Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science


The term “selective matings” implies the selection of a sire to breed to each female on an individual, rather than a group or herd basis. Mating systems, other than random mating, may be classed either as the mating of like to like or as the mating of unlikes. This likeness or unlikeness may be based either on blood relationship or on individual appearance. The advantage and limitations of each mating system have been well worked out on a theoretical basis, and some of system have been thoroughly tested by experimentation and in the field. In actual practice many breeders use a combination of two or more of these systems. The perfect mating system or combination of mating systems has not been found, and because of the complexity of the problem there probably could be no perfect system that would work in all herds. Nevertheless, any system that could increase the percentage of desirable offspring enough to make an economic gain for the breeder without harming the breed as a whole would seem to be worth consideration. It is unlikely that any recently devised system of mating could be considered now in principle. The system with which this thesis deals is one involving the mating of unlikes based on the individual appearance of the animals. This may also be called corrective mating, compensatory mating, or negative assertive mating on the basis of somatic resemblance. Breeders of all classes of livestock have long used the mating of unlikes as an effective method of correcting in their herds. Many examples, such as the use of long stretchy board for improving conformation when the sows are short and fat, could be cited to illustrate the mating of unlikes. All of these illustrations, however, would involve the same general principle-that of mating each animal to one which is equally extreme but in the opposite direction in order to increase the tendency for obtaining the desired intermediate in the offspring. The specific system studied here is an application of this principle to dairy cattle. It is known as the Animal Analysis Associates system of analyzing dairy cattle. This system will hereafter be designated by its trademark-a.A.a. The a.A.a. program was originated by William A. Weeks of Rockford. Illinois, formerly a Holstein breeder in partnership with his father in Vermont, and also a former official classifier for the Holstein-Friesian Association of America. Mr. Weeks started his analyzing program on June 21, 1950. Five other men become analyzers the first year, and by July of 1951 approximately 429 Holstein herds in 16 states had been analyzed. At the present time the total number of herds that have had some work done by a.A.a. exceeds 5000. Over 100000 animals have been analyzed, 90 percent of them are Holsteins, and most of these Holsteins are registered. The a.A.a. staff has grown to men distributed throughout the dairy regions of the United States. The opinions of dairymen regarding the a.A.a system vary greatly. Very little, if any research data have been published on this system. A controlled breeding experiment for determining the merit of a mating system such as this would require a great deal of time and expense. The only available date for studying the a.A.a system were to be found in the various herds where the system has been in use for several years. Therefore, it was decided that a survey of the herds using the a.A.a system should be conducted. The objectives of the study described herein are as follows:(1) To gather data and information on the a.A.a system for determining whether or not the system has merit in the breeding of better dairy cattle. (2) To determine whether or not the a.A.a. system can be learned by others. (3) To study the feasibility of carrying out a controlled breeding experiment to determine merits of the a.A.a. system. (4) To determine the acceptance of the a.A.a. program by the breeders and artificial insemination associations.

Library of Congress Subject Headings

Dairy cattle -- Breeding


Includes bibliographical references (pages 53-56)



Number of Pages



South Dakota State University


In Copyright - Non-Commercial Use Permitted

Included in

Dairy Science Commons