marker-assisted selection in wheat - ictsd

242Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishbreeding animals genotyped will be smallin relation to the total number of animalsevaluated based on phenotype, making anintegration of genotypic information withthe full evaluation procedure less sensibleat this stage. Finally, service providersoffering the genotyping results are oftendifferent from the service providers of EBVwhich inhibits a full integration of geneticinformation to the breeder.In New Zealand, a significant and rapidlyexpanding part of the performancerecording sheep industry already usesDNA parentage and the above-mentionedtests are now often provided as part of thatsystem. At this point in time, DNA fractionalparentage (Dodds, Tate and Sise,2005) is included within the SIL system,but MAS EBVs for some of the abovementionedtests (Inverdale, LoinMax) areonly carried out on a stand alone basis, inthe case of LoinMax since 1997.Goat MASA GAS programme is operational for thealpha-S1 casein gene for dairy goats inFrance (Manfredi, 2003). The gene is associatedwith protein content and protein yield.In this programme, young bucks are preselectedwithin families based on genotype.The programme is run by a cooperative AIcentre (Capri-IA) and, although started upwith government funding, it is now almostrunning on a fully commercial basis.MAS in developing countriesMost breeding programmes in developingcountries, if existing at all, are small-scalewith modest objectives. Usually, the challengeis to foster the flow of information(measurement and evaluation) as well as theflow of genes (dissemination of improvedstock). These processes are often inhibitedby infrastructural, logistical and socioeconomicfactors. Clearly, gene markertechnology will not be the first priorityin many of these programmes. However,where gene tests exist for clearly definedcharacters with substantial economic benefit,gene markers and MAS could be verybeneficial. Introgression of disease resistancegenes into productive breeds could beof great value, but few of these examplesexist in sheep and goats.A good example of a clear gene effectsuccessfully implemented in a MAI programmeis found in India (Nimbkar et al.,2005). The Booroola gene is being introgressedhere from the small Garole breedinto the local Deccani breed that is suitablefor meat production but has a limitedreproductive performance. The Booroolagene has tremendous economic effects inthis production system, raising the weaningrate by nearly 50 percent. The breedingprogramme is undertaken by a researchinstitute, but there are clear strategies andactivities to ensure that the improved stockfinds its way to shepherd flocks. Evaluationof the results in these shepherd flocks is anexplicit part of the project, and initial resultslook very promising. Therefore, MAS andMAI should not be ruled out for breedingprogrammes in developing countries, butshould be assessed based on the merit ofeach case. However, implementation ofgene marker technology will only workwithin the framework of a sound existingbreeding programme, ensuring the prerequisitethat genetic information is valued andthat the gene marker accounts for substantialeconomic merit.ConclusionSheep and goat breeding programmes existin low- to medium-input agricultural systemswhere there are many independentbreeding units and where trait recording