Noninvasive assay on stomach evacuation velocity for pacific bluefin tuna Thunnus orientalis fingerlings
2018
Takii, K. (A-marine Kindai, Wakayama (Japan)) | Kai, T. | Fukawa, T. | Katoh, A. | Takakuwa, F. | Takaoka, O. | Biswas, A.
A noninvasive assay for estimating stomach evacuation velocity and daily meal frequency for a commercially available artificial diet was evaluated using Pacific bluefin tuna fingerlings. This was attributed to the hypothesis that fish could consume a diet until filling up a gap of the stomach after a feeding until satiation. Consecutive feeding frequencies of 4, 11 and 3 meals daily from 7:00 to 17:00 for 5 days each, were conducted on a single group of 1,200 fingerlings, weighing 70-190 g in a net cage. The daily feed intake linearly increased with passing the feeding protocols. For each daily feeding event, % daily feed intake of a first meal was higher than those of second meals onward in a day. The stomach evacuation velocity expressed as a slope, subtracting accumulative % daily feed intake of a second meal onward from that of a first meal, was y = -6.94x + 29.6, y = -7.08x + 31.2 and y = -7.07x + 44.4 for 4, 11 and 3 meals daily, respectively. These results indicate that the stomach evacuation velocity of the fingerlings was estimated to be around 7% daily feed intake per hour, and daily meal frequency was 3 or 4 until apparent satiety was achieved with the artificial diet.
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