Desempenho zootécnico de juvenis de tilápia-do-Nilo alimentados com diferentes relações amido:proteína dietéticas e submetidos à restrição alimentar cíclica

Abstract

There are strategies used to reduce fish production costs and mitigate environmental impacts. This may be possible such as the use of non-protein energy sources in feed formulations and adequate food management. The objective of this study was to evaluate the effect of the starch: protein ratio on the performance of Nile tilapia (Oreochromis niloticus) juveniles under cyclic feed restriction. A total of 405 Nile tilapia juveniles distributed from a completely randomized design in a 3 × 3 factorial scheme were used, totaling nine treatments with three replicates of 15 animals. The treatments consisted of three starch: protein ratio (0.53-low, 0.69-medium and 0.96-high) and three cyclic feed restriction strategies (0 - fish fed daily, 1 fish submitted to a day of food restriction followed by three days of refeeding; 2- fish submitted to two days of feed restriction followed by three days of refeeding. There was a significant interaction between the days of restriction and the starch: protein ratio only for food consumption, viscerosomal index, muscle fat and volume density of hepatic steatosis. The feed conversion was negatively affected (P <0.05) with the increase of the days of restriction or with the increase the of starch:protein ratio. The productive value of protein or energy decreased with increasing number of days of restriction. The increase in starch:protein ratio increased body and muscle fat contents (P <0.05). Feed restriction in one-day cycles, followed by 3 days of refeeding, has a significant effect on the reduction of liver fat, when a diet with a low starch: protein ratio is provided. In conclusion, changes in the starch:protein ratio did not influence the response to different periods of feed restriction. Animals submitted to one day food restriction cyclic present partial compensatory response and, starch:protein ratio above 0.69 worsen the zootechnical performance of juveniles of Nile tilapia.