Chemical Composition of Esophageal-Fistula Forage Samples as Influenced by Drying Method and Salivary Leaching1

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Abstract
Esophageal-fistula forage samples were collected in screen-bottomed bags from cows grazing post oak savannah range, and in both screen-bottomed and watertight bags from Coastal bermudagrass pastures. These esophageal-fistula samples and hand-plucked Coastal bermudagrass samples were dried by freeze-drying, oven-drying (60 C) and air-drying methods. Freeze-dried esophageal samples were significantly higher (P<.05) in total nonstructural carbohydrates (TNC) and hemicellulose, but lower in acid detergent lignin than oven- and air-dried samples. Freeze-dried hand-plucked bermudagrass was higher in TNC than oven- or air-dried samples; however, no significant changes in crude protein and cellulose were detected among methods of drying. Compared with freeze-drying, organic matter (OM) losses from oven- and air-drying ranged from 9 to 13% for esophageal-fistula samples and from 4 to 5% for hand-plucked Coastal bermudagrass. Higher OM losses from fistula samples than hand-plucked samples might be attributed to their higher moisture content, longer drying time, and plant enzymatic activity. Accurate comparisons of the three drying methods were possible only when the data were expressed as grams of constituent remaining per 100 g of original OM. Delaying freezing of esophageal samples for 4 hr did not alter chemical composition of samples. Samples from screen-bottom collection bags, as compared with watertight bags, were higher in crude protein and lignin, but lower in TNC. This may be a result of leaching. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.