Genetic variation in disease resistance among farm animals

Abstract

This background study paper reviews the results of scientific investigations involving genetic control mechanisms for resistance/tolerance in farm animals to specific viral, bacterial, parasitic and prion diseases. The paper presents the most prominent documented examples for resistance/tolerance in cows, sheep and goats, pigs and poultry. The importance of genetically heterogeneous populations is highlighted, particularly as they impact response to epidemics, their duration, lower mortality rates, etc. Genetic studies on resistance in farm animals to a variety of etiological infectious agents can be determined at three genetic levels of variation: species, breed and unique genetic variation among individual animals. Depending upon the etiology of disease and the available animal resources, strategies for developing genetic disease management can be developed at the following levels: selection of breeds that are particularly well adapted to the local environment, breeding methods which include the introduction of genes exhibiting genetic resistance/tolerance towards pathogenic organisms, and the selection of individual animals with a high level of specific pathogen resistance. The most recent epidemic zoonoses illustrate how important it has become to develop global mechanisms for control of zoonoses and consequently the vital role of veterinary services in disease control.

U radu je dat pregled rezultata proučavanja genetičke kontrole rezistencije/tolerancije proizvodnih životinja na pojedine virusne, bakterijske, parazitske i prionske bolesti. Navedeni su najbolje dokumentovani primeri rezistencije/tolerancije kod goveda, ovaca i koza, svinja i živine. Istaknut je značaj genetički heterogenih populacija u pogledu odgovora na epidemije, niži mortalitet, dužinu trajanja epidemije i dr. Gentička proučavanja rezistencije životinja prema infekcijama različite etiologije definisana su na tri genetička nivoa koji se odnose na vrstu, rasu i individualne genetske varijacije. U zavisnosti od etiologije bolesti i raspoloživih animalnih resursa, strategija unapređenja genetičke kontrole bolesti može se zasnivati na: izboru lokalno adaptiranih rasa, primeni metoda ukrštanja sa ciljem da se introdukuju geni od značaja za genetičku rezistenciju/toleranciju prema patogenima i selekciji jedinki sa visokim stepenom rezistencije prema patogenima. Nedavne epidemije zoonoza ukazuju na značaj globalne kontrole zoonoza i važnu ulogu veterinarske službe u suzbijanju ovih bolesti.