Contenido de nutrientes de especies leñosas en la estepa patagónica, Argentina.

Woody plants constitute a vital food reserve for the herbivores inhabiting the Patagonian steppe. In a preliminary study, some of these plants showed a high content of ether extract (FAT). To determine whether the low availability of nitrogen in soils leads to low forage quality and whether a high FAT content correlates with a high amount of nutritive lipids, namely fatty acids (FA), chemical parameters of forage quality of aerial parts of thirteen woody plants from this steppe were analyzed. Plants showed moderate or low crude protein (CP) content, and, independently of the FAT content, all samples had approximately the same total content of FA (TFA), with an average of 1% of dry matter. The highest CP content was found in aerial parts of Atriplex lampa (13%), Atriplex sagittifolia (10%), Adesmia salamancensis (10%) and seeds of Retanilla patagonica (22%). This parameter and the values of digestibility (DMD) defined these four species as those with best forage quality. Except for A. lampa and Berberis microphylla, which have been previously studied in other regions of Argentina, this is the first report on the nutritional quality of woody species from the Patagonian steppe.