Icelandic sheep
The Icelandic sheep (Icelandic: íslenska sauðkindin)[1] is a breed of domestic sheep. The Icelandic breed is one of the Northern European short-tailed sheep, which exhibit a fluke-shaped, naturally short tail. The Icelandic is a mid-sized breed, generally short-legged and stocky, with face and legs free of wool. The fleece of the Icelandic sheep is dual-coated and comes in white as well as a variety of other colors, including a range of browns, grays, and blacks. They exist in both horned and polled strains. Generally left unshorn for the winter, the breed is very cold-hardy. Multiple births are very common in Icelandic ewes, with a lambing percentage of 175% - 220%. A gene also exists in the breed called the Þoka gene, and ewes carrying it have been known to give birth to triplets, quadruplets, quintuplets, and even sextuplets on occasion.
Ewes can be mated as lambs as early as five to seven months, although many farmers wait until the ewe's second winter before allowing them to breed. They are seasonal breeders and come into estrus around October. The breeding season can last up to four months. Rams become mature early and can start breeding as early as five months.
Descended from the same stock as the Norwegian Spelsau, brought to Iceland by the Vikings, Icelandic sheep have been bred for a thousand years in a very harsh environment. Consequently, they are quite efficient herbivores.
Color genetics
The colors of Icelandic sheep are inherited in a similar way to those of other sheep, but they display more variety in color and pattern than most other breeds, and there are some variations not seen in other sheep. Each sheep carries three genes that affect the color of the sheep, and for each gene, there are dominant and recessive alleles. Each lamb will receive one allele from each parent of each of the genes shown below.[2][3]
| Locus | Gene name | Dominant alleles | Recessive alleles |
|---|---|---|---|
| B | Base color | black | brown (moorit) |
| A (agouti gene) | Pattern | white (gray, badgerface, mouflon) | (gray, badgerface, mouflon) solid |
| S | Spotting | no spotting | spotting |
Color
The base color of all Icelandic sheep is either black, white or moorit (brown), each coming in a variety of shades and tones. Black is the dominant allele. The appearance of these colors can be altered by patterns and spotting.
Pattern
There are six patterns alleles in the breed. The most dominant pattern of these is white, which will conceal any other pattern, color or spotting that may be present, producing a solid white sheep.
There are several other patterns which will change the appearance of the color the animal shows. One of these is gray, which, together with the base color gene, will give rise to either gray black or gray moorit. Another is "badgerface", which shows as lighter coloration on the back, sides, neck, ears and face, with a darker color on the underbelly, under the tail, parts of the neck and around the eyes. Once again, this pattern will show as either grey badgerface or moorit badgerface. A further pattern is "mouflon". These sheep will be light-colored where badgerface sheep are dark, and dark where badgerface sheep are light.
The gray, badgerface, and mouflon patterns are equally dominant. A sheep can display any of these patterns individually, or they can display two of them at the same time. Sheep carrying both badgerface and mouflon show as plain-coloured sheep with slightly darker markings where the two patterns meet.
There is also a single allele that is currently found only in Iceland that displays as gray mouflon – it is separate from the normal mouflon pattern. This single gene is dominant to all genes other than white.
The least dominant pattern is solid, which is essentially no pattern at all. Solid-patterned animals will simply show their base color all over. To be solid, a sheep must inherit the solid pattern from both parents – the parents could be solid themselves, or they could carry a solid allele hidden by another other pattern allele.
White sheep can also carry any one of the five other patterns, but it will be hidden by the dominant white color (note that white in sheep is genetically a pattern, not a color).
Spotting
This gene gives rise to white markings on the feet, face, head or over large parts of the body. The unspotted areas may be any of the patterns and colors described above.
There are two alleles for spotting: spotted, and unspotted; unspotted is dominant. Only when bearing two spotting alleles will the sheep display spotting.
Meat production
In Iceland, this breed is almost exclusively bred for meat.[4] Lambs are not fed grain or given hormones. The lambs are ready for killing by four to five months, when they weigh 70 to 90 pounds (32 to 41 kg). The meat has a fine grain and distinct, delicate flavor. The meat of the Icelandic sheep is considered a gourmet style of meat.
Fiber
Icelandic fleece is dual-coated. In Icelandic the long outer coat is called tog and the fine inner coat þel. When separated, the outer and inner coats are used for different woolen products.
Tog
Tog is generally classified as a medium wool around 27 micrometres in diameter. It is good for weaving and other durable products.
Þel
Þel, being the finer wool and classified as such, is generally around 20 micrometres in diameter. This fine wool is used for garments that touch the skin.
Tog and þel are processed together to produce lopi, a distinctive knitting wool that is only made from the fleece of Icelandic sheep.
Milk
Historically Icelandic sheep were used for milk. There is an eight-week period where Icelandic ewes give milk. After the first two weeks, the lambs were weaned off the mother's milk. Then for the next six weeks, the ewes would be milked daily. Most provided about 1 litre (2 imp pt) of milk per day, while good ewes gave 2 litres (4 imp pt) to 3 litres (5 imp pt). The milk was used directly, or made into butter, cheese, an Icelandic soft cheese called skyr, or naturally sweet yogurt. Sheep milk is good for cheese, because it is high in fat and dissolved solids. A high yield of high-quality cheese can therefore be made from small amounts of the milk.
Sheep are not milked in Iceland today, and instead the lamb is allowed to continue suckling.
References
- ↑ The word íslenski is written in lowercase: Orthographic rules (ritreglur) at the Icelandic Language Institute (Íslensk málstöð), section II. Upper- and Lower-Case Letters, subsection 9: Words derived from proper nouns are generally capitalized, [...] This never applies to adjectives containing -sk-.
- ↑ An attempt to determine the pattern of inheritance of coat colors in hair sheep. Livestock Research for Rural Development, Vol. 16, Art. #6. Saldaña-Muñoz V R, Torres-Hernández G, González-Camacho J M, Díaz-Rivera P, González-Garduño R and Rubio-Rubio M 2004: Retrieved August 2, 2006
- ↑ Susan Mongold. "Color Genetics in Icelandic Sheep". Retrieved 2009-04-07.
- ↑ "Icelandic". Breeds of Livestock. Oklahoma State University, Dept. of Animal Science. Retrieved 2009-04-17.
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