The Israeli Journal of Aquaculture - Bamidgeh 55(2), 2003, 123-131

THE INFLUENCE OF MULTIPLE MEALS ON THE
GASTRIC EVACUATION RATE IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)


Ahmet Adem Tekinay*
Department of Aquaculture, Fisheries Faculty, Çanakkale Onsekiz Mart University, Çanakkale, Turkey

Yusuf Güner
Department of Aquaculture, Faculty of Fisheries, Ege University, Izmir, Turkey

Ilhan Akbas
Akbas Trout Farm, Erdek, Balikesir, Turkey

Hüsnü Baysal
Department of Mathematics, Faculty of Science and Art, Çanakkale Mart University, Çanakkale, Turkey

(Received 5.11.02, Accepted 4.2.03)

Key words: gastric evacuation rate, multiple meals, rainbow trout

Abstract

Rainbow trout, Oncorhynchus mykiss (mean weight 70.81.0 g SEM) raised in the Sea of Marmara (Turkey), were used for a preliminary gastric evacuation study. After being starved 72 hours, three groups of 110 fish, each, were fed ad libitum once, twice or three times in a single day. Ten fish from each group were withdrawn and killed in an anesthetic solution during each sampling at 0, 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 hours following the last feeding. Gastric material was removed from the fish and dried for gastric evacuation modelling. Gompertz and logistic models (with fixed asymptotes) best explained the data. The gastric emptying rate of the trout offered a single meal (Group A) was faster than those fed two (Group B) or three (Group C) meals while the emptying patterns of Groups B and C were similar to each other. The time required to evacuate 95% of the gastric material from the first meal was estimated as 54.3, 68.0 and 67.8 h for Groups A, B and C, respectively, according to the Gompertz equations (with a fixed asymptote).


*Corresponding author: Tel.:+90-286-2180542, fax:+90-286-2180543,
e-mail: aatekinay@comu.edu.tr

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