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Genetic parameters of wool production traits for corriedale sheep in southern Brazil^*

Ricardo A. Cardellino^I; José C.S. Osório^I; José L.V. Guerreiro^I

Departamento de Zootecnia, Universidade Federal de Pelotas, 96100 Pelotas, RS, Brasil. Send correspondence to R.A.C.

ABSTRACT

Production records of 695 two-toothed male and female sheep of the Corriedale breed, reared from 1978 to 1980 under extensive grazing conditions on 6 farms in southern Brazil, were used to estimate heritabilities and genetic correlations for wool production traits: greasy fleece weight (GFW), body weight (BW), fineness class (F), color score (C), handle score (H), character score (CH), staple length (SL), crimps per centimeter (CC), percentage clean yield (Y), clean fleece weight (CFW) and average fiber diameter (D). Genetic parameters were estimated by half-sib analyses, after adjustments for sex and contemporary groups by a linear model. Heritabilities were: 0.42 (GFW), 0.27 (BW), 0.14 (F), 0.13 (C), 0.0 (H), 0.0 (CH), 0.42 (SL), 0.34 (CC), 0.26 (Y), 0.31 (CFW) and 0.72 (D). The genetic correlations involving GFW were: 0.95 (GFW-CFW), 0.71 (GFW-SL), 0.53 (GFW-Y) and 0.67 (GFW-D). An increase in D is expected as a result of selection for CFW and SL since genetic correlations were 0.74 and 0.49 respectively. Subjectively appraised traits (F, C, H and CH) as well as BW; had zero genetic correlation with all other traits. In general, the genetic parameters estimated for the economically important traits agree with average Australian values.

Keywords: genetic; wool; sheep.

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* Part of this research was carried out at the University of Bonn, FRG, where R.A.C. was Visiting Researcher from 1982 to 1984, Alexander von Humboldt Foundation Scholarship.