A Comparison of Volatile Chemicals from Orchardgrass (Dactylis glomerata L.) Varieties with Different Palatabilities

Abstract

The composition of volatile chemicals extracted from fresh material of nine orchardgrass varieties with different palatabilities to heifers, was analyzed by means of a gas chromatograph (GC) and gas chromatograph-mass spectrometry (GC-MS) for five harvests in 1992. There were few differences, with one major exception, between volatile profiles of the nine varieties at each of the harvest times on the GC and GC-MS chromatograms. The four French varieties ; Lude, Lully, Lutetia, and Prairial, contained a specific compound which was not found in the other, non-French varieties. From its mass spectra, which was obtained by GC-MS, it was assumed to be diterpene. The amount of this compound in Lude, more palatable variety, tended to be higher than those of less palatable varieties, Lully, Lutetia, and Prairial. The correlation coefficient between the amount of this compound and their preferences in the four varieties was 0.51 (p<.05), except for the reproductive seasons when the degree of heading is known to be very negative with palatability. This result suggested that this compound might be one of the preference determinants in Lude, which was tend to be a palatable variety throughout the experiment period. However, the presence of the chemical by itself could not account for all the differences in palatability among the orchardgrass varieties.