Effect of feeding frequency on gastric evacuation and the return of appetite in tilapia Oreochromis niloticus (L.)

The rate at which food is consumed and the efficiency with which it is utilized are prime factors in determining growth rate. There is a positive relation between growth and feeding frequency. Additionally, feeding frequency is strongly correlated with gastric evacuation time (GET). Nile tilapia Oreochromis niloticus were fed to satiation with a pelleted diet at two different feeding frequencies (three meals day(-1) and five meals day(-1)) to evaluate the effects of feeding frequency on gastric evacuation and the return of appetite. Ferric oxide was used as an inert indicator to follow gastric evacuation and gastrointestinal (GI) transit. Following an initial meat to satiation with the ferric oxide containing diet, fish were serially dissected at 0, 0.5, 1, 2, 4, 6, 8, 12, and 24 h post-prandially. The fish remaining in the treatments receiving three meals day(-1) were fed to satiation again at 1200 and 1700 In. The fish remaining in the treatments receiving five meals day(-1) were fed to satiation again at 1000, 1200, 1500, and 1700 h. Gastric evacuation rates (GER) for both treatments were curvilinear and were best described by a surface-area dependent model. The equation describing GER for fish fed three meals day(-1) was V-T=67.0e(-0-153(x)) and for fish fed five meals day(-1) was V-T=85.0e(-0-149(x)). The instantaneous evacuation rates obtained by linearizing the data were not significantly different and suggest gastric evacuation is independent of feeding frequency. Fish fed at 4-5-h intervals consume as much as they have evacuated. Fish receiving meals at 2-3-h intervals exhibit gastric overload. The return of appetite following a satiation meal is approximately 4 In in Nile tilapia held at 28 degreesC. Satiation feeding of tilapia at 4-h intervals should increase production efficiency. (C) 2004 Elsevier B.V. All rights reserved.