The Israeli Journal of Aquaculture - Bamidgeh 54(2), 2002
The Annual Dan Popper Symposium


FUNCTIONAL AND MORPHOLOGICAL ASPECTS OF THE
GASTROINTESTINAL TRACT OF TILAPIA


Tal Tzafrir-Prag¹, Ingrid Lupatsch², David Sklan¹*

1 Faculty of Agriculture, Hebrew University of Jerusalem, P.O.Box 12 , Rehovot 76100, Israel
2 Israel Oceanographic and Limnological Research, National Center for Mariculture, P.O.Box 1212, Eilat 88112, Israel


Abstract

Tilapia are widely grown in Israel since they can feed on low trophic levels and are opportunistic omnivores. Further, they survive well in low quality water and are tasty. This study reports on functional and morphological aspects of the digestive tract of Oreochromis niloticus x O.aureus. No correlation was found between the length of the gastrointestinal tract and body size, possibly because these fish are hybrids. Microscopic examination revealed different patterns of villi along the tract, with villi becoming more sparse and wider distally. Digestive enzymes were secreted by the hepatopancreas and their activity decreased from the proximal small intestine distally. Diets of fishmeal or wheat-fishmeal resulted in maximal absorption of protein and fatty acids in the proximal small intestine, decreasing distally. Overall digestion of protein was 95.52% and 83.2% and of fat 94.5% and 77.5% for fishmeal and wheat-fishmeal, respectively. Digestion of energy was 85-90%.

*Corresponding author. E-mail: sklan@agri.huji.ac.il

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