ChileanJAR

In the Steppe zone of Aysén, extensive sheep management is practised. Lambs are sold in March, when natural weaning has occurred. Lamb-weaning at shearing is proposed (early January), with about 2.5 months of age, for fattening in softer grass pastures, of the Intermediante zone. Three stocking rates were utilised: 40, 30, and 20 lambs/ha (T1, T2, and T3, respectively). Castrated Corriedale lambs grazed an indigenous pasture in Valle Simpson (45º 43' lat. S; 75º 05' long. W) for 56 days (21.01.85 - 18.03.85). Final liveweights (averages 27.4 to 28.5 kg) did not differ significantly (P > 0.05) between groups. Daily gains had initial maximums of 191, 174 and 193 g/day, minimums of -25, -29, and 4 g/day and averages of 66, 69, and 85 g/day, for T1, T2, and T3 respectively. Meat production during the experimental period was 149 (T1), 117.1(T2), and 95.5(T3) kg/ha. Body condition at the end of the experiment was 2.42 (T1 and T2) and 3.02 (T3) grades, significantly higher (P < 0.05) for the lower stocking rate group (T3). Parasite level detected was low. Forage availability and specially its nutritive value were limiting for lamb growth. Stocking rates used were probably too high for non improved indigenous pastures of the zone.