Productivity and Reproductive Performance of Mixed-Age Ewes across 20 Years of Selection for Ultrafine Wool in Uruguay

This study reports the phenotypic trends for wool, growth, and reproductive traits in mixed-age ewes after twenty years of genetic selection. Data were obtained from Merino nucleus flock Uruguay between 1999 2020. Overall, aim this selection was to reduce fiber diameter (FD) increase both clean fleece weight (CFW) live (LW). on ewe wool traits, LW, body condition score (BCS), total number lambs weaned (TLW), LW (TWW) across all lambing opportunities (1–8 mating seasons) analyzed. Between 1292 2063 measured, depending trait considered. Ewe FD decreased by approximately 3 µm (19–16 µm), whereas greasy (GFW) increased 0.2 kg. improvement accompanied increases at (3 kg), decreases BCS (approximately 1 unit), a small positive change TWW years. demonstrated that increasing farmer income selecting finer heavier fleeces, animals can be without compromising lifetime reproduction.