RESUMEN

The objective of the present study was to examine if near infrared reflectance spectroscopy (NIRS) could be used to predict degradation parameters and effective degradation from scans of original forage samples. Degradability of dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of 61 samples of perennial ryegrass (Lolium perenne L.) and orchardgrass (Dactylis glomerata L.) was tested by using the in situ technique. The grass samples were harvested at three different stages, early vegetative growth, early reproductive growth and late reproductive growth. Degradability was described in terms of immediately rumen soluble fraction (a fraction, for DM and CP only as NDF does not contain a soluble fraction), the degradable but not soluble faction (b fraction) and the rate of degradation of the b fraction (c value). Overall effective degradability of DM, CP and NDF was also calculated. Near infrared reflectance spectroscopy was examined for its ability to predict degradation parameters and to make a direct prediction of effective degradation from scans of the original samples of perennial ryegrass and orchardgrass. Prediction of effective degradation of the different feed fractions showed different accuracy. The coefficients of determination (R(2)) from regressions of predicted vs. measured effective degradation, using a cross-validation method, were 0.92 for DM, 0.78 for CP and 0.61 for NDF. The attempt to predict the degradation parameters (a, b and c) by NIRS was less successful as the coefficients of determination for the degradation parameters were low. Concentrations of CP and NDF in the original samples were predicted by using NIRS and the validated R(2) value was 0.98 for CP and 0.92 for NDF. It is concluded that using NIRS predictions from scans of original samples is a promising method to obtain values for the effective degradation of DM, CP and NDF in ruminant feeds, but that larger calibration sets are necessary for obtaining improved accuracy.

Asunto(s)

Fibras de la Dieta/análisis , Proteínas en la Dieta/análisis , Digestión , Rumen/metabolismo , Espectroscopía Infrarroja Corta/veterinaria , Alimentación Animal/análisis , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Bovinos , Dactylis/química , Detergentes , Fibras de la Dieta/metabolismo , Proteínas en la Dieta/metabolismo , Lolium/química , Valor Nutritivo , Valor Predictivo de las Pruebas , Espectroscopía Infrarroja Corta/métodos

RESUMEN

A potentiometric electronic tongue (ET) consisting of eight cross-sensitive chemical sensors and a standard pH electrode has been applied for analysis of simulated fermentation solutions typical for fermentation processes with Aspergillus niger. The electronic tongue has been found capable of simultaneous determination of ammonium, citrate and oxalate in complex media with good precision (typical error within 8%). The system preserved high sensitivity to the targeted substances also in the presence of sodium azide, which is commonly used for suppressing microbial activity in real-world fermentation samples. Sensor performance was fast and reproducible which promises well for routine application of the electronic tongue for fermentation process monitoring.

RESUMEN

The pH changes occurring in a carcass during the first 24 h after slaughter are important for the quality of the final meat or meat products. Protein denaturation will occur if pH falls to too low a level or if a relatively low pH sets in at a time after slaughter where the carcass temperature is still high. This will result in meat with poor water holding capacity and in extreme cases in meat that is PSE. pH is measured electrochemically using either glass or solid state (IS-FET) electrodes. However, electrochemically based methods are slow to use and do not offer good precision on unhomogenized meat. In this work it has been investigated whether pH can be measured spectroscopically in reflectance using the visual and near infrared spectral regions. On a limited number of pig meat samples (46 longissimus dorsi and 46 semimembranosus muscles) correlations of 0.85 have been achieved using the fast spectroscopic techniques opposed to glass electrode measurements done in duplicate. The prediction errors for the spectroscopic techniques are found to be comparable to the precision of the reference method.