Effects of Moisture Determination Method on Estimates of Digestibilities and Intakes of Conserved Alfalfa

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Abstract
Digestibilities, N balances, and voluntary intakes of 6 silage-hay diets fed to sheep were used to contrast different methods of determination of dry matter. All wet samples of feed, feed refusals, and feces from 24 wethers were analyzed in triplicate for dry matter by: forced air drying at 90.degree. C for 24 h; vacuum oven drying at 70.degree. C under pressure of less than 75 mm Hg for 24 h; toluene distillation (uncorrected); toluene distillation (acid corrected); and by a chemical saponification method. There were significant differences in dry matter between methods. Dry matter digestibility of hay was overestimated by 6.8% when forced air drying was used rather than the chemical method while that of a formaldehyde-treated silage was underestimated by 5.5%; the digestible energy intake of the formaldehyde-treated silage was underestimated by 15.1%, and that of the hay overestimated by 6.9%. N balance was 75.9 and 7.4 g/head per day for hay and untreated silage when forced air dry matter and Kjeldahl N on the dried sample were combined while values were 25.6 and -42.1 g/head per day when data by chemical method were used with Kjeldahl N on the wet sample. Differences in estimates of dry matter may explain some of the anomalous dietary comparisons for silage and hay.