MATERIALS AND METHODS
Fish and sample preparation
Three hundred male Nile tilapia
(Oreochromis niloticus L.) from the Faculty of
Fisheries, Kamphaeng Saen campus, Kasetsart
University were used in this study. They were
divided into 3 groups (100 fish per group) with an
average weight of 5.7±0.5, 35.8±2.5 and 92.1±5.9
g, respectively. Fish were acclimated for one week
by feeding twice per day with 28, 30 and 35%
protein feed for the 92.1, 35.8 and 5.7 g fish,
respectively. The upper and lower intestines,
pseudostomach and liver were collected from 100
fish in each size group and weighed 16 hours after
feeding. Samples were stored at -80°C until used.