One century of genetic changes in pigs and the future needs
Authors: Merks Jan W.M. 
Published: June 2019

Breeding programmes and improved knowledge of genetics have resulted in gradually increased genetic changes in pigs. In this paper the genetic changes in the European pig during the last century are analysed and compared with societal needs for the following decades. Dutch data are used to support the general trend in Europe and results of an EC project on breeding and society are used to identify societal needs.

Genetic changes in pigs started early this century, mainly in Northern Europe, by the gradual set up of local and regional breeding programmes. In the first 60 years the goal of these programmes was focussed only on leanness and feed efficiency. However, type, leg quality and breed characteristics were of utmost importance in these years for some breeding programmes. During these decades the genetic changes were negligible for reproduction traits. Progress was achieved especially for breed characteristics like type and colour and later also backfat thickness, daily gain and consequently improved feed efficiency.

With the introduction of crosses in the early 60's, specialisation in dam and sire lines but moreover in breeding programmes arose in the pig industry. This specialisation resulted rapidly in increased genetic changes, more breeds and/or lines and breeding goals that supported efficient lean meat production systems. Especially in the sire lines, this specialisation resulted in increased progress for daily gain, backfat thickness and feed efficiency. Improved knowledge of genetics increased genetic changes in leanness and feed efficiency during the last few decades, but at the same time attention could be and was paid to fertility and vitality. During the last decade most European pig breeding programmes realised anual genetic progress for daily gain of +20 g/day, lean meat % of +0.5% and litter size of +0.2 piglet/litter. Molecular genetics does not enable more genetic change for these traits, but does so especially for expensive or difficult to measure traits, e.g. meat quality, health and longevity. In commercial pig breeding programmes selection limits have not been reached yet. Nevertheless, there are experimental results that indicate unintended side effects of the present breeding goals.

Next to changes in breeding possibilities, the societal needs have also changed. During the first 80–90 years of the century, pig producers were aiming at production of lean meat at low(er) prices. In this period low prices were more important than quality and/or welfare of the pigs. Nowadays, diversification in consumers' needs is growing and quality of the product (including production circumstances) is important in Western Europe. The market for pork is changing from a market of producers into a market of (potential) buyers. Clearly, the success of any pig breeding programme next century will be judged by the consumer. Where a newly bred, or genetically modified, variety of animal fails to provide something people are prepared to buy, the breeding programme will be judged a failure. In this respect ethical issues are also becoming more important. Modern breeding techniques can threaten animal welfare; a very fast increase in one or a few traits can easily result in an insufficient increase or adaptation of the organs and skeleton. Animal integrety is another important issue, especially related to genetically modified animals. Clearly, the relationship between animal and human interests is central to any view.

From the analysis of genetic changes in pigs and the present and foreseen changes in market demands, it may be concluded that the pig breeding programmes were very successful; but they will have to change their goals. Less emphasis will be needed on low cost price and more emphasis on product quality, biodiversity and well balanced genetic changes for economically important traits.