Corriedale wool ranging from 25 to 30 microns diameter. Fleece from a mature ewe will weigh with a staple length of . After cleaning, a yield of 50 to 60% of the raw fleece weight is common. Mature rams will weigh ; ewes can weigh from . This breed was developed in Australia and New Zealand by extensive breeding and culling as a cross between Merino and Lincoln sheep The goal was to develop a breed that would thrive in lower rainfall areas and supply long-staple wool. James Little was the original breeder. The name comes from a property in the
Rideau Arcott traits they wanted to be expressed in the breed. The research flock was closed in 1974, and the breed was distributed to shepherds beginning in 1988. The Rideau name is a common one in Ottawa. The latter half of its name is an acronym for the Animal Research Centre in Ottawa. One of only a few livestock breeds developed in Canada, the Rideau is a synthesis of many different breeds. The breed is genetically 40% Finnish Landrace, 20% Suffolk, 14% East Friesian, 9% Shropshire and 8% Dorset Horn; the remaining 9% is Border Leicester, North Country Cheviot, Romnelet and Corriedale.