Morfohistologie en ensiematiese werking van die spysverteringskanaal van Labeo capensis (Teleostei : Cyprinidae)

• Main Author: Coetzee, Johannes Petrus Roux
• Published: 2014
• Subjects: Labeo capensis - Anatomy; Alimentary canal - Physiology; Freshwater fishes - Research - South Africa - Transvaal
• Online Access: http://hdl.handle.net/10210/9086

M.Sc. (Zoology) === Temperature plays a very important role in the metabolic environment of coldblooded animals such as fish. The primary objective of this study was to evaluate the quality of digestive processes and the importance of temperature in the digestive system of Labeo capensis. An important consideration in the choice of the experimental animal was the economic potential and widespread occurrence of Labeo capensis in the riversystems of the Transvaal. The experimental animals were kept at three different acclimation temperatures ( 14, 19 and 25 + 1°C) for a period of six weeks. An assessment of the influence of acclimation temperature on enzyme activity vas made using test kits supplied by BOERINGER-MANNHEIM. No information exists on the morphohistology of Labeo capensis and therefore investigation on the anatomy of the digestive system was carried out in this survey. The ventro-anterior mouth is ideally situated for bottom-feeding. Pharyngeal teeth and a pharyngeal pad (or palatal organ) is situated dorsally at the entrance to the oesophagus. A short oesophagus, which possesses both a supra- and infraoesophageal valve, exists. No stomach is present and the intestinal bulge affixes the intestine to the oesophagus. The exceptionally Iona intestinum proper lies coiled in the abdominal cavity. No rectum can be identified. The micro-anatomy of the intestinal proper and bulge differs minimally. The intestinal bulge possesses longer, slimmer villi in comparrison of the flat thickened villi of the intestine proper. The bulge lacks a longitudinal muscle layer. L. capensis cellulase and dicarrboxylase activty may be contributed to the intestinal microflora and/or foodstuffs present in the digestive system. Amylase possesses the highest and the proteases (trypsin and chymotrypsin) the lowest activity. The effect of acclimation temperature is most evident on amylase, and to a lesser extent on the phosphatases. Trypsin and chymotrypsin activity is less affected by acclimation temperature, although a distinctive loss of activity is recorded for both these enzymes. The loss of acid phosphatase activity is partially contributed to the rise in intestinal pH. The effect of reaction temperature was measured and recorded as AT-values.