Starvation and low feeding levels result in an enrichment of 13C in lipids and 15N in protein of Nile tilapia Oreochromis niloticus L.
Abstract:The influence of different feeding levels below and slightly above maintenance on whole body 13C and 15N values of Nile tilapia Oreochromis niloticus was examined. The energy budget of each fish was determined by indirect calorimetry. The 13C values of the lipid-free material of Nile tilapia fed below and slightly above maintenance level did not differ between the feeding groups, but the 13C values in the lipids and the 15N values of the lipid-free material showed small but significant differences. Those fish with a negative lipid retention had significantly higher 13C values in the lipid fraction compared to fish that synthesized fatty acids. There was a significant negative correlation between the amount of energy metabolized by the fish and both the 13C values in the lipids and the 15N values of the lipid-free material. Fasting and feeding below the maintenance level may influence the isotopic composition of animals and should therefore be considered in ecological and nutritional studies.
Document Type: Regular Paper
Affiliations: 1: Department of Aquaculture Systems and Animal Nutrition in the Tropics and Subtropics, University of Hohenheim, Stuttgart, Germany 2: Institute for Animal Physiology and Animal Nutrition, Georg-August University Göttingen, Göttingen, Germany
Publication date: July 1, 2007