Overview of Genomic Selection in Zimbabwe
Animal production is likely to grow in both the developed and developing countries. To meet future needs, genetic and genomic improvement of animals must increase. Agriculture currently contributes about 6 % to the gross domestic product (GPD) and ranks third after mining and tourism in the economy of Zimbabwe. Livestock are estimated to contribute about 19% to the agricultural GDP. This is in contrast to 45% contribution in highly developed economies, clearly indicating a production gap. About 66% of the population derives its livelihood from agriculture, with 40% doing so from the livestock sector.Rural farmers have an average of 1-4 beehives for subsistence, with a few commercial producers with up to 300 beehives. Production by most smallholders is largely for home consumption. Production is estimated at 150 tonnes annually, leaving a 60% unmet demand, especially by pharmaceuticals firms and supermarkets. As a result, this gap is met by imports from Zambia, Malawi and South Africa.
Variation among individual animals is caused by genetic and environmental differences. If one considers all the different breeds of sheep and goats and various strains within breeds one can conclude that there is a wide variation in performance traits for o small ruminants. All traits provide a high selection potential. There is much greater potential for increasing both biological and economic efficiency of lamb and kid production through genetic improvement. Such potential depends on the magnitude of genetic parameters for the traits of economic importance. Selection for traits of economic importance has not been exploited fully in small ruminants. This is well illustrated with Matabele goat. In Matableeland South and North provinces there are differences in the Matabele goat in terms of horns and ears. This is so conspicuous that one can categorize them into local area strains. There are Matabele goat strains of Gwanda (Tuli), Kezi, Plumtree Ntabazinduna, Beitbridge and Mbembesi districts. Similarly this can also be said of the Mashona East African type of goat and the Save sheep of Zimbabwe.
The Zimbabwe Herd Book was established by an Act of Parliament in 1980 to oversee the registration of pedigree livestock. Stud breeding involves the controlled mating of livestock and detailed birth notifications of progeny with parents are recorded with the Herd Book. In addition, stud breeders record the fertility, survival and growth performance.
Livestock production depends on three pillars: genetics, health and husbandry. Stud Breeding - genetics - is the cornerstone of commercial livestock production. A strong commercial industry is dependent on a healthy and vibrant stud industry to offer stud/breeding stock that meet requirements in a range of production environments and market scenarios. At its annual National Sales, all animals on offer have undergone veterinary examination and inspection so that the livestock industry is offered a wide range of top-quality genetics. Stud breeding is a long-term passion where breeders strive to breed the ‘best’ animal. Breeders apply modern breeding technologies to carefully select animals to be parents of the next generation and in so doing, improve the genetic merit of future generations.
Breeders also select parent material from outside the country in the form of live imports, semen and embryos. Stud breeding also requires the meticulous recording of parentage (pedigree) as well as specific performance data that measures reproduction, survival and growth. These performance figures, together with the parentage information, are used to select the best animals to be parents of the next generation. Genetic improvement is therefore passed on from generation to generation and from the stud herd to the commercial herd.
ZHB has recently implemented Breed Plan, the leading performance evaluation software from Australia. The industry can now avail itself of the latest technologies that provide both breeders and commercial producers with accurate genetic assessment of animals that are selected for breeding purposes. A wide range of genetic material is also available for commercial producers who want to select the best breeds and breed combinations to meet their particular production environments. It is more economical to select the right breed for a particular production environment than adapt the environment to meet the requirements of the breed.
In Zimbabwe, Pure breeds of Tuli, Nguni, and Mashona cattle are available but there a very few breeders registered with the Zimbabwe Herd Book. No performance recording scheme has been developed for small ruminants (sheep and goats) in Zimbabwe. The Zimbabwe Herd Book (ZHB) records ancestry of all recognized livestock breed societies. Almost all major small ruminant (sheep and goat) breeds have registered breed societies. Breed societies were founded for the purpose of establishing breed purity by recording ancestry and defining the standards towards which selection should be made. Identification of sheep and goats is done by individual farmers. They also record ancestry. There is a need for a national performance recording scheme in small ruminants. This should involve data collection by participating farmers or a responsible agent and submission to a data processing centre. The data should be analyzed at the centre to obtain estimates of breeding values of tested animals. These estimates are returned to the farmer and form the basis of selection within, and between herds. Farmers can have selection programmes on their farms and also make informed decisions when buying breeding stock; focus on traits of economic importance taking into account the age. To have a huge impact, selection needs to be done at a large scale hence clustering, forming cooperatives and swapping animals can be helpful. This approach also decreases inbreeding that characterises the small -scale sector. Records and information are critical in breeding and selection together with some infrastructure.