APPARENT DIGESTIBILITIES OF FEED COMPONENTS FROM FISH-MEAL OR PLANT PROTEIN-BASED DIETS IN COMMON CARP AS AFFECTED BY WATER TEMPERATURE

Apparent digestibility coefficients (ADCs) of macro- and micronutrient s and energy of two diets were measured with common carp Cyprinus carp io reared at two water temperatures (18 and 25 degrees C). Two diets c ontaining either soy protein concentrate (SPC) or Norwegian herring me al (FM) as a major protein source were formulated. Dicalcium phosphate was incorporated at a level of 4 % of the former diet. Duplicate grou ps of 20 fish (body weight: 55 g) were fed by hand twice a day to appa rent satiety. After a 7-day conditioning period, faecal collection was made over 10 days using an automatic faeces collector. ADC of dry mat ter was not different (P > 0.05) between fish fed the two diets at 18 degrees C, but at 25 degrees C, we observed a higher ADC value in fish fed the FM diet than in those fed the SPC diet. ADC of protein was hi gher in fish fed the SPC diet than in the FM groups at either temperat ure. ADC of lipids was not different between the two groups at 25 degr ees C but was found to be higher in fish fed the SPC diet than in the FM group at 18 degrees C. ADCs of energy and ash of the two fish group s remained constant at both water temperatures. Availability of phosph orus was significantly higher (P < 0.05) from fish meal based diets th an from SPC based diets at both temperatures. A more striking effect o f dietary protein source was found in the availability of calcium, whi ch was lower in carp fed SCP based diets. (C) Ifremer/Elsevier, Paris.