Swine breeders in this country have been handicapped by not having had a satisfactory basis for the effective selection of their breeding stock. The judging of livestock by experienced men based on visual inspection has been responsible for considerable progress, but it should be supplemented by additional facts in order to determine accurately such essentials as ability to reproduce efficiently, to grow rapidly and to convert a unit of feed into a near-maximum of quality meat and by-products.

Actual records of performance have been used for years as a basis for the breeding of race horses. The dairyman and the poultryman also use records of performance. The regular weighing of the milk from each individual cow and the testing of the fat content of the milk by means of the Babcock test, and the trap-nesting of hens are modern, more fundamental methods of discriminating between desirable and undesirable animals. Swine breeders have not had a record of the performance of their sows and, consequently, have been greatly handicapped.