Seasonal nutritive value of native grasses of Argentine Calden Forest Range

This study assessed the nutritive value of the most important forage species of the Calden forest (central semi-arid La Pampa, Argentina), for samples collected in fall, winter and spring, under grazing conditions and during two successive years, for ranges of good and fair conditions. The crude protein concentration (CP) of short-winter grasses (Piptochaetium napostaense, Poa ligularis, Stipa clarazii and Hordeum stenostachys) was about 10%. Mid-winter grasses (S. tenuissima and S. gynerioides) never reached 6% CP. Summer grasses (Digitaria californica and Trichloris crinita) ranged from 7% to 9% CP. In vitro dry matter digestibility (IVDMD) was similar among short-winter and summer grasses (40–50%). Mid-winter grasses had the lowest IVDMD for all seasons (<40%). Effects of sampling year and range condition on CP were consistently significant only for short-winter grasses. Good condition ranges provide a more acceptable forage supply than fair condition ranges.