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A Note on the Estimation of the Dry Matter Concentration of Ruminal Particulate Digesta
P. Shiels, A. P. Moloney, P. O'Kiely and M. G. Porter
Irish Journal of Agricultural and Food Research
Vol. 38, No. 2 (1999), pp. 251-254
Published by: TEAGASC-Agriculture and Food Development Authority
Stable URL: http://www.jstor.org/stable/25562363
Page Count: 4
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Toluene distillation with correction for volatiles in the distillate is still considered the most appropriate method for measuring the dry matter (DM) concentration of fermented materials. However, as fermented materials are frequently oven dried, this study was carried out to examine the effect of oven drying on the DM concentration of ruminal particulate digesta and to construct a relationship to allow correction of oven DM concentrations for volatiles lost by drying. Samples (n = 18) of ruminal particulate digesta, collected from steers on a grass-silage diet were divided into four sub-samples. Sub-samples were dried at 60 °C or 98 °C, DM concentration was recorded and volatile components were extracted into distilled water. The concentrations of volatiles were measured in the fluid phase of a third sub-sample. The DM concentration of a fourth sub-sample was measured by corrected toluene distillation. The sample set had a mean toluene DM concentration of 127 (s.d. 11.3) g/kg. The following correction equation was obtained for the result (DM60) from drying at 60 °C: DM (60 °C-corrected) = DM60 (g/kg) + (0.918ammonia (g/kg DM60) + 0.533lactic acid (g/kg DM60) + 0.86volatile fatty acids (g/kg DM60))DM60 (g/kg) ÷ 1000. Digesta DM concentrations measured by toluene distillation, oven drying at 60 °C and oven drying at 60 °C with correction were 127, 119 and 126 (s.e.d. 1.8) g/kg, respectively. It is concluded that oven drying at 60 °C with correction for loss of volatiles gives an accurate estimate of DM concentration of ruminal particulate digesta.
Irish Journal of Agricultural and Food Research © 1999 TEAGASC-Agriculture and Food Development Authority