About Canadian Arcott Sheep

Agriculture Canada – Full publication can be seen below

https://publications.gc.ca/collections/collection_2012/agr/A63-1886-1992-eng.pdf

ARCOTT BREEDS
Developmental stage
Original breeds
In 1966 the ewe flock in Ottawa consisted of approximately 160 Shropshire, 190 Suffolk, and 90 OS, a synthetic strain previously developed at Ottawa from Leicester, North Country Cheviot, Romnelet, and Suffolk breeds (each contributed approximately 25%). In the following 3 years 16 Shropshire, 20 Suffolk, and 18 OS rams were used to produce purebred and crossbred offspring.
To increase the flock size and broaden the genetic base, additional ewes were transferred to Ottawa from Agriculture Canada research establishments at Lennoxville and La Pocatiere. In 1968, 59 Suffolk ewes were transferred. In the following year 49 Leicester, 24 Suffolk, 13 North Country Cheviot, 9 Canadian Southdown, 8 New Zealand Southdown cross, 1 Canadian Southdown cross, 4 Corriedale cross, 6 Leicester cross, 219 Dorset cross, 12 North Country Cheviot cross, and 34 Suffolk cross ewes were transferred to establish the foundation flock in Ottawa. In 1973 an additional 16 Dorset and 59 Dorset cross ewes were transferred to increase the ewe flock. An additional three Lincoln rams were purchased from the University of Alberta in 1969 to develop the Canadian Arcott.
Importing exotic breeds
Many exotic breeds were identified as potential sources of germplasm. Only those that met the animal health requirements and that would complement breeds in Canada were imported. In choosing breeds with potential for genetic improvement, researchers emphasized high fertility, year-round breeding, growth rate, carcass quality, milk yield, and production of heavy white fleece. Those chosen for multiplication into the foundation stock were Ile de France, Finnsheep, and East Friesian.
Ile de France, developed in France from a cross between English Leicester and Merino, is characterized by rapid growth rate, heavy­muscled carcass, and a long breeding season. In 1970 and later, Agriculture Canada imported 11 Ile de France rams from Scotland to be incorporated into the Canadian Arcott breed.
Finnsheep were chosen to contribute prolificacy to the two dam breeds, Outaouais Arcott and Rideau Arcott. In November 1966 Agriculture Canada purchased three Finnish Landrace rams imported from Scotland by the University of Manitoba and an additional two yearling rams and eight bred yearling ewes imported from Finland by Finnsheep Ltd.
The East Friesian, a large dairy breed from Germany with a lambing percentage of 200, was chosen to contribute high milk production and prolificacy to Rideau Arcott. In 1970 Agriculture Canada imported five rams of this breed from Scotland.

Mixing the breeds 

Three Suffolk and three Finnish Landrace rams were mated to 240 ewes (approximately 80 each of Suffolk, Shropshire, and OS) in isolated quarantine facilities established at the Centre for Food and Animal Research. At the same time, specific matings required to produce the foundation breeding stock were established by mating rams of East Friesian, Finnish Landrace, Ile de France, and Suffolk to Shropshire, Suffolk, and OS ewes and their crosses. 

In 1972 the flock was closed to any introduction of new germplasm. After the quarantine ended in 197 4, all sheep were housed in a controlled environment. Sheep were separated into two flocks, A and B, to establish an accelerated lambing program. Breeding was practiced for lambing at 4-month intervals (February, June, and October) under an 8-month breeding cycle. Beginning in 1977, after 5 years of closed breeding, the strains were considered to be new breeds. For the next 4 years, researchers carried out minimal selection to maintain a genetic base. 

In 1980 lambs were delivered by hysterectomy-a technique used to produce specific pathogen-free (SPF) swine herds-to establish a disease-free flock. Sheep delivered by hysterectomy were bred to reestablish flocks A and B. Researchers used 50 rams and 400 ewes to develop each Arcott breed. 

Identifying and selecting Arcotts 

Arcotts that were originally known as ARC (Animal Research Centre, now called the Centre for Food and Animal Research) synthetic strains 1, 2, and 3 were later named Canadian, Outaouais, and Rideau, respectively. In the selected strains, ewes were mated at a ratio of 10-12 ewes per ram until 1980. Later the ratio was reduced to eight ewes per ram. Mating groups were designed to avoid matings among half-sibs or closely related animals while breeding each ram to a representative sample of ewes from the strain. Rams were used over two consecutive breedings, and ewes were retained for four lambings, based on their ability to produce lambs at 8-month intervals. Usually, any ewe that failed to lamb was culled. However, ewe lambs exposed to rams at 6.5-7.5 months were given a second chance. There was no selection for wool quality or fleece yield. Lambs with severe physical abnormalities were culled. Animals were subjected to the following intensive conditions: exposure to artificial light periods and to hormone treatment, both of which induce out-of-season heat; management to lamb every 8 months; and exposure to a controlled environment. The animals that could not cope with these conditions were automatically disposed of.

The Canadian breed was selected for lean muscle mass and growth rate, based primarily on individual lamb growth. Less emphasis was placed on litter size. After 1984 an index that also included full and half-sib’s growth performance was used to select the lambs. 

The Outaouais and Rideau breeds were selected primarily on the basis of prolificacy of their dams, with lesser attention to individual lamb growth. After 1984, selection for prolificacy was based on an index of lifetime performance of their dam and maternal and paternal grand dams.
Canadian Arcott
Canadian Arcott are large, rapid-growing and heavy-muscled sheep, developed as a specialized meat-type sire breed for crossing with commercial ewes to produce market lambs.
Breed composition
The primary contributors were Suffolk (37%), Ile de France (28%), Leicester (14%), North Country Cheviot (7%), and Romnelet (6%), with minor contributions of 8% from Shropshire, Lincoln, Southdown, Dorset, East Friesian, Finnsheep, and Corriedale.
Description
Physical appearance
Color

1) Generally white, although color may appear on the head and legs.

Head

1) Medium in length and width.

2) Face white or mottled, free of wrinkles and wool.

3) Nose with a prominent bridge of a slightly aquiline cast (Roman).

4) Ears medium in length and slightly drooping (semi-pendant).

Neck

1) Medium in length.

2) Blends smoothly into the shoulders.

3) No wrinkles.

Body

1) Shoulders trim, well-rounded, blending smoothly into the body.

2) Chest deep and wide, blending smoothly into the body.

3) Back strong, straight, and level, carried well out to the dock.

4) Loin long, wide, and deep.

5) Rump long, full, and well-muscled.

6) Mature ewes weigh 75-95 kg.

7) Mature rams weigh 80-100 kg.

Legs

1) Heavily muscled, extending well into the stifle.

2) Heavy-boned, square-set, free of wool, and covered with white or

mottled hair.

3) Pasterns short and strong.

Tail

1) Tail is long, narrow, and covered with wool.

Wool Cover

1) Body is completely covered with wool, which extends to the belly.

Wool Quality

1) Fleece is of medium grade.

Performance

Reproduction

Sexual maturity

Ewe lambs weighing 49 kg conceive at 230 days old.

Breeding season

Ewes lambed at eight monthly intervals in February, October, and June under an accelerated system.

Gestation length

Length of gestation averages 147 days.

Age at first lambing

Ewe lambs can be mated at 7 months to lamb at 1 year old.

Fertility
Under an accelerated system, the fertility rate is 37% for ewe lambs
and 70% for adult ewes.
Litter size
Ewe lambs produce an average of 1.3 lambs; adult ewes, 1.9 lambs.
About 65% of ewes produce multiple births.
Lamb mortality
Lamb mortality caused by stillbirths and neonatal deaths was 10%. Of
the lambs alive at birth, 4% died during artificial rearing (21 days) and
a further 3% at 21-91 days old.
Production
Lamb weight
Lambs weigh an average of 4.0 kg at birth and grow 286 g/day from
birth to 21 days, at which time they are weaned from milk replacer,
and 297 g/day at 21-91 days old. At 118 days old, lambs weigh 37 kg.
Total lamb weight per ewe per lambing was 8.4, 18, and 55 kg at birth,
21 days, and 91 days, respectively.
Meat production and carcass quality
Lambs slaughtered at 117-120 days produced carcasses with a large
loin-eye muscle of 13.4 cm2 and adequate fat cover of 6.6 mm. The
amount of meat produced was estimated to consist of 44% of the
carcass.
Wool production
Ewes produced fleece weighing 2.4 kg for 8 months of growth.
Specific attributes
Presence of horns
Ewes are hornless, although some rams may have scurs. Animals with horns or scurs are ineligible for registration.
Temperament
Canadian Arcott are docile and easy to handle.