Hitch-hiking effect and linkage disequilibrium: the example of two closely linked loci in the pig, Halothane Sensitivity (HAL) and Phosphohexose Isomerase (PHI)

Abstract

Authors worked out a breeding scheme in order to utilize the yearly genetic progress in milk and beef production as well as "hybrid vigor" and "type heterosis". Latter term is proposed to be introduced into the terminology of animal production. This scheme which integrates milk and beef production, keeps space with the international genetic progress and attains a heterosis effect over 6 0 per cent in milk production and at the same time assures a heterosis effect (hybrid vigor as well as type heterosis) of i oo per cent in the single suckler cow stock as well as in the population for direct fattening. In this scheme pure breeding is practiced only in herds meant for producing sires of high genetic quality whereas in milk and beef production only crossbred populations are involved. The scheme is already in practice within a large scale experiment of 6 ooo cows in criss-cross breeding by using the best genetic material of USACanadian and Danish f e y sey breeds and of three types of beef breeds. In this conception breeds are no more the objects of production but the building bricks of the production systems. (TxoNtsorr, 1977 ) showing that a possible source of linkage disequilibrium may be the hitch-hiking effect of a selected locus on another closely linked neutral locus.