In 1926, as one of a succession of protectionist measures, England prohibited the import of all fresh meat from continental Europe. This was a serious blow to Dutch pig farmers, who had sold over 36 tons of fresh pork to the English in 1925, more than half of the total export of pork. Processed meat such as bacon was left out of the import restrictions. As a result, Dutch pig farmers were more or less forced to breed pigs that yielded good quality bacon, instead of the fresh meat pigs that had been bred up to then. Yet by switching to the export of bacon, the Dutch had to compete with Danish pig farmers who controlled the London bacon market. To meet this competition, Dutch pig farmers built progeny testing stations in which the offspring of breeding sows were fattened in a controlled environment. The results of these testing stations were used to determine the breeding value of the individual sows.

Many, very different groups of people were involved in the process leading up to the progeny testing stations, including pig breeders, scientists, livestock consultants, journalists and veterinarians. This chapter will consider the exchange of information between these groups and will show how an innovation like progeny testing stations can be explained as a result of a broad change in breeding practices, rather than as the outcome of a straightforward, top-down implementation of (scientific) knowledge.

In recent years, there has been a growing number of publications dealing with similar issues in the history of twentieth-century breeding. In this literature, the influence of Mendelian genetics on breeding practices is often the subject of investigation. It has become clear by now that the influence of Mendelian theory on early twentieth-century developments within breeding was small. The laws of inheritance were not easily applicable to characteristics such as milk yield, egg production and meat growth. Still, in the Netherlands, Mendel's theory was well understood at the time among pig breeders and, as shall be shown, they did not hesitate in applying this knowledge in their daily practice. However, this was done not to ‘rationalize’ pig breeding in the way geneticists and some livestock consultants had in mind, but rather to understand and gain control over very specific qualitative characteristics such as skin colour.