Differences in natural carbon isotope ratios of milk and hair from cattle grazing tropical and temperate pastures (original) (raw)
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An experimental study of carbon isotopes in the diets, feces and hair of mammalian herbivores
Can J Zool, 2003
The carbon-isotope composition of hair and feces offers a glimpse into the diets of mammalian herbivores. It is particularly useful for determining the relative consumption of browse and graze in tropical environments, as these foods have strongly divergent carbon-isotope compositions. Fecal δ 13 C values reflect the last few days consumption, whereas hair provides longer term dietary information. Previous studies have shown, however, that some fractionation occurs between dietary δ 13 C values and those of hair and feces. Accurate dietary reconstruction requires an understanding of these fractionations, but few controlled-feeding studies have been undertaken to investigate these fractionations in any mammalian taxa, fewer still in large mammalian herbivores. Here, we present data from the first study of carbon-isotope fractionation between diet, hair, and feces in multiple herbivore taxa. All taxa were fed pure alfalfa (Medicago sativa) diets for a minimum period of 6 months, at which point recently grown hair was shaved and analyzed for carbon isotopes. The mean observed diet-hair fractionation was +3.2‰, with a range of +2.7 to +3.5‰. We also examined diet-feces fractionation for herbivores on alfalfa and bermudagrass (Cynodon dactylon) feeds. The mean diet-feces fractionation for both diets was -0.8‰, with less fractionation for alfalfa (-0.6‰) than bermudagrass (-1.0‰). Fecal carbon turnover also varies greatly between taxa. When diets were switched, horse (Equus caballus) feces reflected the new diet within 60 h, but alpaca (Lama pacos) feces did not equilibrate with the new diet for nearly 200 h. Thus, fecal carbon isotopes provide far greater dietary resolution for hindgut-fermenting horses than foregut-fermenting alpacas.
Canadian Journal …, 2003
The carbon-isotope composition of hair and feces offers a glimpse into the diets of mammalian herbivores. It is particularly useful for determining the relative consumption of browse and graze in tropical environments, as these foods have strongly divergent carbon-isotope compositions. Fecal δ 13 C values reflect the last few days consumption, whereas hair provides longer term dietary information. Previous studies have shown, however, that some fractionation occurs between dietary δ 13 C values and those of hair and feces. Accurate dietary reconstruction requires an understanding of these fractionations, but few controlled-feeding studies have been undertaken to investigate these fractionations in any mammalian taxa, fewer still in large mammalian herbivores. Here, we present data from the first study of carbon-isotope fractionation between diet, hair, and feces in multiple herbivore taxa. All taxa were fed pure alfalfa (Medicago sativa) diets for a minimum period of 6 months, at which point recently grown hair was shaved and analyzed for carbon isotopes. The mean observed diet-hair fractionation was +3.2‰, with a range of +2.7 to +3.5‰. We also examined diet-feces fractionation for herbivores on alfalfa and bermudagrass (Cynodon dactylon) feeds. The mean diet-feces fractionation for both diets was -0.8‰, with less fractionation for alfalfa (-0.6‰) than bermudagrass (-1.0‰). Fecal carbon turnover also varies greatly between taxa. When diets were switched, horse (Equus caballus) feces reflected the new diet within 60 h, but alpaca (Lama pacos) feces did not equilibrate with the new diet for nearly 200 h. Thus, fecal carbon isotopes provide far greater dietary resolution for hindgut-fermenting horses than foregut-fermenting alpacas.
Stable Isotope Carbon Content of Various Tissues in Calves
Canadian Journal of Animal Science, 1984
There are major isotopic fractionation steps involved in the fixation of atmospheric CO2 to form plant tissues. The objective of the present work was to determine if such fractionation occurs in metabolic animal processes. 13C/12C ratios were measured in various tissues. CO2 expired was enriched, duodenal mucosa was similar and other tissues were depleted in 13C compared to diet composition. Key words: Carbon 13, tissue composition, calf
Experimental determination of dietary carbon turnover in bovine hair and hoof
Stable isotopes measured in keratinized tissues like hair or hoof have proven to be a useful tool for reconstructing the dietary history of animals with a weekly to daily resolution. Quantitative reconstruction of dietary preferences requires a precise estimate of tissue turnover by means of controlled feeding experiments. We determined the turnover rates of carbon in hoof and tail hair of growing steers (Bos taurus L., 1758) fed a C3-based diet, followed by a C4-based diet, for 168 d. As with horses, turnover in steer hair was successfully described by a three-pool modelling approach, with apparent half-lives of 1.7, 7.7, and 69.1 d for each of the pools, each contributing 53%, 20%, and 28% of the total signal, respectively. Two pools only were identified in bovine hoof, which recorded the diet switch more slowly than hair with a reduction in the amplitude of short-term isotope changes. We interpreted this result as a sampling artefact and found that the hooves reflected the same pools as the hair if growth geometry is taken into account. The model parameters defined in this study allowed us to quantitatively reconstruct previous diets of steers of different breeds and individual history with a precision of ±1%.
C and N stable isotope variation in urine and milk of cattle depending on the diet
Analytical and Bioanalytical Chemistry, 2006
Urine and milk samples of cattle under different feeding regimes were analysed of stable carbon and nitrogen isotopic composition over a period of six months. The isotope ratios were measured with isotope ratio mass spectrometry (IRMS). The 13 C values of milk and urine were dependent on different feeding regimes based on C 3 or C 4 plants. Under grass feeding the 13 C values are more negative than the under maize feeding. In comparison to urine the 13 C values of milk are more negative independent of the feeding regime. Under grass feeding the analysed milk and urine samples are enriched in 13 C relative to the feed, whereas under maize feeding the 13 C/ 12 C ratio of urine is in the same range and milk is depleted in 13 C in comparison to the diet. The difference of the 15 N/ 14 N ratio between the two feeding regimes is less pronounced than the 13 C/ 12 C ratio. The 15 N values in urine require more time to reach the new equilibrium, whereas the milk samples show no significant differences between the two feeding regimes.
Stable carbon and nitrogen isotopic fractionation between diet and swine tissues
Scientia Agricola, 2006
Naturally occurring stable isotope ratios can be a powerful tool in studies of animal nutrition, provided that the assumptions required for dietary reconstruction are validated by studies such as the one presented here. The objective of this study was to document the magnitude of isotopic fractionation between swine diet and their different tissues. For this, the isotopic ratios of carbon and nitrogen of the diet and selected tissues (hair, nail, liver, muscle, fat and cartilage) were determined. The d13C and d15N of the diet were -15.9 and 1.3, respectively, and all d15N of swine tissues were 2.2 to 3.0 enriched in 15N in relation to the diet. Little variation in d15N occurred among tissues, with exception to liver that was less enriched in 15N than the nail. Nail and hair presented no 13C enrichment relative to diet. Cartilage was ~1.0 enriched in 13C as compared to diet. Liver and muscle were on average 2.1 more depleted in 13C in relation to diet as well as fat tissues. Some of the C and N isotope ratios of swine tissues differed in organs, but the isotopic fractionation trends among tissues appears to be similar to other mammals. Therefore our data provide a good baseline to interpret stable isotope patterns in domestic mammals (such as swine) in controlled or semi-controlled experiments.
Agriculture, Ecosystems & Environment, 2005
Organic matter is an important source of information on the transport and consolidation processes of sediments. In this study, the isotopes of carbon and nitrogen (δ 13 C and δ 15 N), total organic carbon (TOC), total nitrogen, carbon/nitrogen (C/N) ratio, and 13 C-NMR were utilized to understand the origin and behavior of organic material in the Abrolhos region. It were analyzed nine sediment cores taken from a mangrove, a channel between the mainland and the coral reefs. The average value of the C/N ratio in the mangrove was 18, which characterizes purely terrigenous areas. For the reefs, the average value of the C/N ratio was 8,which is characteristic of marine and coastal regions. For the sediment cores taken from the channel, the average value of the C/N ratio was 10, a typical value of areas under the influence of mangroves. The mean values of δ 13 C were-26.9‰ for the mangrove,-20.7‰ for the channel region, and-18.2‰ for the reefs. This variation is associated with the main source of organic matter, which in the mangrove is derived from vascular plants (mainly C3 metabolism) and for the reefs is derived from phytoplankton. The 13 C-NMR results corroborate the isotopic and elemental analyses. The analyses of these cores indicate that the anthropogenic influence on the coast did not significantly alter the composition of the material that has been deposited in about the last 80 years in the region of study.
Scientific Reports
Stable isotopes are useful for estimating livestock diet selection. The objective was to compare δ13C and δ15N to estimate diet proportion of C3–C4 forages when steers (Bos spp.) were fed quantities of rhizoma peanut (Arachisglabrata; RP; C3) and bahiagrass (Paspalumnotatum; C4).Treatments were proportions of RP with bahiagrass hay: 100% bahiagrass (0%RP); 25% RP + 75% bahiagrass (25%RP); 50% RP + 50% bahiagrass (50%RP); 75% RP + 25% bahiagrass (75%RP); and 100% RP (100% RP). Feces, plasma, red blood cell (RBC), and hair were collected at 8-days intervals, for 32 days. Two-pool mixing model was utilized to back-calculate the proportion of RP based on the sample and forage δ13C or δ15N. Feces showed changes using δ13C by 8 days, and adj. R2 between predicted and observed RP proportion was 0.81 by 8 days. Plasma, hair, and RBC required beyond 32-days to reach equilibrium, therefore were not useful predictors of diet composition during the study. Diets were best represented using fecal...
Turnover of carbon isotopes in tail hair and breath CO 2 of horses fed an isotopically varied diet
Oecologia, 2004
Temporal stable isotope records derived from animal tissues are increasingly studied to determine dietary and climatic histories. Despite this, the turnover times governing rates of isotope equilibration in specific tissues following a dietary isotope change are poorly known. The dietary isotope changes recorded in the hair and blood bicarbonate of two adult horses in this study are found to be successfully described by a model having three exponential isotope pools. For horse tail hair, the carbon isotope response observed following a dietary change from a C 3 to a C 4 grass was consistent with a pool having a very fast turnover rate (t 1/2~0 .5 days) that made up~41% of the isotope signal, a pool with an intermediate turnover rate (t 1/2~4 days) that comprised~15% of the isotope signal, and a pool with very slow turnover rate (t 1/2 140 days) that made up~44% of the total isotope signal. The carbon isotope signature of horse blood bicarbonate, in contrast, had a different isotopic composition, with 67% of the isotope signal coming from a fast turnover pool (t 1/2 0.2 days),~17% from a pool with an intermediate turnover rate (t 1/2~3 days) and~16% from a pool with a slow turnover rate (t 1/2~5 0 days). The constituent isotope pools probably correspond to one exogenous and two endogenous sources. The exogenous source equates to our fast turnover pool, and the pools with intermediate and slow turnover rates are thought to derive from the turnover of metabolically active tissues and relatively inactive tissues within the body, respectively. It seems that a greater proportion of the amino acids available for hair synthesis come from endogenous sources compared to the compounds undergoing cellular catabolism in the body. Consequently, the isotope composition of blood bicarbonate appears to be much more responsive to dietary isotope changes, whereas the amino acids in the blood exhibit considerable isotopic inertia.
Diet induced differences in carbon isotope fractionation between sirenians and terrestrial ungulates
Marine Biology, 2007
Carbon isotope diVerences ( 13 C) between bioapatite and diet, collagen and diet, and bioapatite and collagen were calculated for four species of sirenians, Dugong dugon (Müller), Trichechus manatus (Linnaeus), Trichechus inunguis (Natterer), and the extinct Hydrodamalis gigas (Zimmerman). Bone and tooth samples were taken from archived materials collected from populations during the mid eighteenth century (H. gigas), between 1978 and 1984 (T. manatus, T. inunguis), and between 1997 and 1999 (D. dugon). Mean 13 C values were compared with those for terrestrial ungulates, carnivores, and six species of carnivorous marine mammals (cetaceans = 1; pinnipeds = 4; mustelids = 1). SigniWcant diVerences in mean 13 C values among species for all tissue types were detected that separated species or populations foraging on freshwater plants or attached marine macroalgae ( 13 C values < ¡6‰; 13 C bioapatite-diet »14‰) from those feeding on marine seagrasses ( 13 C values > ¡4‰; 13 C bioapatite-diet »11‰). Likewise, 13 C bioapatite-collagen values for freshwater and algal-foraging species (»7‰) were greater than those for seagrass-foraging species (»5‰). Variation in 13 C values calculated between tissues and between tissues and diet among species may relate to the nutritional composition of a species' diet and the extent and type of microbial fermentation that occurs during digestion of diVerent types of plants. These results highlight the complications that can arise when making dietary interpretations without having Wrst determined species-speciWc 13 C tissue-diet values.