ13C = − 25.43 + 8.59e−0.0533t with T = 13 days. The C3 diet was considered more appropriate based on its palatability and consequent larger food intake than the C4 diet, resulting in an increased muscle δ13C change rate. However, for future studies, would be necessary to mix both the C3 and C4 feedstuffs to formulate diets nutritionally appropriated, with contrasting stable isotopes signatures. Tissue δ13C change rate is therefore indicated as a promising tool to better understand the biotic and abiotic factors that influence nutrients utilization from the diet and animal growth.