Guillermo Garcia D.1 y Pedro Joustra P.2

Samples of Early French and German Merino wool from the central zone of the country were studied with the purpose of establishing the amount of variability of the diameter of the fibers and its relationship to resistence. The diameter of fibers was measured in the middle section of the growings conesponding to Summer, Autumn, Winter and Spring. The samples were taken during the years 1961, 1962, 1963 and 1964 and they were obtained at different localities. A notorious seasonal variability is observed on the diameter of fibers, considering the different years and origin of the sheep. The lowest values occur on the Autumn and Winter growings and the largest ones in Summer for the Early French Merino. This variability is due to the seasonal changes of the feed supplied by the natural pastures. The seasonal variability of the diameter, spread between minimum values of 11,54% (23,07 to 20,41 μ) to maximum values of 24,77% (23,62 to 17,77 μ) . The observed variability represents a deerease of the resistence between 20 and 40%. The minimum variability in diameter and resistence is found in the sheep that were supplemented during the critical period at the end of pregnancy ami were on well managed pastures. The Autumn supplementation of the sheep in the central zone would be recommended not only in arder to get better quality wool, which could also be obtained through managing practices but mainly to avoid loses of sheep by methabolic diseases and lambs that are born weak.

1 Ingeniero agrónomo, Servicio Ovinos y Lanas, Departamento de Ganadería, Ministerio de Agricultura.
2 Ingeniero Agrónomo. Proyecto Producción Ovina, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias.