Título: Prediction test for wool yellowing susceptibility in corriedale
Autores: Neimaur, k.; Sienra, I. y Kremer,R.
Publicación: World Congress Animal Production, Porto Alegre, Brasil. October 26-31. CD. 2003.


Wool scoured colour is one of the features that must be improved in Uruguayan wool. It is associated with the presence of fleeces with yellow discoloration of different intensity and extension, which increases in rainy years and determining a difficult in the detection of susceptible animals. In the current investigation, the effects of incubation on wool colour are studied in Corriedale. The aim of this study is to develop a predisposition test to yellow discoloration in order to detect susceptibility. Two experiments were carried out using wool samples collected from Corriedale animals. In the first one 19 wool samples from different aged group were incubated by duplicate and in the second one 63 hoggets were used. In both cases pre incubation and post incubation clean colour measure was made using the Hunterlab Colorimeter. Wool was incubated at 40ºC for 6 days to provide an environment conducive to wool yellowing. The results obtained showed a correlation of 0.88 (P<0.01) between duplicated samples and significant differences between yellowness (Y-Z) values pre and post incubation (7.95 and 11.48). Significant differences between Y-Z values pre and post incubation and brightness (Y) pre and post incubation in the 63 hogget samples immediately processed after shorn were found (-0.53 and 4.72; 65.3 and 61.8 respectively; P<0.01).The correlation between pre and post incubation values was of 0.56 and 0.50 (P<0.01) in each year that indicates a different yellowing susceptibility of sheep.

This test has high values of repeatability and it can reproduce environmental conditions that produce wool yellowing.

Título: Incidence of skin spots and pigmentation in corriedale sheep
Autores: Kremer, R.; Urioste, J-I.; Naya, H.; Rosés, L.; Rista, L. y López, C.
Publicación: World Congress Animal Production, Porto Alegre, Brasil. October 26-31. CD. 2003.


The occurrence of black/brown fibers in wool from Corriedale sheep is recognized as a fault which reduces its value (15 - 18 %) when the number exceeds 300 fibers/kg tops. In Uruguayan wool it is of 5000 fibers/kg top, most of them from environmental origin (faeces and urine dyeing). With appropriated clip preparation, it diminishes to 800-1000 fibers, remaining those from a genetic source. Skin spots with black/brown fibers and isolated pigmented fibers are the probable origin of these fibers.

The objective of this study was to quantify the incidence of skin spots in wool bearing area of Corriedale sheep, as well as pigmentation score of the mouth and spotting in the face as a way to identify correlated characters. On two Corriedale flocks (n = 764), at shearing, a close inspection was performed to identify spot presence, number, area (mm2 determined with a caliper), location (dorsal vs. side) and score (1 to 5 - according to estimated percentage of black/brown fibers in the spot). Simultaneously, a pigmentation score (1 to 5) of mouth was assigned and spotting (number and area) of face was determined.

On average, 70.8 % of the sheep presented skin spots, in these animals the median of the number of spots/sheep was 4, with a total area of 179 mm2. Of all spots detected (n = 3500), 73.5 % had a score of 1 (up to 20 % of black/brown fibers). Pigmentation in the mouth and percentage of spotting in the face was higher (P<0.01) in spotted sheep.