Stocking rate with sheep on the range of the Mediterranean subhumid zone of Chile. IV. Intake and seleetivity

Alfredo Torres B.1, Julia Avendaño R.2, Carlos Ovalle M.3 y Osvaldo Paladines M.4

The trial was carried out on a natural pasture ("espinal") from the dryland zone of the Mediterranean subhumid area (October, 1982 to August. 1983), at the Cauquenes Subexperimental Station (INIA). The objective of the trial was to quantify pasture intake and its selection by sheep, and to establ ish relations between seasons of the year and three stocking rates (1.5, 2.5, and 3.5 sheep/ha). Arandomized design, with a factorial arrangement of twelve treatments, with three and four repl ications for selectivity and intake, respectively, was used. During all seasons, forage availability was low and was inversely related to stocking rate; the maximum was in spring (694 kg D.M.lha with 1.5 sheep/ha) and the minimum was in winter (87 kg D.M./ha with 3.5 sheep/ha). Aira caryophyllea and Leontodon nudicaulis showed the larger production in D.M., but were refused by the sheeps, specially under the lower stocking rates. Legumes and other minor species were prefered, and grasses were next in preference. Also, Acacia caven and Shinus polygamus leaves and fruits were found in the extruded intake, improving the diet during summer and autumn. Digestibil ity and protein levels of the extruded inta ke were 6% and 100% above the pasture corresponding indexes. Digestible protein intake was above sheep requirements during spring and winter. Metabolic energy intake did not cover animal maintaining requeriments during winter; in summer and autumn, it covered the lowest range limit that literature establishes, being satisfactory only during spring.

1 Estación Experimental Remehue (INlA), Casi Ila 24-0. Osorno, Chile.
2 Subestación Experimental Cauquenes (IN/A), Casilla 165, Cauquenes, Maule, Chile.
3 Estación Experimental Quilamapu (INIA), Casilla 426, ChiIlán, Chile.
4 Facultad de Agronomía, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.