title: Fasting and refeeding cause rapid changes in intestinal tissue mass and digestive enzyme capacities of Atlantic salmon (Salmo salar L.).
abstract: Fasting and refeeding effects on gastrointestinal morphology and digestive enzyme activities of Atlantic salmon, held in tanks of seawater at 9 degrees C and 31 per thousand salinity, were addressed in two trials. Trial 1: Fish (mean body mass 1190 g) were fasted for 40 days and intestines sampled at day 0, 2, 4, 11, 19 and 40. Trial 2: Fish (1334 g), fasted for 50 days, were refed and sampled at day 0, 3 and 7. Mass, length, protein, and maltase, lactase, and leucine aminopeptidase (LAP) activities were analyzed for stomach (ST), pyloric caeca (PC), proximal (PI), mid (MI), and distal intestine (DI). PC contributed 50% of gastrointestinal mass and 75% of enzyme capacity. Fasting decreased mass and enzyme capacities by 20-50% within two days, and 40-75% after 40 days. In PC, specific brush border membrane (BBM) maltase activity decreased whereas BBM LAP increased during fasting. Upon refeeding, enzyme capacities were mostly regenerated after one week. The results suggest that refeeding should start slowly with about 25% of estimated feed requirement during the first 3 days, but may then be stepped up rapidly. Investigations of digestive processes of fed fish should only be performed when intestines are feed-filled to avoid bias due to effects of fasting.
authors.affiliation: Aquaculture Protein Centre, Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway. ashild.krogdahl@veths.no
authors.forename: Ashild
authors.initials: A
authors.lastname: Krogdahl
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Bakke-McKellep
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D004063:Digestion; D004435:Eating; D005215:Fasting; D005508:Food Deprivation; D005753:Gastric Mucosa / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000473:pathology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000473:pathology*; D007931:Leucyl Aminopeptidase / Q000737:chemistry; D008871:Microvilli / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism / Q000473:pathology; D020317:Salmo salar; D013696:Temperature; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D007931:Leucyl Aminopeptidase