Compensatory growth in Nile tilapia Oreochromis niloticus: feed conversion ratio, size heterogeneity, and proximal composition

Abstract

A feeding test was performed to evaluate compensatory growth in the Nile tilapia (Oreochromis niloticus) and to assess changes in feed conversion ratio (FCR), body condition, and carcass composition associated with the imposed feeding strategy. The experiment was carried out under two different stages, restricted (RS) and compensated (CS), with six weeks long each other. Three hundred juveniles of Nile tilapia (average weight of 16.4 ± 0.2 g) were divided into three treatments and one control. The control group was fed to apparent satiation four times a day in both stages. The RS treatments were based on 100% (RS100), 80% (RS80), and 60% (RS60) of a feeding chart, respectively. In the next six weeks, fishes from the CS treatments (CS100, CS80, and CS60) were then fed to apparent satiation four times a day. In the RS, the control group displayed the most considerable weight gained, but with a significant FCR. Nevertheless, in the CS, the previous restricted treatments (RC80 and RC100) showed a compensatory growth, with a smaller FCR than the control group. The restricted-compensated rations did not have a significant effect on the size heterogeneity; when the food is restricted, fish use to moisturize their tissue to compensate for the muscle loss until they receive more food. However, when the food restriction levels are too high, the weight gain, lipid, and protein levels do not recover as they were before. Thus, restricted (marginally) and compensatory feeding strategies provide evidence that growth rates of fishes can be regulated.