Criolla is the name of the "local" breed of sheep in Uruguay. Sheep are predominantly a commercial enterprise, with the focus on white wool (Polwarth and Corriedale) for the wool market. Sheep with colored fleece—grey, tan, chocolate, or the predominant dark brown—have been considered undesirable and the wool of lesser value. Many of these sheep are Criolla. Criolla are thought to descend from the Navajo-Churro sheep the Spanish brought over to central and South America hundreds of years ago. Modern genetics are probably predominantly Corriedale and Polwarth, and Criolla sheep have a wide variety of fleece characteristics: staple length, softness, color, dual coat versus blocky crimpy soft locks. The wool can be highly variable between sheep, but La Piccolina's flock typically has a blocky staple with well-defined crimp, very soft hand, and fine fiber diameter, with a broad color range and some sheep with more robust, dual-coated fleece as well.
The sheep themselves are of small stature, measuring between 60 and 70 cm at the withers. La Piccolina's Criolla flock is of very sweet and docile disposition, excellent mothers, and have a very hardy constitution. The sheep graze year-round on the farm's lush, green pastures; they are never fed hay or grain, and the wool has very little vegetable matter. Year-round sun exposure has left the locks with a wonderful dusting of color at the tip; when spun, it creates a heathered appearance to the finished yarn.