Individual protein balance strongly influences ?15N and ?13C values in Nile tilapia, Oreochromis niloticus

Gaye-Siessegger, Julia; Focken, Ulfert; Abel, Hj.; Becker, Klaus

doi:10.1007/s00114-003-0496-2

Cited by 56 publications

(50 citation statements)

References 19 publications

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“…For example, isotopic diVerences among sexes and age classes within species are generally thought to represent intra-speciWc niche partitioning (Forero et al 2005;Bearhop et al 2006). However, studies by Hobson et al (1993), Cherel et al (2005), Gaye-Siessegger et al (2004a), and others demonstrate that physiological status may present an additional source of isotopic variation. If large enough, factors such as nutritional status and growth could potentially confound dietary interpretation of isotope signatures of wild individuals.…”

Section: Introductionmentioning

confidence: 93%

Disentangling effects of growth and nutritional status on seabird stable isotope ratios

2008

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A growing number of studies suggest that an individual's physiology affects its carbon and nitrogen stable isotope signatures, obscuring a signal often assumed to be only a reflection of diet and foraging location. We examined effects of growth and moderate food restriction on red blood cell (RBC) and feather delta(15)N and delta(13)C in rhinoceros auklet chicks (Cerorhinca monocerata), a piscivorous seabird. Chicks were reared in captivity and fed either control (75 g/day; n = 7) or ~40% restricted (40 g/day; n = 6) amounts of high quality forage fish. We quantified effects of growth on isotopic fractionation by comparing delta(15)N and delta(13)C in control chicks to those of captive, non-growing subadult auklets (n = 11) fed the same diet. To estimate natural levels of isotopic variation, we also collected blood from a random sample of free-living rhinoceros auklet adults and chicks in the Gulf of Alaska (n = 15 for each), as well as adult feather samples (n = 13). In the captive experiment, moderate food restriction caused significant depletion in delta(15)N of both RBCs and feathers in treatment chicks compared to control chicks. Growth also induced depletion in RBC delta(15)N, with chicks exhibiting lower delta(15)N when they were growing the fastest. As growth slowed, delta(15)N increased, resulting in an overall pattern of enrichment over the course of the nestling period. Combined effects of growth and restriction depleted delta(15)N in chick RBCs by 0.92 per thousand. We propose that increased nitrogen-use efficiency is responsible for (15)N depletion in both growing and food-restricted chicks. delta(15)N values in RBCs of free-ranging auklets fell within a range of only 1.03 per thousand, while feather delta(15)N varied widely. Together, our captive and field results suggest that both growth and moderate food restriction can affect stable isotope ratios in an ecologically meaningful way in RBCs although not feathers due to greater natural variability in this tissue.

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Section: Introductionmentioning

confidence: 93%

Disentangling effects of growth and nutritional status on seabird stable isotope ratios

2008

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“…The protein and lipid utilization was significantly lower in fish fed the highprotein diet (Diet P56). In a previous study, Nile tilapia were fed three semi-synthetic wheat-based diets that differed in their protein contents (35.4, 42.3, and 50.9%;Gaye-Siessegger et al 2004). The feeding level was also relatively low (5 g per kg 0.8 per day).…”

Section: Digestibility Of the Dietsmentioning

confidence: 99%

Effect of dietary protein/carbohydrate ratio on activities of hepatic enzymes involved in the amino acid metabolism of Nile tilapia, Oreochromis niloticus (L.)

Gaye-Siessegger

Focken

Becker

2006

Fish Physiol Biochem

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This study investigated the influence of different dietary protein/carbohydrate ratios on activities of enzymes involved in the amino acid metabolism as well as on growth performance and body composition of Nile tilapia (Oreochromis niloticus). Fish were fed semi-synthetic diets differing in their protein/carbohydrate ratio. The diets were formulated to be isolipidic and isoenergetic (on the basis of metabolizable energy). Fish were reared individually. After a prefeeding phase, tilapia were randomly assigned to three groups and were fed the experimental diets at a relatively low level. The study lasted 9 weeks. Proximate composition, gross energy content, and activities of aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) in the liver of fish were determined. While the mean growth rate and feed conversion efficiency did not differ significantly among the feeding groups, the body composition showed significant differences. The dietary protein/carbohydrate ratio had no significant effect on the protein and energy gain, but the lipid gain was significantly higher in tilapia fed the low-protein diet. The activities of ASAT and ALAT per gram of liver and per gram of soluble protein were significantly increased in fish fed the high-protein diet. There was a significant positive correlation between the activities of ASAT and ALAT. The activities of both enzymes in the liver were significantly higher in fish with a higher protein gain. Measuring the activities of enzymes involved in the amino acid metabolism can provide more information about the metabolic utilized dietary protein.Keywords Amino acid metabolism AE Alanine aminotransferase AE Aspartate aminotransferase AE Dietary protein/carbohydrate ratio AE Fish

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“…Stable isotope analysis has also been used to distinguish between protein sources and to estimate their relative contribution to an animal's biomass and to infer food quality [12], [13], [14] or determining the length of time an individual has spent in a new environment [15]. The contribution of different protein sources into diets to biomass production can be estimated using isotope-mixing models [16], [17], [18].…”

Section: Introductionmentioning

confidence: 99%

Protein Retention Assessment of Four Levels of Poultry By-Product Substitution of Fishmeal in Rainbow Trout (Oncorhynchus mykiss) Diets Using Stable Isotopes of Nitrogen (δ15N) as Natural Tracers

Badillo¹,

Herzka

Viana³

2014

PLoS ONE

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This is second part from an experiment where the nitrogen retention of poultry by-product meal (PBM) compared to fishmeal (FM) was evaluated using traditional indices. Here a quantitative method using stable isotope ratios of nitrogen (δ15N values) as natural tracers of nitrogen incorporation into fish biomass is assessed. Juvenile rainbow trout (Oncorhynchus mykiss) were fed for 80 days on isotopically distinct diets in which 0, 33, 66 and 100% of FM as main protein source was replaced by PBM. The diets were isonitrogenous, isolipidic and similar in gross energy content. Fish in all treatments reached isotopic equilibrium by the end of the experiment. Two-source isotope mixing models that incorporated the isotopic composition of FM and PBM as well as that of formulated feeds, empirically derived trophic discrimination factors and the isotopic composition of fish that had reached isotopic equilibrium to the diets were used to obtain a quantitative estimate of the retention of each source of nitrogen. Fish fed the diets with 33 and 66% replacement of FM by PBM retained poultry by-product meal roughly in proportion to its level of inclusion in the diets, whereas no differences were detected in the protein efficiency ratio. Coupled with the similar biomass gain of fishes fed the different diets, our results support the inclusion of PBM as replacement for fishmeal in aquaculture feeds. A re-feeding experiment in which all fish were fed a diet of 100% FM for 28 days indicated isotopic turnover occurred very fast, providing further support for the potential of isotopic ratios as tracers of the retention of specific protein sources into fish tissues. Stable isotope analysis is a useful tool for studies that seek to obtain quantitative estimates of the retention of different protein sources.

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Individual protein balance strongly influences ?15N and ?13C values in Nile tilapia, Oreochromis niloticus

Cited by 56 publications

References 19 publications

Disentangling effects of growth and nutritional status on seabird stable isotope ratios

Disentangling effects of growth and nutritional status on seabird stable isotope ratios

Effect of dietary protein/carbohydrate ratio on activities of hepatic enzymes involved in the amino acid metabolism of Nile tilapia, Oreochromis niloticus (L.)

Protein Retention Assessment of Four Levels of Poultry By-Product Substitution of Fishmeal in Rainbow Trout (Oncorhynchus mykiss) Diets Using Stable Isotopes of Nitrogen (δ15N) as Natural Tracers

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