|» Home||» Breeds||» Directory||» About||» News||» Webmart||» Projects||» Gene Bank||» Links||» Join||» Contact|
The Damara of Southern Africa
An Essay On The Genetic Variation Within The Breed
DAWIE DU TOIT
The Himba, an Herero-speaking people, settled during the 16th century in North Western Namibia with their Sanga cattle, Damara sheep and goats. This area is today known as Kaokoveld. The Himba have a nomadic lifestyle and roam freely in search of water and grazing for their livestock. In the 19th century, missionaries and explorers became aware of the Damara sheep which was and still is one of the main sources of livelihood of the Himba. The Himba have been described as Africa's most successful pastoralists.
Over the centuries, the Damara survived a long and perilous migration through Africa, and its genes have to large extent been shaped by natural selection. The Damara had to survive for many centuries without veterinary support in a hostile environment and had to adapt to these conditions. It was only in the middle of the 20th century that commercial farmers became aware of the unique characteristics of the Damara, realizing that the Damara can thrive in a wide range of environments without expensive support systems.
The Coat Colour of the Damara and its place in The World of Coloured Sheep
Like its wild progenitor, the Asiatic Mouflon, the Damara has an outer coat of stiff glossy hair and a short woolly under-coat which grows only in winter. This under-coat is shed in summer.
The Himba always considered the coat colour of their domestic livestock as very important. The different colours and patterns helped the owner to identify his animals. There are also strict rules regarding the colour of livestock that can or cannot be eaten by the various clans within the Himba people.
The explorers who opened the trade routes during the 19th century in Namibia, were particularly struck by the different colours of the Damara. The Swedish explorer, Andersson, 1856, gives us a vivid description of the Damara:
They have no wool, but a kind of short glossy hair (lying close to the skin) covers the body. The greatest peculiarity of these animals is their colour, which is of every hue and tint.
Research into the coat colour genetics in sheep started in the 1920s. During November 2004, I attended the 6th World Congress of Coloured Sheep in Christchurch, New Zealand. The majority of the presentations at the Congress dealt with coloured wool sheep. The wool sheep breeds have been selected for centuries to produce white wool, because white wool can be dyed any colour.
The coloured genes in wool breeds therefore in time became rare, and are mostly present in recessive genes. The selection for coloured wool sheep is a long process. There is, however, a market for naturally coloured wool fleeces which are sold mainly to the handcraft industry at a premium. At the Congress I met some of the world's foremost geneticists with an interest in the coat colour of domestic animals. I did two presentations on the Damara, which were very well received by the over 200 Congress participants.
The coat colour of a sheep is controlled by a number of pairs of genes. Each pair is situated at a specific position, called a locus (Latin for "place" – plural loci) on one of the various pairs of chromosomes. Alleles are the different genes (options) that can occur at a particular locus. At the Extension locus there are two alleles. If the dominant black allele is present, the sheep would be black. This allele is common in the Karakul breed. If the wild allele is present at the Extension locus the colours and patterns at the Agouti locus can be seen - in other words the dominant black gene overrides the alleles of the Agouti locus. The most dominant colour at the Agouti locus is white/tan and the most recessive allele is also black (due to the nonagouti allele). So when one sees a black Damara it can be due to either the dominant black allele at the Extension locus or the nonagouti allele at the Agouti locus. Between the two extremes of tan and black at the Agouti locus, are all the different patterns and colours of the Damara.
The basic colours produced by the alleles at the Extension and Agouti loci are often modified by genes at other loci. In the white-woolled breeds, the effect of white/tan allele is to change all black or moorit (chocolate brown) eumelanin to tan phaeomelanin. Other genes then take over to dilute or reduce the tan colour, or totally eliminate it so that you get a completely white animal. It is important to remember that white is not a colour, but rather the absence of pigments. Since there has not been a selection for white in the Damara, the tan colour is quite widespread.
Roger Lundie of New Zealand who has studied and researched the coat colour in sheep for almost three decades, was so impressed by the coat colour and patterns of the Damara that he paid a visit to South Africa in July 2005. He summarised his impressions of the Damara as follows:
For more than 25 years I have been studying the genetics of coat colour in sheep whilst running my farm. This visit to see the Damara sheep is my first real contact with a hair sheep breed. Within the hair sheep, because of the fibre type, the colouring shows up in a more vivid way as the contrasts between the tan, black and white are more spectacular. This was even more memorable as the breed has not been selected for any particular colour and so there was this wonderful range of colours, patterns and markings to be seen.
Roger is presently writing a scientific paper on the coat colour of the Damara and I hope to publish it shortly. This should not only be of great academic interest, but should also assist the farmer in managing his coloured Damara sheep flock.
Phil Sponenberg, a Professor at the Virginia-Maryland Regional College of Veterinary Medicine, in the United States of America, also attended the Congress and delivered two papers. His coat colour genetics interests include sheep, cattle, horses, donkeys, goats and alpacas. Phil plans a visit to South Africa during October 2006 and we hope to give him a first-hand experience of the Damara and the Nguni cattle of South Africa and Namibia. Phil has had a look at numerous photographs of the Damara and he writes:
The colours and patterns of the Damara sheep are part of the wonderful heritage of this breed, and it is important to keep the variability of colour into the future. Breeders can assure this by encouraging and celebrating the variability of colour in the breed, instead of focusing on a limited array of colours and patterns as is common in most breeds of sheep. The variability is a key part of the heritage of the breed, and managing this diversity is a key to maintaining the breed.
We are therefore fortunate that the Damara has not gone through a colour bottleneck, leaving the Damara with a wide genetic variation of beautiful skin colours and patterns. We look forward to Roger's and Phil's contributions to our understanding of the coat colour of our domestic animals and their suggestions for colour breeding strategies.
The fact that the Damara has not gone through a colour bottleneck also means that there is a wide genetic variation that ensures its general fitness and vitality. In our modern western livestock industry the emphasis is on productivity in controlled environments. Modern pharmaceuticals ensure further that domestic animals with less robust genes survive and reproduce. The Damara, on the other hand, is one of only a few sheep breeds in Southern Africa that, over the millennia, walked all the way down Africa with their African pastoralists. The Damara has in the process been exposed to the vagaries of nature. This resulted in a breed rich in fitness traits such as its high resistance to most sheep diseases and internal parasites. The new trend of "breeding for disease resistance" is therefore easily attainable with a breed like the Damara.
The general conformation of the Damara has also been shaped to a large extent by natural selection and there is a striking resemblance between the Damara and the African antelope. The sloping rump of the Damara ensures that the ewes can lamb with ease. The prominent withers and relative long legs of the Damara aid its mobility. The vital and reproductive organs of the Damara are not so close to the searing reflective heat of the earth in summer, thereby reducing heat stress. It can with ease cover vast distance in search of grazing and it can use its sheer athleticism to escape from predators.
At three months, most Damara lambs are almost jackal-proof. The strong herd instinct of the breed affords further protection for young and vulnerable lambs. One can only surmise that a predator like the jackal finds it rather intimidating to take a lamb from a flock of sheep bunched together in a tight circle at night. The strong libido of Damara rams, coupled with the fertility and good mothering ability of Damara ewes, ensure that ewes produce a lamb every eight months. A high percentage of these lambs are weaned.
It is, however, the cumulative effect of all these genetic traits in one breed that makes the Damara one of the world's most valuable sheep breeds. These traits can easily fall by the wayside if we do not select our sheep within well-considered parameters. The challenge for Damara breeders is to preserve these traits for the future. The breed is ideally suited for the harsh, extensive South African conditions.This article is from the South African Stud Breeder Magazine, with the author's kind permission. Dawie du Troit is also editor of the book The Damara of Southern Africa which is available from him at firstname.lastname@example.org
• » Damara Sheep •
| » Go to Rare Breeds Home Page |
See also Navigation Bar at top of this page