Prediction of nutritive value of hay from differential scanning calorimetry measurements on forage and feces

Abstract

Prediction of nutritive value of hay from differential scanning calorimetry measurements on forage and feces. Can. J. Anim. Sci. 78: 449-451. Differential scanning calorimetry measurements were conducted with six alfalfa and nine grass hays and corresponding cattle feces. Feces and hays gave different responses. Relatively low correlation coefficients between hay minus fecal response curves and cattle intake and organic matter digestibility measurements indicated that such differences were of little practical value in predicting forage nutritive value. Mots clés:Calorimétrie différentielle à balayage, fourrage, bovin, fèces, digestibilité, prise alimentaire Differential scanning calorimetry is a technique that records the amount of energy that must either be supplied to or withdrawn from a sample in order to maintain a zero temperature differential between the sample and a thermally inert reference material whilst the sample and reference are heated according to a pre-determined temperature program (Daniels 1973). Applications of DSC are diverse. Researchers in food science have used the technique to study the physical transitions that take place in starch and protein during heating (Biliaderis 1983). Lipska-Quinn et al. (1985) examined the lignocellulosic components of rice straw with the technique. Kunihisa and Ogawa (1988) used DSC in their investigations of cellulose crystallization reactions. The DSC technique has been used to examine the biological degradation of wood (Campanella et al. 1991), leaf and needle litter (Reh et al. 1990), and mushroom compost and wheat straw (Sharma 1990). Most of these studies attributed the measured differences between virgin and partially degraded materials to semi-quantitative changes in the cellulose, hemicellulose and lignin components caused by fungal organisms. Chemical and physical constituents of peat have been estimated with DSC coupled with TGA with similar accuracy as achieved with near infrared reflectance spectroscopy (Bergner and Albano 1993). This information suggests that DSC might be useful as a multivariate technique in predicting the nutritive value of forages. However, Walshaw et al. (1998) observed that DSC results were not related to DMI or digestibility of hay by cattle, although protein and NDF content could be predicted with some degree of accuracy (R 2 = 0.61 and 0.72, respectively) by relating heat fluxes at various temperatures to these constituents using stepwise multiple regression techniques.Since DSC has been used to differentiate lignocellulose material which has undergone biological degradation, use of differences between hay and fecal DSC curves might be more accurate for predicting the digestibility of feeds than the relationship of DSC measurements on feeds only, as used in the study of Walshaw et al. (1998). This study was therefore conducted to determine if differences between DSC measurements of feed and corresponding cattle fecal material would provide useful information concerning the bioavailability of lignocellulose material to ca...