Genetic Improvement of Livestock for Organic Farming Systems

Summary

Over the last two decades, more and more farmers converted from conventional to organic farming systems. The few breeds and genetic lines which are intensively used in conventional production systems are not necessarily well adapted to the conditions in organic farming, because genotype * environment interactions may cause individual genotypes performing well in one environment to do poorly in another surrounding.
An example in poultry is given, illustrating that laying hens which were selected for high egg production in a cage, had a considerable decrease in number of eggs laid in a free-range system and furthermore developed unfavourable behaviour patterns like feather pecking. The range of phenotypes produced by one genotype can be determined by variation in the environment and visually demonstrated in reaction norm curves. As one example for this phenomenon, reaction norm curves depicting the environmental sensitivity for fertility in dairy cattle were shown.
It is suggested to develop new selection indices and to apply them to the existing stock. Different possibilities for these new indices which contain production as well as functional or fitness traits are given. Summing up, organic farming systems may crave a different type of livestock which can be accounted for in a breeding context.