Fecal nitrogen concentration as a nutritional quality indicator for European rabbit ecological studies (original) (raw)
Related papers
Facts From Feces: Nitrogen Still Measures Up as a Nutritional Index for Mammalian Herbivores
Journal of Wildlife Management, 2008
Fecal nitrogen (FN) has been applied widely as an index of dietary quality in studies of nutritional ecology of free-ranging and captive vertebrate herbivores, particularly ruminants. Three related articles in the Journal of Wildlife Management (JWM; Starkey 1985, 1987; have been cited (n ¼ 150) in 87 publications and 39 peer-reviewed journals. The critique by and the reply by Leslie and Starkey (1987) on limitations and appropriate applications of FN have been used to justify use of FN or negate its value as a nutritional proxy. We undertook a retrospective analysis of FN applications since 1985, largely because we sensed that methodological cautions noted in the 3 JWM publications were not being followed, leading to faulty conclusions and management applications, and that application protocols needed updating. From January 1986 through July 2007, the 107 species-by-continent applications of FN, citing the 3 JWM publications singly or in any combination, were diverse; FN was used in various ways on 5 continents and for 50 wild and domestic species. Cumulative rates of departure from recommended FN applications increased in recent years, largely in studies that compare different species while failing to fully acknowledge that differences likely reflected digestive capabilities rather than differences in some aspect of dietary intake. Post-1985 research on plant secondary compounds (e.g., tannins) has refined limitations to the application of FN, permitting more straightforward protocols than were possible in 1985. Although use does not necessarily reflect value, the number of published applications during the past 22 years indicates that peer reviewers from a variety of scientific disciplines view FN as a suitable proxy for nutritional status, which can be used to contrast study units when carefully defined by the study design. Any index can have shortcomings, and there are still circumstances when application of FN is problematic. Precise prediction of intake with FN under field conditions is still hampered by inherent variability, but contrasts of comparable study units and species can be appropriate. Published protocols for FN, as amended herein, should be adhered to, and conclusions are strengthened by the use of multiple nutritional indices.
Animals
European wild rabbit (Oryctolagus cuniculus) populations have drastically reduced, and recently, rabbits have been classed as “endangered” by the IUCN. This animal plays an important ecological role in Mediterranean ecosystems and its introduction could significantly contribute to ecological restoration. Rabbits have high nutrient requirements that apparently cannot be covered in all ecosystems, and there are clues that nutrition can limit their abundance and density. On the other hand, some studies reflect the effects of food availability on the metabolomic status of other animal species, but there are no specific studies on this keystone species. The main aim of this work is to find biomarkers to assess the previous levels of ingestion of European rabbits (Oryctolagus cuniculus). To address this gap, gastric content and blood samples were collected from European rabbits (n = 99) in a Mediterranean area for the analysis of glucose, non-esterified fatty acids (NEFA), plasmatic urea ...
Measurement of dietary nutrient intake in free-ranging mammalian herbivores
Nutrition Research Reviews, 2000
The nutrient intakes of mammalian herbivores depend on the amount and the nutrient content of the plant species and plant parts which they eat. We review the merits of oesophageal-fistulated (OF) animals, microhistological procedures, stable C-isotope discrimination and plant cuticular-wax markers as methods for estimating diet composition and intake in both ruminant and non-ruminant herbivores. We also briefly discuss methods based on grazing behaviour measurements or on H2O or Na turnover, and methods for estimating supplement or soil intake. Estimates of intake in ruminants are often based on separate measurements of faecal output and herbage digestibility. We review this approach and emphasize that, under some circumstances, the applicability ofin vitrodigestibility estimates based on OF extrusa is questionable. We discuss how plant-wax marker patterns can be used to check whether OF and test animals are consuming similar diets, but also emphasize that a major advantage of the u...
Animal Production Science, 2014
Integrating the interaction between cell wall components through a lignin and neutral detergent fibre ratio as a cell wall digestibility (CWD) index may provide a suitable method for diet quality and fibre digestibility estimation. Predictive faecal-Fourier-transform (FT)-near infrared reflectance spectroscopy (NIRS) equations useful for CWD determination were developed as an integrative assessment of the digestibility and quality of the diet selected by red (Cervus elaphus hispanicus) and fallow (Dama dama) deer in southern Spain. A chemometric regression was used from spectra of faeces and wet chemical rumen contents analysis as reference data coupled with partial least-squares. The accuracy and feasibility of the equations obtained for red and fallow deer samples separately were evaluated, as well as after pooling all samples for both species. The predictive equations had a high linearity with correlation coefficients (r) ranging between 0.89 and 0.99, as well as a reliable accuracy considering the errors of prediction (RMSEP 0.57-0.87), calibration (RMS 0.04-0.45) and cross-calibration (RMSECV 0.80-1.12) in relation to the range of values for which the NIRS calibration was set for each parameter, giving very good RER (residual error value) indices (7.44-13.23). The ability of the calibration equations to predict new samples from the same deer populations was also assessed through an external validation. Equations obtained for the red deer data were successfully applied not only to red deer but also to fallow deer, and vice versa. Feasible CWD simultaneous determination in red and fallow deer was also obtained by using the broad-based equations. There was variation of the CWD index throughout the year and differences between the two deer species. A lower CWD of the forage was recorded in red deer, while a lower CWD ratio was detected at the end of winter coinciding with the highest browsing levels in both species. This technique has potential to enable closer examination of the non-grass variables and distinguish between browse and herbage feeding behaviour. The faecal-NIRS method of CWD ratio determination is a useful, non-invasive tool for monitoring variations in the diet quality of Mediterranean deer in their natural environment.
Determining the quality of diets of grazing animals
2010
Predicting growth rates or determining the needs for supplementary feeding of grazing animals requires knowledge of the nutritive value of the diet the animals are consuming. Faecal analyses are non-invasive and effective methods for compiling information about the diets of animals. In this study the usefulness of faecal chemistry and near infrared spectroscopy (fNIRS), either used individually or in combination to predict the quality of mixed diets fed to sheep, was investigated. Faecal nitrogen, ash, neutral detergent fibre and lignin contents can be successfully used to predict the metabolisable energy content and the organic matter digestibility of the diet as well as the type of rumen fermentation (in terms of short chain fatty acids) whilst fNIRS calibration equations can be successfully used to predict the crude protein, total phenolic and total tannins contents of mixed diets consumed by sheep. 2003) and metabolisable energy (ME) content (Kamler & Homolka, 2005) of typical (...
Italian Journal of Animal Science, 2010
The aim of this work was to examine whether faecal profiling using NIRS could be profitable for promote the Best Available Techniques (BAT) in the rational feeding of rabbits. A set of 51 feed samples, taken from 12 experimental diets, and of 66 dried grouped faeces samples, belonging to four nutrition experiments, with 130 ad libitum registered feed intakes (CV=25%), were submitted to a UV-Vis-NIRS scan (350-2500 nm) in order to calibrate the chemical composition and nutritional parameters, the ingestion aptitude and digestibility. A chemometric system has made it possible to contemporary use the spectrum of the input diet concatenated together with the spectra of the related output pool of the dried faeces. The daily measured feed intake, in absolute or in relative terms as ingestion per unit of metabolic weight, obtained a good resolution for the spectra of the feeds (R 2 cv =0.80 and 0.75, respectively), for the faeces (0.81 and 0.80) and for the joint evaluation of the concatenated spectra (0.87 and 0.81). The intake was positively correlated to the mineral, insoluble ash, protein, gross energy, crude fiber and acid detergent fiber (ADF) content in the feeds, and negatively correlated to the N-free extract, lignocellulose and all the digestibility coefficients, except crude fiber. Very significant improvements, on average equal to 0.20 R 2 points, were also provided to the digestibility coefficients when using the concatenated method; in decreasing order: neutral detergent fiber (R 2 cv =0.00, 0.18 and 0.50 for the feeds, faeces and concatenated, respectively), ADF (0.00, 0.45 and 0.62), ether extract (0.53, 0.52 and 0.86), crude protein (0.53; 0.53 and 0.75), and gross energy (0.61; 0.74 and 0.83). The results corroborate previous knowledge and show the possibility of using NIRS faecal profiling in rabbit nutrition, which together with the NIRS of the feeds, could contribute to nitrogen monitoring.
PloS one, 2017
Optimal management of free-ranging herbivores requires the accurate assessment of an animal's nutritional status. For this purpose 'near-infrared reflectance spectroscopy' (NIRS) is very useful, especially when nutritional assessment is done through faecal indicators such as faecal nitrogen (FN). In order to perform an NIRS calibration, the default protocol recommends starting by generating an initial equation based on at least 50-75 samples from the given species. Although this protocol optimises prediction accuracy, it limits the use of NIRS with rare or endangered species where sample sizes are often small. To overcome this limitation we tested a single NIRS equation (i.e., multispecies calibration) to predict FN in herbivores. Firstly, we used five herbivore species with highly contrasting digestive physiologies to build monospecies and multispecies calibrations, namely horse, sheep, Pyrenean chamois, red deer and European rabbit. Secondly, the equation accuracy was ...