Stocking rate with sheep on the range of the Mediterranean subhumid zone. III. Animal behaviour

Carlos Ovalle M.2, Julia Avendaño R.2, Hernán Acuña P.1 y Patricio Soto O.1

A Mediterranean subhumid range (called "espinal") was evaluated with seven set stocking rates (1.0; 1.5; 2.0; 2.5; 3.0; 3.5; and 4.0 ewes/ha/year), during eight years. Each treatment had ten Suffolk Down ewes, grazing continuously all year round. Variables measured were: ewes' liveweight changes during the year, their fertility and prolificity; lambs' birth and weaning weights; lambs' mortality; and meat and wool productions. Ewes' prol ificity decreased from 146 to 105%, between the extreme stocking rates, and was closely related to the nutritional plane, expressed by liveweight at mating, and forage availability thirty days before the beginn ing of mating. Stocking rate also affected fertil ity: it was 94 and 83%, with 1.0 and 4.0 ewes/ha/year, respectively. The effect of stocking rate on the above reproductive indexes, determined lambing percentages of 134 and 86, for the extreme treatments, respectively. Also, liveweights and percentages of lambs weaned were inversely related to stocking rateo Liveweigbt production/ha/year was highest (74 kg) with 2 ewes/ha/year, during the last six years. At higher stocking rates, this production decreased.

1 Estación Experimental Quilamapu (INlA), Casi lIa 426, ChiIlán, Chile.
2 Subestación Experimental Cauquenes (INIA), Casilla 165, Cauquenes, Maule, Chile.