Fish decrease their feed consumption as they approach their level of satiety, which can result in wasted feed and could compromise the well-being and growth of the animals due to water contamination. Restricted feeding through a DAT (daily feeding rate) can be an alternative, as it can have a direct impact on feed utilization. This research was carried out for 56 days, using 96 fingerlings previously subjected to a hormonal reversal process with an initial weight of 5 ± 1.5 g. A factorial design was used with commercial feeds A and B with crude protein (CP) at 40% and 36%, respectively, with initial daily feeding rates (DFR) of 5% and 7%; these were neither isoproteic nor isoenergetic (Table 1). Every 15 days weight (P), standard length (LE), total width (AT), thermal growth coefficient (CTC), specific growth rate (SGR), condition factor K (FK), feed conversion rate (FCR), protein efficiency rate (PER) and the viscerosomatic index (IVS) were measured.
Food energy was the main determinant in the PD:ED ratio, which was estimated at 91.04 g PD/Mcal ED for A and 82.66 g PD/Mcal ED for B; both less than those specified according to their label. Significant differences (p < 0.05) were observed between treatments according to the initial DFR applied (Table 2). The DFR of 7% resulted in better growth variables (P, LE, AT, SGR, and CTC) and the DFR of 5% in the efficiency variables (PER and FCR). Food alone significantly affected (p = 0.035) the final LE and the DFR food interaction on IVS (p = 0.016).
Although the type of feed did not determine the performance of the animals and the PD:ED ratios were slightly lower than recommended, both were adequate for the growth phase of the animals in the present study. Most of the zootechnical parameters generated conform to other studies found, so they can be considered a good reference to use in conditions similar to this research.