article is based on the full lecture held by Dr. Stefan Adalsteinsson
during the Shetland Sheep 2000 Conference in Lerwick late september 2000.
STEFAN ADALSSTEINSSON, a native of Iceland, is a graduate of the
Agricultural University of Norway. After obtaining a Ph D. from the
Edinburgh University he returned to Iceland to research into the various
species of domestic livestock. As Chief Geneticist he has published much
original work on the inheritance
of wool qualities and colours in sheep. He became Chief on the Farm
Animals Research Division for the Icelandic Ministry of Agriculture. Later
he became Administrative Director of the Nordic Gene Bank of Farm Animals,
NGH for six years.
this project we would like to draw attention especially to two works by
Adalsteinsson, S. 1970. Colour inheritance in Icelandic sheep, J.Agric.Res. Icel. 2, 1-135
Adalsteinsson, S. and Wardum,
H. 1978. Frequency of colour genes in Faeroe Islands sheep. Journal
of Heredity 69: 259-262.
Colour markings in the Faroe Islands Sheep will be a central subject, during this year!
The Shetland breed belongs to the North-European group of horned, short-tailed sheep. To this group belong The Faeroe Islands sheep, the Norwegian Spaelsau, Swedish short-tailed sheep, the Finnsheep, the Icelandic sheep, the Romanov sheep and old sheep breeds in North-Eastern Poland (Wrozowska sheep) and the northern part of Germany (Heidschnücke).
The Shetland sheep is very much a native of the islands, and was, until recently, not found in many places elsewhere, except in the Mainland of Britain. But since Shetland sheep were imported to Canada in 1980 and further from Canada to the US in 1986, an increasing number of Shetland flocks is being formed in North-America.
The Shetland sheep has probably not greatly changed during the past hundred years. Although the Cheviot and the Blackface have been taken to the islands and there are a number of flocks of the latter, crossing would seem to have made less difference to the native Shetland sheep than one might have expected.
The fleece of the short-tailed breeds is double coated, with an outer and inner coat. The distinction between the outer and inner coat is probably least pronounced in the Shetlands, the Finnsheep and some of the Swedish short-tailed breeds.
Some of the short-tailed breeds show extremely high fecundity, especially the Finnsheep and the Romanov. Within Iceland a single high fecundity gene is known, the so-called Thoka gene, with litters up to quintuplets. In older reports on Shetland sheep, reasonably high fecundity has been reported, with considerable proportion of twins, and even some triplets.
The horn types in the short-tailed breeds vary. In Shetland of today rams are horned and ewes polled. The horns of the rams are usually nicely rounded, not too heavy, nor too close together. Fully grown horns in both sexes is a characteristic of most Icelandic sheep, but in some strains both males and females are polled, or the males may have rudimentary or aberrant horns. Polled in both sexes is now the main horn type in the Norwegian spaelsau, but some 50 years ago horned in both sexes was found in some unimproved strains. Polled in both sexes is dominant to both fully grown horns in both sexes and horned in males and polled in females. Horned in males and polled in females, as in the Shetland sheep, is therefore recessive to the two other horn forms described above.
for fine wool
The Old Statistical Account of Scotland (1797) contains a description of sheep husbandry in Scotland, as well as of the Old Scottish Shortwool. The sheep in certain parts of Scotland were constantly attended by a boy or a girl during the day, whom they followed to and from the pasture. They were penned in a house with slatted walls during the night. These very small flocks were the responsibility of the whole family, and competition existed between the children about who should possess the handsomest and most valuable animal within the flock. This means that animals for future stock were selected on merit, long before scientific selection for improvement was invented. It is believed that by those means the fleece of these sheep was improved to such a degree that their wool was preferred to any wool then known in the neighbouring markets. Later developments in Scotland lead to the eradication of sheep flocks of this type, and no trace of these sheep is now found.
But lack of knowledge does not mean that the same process of selection has not been carried out elsewhere. It seems likely that the wool on the Shetland sheep has been improved in a comparable manner, by selecting for breeding the animals with the best wool type.
example from Iceland
There is a short way from selecting a sheep for its wool quality at shearing to select a ram lamb for breeding on its own wool quality, or on the wool quality of its dam. Fact is that in the North-Eastern part of Iceland the sheep grew much finer wool than sheep in other parts of the country. It is likely that this improvement in wool quality was the result of deliberate selection of breeding animals.
Sheep in North America
The following desription of Shetland sheep and its wool in America is taken from the NASSA website in July 2000, about Shetland wool production in the US.
”A very important characteristic of the Shetland Sheep is their beautiful wool, upon which the world-renowned Shetland wool is one of the finest and softest of any UK breed, with an average fiber diameter of 23 microns. Highly variable, the Shetland fiber can range very much, from an incredibly fine, soft fiber found around the neck to a coarser, almost double coated, wool used to make rugged, warm fabrics like woven tweeds and Fair Isle Knitwear.
Shetland wool is some of the finest among the UK breeds. It is soft, yet strong and durable, and is a delight to spin. The finest of the Shetland yarns, spun from selected neck wool, were knit into lace shawls so fine they could be drawn through a wedding ring!
Fleeces usually weigh between 2 to 4 pounds, but 5 and 6 pound fleeces are not uncommon. Typically, on the Shetland Islands, the fleece staple length is 2 to 4 1/2 inches; however, we are also seeing staple lengths of 6 inches in the US. This may be a function of the richer, more nutritious diet available to the animals here versus the wild heath and grasses available on their native islands.
Occasionally, the wool will shed in late spring as it did generations ago when it was "rooed" or pulled off by hand. This tendency toward molting, along with evidence of a slight double coat, and a rich variety of natural colors is indicative of the breed’s primitive nature.”
Two colour patterns are found in Table 2 which should have been shown in Table 1. These are the patterns gulmoget and katmoget. In the list, gulmoget is correctly described as the opposite of katmoget. But these two phenomena are not markings, but patterns, and are produced by genes which produce cryptic colouration in the young. The gulmoget pattern is for example found in sheep and in the field mouse, and the katmoget pattern in sheep and in the badger. The katmoget has therefore been called badgerface in English and the gulmoget reversed badgerface.
It should be made clear that in many cases particular types of markings are described as white patches on coloured background, while in many cases they are also given the mirror effect of the first description, i.e. coloured markings on white background. An example is Sponget - dark coloured with small white spots, or conversly, which means that Sponget can either be dark coloured with small white spots, or white with small coloured spots.
to my personal experience, colour markings in sheep are of only one kind.
They are white pathces on coloured background. I therefore have called
them white markings in my work on colour inheritance in sheep.
Of the 30 markings 15, or 50%, have names that have a comparable counterpart in Icelandic, in spite of 1100 years of separation. This is a remarkable example of how certain aspects of culture of sheep keeping has been kept alive, by giving the colour markings a name in the distant past. The sheep owners have stuck to the names of the markings in both countries and the names have survived a separation of more than a thousand years. This is heritage at its best.
It is noticeable that the white markings in both Iceland and Shetland have names that originally come from the Norwegian language. These names must have been used in Norway at the time of settlement in both Shetland and Iceland, because that is where the sheep in both countries came from. The fact that the names of these markings are not found in Norway any longer must be due to the introduction of white-coloured British breeds in the 19th Century to Norway. This led to topcrossing of the old multicoloured short-tailed female sheep with imported rams. The old colours disappeared under the white colours from Britain, and the names were soon forgotten when the colours were no longer seen.
In farm trials, where Shetland-Cheviot ewes were compared to Scottish Halfbred and Greyface, the Shetland-Cheviot returned every year over a six-year period gross margin per acre of between 25% and 33% higher than the larger crossbreds on trial.
The Shetland-Cheviot ewe is a hardy, thrifty and milky ewe with outstanding ability to produce a lamb with good conformation from improved grazing. Other factors adding to the picture, such as few problems at lambing, good mothering ability and ease of handling, make this ewe more appealing to the practical sheep man. This ewe is highly economical, eating around one third less grass, silage and concentrates than the larger crossbreds under a variety of conditions. She adapts readily to more intensive systems, such as winter housing. She will produce prime quality lamb from a terminal sire, thriving under a range of conditions, and producing on less food intake than most other breeds, giving value for money. 
story from Iceland
Hakon had in autumn 1913 bought 60 ewes from a district in the South-East of the country, called Oeraefasveit. The sheep in that district were unimproved and of low weight, and produced light lambs. When the new sheep had recovered from being driven to their future home in Arnaldsstadir, they weighed on the average 31.5 kg, the lightest one 27.5 kg. At tupping time they were mated to a ram from the North-East, weighing about 100 kg. This ram was out of a strain that had been selected for increased weight and good fleshiness for several decades. In autumn 1914, one of the bought in ewes, weighing 38 kg herself, had a male lamb that weighed 40.5 kg. Several other of the ewes produced lambs that outweighed their dams.
The point of this Icelandic story is that the Icelander did not utilize the excellent milking ability and low feed requirement of the ewes from Oeraefasveit for planned crossbreeding. Instead the ewes were topcrossed repeatedly with selected heavy rams from the North-East. The new generation of ewes soon became as heavy as the ewes in the North-East district. Their ability to produce lambs that outweighed their dams very quickly disappeared.
third example from Iceland
In the old Lawbook, a three year old wether, or older, of the leader sheep strain was metfe, which means that it did not have a settled price as other sheep in the flock, but had to be valued by three men from the buyer and three from the seller.
No comparable type to the Icelandic leader sheep is known outside Iceland. In the Faeroe Islands, a sheep type called vargur was known. Sheep of this type would run wild in the mountains, and they tried by all means to escape from being brought down to the sheds. This type of sheep may have had a certain type of leader instinct, but an instinct that was impossible to control. The Icelandic Leaders will follow the route pointed out by the shepherd, and they will be careful, not to run too fast in front of the flock. The speed of a good leader should match the pace of the ordinary sheep.
If owners of Shetland sheep, or owners of related short-tailed sheep in the Orkneys, Hebrides or elsewhere, have heard of a type of sheep with something like the Icelandic leader, it would be very interesting to hear about it.
future of Shetland Sheep
The breeding aim of Shetland sheep today seems to vary considerably, to judge from articles on the Internet. Some people put emphasis on fineness or crimp of wool fibres, others accept variation in wool quality, but want a multitude of wool colours. Still others seem to go in for horns in females, and several other directions of selection can be envisaged.
Professor D. P. Sponenberg, in Virginia-Maryland Regional College of Veterinary Medicine, has written an interesting article about the Shetland sheep situation of today. I shall in the following try to emphasize the highlights of Sponenberg’s article.
Sponenberg emphasizes that a breed is initially a result of a founder effect, by which the original gene pool in the breed was determined. Some genes of the parents of the founder animals did not succeed to enter the founder population. A second mechanism which affects the gene pool is isolation. The environment may favour one type of animals and disfavour others.
Selection can also produce uniqueness. Breeders want to select for or against specific characteristics, such as size, colour, horns, wool types, etc., but the wishes of breeders will vary. The varied attitude of breeders tends, however, to conserve variation.
Sponenberg defines three stages of variation within a breed or population. At the first stage we have a landrace, which shows considerable variation. The second stage of variation arises when the landrace is turned into a standardized breed. Types that do not conform to the standard are excluded from breeding. The third and final stage of unifying the breed still further converts it into industrialized stock. That stock is highly and scientifically selected for narrow environments, specific inputs and carefully defined selection goals. Modern examples of such stock are poultry, pigs and even dairy cows.
During this process, variation is lost, and predictability is increased. Breeds and industrial stocks breed more true to type than a landrace does.
In order to minimize loss of variability, in the case of Shetland sheep, breeding animals should be graded into groups by breed standards. Animals within the same group are regarded as equals in breeding value. By this method, the heavy weight that is put on individual champions does not enter the picture, and greater variability is retained.
Sponenberg’s advice to breeders of Shetland sheep is to discuss in depth what they want to do with the Shetland sheep, what they want to keep, and what they don’t want to loose. They should keep variation, not loosing it to the forces of the showring. Vulnerability of the breed should be evaluated before the breed is up to any threat of losing variation. Sponenberg’s final words of warning are those:
”So much has been lost from so many breeds that it would be a shame for the Shetland breeders to not learn from the mistakes of others.”
Gene Bank for Farm Animals
(Nordisk Genbank - Husdyr, NGH)
The Gene Bank was given the responsibility to follow up, within the Nordic countries, the possible risk of breeds or populations of farm animals decreasing in number of breeding animals, so that they might run into danger of extinction. This task was met by collecting information on the number of breeding animals of all known breeds or populations of farm animals, and implementing necessary measures to ensure continued survival of these breeds or populations.
At the outset, main emphasis was put on cattle breeds. A large genetic project was formulated, and finances obtained from The Nordic Council of Ministers to carry it through. In this project, blood samples from all the Nordic cattle breeds were obtained and analysed, and the results used to work out the genetic relationship between the breeds.
This exercise gave as a result that the old cattle breeds in the Nordic countries could be divided roughly into two groups, one having their roots in the Northern part of the Nordic countries, presumably arriving there along a route north of the Baltic Sea, and spreading into Finland, Sweden and Norway. Icelandic cattle had arrived to Norway via the northern route, and from there to Iceland. A second group of cattle had arrived via a southern route, presumably first to Denmark and from there to the southern parts of Sweden and Norway.
A second project was planned in 1996. That project was aimed at analysing the relationship between Nordic sheep breeds. The breeds in question have all been sampled for blood, and most of the blood samples, as far as I know, have been analysed. What now remains is to collect the data from the analyses, and compare the breeds in order to establish their relationship to one another.
It is well known to the present audience that many breeds of the Nordic short-tailed group of sheep occur in the Nordic countries. Through this project, one may be able to trace the relationship between the individual breeds or breed groups in greater detail than can be done by written records only.
Information or suggestions on new markets, for sheep, wool, woollen goods, cured skins, either in full fleece or clipped, items made from horns for decoration, new dishes from lamb meat or mutton, etc., all such ideas might be of value for a few, or for many. The main idea is that the Shetland breed of sheep is unique, it has many special characteristics which other breeds have not, and many of these may be made valuable through good salesmanship.
As a closing remark, I want to make a statement to those interested in making the best out of Shetland sheep: If you are well prepared for your task and believe in what you are doing, there is a good possibility of success.
I wish you, the audience here today, and all owners and keepers of Shetland sheep, the best of luck for the future.
S. 1970. Colour inheritance in Icelandic sheep, J.Agric.Res.
Icel. 2, 1-135
S. and Wardum, H. 1978.
Frequency of colour genes in Faeroe Islands sheep. Journal of Heredity, 69:259-262.
Thorbergsson 1918. [Ram exhibitions in Eastern Iceland in autumn 1917]. Bunadarrit 32, 191-196.[In Icelandic]
J.V. and Adalsteinsson, S. 1985. Single genes for fecundity in Icelandic
sheep. In: Land, R.(Ed.): Genetics
of Rreproduction in Sheep. Butterworths, London, 159-168.
J.V., Birgisson, L.G. and Adalsteinsson, S., 1994. Leader sheep in Iceland.
5th World Congr.Genet.Appl.Livest.Prod., Vol.20:162-164.
Sheep Association, 1998. British
Sheep. Ninth Edition. NSA.
North American Shetland Sheepbreeders Association (NASSA), July, 2000. Website: http://www.shetland-sheep.org/index.html
Ólafur Halldórsson, 1904 (Editor). Jónsbók. Kong Magnus Hakonssons Lovbog for Island. Vedtaget paa Althinget 1281.
K. 1980. Sheep of the World.
M.L. 1983. Sheep and Man.
H. 1933. Vikingeminner i Vest-Europa.
H. Aschehoug & Co. Oslo.
D.P. 1993. The Need to Conserve Different Types of Shetland Sheep. NASSA
Vangen, O., Adalsteinsson, S., Neimann-Soerensen, A., Maijala, K.,Danell, B., Maeki-Tanila, A. and Eythorsdottir, E. 1994. Activity programme for Nordic Gene Bank for Farm Animals. Proc. 5th World Congr.Genet.Appl.Livest.Prod., Vol.21:544-547.