In South-Africa, the demand for lamb and mutton exceeds 190 000 tonnes per year, most of which is produced by the roughly 8000 commercial sheep farmers throughout the country. Even though sheep farmers are found in all nine provinces, the majority are concentrated in the more arid regions of South Africa such as the Karoo and parts of the Western Cape. These semi-desert areas often fall in winter rainfall regions, resulting in harsh production conditions with many challenges. These challenges served as the basis for the development of the Dormer sheep; a breed with the potential to produce slaughter lambs unlike any other.
The first sale of Dormer rams was held in 1947 at Elsenburg, the research station where this remarkable breed was developed over a period of roughly ten years. Scientists from the Elsenburg research station were determined to develop a breed particularly well adapted to the harsh conditions of the cold and wet winter rainfall areas of South Africa, without having to compromise on their ability to produce meat rapidly and economically. As such, they conducted a series of extensive slaughter-lamb experiments to determine the best existing breeds that would achieve these aims and objectives.
In the beginning stages of these experiments, Merino ewes were crossed with a variety of rams to determine which crosses resulted in the desired characteristics. Later on, the larger German Merino was used on the Merino ewes to improve their mutton configuration and increase the size of the progeny, without changing the merino’s wool characteristics. Merinos were decided on due to their high fertility and fecundity, good milk production and relatively long breeding seasons. These crossbred Merino ewes were then mated with rams of different breeds, including the Dorset Horn rams – these rams shared the same fertility qualities the Merino ewes showed, whilst also having a fairly long breeding season. Because of the risky local market of the time, lambs from these crossings would have had to be able to compete with slaughter lambs from Australia and New Zealand when exported to the overseas market, and so breeding rams were imported from Australia and England. This consideration was taken very seriously when the Dormer was still in its development stage, and after more that 6000 lamb carcasses were exported to the Smithfield market in England as experimental consignments, it was confirmed that the best slaughter lambs were offspring of the Dorset Horn rams.
The conclusion was made that lambs from the Merino ewes, when crossed with Dorset Horn rams, showed the most remarkable performance with regards to live mass gain and carcass quality, whilst also being the only cross to produce satisfactory lambing percentages in autumn. In the Western Cape, this trait is utterly important as winter pastures are primarily used to produce slaughter lambs. In addition to this, winter rainfall regions pose a large risk of infection with Muellerius capilaris, a lung parasite. This parasite resulted in abnormally high mortality rates under mature Dorset horn sheep but seemed to have no effect on the mortality rates of the SA Mutton Merino produced under the same conditions. The high resistance of the SA Mutton Merino to this parasite, combined with the excellent mutton qualities and growth rate of the Dorset Horn resulted in the ideal slaughter lamb for the winter rainfall area. To start out the new breed, it was crucial that good breeding material that showed no signs or symptoms of the lung infection would be utilised, therefore 10 Dorset Horn rams were imported from studs in Australia. After strict inspections, only four of these were selected for eventual use in the Elsenburg research flock. Apart from the Elsenburg flock, private farmers also went on to breed Dormers and participated in the development of the breed.
Today, the Dormer is a breed known for its high fertility, excellent mothering abilities, ease of lambing and long breeding season – making this one of the most efficient mutton breeds in the country, especially under extensive conditions in the winter rainfall regions. Additionally, the lambing percentage of this breed is between 120 and 150%, depending on specific conditions and management practices. In terms of production qualities, the Dormer can also boast with high slaughter percentages and early maturation, as well as exceptionally high average daily gains. These qualities also make the breed particularly well suited to the feedlot enterprise. Compulsory performance testing combined with the implementation of breed standards has led to dramatic improvement of the breed over the last decade.
Many sheep farmers believe that the Dormer is the answer for the lamb and mutton industry in South Africa, and with the ever-increasing demand farmers have for this breed, the high quality and high value of the Dormer is self-evident.
Author: Suné Bartman (MSc Agric Production Physiology and Product Quality)