The Possibility of near Infrared Spectroscopy for Evaluation of Microbial Nitrogen Content of in Sacco Feed Residues and Duodenal Digesta of Sheep

Abstract

This study aimed to estimate by near infrared (NIR) spectroscopy the microbial nitrogen content (MN) of feed residues from in sacco degradability trails and duodenal digesta of sheep. NIR spectra from 50 samples of duodenal digesta, and from in sacco residues-110 samples of alfalfa hay and 38 samples of maize silage were obtained using an NIRSystems 4250 spectrophotometer. The microbial nitrogen (MN) content of part of the alfalfa hay in sacco residues (78 samples) was calculated from the percentage of 15 N enrichment compared to enrichment in the original samples; for the rest of the alfalfa samples and samples of maize silage residues were determined by diaminopimelic acid (DAPA) as a bacterial marker, and MN of duodenal digesta samples by the purine N (RNA equivalent) content as a microbial marker. The calibration equations were developed by modified least squares as the calibration method. The microbial content of all kinds of samples was accurately calibrated and crossvalidated. A standard error of cross validation (SECV) of 0.418 g microbial N kg -1 DM, a coefficient of determination for the cross validation of 0.925 and a ratio of standard deviation of population and the SECV of 3.88 were obtained for the alfalfa 15 N labelled hay residues. For maize silage residues, the corresponding values were 0.832, 0.938 and 3.90, and for duodenal digesta samples the values were 1.05, 0.962 and 5.19, respectively. Prediction of MN as percentage of total N of the samples gave approximately the same level of accuracy. For example, the SECV was 2.35% units, cross-validation R 2 was 0.953, SD/SECV was 4.60 for alfalfa 15 N labelled hay residues. Despite the different origin of the analysed samples (feed residues and duodenal digesta), the NIR spectroscopy determination of MN content of all samples was based on spectral data at very similar wavelengths. The study indicated that NIR spectroscopy has the potential to predict microbial nitrogen content and to distinguish MN from total N content of in sacco feed residues and duodenal digesta.

Multivariate calibration of near infrared spectra for predicting nutrient concentrations of solid moose rumen contents

“…Particularly, the 2148-2200 nm band has been demonstrated as useful to predict protein in forage (Andrés et al 2005) and agricultural products (Shenk et al 2001). Similar to our results, Atanassova et al (1998) found absorption bands in 1720-1891 nm, 1930-2090 nm and 2090-2500 nm wavelength regions useful to predict microbial-N content of in sacco feed residues and duodenal digesta of sheep.…”

“…For free-browsing ungulates, like moose, it is legitimate to expect heterogeneity in chemical fractions of lignin in the diet due to spatio-temporal variation in the type, availability and maturity of the feed. Anyway, the model parameters for the prediction of microbial-N and lignin concentrations in our study are comparable or even better than those observed for duodenal digesta (microbial-N: R 2 = 0.88, SEcv = 3.80; Atanassova et al 1998) and other herbage (Lignin: R 2 adj = 0.66, SEP = 7.18 g kg −1 DM; Andrés et al 2005).…”

On-Line Monitoring of Rumen Fluid in Milking Cows by Fibre Optics in Transmittance Mode Using the Longer NIR Region

“…5 NIR has already been shown to be able to monitor biological processes and has been used for the better understanding of the kinetics, the rate and extent of degradability of different forages in rumen. 6,7 Therefore, in this paper we report on and evaluate the applicability of a specially-designed and developed fibre optic for the on-line NIR measurement of rumen fluid in milking cows.…”

Novel frontier in wildlife monitoring: identification of small rodent species from faecal pellets using Near-Infrared Reflectance Spectroscopy (NIRS)

“…In contrast, differences in microbial flora could translate to some exposure-resistant differences in rodent fNIR-spectra. For instance, diaminopimelic acid (DAPA), a marker of gut microbe derived N in feces (Karr-Lilienthal et al, 2004) has good NIRS calibrations (Atanassova, Todorov, Djouvinov, Tsenkova, & Toyoda, 1998), and has been found to retain stable concentrations in exposed deer feces (Kamler et al, 2003). In summary, rodent species identification is likely to rest on a multitude of fecal constituents, many of which link with phylogenetic distance (Ley et al, 2008; Zierer et al, 2018), and have varying resistance to exposure and decay.…”