Differences in natural carbon isotope ratios of milk and hair from cattle grazing tropical and temperate pastures (original) (raw)
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.
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
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.
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...
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.
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.
Turnover of stable carbon isotopes in the muscle, liver, and breath CO2 of alpacas (Lama pacos)
Rapid …, 2006
Stable carbon isotope analysis of animal liver and muscle has become a widespread tool for investigating dietary ecology. Nonetheless, stable carbon isotope turnover of these tissues has not been studied in large mammals except with isotopically labelled tracer methodologies, which do not produce carbon half-lives analogous to those derived from naturalistic diet-switch experiments. To address this gap, we studied turnover of carbon isotopes in the liver, muscle, and breath CO 2 of alpacas (Lama pacos) by switching them from a C 3 grass diet to an isonitrogenous C 4 grass diet. Breath samples as well as liver and muscle biopsies were collected and analyzed for up to 72 days to monitor the incorporation of the C 4 -derived carbon. The data suggest half-lives of 2.8, 37.3, and 178.7 days for alpaca breath CO 2 , liver, and muscle, respectively. Alpaca liver and muscle carbon half-lives are about 6 times longer than those of gerbils, which is about what would be expected given their size. In contrast, breath CO 2 turnover does not scale readily with body mass. We also note that the breath CO 2 and liver data are better described using a multiple-pool exponential decay model than a single-pool model.
Canadian Journal of Zoology, 2000
The amount of isotopic fractionation (change in isotope ratios) between diet and animal tissues is generally poorly known and may be affected by trophic position. Diet-tissue fractionation of stable-carbon and-nitrogen isotopes was measured in several tissues of red foxes (Vulpes vulpes) raised on a commercial pellet feed. Stable carbon isotopic fractionation in red fox was positive for all tissues and was greatest in fur (2.6‰), intermediate in muscle (1.1‰), and least in liver and blood fractions (0.4-0.6‰). These carbon isotope fractionation values were greater than those previously measured for mammalian herbivores but were similar to values for marine mammals in most tissues. Little variation in stable nitrogen isotopic fractionation occurred among tissues, except in the blood fractions. Nitrogen isotopic fractionation was much higher in blood serum (4.2‰) than in liver, muscle, and fur (3.3-3.5‰). Cellular fractions of blood had the lowest fractionation values (2.6‰). There was a significant age effect in nitrogen-but not in carbonisotopic fractionation. Subadult foxes (<1 year) were significantly enriched in 15 N compared with adult foxes for fur, muscle, and liver (no blood was collected from adults). The cause of this enrichment is unclear, but it may be related to the higher rate of protein synthesis and catabolism in growing animals. This study is the first to report isotopic fractionation values for a terrestrial mammalian carnivore. Such estimates are necessary to interpret stable-isotope patterns in wild carnivores. Résumé : L'importance du fractionnement des isotopes (changement dans les rapports entre les isotopes) entre le régime alimentaire et les tissus est généralement mal connue et peut être affectée par la position trophique. Le fractionnement régime-tissus des isotopes de carbone stable et d'azote a été mesuré dans plusieurs tissus de Renards roux (Vulpes vulpes) nourris de boulettes commerciales. Le fractionnement des isotopes de carbone stable chez le renard était positif dans tous les tissus et c'est dans la fourrure qu'il était le plus élevé (2,6 ‰), il était intermédaire dans les muscles (1,1 ‰) et c'est dans le foie et dans le sang qu'il était le plus faible (0,4-0,6 ‰). Les valeurs du fractionnement des isotopes de carbone se sont avérées plus grandes que les autres valeurs mesurées chez des mammifères herbivores, mais semblables à celles des mammifères marins pour la plupart des tissus. Il y avait peu de variation dans le fractionnement des isotopes d'azote stable entre les tissus, sauf dans les fractions du sang. Le fractionnement de l'azote dans le sérum sanguin (4,2 ‰) était beaucoup plus élevé que dans le foie, les muscles ou la fourrure (3,3-3,5 ‰). Les fractions cellulaires du sang avaient le plus faible taux de fractionnement (2,6 ‰). L'âge avait un effet significatif sur le fractionnement de l'azote, mais pas sur celui du carbone. Les subadultes (<1 an) étaient significativement plus riches en 15 N que les adultes, dans la fourrure, les muscles et le foie (aucun prélèvement de sang n'a été fait chez les adultes). La cause de cet enrichissement n'est pas claire, mais il se peut qu'il soit attribuable au taux plus élevé de synthèse et de catabolisme des protéines chez les animaux en croissance. Cette étude est la première à donner des valeurs de fractionnement pour des mammifères terrestres carnivores. De telles estimations sont nécessaires à l'interprétation des patterns d'isotopes stables chez les carnivores sauvages.
Short-term diet changes revealed using stable carbon isotopes in horse tail-hair
Functional Ecology, 2004
1. We demonstrate the potential of extracting high-resolution dietary information from stable carbon isotopes (δ 13 C) in horse tail-hair, in response to short-term changes in diet in controlled feeding experiments. 2. Tail hairs were sampled from six horses that had been equilibrated to C3 forage and were then subjected to a series of short-term diet switches to the C4 Coastal Bermuda Grass (Cynodon dactylon L.). Four of these horses were equilibrated to Alfalfa (Medicago sativa L.) and were then subjected to 1-, 3-and 7-day diet spikes of the C4 grass. The remaining two horses were equilibrated to a C3 grass mix (Dactylis glomerata L. and Festuca arundinacea Schreb.) and then subjected to a 7-day diet spike of C4 grass. 3. The effects of the short-term diet switches were easily observable in the hair. The 1-, 3-and 7-day spikes showed an increasing deviation from the prespike equilibrium value of 1•0‰, 2•9‰ and 5•6‰ (7-day treatments averaged). 4. Isotopic chronologies of individual hairs were created and plotted against a threepool, exponential-decay model. With small alterations to the original model parameters, our data are well explained by this model. 5. This study indicates that information about diet is recorded with high resolution in hair. This method could be applied to both modern and ancient samples, greatly enhancing the temporal resolution of diet reconstruction studies.
Oecologia, 1999
The isotope enrichment e* of 13 C between tooth enamel of large ruminant mammals and their diet is 14.1 0.5&. This value was obtained by analyzing both the dental enamel of a variety of wild and captive mammals and the vegetation that comprised their foodstus. This isotope enrichment factor applies to a wide variety of ruminant mammals. Non-ruminant ungulates have a similar isotope enrichment, although our data cannot determine if it is signi®cantly dierent. We also found a 13 C isotope enrichment e* of 3.1 0.7& for horn relative to diet, and 11.1 0.8& for enamel relative to horn for ruminant mammals. Tooth enamel is a faithful recorder of diet. Its isotopic composition can be used to track changes in the isotopic composition of the atmosphere, determine the fraction of C 3 or C 4 biomass in diets of modern or fossil mammals, distinguish between mammals using different subpathways of C 4 photosynthesis,and identify those mammals whose diet is derived from closed-canopy habitats.
Canadian Journal of Fisheries and Aquatic Sciences, 1996
The amount of isotopic fractionation (change in isotope ratios) between diet and animal tissues is generally poorly known and may be affected by trophic position. Diet-tissue fractionation of stable-carbon and -nitrogen isotopes was measured in several tissues of red foxes (Vulpes vulpes) raised on a commercial pellet feed. Stable carbon isotopic fractionation in red fox was positive for all tissues and was greatest in fur (2.6‰), intermediate in muscle (1.1‰), and least in liver and blood fractions (0.4-0.6‰). These carbon isotope fractionation values were greater than those previously measured for mammalian herbivores but were similar to values for marine mammals in most tissues. Little variation in stable nitrogen isotopic fractionation occurred among tissues, except in the blood fractions. Nitrogen isotopic fractionation was much higher in blood serum (4.2‰) than in liver, muscle, and fur (3.3-3.5‰). Cellular fractions of blood had the lowest fractionation values (2.6‰). There was a significant age effect in nitrogen-but not in carbonisotopic fractionation. Subadult foxes (<1 year) were significantly enriched in 15 N compared with adult foxes for fur, muscle, and liver (no blood was collected from adults). The cause of this enrichment is unclear, but it may be related to the higher rate of protein synthesis and catabolism in growing animals. This study is the first to report isotopic fractionation values for a terrestrial mammalian carnivore. Such estimates are necessary to interpret stable-isotope patterns in wild carnivores.
Isotopic turnover of carbon and nitrogen in bovine blood fractions and inner organs
Rapid Communications in Mass Spectrometry, 2014
RATIONALE: Isotope ratio analysis of bovine tissues is a tool for inferring aspects of the dietary history of cattle. The objective of this experiment was to quantify the carbon (C) and nitrogen (N) isotopic turnover in blood (serum and residue) and inner organs (liver, kidney, heart and brain) of beef cattle. METHODS: Growing beef cattle (n = 70 in total) were either switched from a control diet containing barley and urea to an experimental diet containing maize and 15 N-enriched urea, for various intervals prior to slaughter or maintained on the control diet for 168 days pre-slaughter. Samples of blood, liver, kidney, heart and brain were collected at 0, 14, 28, 56, 112 and 168 days and analysed using Isotope Ratio Mass Spectrometry. RESULTS: After 168 days, C-and N-isotopic equilibrium was reached in the blood serum, liver and kidney, approached in the heart and brain, but not reached in the non-serum component of blood. The estimated C and N half-lives were 16.5 and 20.7 days for liver, 19.2 and 25.5 days for kidney, 29.2 and 35.6 days for blood serum, 37.6 and 49.9 days for heart, 53.3 and 52.2 days for brain and 113.3 and 115.0 days for the non-serum blood residue, respectively. Modelling the C and N turnover in the different tissue combinations revealed that a combined analysis of liver and heart as well as brain and kidney can provide the most accurate estimation of the timing of the diet switch. CONCLUSIONS: Based on the difference in turnover rates, bovine soft tissues can provide isotopic information on shortand long-term dietary changes, which in turn may be linked to the geographic or production origin of beef cattle. This study also provides basic biological data on organ C and N turnover in a large herbivorous mammal.
Do grazer hair and faeces reflect the carbon isotope composition of semi-arid C3/C4 grassland?
Basic and Applied Ecology, 2010
The carbon isotope composition (d 13 C) of C3/C4 mixed grassland is reflected in the d 13 C of diet, hair or faeces of grazers, if 13 C discrimination ( 13 D) between grassland vegetation and these tissues is known and constant. However, these relationships could be modified by selective grazing or differential digestibility of the C3 and C4 components, potentially creating a bias between grassland and grazer tissue d 13 C. Importantly, these factors have never been studied in detail. We investigated the relation between d 13 C of C3/C4 grassland vegetation and that of faeces and hair of sheep in a 3-year (2005)(2006)(2007) experiment in the Inner Mongolian semi-arid steppe. The experiment employed six stocking rates (0.375-2.25 sheep ha À1 year À1 ; four replications), which allowed for a large variation in species composition, digestibility, and diet selection. Faecal-nitrogen content, a proxy for digestibility, decreased from 1.9% to 1.5% during the grazing period due to aging of the herbage. At the same time, the C3/C4 ratio decreased due to the later growth initiation of C4 species. 13 D between diet and faeces ( 13 D DF ; 0.6%) and between diet and hair ( 13 D DH ; À3.9%) were not influenced by stocking rate, period in the season or C3/C4 ratio. Moreover, faeces-hair discrimination ( 13 D FH ; À4.3%), which reflects differences between digestibility of the C3 and C4 components, did not vary along the different gradients. The d 13 C of grassland vegetation can be estimated from the d 13 C of sheep faeces and hair, provided that 13 D was accounted for. This is useful for landscape-or regional-scale investigations or reconstruction of C3/C4 vegetation distribution from faeces and hair, which provide different temporal and spatial integration of grassland isotope signals.
Trophic Discrimination Factors of Stable Carbon and Nitrogen Isotopes in Hair of Corn Fed Wild Boar
PLOS ONE, 2015
Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissueand species-specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ 13 C) and nitrogen (Δ 15 N) isotopes were determined from hair samples. The mean Δ 13 C and Δ 15 N in wild boar hair were-2.3 ‰ and +3.5 ‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d-1. Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types.
C isotopic composition in C3 and C4 plants for forage intake estimation
Symposium Strategic Practices for Mitigating Greenhouse gas Emissions in Grassland Systems, 2023
Carbon (C) constitutes 40 to 50% of the organic matter on the planet and is present in various reservoirs. It naturally occurs as two stable isotopes: 12 C and 13 C; the lighter isotope represents 98.89% of all the carbon. The ratio between the heavier and lighter isotopes can vary due to the isotopic fractioning that occurs during physical, chemical, and biological processes. The isotopic ratio of a sample is commonly expressed using the delta notation (δ 13 C), which represents the deviation of this ratio from the PDB standard. The isotopic methodology compares the δ 13 C of a source with the δ 13 C of a specific product. In the case of vegetation studies, the source is atmospheric CO 2 , and the product is the organic molecule produced by plants during photosynthesis. Due to the characteristics of their photosynthetic processes, C 3 and C 4 plants exhibit distinct isotopic fractioning, with C 3 plants showing more negative δ 13 C values than C 4 plants. This difference allows us to use a simple mixing model to estimate the intake of different proportions of C 4 and C 3 plants under grazing conditions. In a recently published study, samples of pigeon pea (C 3), Urochloa spp. (C 4), and steers feces were collected in an intercropped system, during the dry and rainy seasons of the year, and isotopically analyzed. The results showed low intake of pigeon pea during the rainy period, but during the dry period the proportion of the legume in the diet reached about 40%. This allowed us to present the nutritional characteristics of the diet, considering the proportion of pigeon pea in the diet during the experimental period.