Resumen

DUMONT L, Juan Carlos; ANRIQUE G, René  y  ALOMAR C, Daniel. Effect of Two Systems of Dry Matter Determination on the Chemical Composition and Quality of Direct Cut Oat Silage at Different Phenological Stages. Agric. Téc. [online]. 2005, vol.65, n.4, pp.388-396. ISSN 0365-2807.  http://dx.doi.org/10.4067/S0365-28072005000400005.

At the Remehue Regional Research Center, National Agricultural Research Institute (INIA), Osorno, Chile, a study was carried out to evaluate the effects of two methods of dry matter (DM) determination on the chemical composition of direct-cut oat (Avena sativa L.) cv. Llaofén silages. The oats were harvested at the stages of stem elongation (Early), ear emergence (Medium) and milky-doughy stage (Late). Silage samples were submitted to ventilation oven drying and to toluene distillation. From early to late stages, toluene DM yield increased from 4.7 to 9.7 t ha^-1 and toluene DM, acid detergent fiber (ADF), and crude fiber (CF) increased from 15.4 to 27.4%; 29.8 to 36.7% and from 25.2 to 28.2%, respectively; the contents of crude protein (CP), ether extract (EE), ash (CT), metabolizable energy (ME) and gross energy (GE) decreased from 13.7 to 6.6%, 3.9 to 2.6%, 2.69 to 2.01 Mcal kg^-1 and 4.91 to 4.59 Mcal kg^-1, respectively. Toluene DM content was 3.4 percent greater than that obtained in the oven, therefore toluene based composition was diluted between 12 and 20% depending on growth stage and specific component analyzed. A positive interaction was found between method of DM determination and protein content, showing that at early stages, the effects of oven drying on N losses were more pronounced. It was concluded that for direct cut oat silages, without use of additives, the DM determined in the oven should be increased by the factor 3.4 to compensate for the loss of volatile compounds.

Palabras clave : oats; silage; dry matter; toluene.