Gastric Emptying and the Enzymatic Activity in the Stomach of Amphiprion ocellaris Fed on Artificial Diet

Abstract

This study aims to elucidate the gastric emptying process of clownfish fed on artificial diet using two gastric evacuation models and to determine the pepsin activity in the digestion process in relation to feeding time. Regression analysis was used to evaluate the adequacy of 2 models; Anderson's [S t in describing the gastric emptying rate. Grove's model provided a better fit with higher r 2 value, with the calculated parameters of maximum meal size at time 0 (S 0 ) = 0.195 g and gastric emptying rate (K) = 0.0165 g h -1 . There was no initial delay phase as predicted and the evacuation followed a curve. Pepsin activity in the stomach showed rapid responses to food intake, where activity was detected at 1 h after feeding and reached its peak at 2 h after feeding. Pepsin activity decreased since then until the 12th h after feeding where it reached the lowest point. An increase of pepsin activity was detected later, where a small boost was detected at 24 h after feeding to digest the remaining food item in the stomach before the pepsin secretion decreased and maintained at pre-feeding level. Fast response of digestive enzyme in stomach implied that clownfish is equipped to utilize infrequent and irregular meals effectively. ABSTRAK Kajian ini bertujuan untuk menjelaskan proses pengosongan perut ikan badut yang diberi diet buatan dengan menggunakan dua model pengosongan gastrik dan untuk menentukan hubungan antara aktiviti enzim pepsin dalam proses pencernaan dengan masa selepas makan. Analisis regresi digunakan untuk menentukan ketepatan dua model; model Anderson [S t = S o (1-S o (α-1) ρ(1-α)t) 1/(1-α) + ξ] dan model Grove [S t = (S oα -αKt) 1/α ], dalam penentuan kadar pengosongan perut selepas makan. Model Grove lebih sesuai kerana mempunyai nilai r yang lebih tinggi dengan parameter yang dikira merupakan saiz hidangan maksimum pada masa 0(S 0 ) = 0.195 g dan kadar pengosongan perut (K) = 0.0165 g per jam. Tiada fasa lewat pada permulaan proses penghadaman seperti yang dianggarkan dan pengosongan perut adalah sejajar dengan lengkungan. Aktiviti enzim pepsin dalam perut menunjukkan tindak balas yang pantas terhadap pengambilan makanan dengan aktiviti pepsin dikesan seawal 1 jam selepas makan dan mencapai kemuncaknya pada masa 2 jam selepas makan. Aktiviti pepsin kemudiannya semakin menurun sehingga mencapai tahap terendahnya pada jam 12 selepas makan. Selepas itu, aktiviti pepsin meningkat semula dan terdapat rangsangan kecil dalam rembesan enzim yang dikesan pada 24 jam selepas makan. Aktiviti pepsin kemudiannya menurun semula kepada tahap sebelum makan. Tindak balas yang cepat terhadap pengambilan makanan menunjukkan ikan badut mampu menghadapi keadaan pembekalan makanan yang tidak menentu dengan berkesan.

Metabolic rates, feed intake, appetite control, and gut transit of clownfish Amphiprion ocellaris exposed to increased temperature and limited feed availability

“…Gut passage time is affected by many factors, such as the feeding regime (García-Ortega et al, 2010), feed quality (Nguyen et al, 2018), and temperature (Das et al, 2018;Volkoff and Rønnestad, 2020). Previous studies in A. ocellaris (Khoo et al, 2019) showed that 72-h fasting fish kept at 27 • C emptied the stomach after 36 h, and the gastric emptying rate depended on meal size. In the present study, the gut transit was faster at higher temperatures.…”