The Cormo sheep breed is from a system of breeding in which selection is based on scientific measurement of commercially desirable characteristics.

• The criteria for selection are: 
• Clean fleece weight. 
• Fiber diameter (17-23 micron range). 
• Fast body growth rate, or body weight. 
• High fertility. 

 

Scientific instruments and laboratory procedures are used to measure these characteristics, replacing the traditional subjective visual assessments. The results are stored and analyzed by computer. No pedigrees are kept. Sheep are numbered and computer management makes Cormo the most strictly scientific genetic improvement scheme in the industry’s history. 

In 1960 the owner of Dungrove, Ian Downie, was running a high quality flock of Superfine Saxon Merinos. Commercial considerations led him to two conclusions:

• There was a need for a more fertile, higher wool producing and larger framed sheep.
• A trend would develop towards the purchase of wool according to objective measurement and breeding program should be instigated to meet this demand. 

 

In seeking scientific help he learned of large scale breeding trials conducted at Trangie, New South Wales, Australia, by Dr Helen Newton-Taylor, chief geneticist with the Division of Animal Genetics of the Commonwealth Scientific and Industrial Research Organization, in collaboration with Dr R.B. Dun and Dr F. Morley. 

The Senior Sheep and Wool Officer of Tasmania’s Department of Agriculture Mr B.C. Jefferies, devised a breeding program which was based on the Trangie experiments and designed to meet Mr Downie’s requirements. 

Stud Corriedale rams were crossed with 1200 Superfine Saxon Merino ewes and those progeny which met rigid selection criteria, assessed by objective measurement, became the Cormo ram breeding nucleus. The word Cormo is derived from letters from the names of the two parent breeds. 

Since the initial cross-breeding in 1960, Dungrove has maintained a ram-breeding nucleus flock within its main commercial flock. The nucleus of 2000 ewes produces sires for both the nucleus and the commercial flock of 8000 ewes. No outside rams are introduced and those within the nucleus are culled rigorously for commercial faults. 

Rams born in Tasmania in October (Southern Hemisphere spring) are tip shorn and weaned in January. They graze naturally all year before being shorn again in December, when body weights are measured and wool samples sent to a laboratory for assessment. When results are known, a final selection is made, based on: 

• Clean fleece weight
• Fiber diameter (21-23 microns)
• Type of birth, with twins preferred
• Body weight. 

 

The top 3 per cent of rams, assessed by these criteria, are retained for breeding. Selected rams remain active in the breeding nucleus for only two years, so there is a rapid turnover of genetically improving sires. Recent computer data shows the flock is continuing to improve genetically. 

Ewes, born either into the ram nucleus flock or the commercial flock, are culled for obvious commercial faults. At the hogget shearing, those remaining are assessed for greasy fleece weight and fiber diameter. Animals failing to meet prescribed standards are eliminated. Each year the ewe yearlings from both flocks help to form the ram breeding nucleus. 

Management of the flock at Dungrove complements the scientific culling program. Sheep are not housed, rugged or given supplementary feeding, although they graze from 610 to 1000 meters above sea level at an approximate latitude of 42 South where summers are hot and dry and winters cold and snowy. Annual rainfall averages 21 inches. Genetic defects are exposed and culled naturally in this environment, instead of being concealed by artificial pampering. 

Scientific breeding has given the Cormo a remarkable range of commercial virtues, suited to both the wool and meat industries. These include: 

• Long staple, white high-yield wool
• Soft dense fleece with exceptional consistency (90 percent within two microns of the average)
• Resistance to fleece rot and mycotic dermatitis
• Long and large carcasses with mature ewes weighing 140 – 165 lbs.
• High fertility
• Open faces
• Easy management
• Good herding instinct 
• Producing a finer fleece when crossed with a stronger breed, but retaining body size and fertility.