February 18, 2015

The Objective Evaluation of Pig Breeds in the Netherlands

Today's post is by Steven van der Laan (MSc), one of our Dutch colleagues affiliated with the Descartes Center and whom the blog editors met at the 2014 Annual Meeting of the History of Science Society! Steven is a PhD-candidate from Utrecht University (Netherlands) who is working on the history of pig breeding. His main interests in this research is the relation between scientific research and the practice of pig breeders.
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Before the turn of the nineteenth century, grading of breeding pigs in the Netherlands was mostly done in an unofficial way: a breeder went to the market or to the farm of a colleague, and by using his ‘breeders’ eye’, an embodied skill he had developed through years of experience in breeding pigs, he chose a boar or sow which he thought would improve his own breeding stock. With the establishment of the herdbooks around 1900, it became necessary to quantify the grading process because all pigs had to be evaluated according to the same criteria. The quantification of breed characteristics however turned out to be difficult and, as it eventually turned out, the best way to grade pigs could not do without the breeders’ eye.

Fig. 1. The Yorkshire. (Notice erect ears, low shoulders.)
 The first attempts at quantification consisted of short descriptions of the most prominent characteristics that separated the two breeds that were most commonly held by Dutch farmers, the Yorkshire and the German Landrace (Figs. 1 and 2). The Yorkshire for instance had to have erect ears whereas the German Landrace typically had floppy ears. [1] During the first twenty years after 1900 the descriptions became more and more elaborate in order to achieve complete quantification of the breed characteristics. This trend culminated in the publication of a booklet by veterinarian Engbert Dommerhold that meticulously described every part of a pig’s body. [2] According to Dommerhold, it was not enough for the Yorkshire to have erect ears. A good representative of the breed also had to have ears “fringed by fine hair”, its rump should not be more than 4 centimeters above its withers and the angle between its snout and brow had to be between 100 and 120 degrees, this in contrast to the German Landrace, for which the angle was supposed to be between 120 and 150 degrees.

Fig. 1. German Landrace. (Notice floppy ears.)
While these elaborate descriptions appear to represent an effort to make the judging of pigs more objective, Dommerhold, at the end of his booklet, gave an example of an effective method for grading pigs that disregarded this strive for objectivity and implicitly acknowledged the indispensability of the subjective breeders’ eye. This method was initially developed around 1920 by the herdbook of the provinces of Gelderland and Overijssel and it was based on grading the different parts of the pig. Depending on the breed and the importance of a specific part of the body for that breed, each part was awarded a number of points. For instance, the head of both Dutch breeds could get six points, the German Landrace could get seven points for its chest and the Yorkshire six. If the total number of points was above a certain minimum, the pig was accepted for registration in the herdbook.

Fig. 3. Evaluation form. 
Obviously, the grading according to this method is more subjective than (quantitatively) comparing a particular pig with its breed description, as the points awarded were based on the opinion of herdbook officials and did not relate to any physical measurement. In fact, it might be argued that whereas Dommerhold’s breed descriptions were an effort to replace the breeders’ eye with objective measurements, the new method served largely to accommodate the breeders’ eye. This becomes even clearer when we look at how the method was extended with a weighting factor. In this extended version, the herdbook official did not directly determine the grade, but had to give his opinion on all features of the pig, on the basis of the following list of adjectives: excellent, very good, good, somewhat deviant, strongly deviant, deficient and bad (See Fig. 3). These adjectives each had their own weighting factor, ranging from 1 for excellent to 0 for bad. The total number of points a pig could get for a certain feature were then to be multiplied by this factor. In this extension, subjective notions that were usually used to express an evaluation by the breeders’ eye were thus quantified by connecting them to grades.

It may seem rather curious why Dommerhold, and also veterinarian Hendrik Kroon, both leading figures in the world of pig breeding, were of the opinion that this grading method allowed for more “precision” and less “bias” in the grading of pigs, as it was based on thoroughly subjective notions like excellent and bad. [3]  Their reason for not recommending measuring every part of the pig for grading purposes, was that it did not take into account that the individual parts of the pig had to form a “harmonious” whole, as Dommerhold put it. This is also why in the grading system 25 points were reserved for “general appearance”. Although people like Dommerhold and Kroon thus had a very definite idea about the ideal type for a particular pig breed, as is evident from their elaborate quantitative descriptions, they knew that the evaluation of individual pigs and deciding whether they resembled this ideal type, was a task that could not be accomplished by measuring rods and weighing scales. Measurements could not tell if the individual parts of a pig had the right proportions. The breeders and herdbook officials did have this ability and that is why people like Dommerhold and Kroon deemed the subjective breeders’ eye to be indispensable in the grading of pigs.

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[1]  J. Timmermans, as cited by A. Paridaans, 75 jaar varkensfokkerij in stamboekverband (Veldhoven 1987), p.20.
[2] E. Dommerhold, Het uitwendig voorkomen van het varken (Maastricht 1920).
[3] H. Kroon, Het Varken (Deventer 1924), p. 47.

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