Thermogravimetric evaluation of perennial ryegrass (Lolium perenne) for the prediction of in vitro dry matter digestibility

Abstract

Thermogravimetry (TG) can be used for assessing the compositional differences in grasses that relate to dry matter digestibility (DMD) determined by pepsincellulase assay. This investigation developed regression models for predicting DMD of herbage grass during one growing season using TG results. The calibration samples were obtained from a field trial of eight cultivars and two breeding lines. The harvested materials from five cuts were analysed by TG to identify differences in the combustion patterns within the range of 30-600°C. The discrete results including weight loss, peak height, area, temperature, widths and residue of three decomposition peaks were regressed against the measured DMD values of the calibration samples. Similarly, continuous weight loss results of the same samples were also utilised to generate DMD models. The r 2 for validation of the discrete and the best continuous models were 0.90 and 0.95, respectively, and the two calibrations were validated using independent samples from 24 plots from a trial carried out in 2004. The standard error for prediction of the 24 samples by the discrete model (4.14%) was higher than that by the continuous model (2.98%). This study has shown that DMD of grass could be predicted from the TG results. The benefit of thermal analysis is the ability to detect and show changes in composition of cell wall fractions of grasses during different cuts in a year.

Thermal decomposition, chemical composition, in vitro digestibility and gas production and in situ degradability of oilseed residues from the biofuel industry

“…The use of fiber-rich products, such as agroindustrial by-products, can reduce the cost of feeding animals (Zambom et al 2001). Additionally, Marvin et al (1996) and Sharma et al (2008) reported that thermal analysis gave physical properties associated with quality of ruminant feed. The in vivo evaluation of the nutritive value of feeds through the measurement of feed intake, total tract apparent digestibility and productive performance requires more time and cost as compared with laboratory level experiments.…”

“…Reliable estimates of feed quality may be obtained by simple, low-cost laboratory techniques such as in vitro, in situ and chemical methods (Tilley & Terry 1963;Orskov & McDonald 1979). Additionally, Marvin et al (1996) and Sharma et al (2008) reported that thermal analysis gave physical properties associated with quality of ruminant feed. This technique is based on the variation of mass over time or temperature in thermogravimetric analysis (TG) and measurement of heat flow within samples at a set temperature in differential scanning calorimetry analysis (DSC) (Santos et al 2011).…”

“…() and Sharma et al . () reported that thermal analysis gave physical properties associated with quality of ruminant feed. This technique is based on the variation of mass over time or temperature in thermogravimetric analysis (TG) and measurement of heat flow within samples at a set temperature in differential scanning calorimetry analysis (DSC) (Santos et al .…”