Effect of different ratios of wheat to corn flour in the diet on the development and isotopic composition (delta13C, delta15N) of the red flour beetle Tribolium castaneum.

The back-calculation of the diet is a common application of stable isotopes in animal ecology. The method is based on a predictable relation between the isotopic signature of the diet and the animal's tissues. Frequently, the assumption of a constant difference in isotopic signatures (trophic shift) is made.

Comparison of metabolic rates and feed nutrient digestibility in conventional, genetically improved (GIFT) and genetically male (GMNT) Nile tilapia, Oreochromis niloticus (L.).

Various aspects of energy metabolism and feed digestibility were evaluated in two reportedly improved strains of Nile tilapia (Oreochromis niloticus) namely GIFT (genetically improved farmed tilapia) and GMNT (genetically male Nile tilapia) and compared with those of CNT (conventional Nile tilapia). Fish were stocked individually in a computer-controlled respirometer system at 27+/-0.1 degrees C for 10 weeks.

Improving estimates of trophic shift in Nile tilapia, Oreochromis niloticus (L.), using measurements of lipogenic enzyme activities in the liver.

To test whether the measurement of selected enzyme activities could be used to estimate more precisely the trophic shift of C isotopes, Nile tilapia (Oreochromis niloticus) were fed semi-synthetic diets differing in their lipid contents (1.7%, 5.0%, 10.

Dietary lipid content influences the activity of lipogenic enzymes in the liver and on whole body delta13C values of Nile tilapia, Oreochromis niloticus (L.).

The use of stable isotope techniques for the reconstruction of diets has increased over the last decade. However, isotopic ratios in an animal are not only affected by the composition of the feed, but also by the amount of feed consumed. An uncertainty of up to 1 per thousand for both delta13C and delta15N values has been observed when the feeding level is unknown.

Feeding fish with diets of different ratios of C3- and C4-plant-derived ingredients: a laboratory analysis with implications for the back-calculation of diet from stable isotope data.

Back-calculation of the diet is one of the most frequent applications of stable isotope techniques in animal ecology. These calculations are often based on two assumptions: a constant trophic shift for all dietary items and a linear response of the isotopic ratios to different mixtures of two isotopically distinct feeds. In a laboratory experiment, fish (Nile tilapia, Oreochromis niloticus) were fed semi-synthetic diets prepared either from wheat or corn ingredients, or from three blended diets (25, 50, 75% wheat components).

Individual protein balance strongly influences delta15N and delta13C values in Nile tilapia, Oreochromis niloticus.

Although stable isotope ratios in animals have often been used as indicators of the trophic level and for the back-calculation of diets, few experiments have been done under standardized laboratory conditions to investigate factors influencing delta(15)N and delta(13)C values. An experiment using Nile tilapia [ Oreochromis niloticus (L.)] was therefore carried out to test the effect of different dietary protein contents (35.

Feeding level and individual metabolic rate affect delta 13C and delta 15N values in carp: implications for food web studies.

Stable isotope analyses are often used to calculate relative contributions of multiple food sources in an animal's diet. One prerequisite for a precise calculation is the determination of the diet-tissue fractionation factor. Isotopic ratios in animals are not only affected by the composition of the diet, but also by the amount of food consumed.

Feeding level and diet quality influence trophic shift of C and N isotopes in Nile tilapia (Oreochromis niloticus (L.)).

Many scientists use naturally occurring stable isotopes to reconstruct the diets of animals. However, isotopic ratios may be affected not only by the composition of the diet but also by the amount of food consumed. Thus, an experiment using tilapia (Oreochromis niloticus) was carried out to test the influence of feeding level on delta13C and delta15N of fish given a semi-synthetic wheat gluten/wheat starch based diet.