HISTOLOGICAL METHODS IN THE ASSESSMENT OF DIFFERENTFEED EFFECTS ON LIVER AND INTESTINE OF FISH

This manuscript describes the importance of using histologicalmethods to assess the effects of feed on the liver and intestine of fish. Due to theconstantly increasing world production of fish and other aquatic organisms, it isnecessary to replace fishmeal and fish oil in diets with less expensive raw materialsof plant origin. Due to the increased fiber content, increased presence ofcarbohydrates, antinutritional factors, and inappropriate content of amino acids andnew compounds can have negative effects on the digestive system of fish andtherefore on fitness, health and production characteristics of cultivated fish. Theliver and intestines are the most important organs for the digestion and absorptionof nutrients from feed. Therefore, monitoring histological structure of fish liver andintestine is the method of choice in assessing the effects of nutrient mixtures thatuse raw materials of plant origin. For both of these vital organs the normalhistological structure and the most important results obtained by research arediscussed. This paper presents a critical review of the histological methods used inresearch on feed effects. Results related to the negative effects of raw soy-basedfeed on the occurrence of enteritis in carnivorous fish species are discussed. Theresults point out that use of modern approach in fish pathology such as improvedhistochemical, stereological, scoring, and other analytical methods could be abeneficial approach in an accurate assessment of new feed effects on fish.