The power of the Koehoorn brothers comes evidently from the 'breeding'-pigeonry. Breeders come from famous fanciers: Jos van Limpt 'De Klak', Louis van Loon, Borgmans brothers, Dick Postma and Fernand & Koen Marien. From the flyers, the brothers seldom breed a youngster for their own. For almost 100%, the youngsters (and thus their later racing pigeons) are bred from their 'breeding'-loft! The 'breeding'-loft consists mostly pigeons which are bought as an investment and have no racing experience.
Therefore, it seems reasonable to say that the Koehoorn brothers know a pigeon better than the average pigeon fancier. The reason for this conclusion is that it is diffucult to breed good pigeons from pigeons that never had any racing experience (although they have a good pedigree). But it seems that the Koehoorn brothers can breed exceptionally!
The 'breeding'-pigeonry currently holds 20 'breeding'-couples.