ChileanJAR

The study was carried out in the Valdivia Province (Chile) between April and December, 1992. Seventeen smallfarmer sheep flocks of crossbred sheep from the pre-Coastal mountains, intermediate valley and pre-Andes mountains, were used. Nine flocks were treated with a basic health programm and the other eight were used as untreated control flocks. Mean birth weights and mean growth rates according to sex andlitter size as well as some production data of these flocks were determined. The differences between mean birth weights and the mean growth rates of the lambs from treated and untreated flocks were determined by a one-way analysis of variance. The results showed that sheepfouryears old and older, or sheepyoungerthan ayearwere predominant in these flocks. Fertility percentages were 87.5 and 95.9%; fertility 130 and 125%, and mortality of 7.6 and 3.9% for the controls and treatments, respectively. There were no significant differences (P > 0,05) between the mean birth weights ofthe lambs from the treated and control flocks. However significant differences (P < 0,05) were found according to litter size in each group. The mean growth rates of lambs from the treated flocks were significant higher (P < 0,05) than the mean growth rates of lambs from control flocks, except for male lambs born as twins.