Semiarid Grassland and Winter Cereals for Lamb Production in Northeast Patagonia, Argentina

In northeastern Patagonia where grain crops often led to harvest failure, low yields and a high drought risk, a lamb production system was established. On a 10 years old agriculture wheat cropping was interrupted in 1996, allowing re-vegetation through exclusion of grazing. Natural grassland recovered, prevailing the species Stipa tenuis, Piptochaetium napostaense, Stipa ambigua. Part of the plot was sown to wheat grass (Thinopyrum ponticum). In 1999, to improve sheep feeding, oat (Avena sativa) and barley (Hordeum vulgare) were sown for grazing during winter-spring season. In this system Corriedale sheep, Texel x australian Merino (TEMA) and Ile de France x Australian Merino (ILMA) crosses were tested. Fertility, prolificacy, lamb mortality and weaning were evaluated. No differences among genotypes (α= 0.05) were found. Weaned lamb weight per ewe was significantly higher in cross ewes (p\u3c 0.0035), while production efficiency showed no significant differences among genotypes (α= 0.05), because of the higher body live weight of the crosses (p\u3c 0.0001). Yields of 16.4; 19.4 and 20.2kg lamb hectare–1 for Corriedale, TEMA and ILMA respectively were calculated, which represent an increase of 18 and 23 %. These differences could become economically significant in the production system under study