Mating Systems
Dr. Robert A. Long - Reprinted with permission from Beef Logic
Random Mating
Random mating is the mating of individuals without consideration of either pedigree or performance. In its purist form random mating amounts to allowing the cattle to "run the ranch." Unfortunately, this is essentially what results in many purebred herds which use several unrelated bulls each season and base the selection of those sires on their show ring record at Denver and Louisville or the prediction of a livestock magazine representative as to which bulls will be "hot" next year. Breeders must have a goal and develop a sound, factual plan to achieve it or herd improvement will not occur.
Inbreeding
Inbreeding has a negative connotation with most people. The mating of close relatives in the pedigree of cattle, horses, dogs or people frequently causes alarm. However, inbreeding can be an effective tool in livestock breeding programs when understood and properly used. Defined, inbreeding is simply the mating of animals more closely related than the average of the breed or population from which they come. This definition implies that all animals within a breed are somewhat related and therefore carry a degree of inbreeding, which is true. Breeds are created by inbreeding. However, such inbreeding is rather mild and after a breed is formed the term "inbreeding" usually refers to closely related matings such as full brother/sister or sire/daughter matings. Genes occur in pairs. If each gene of a pair is identical an animal is said to be "homozygous" for that gene and if the genes of the pair are different an animal is termed "heterozygous". In a gene pair of "A" and "a" only three genotypes are possible - AA, Aa or aa. Each new individual receives only one gene of each pair from each parent so the results for each type of mating is as follows:
Type of Mating Offspring
- AA x AA 100% AA
- AA x Aa 50% AA 50%Aa
- AA x aa 100% Aa
- Aa x Aa 50% Aa 25%AA 25%aa
- Aa x aa 50% Aa 50% aa
- aa x aa 100% aa
When inbreeding is initiated in a heterozygous herd and closely related animals are mated the offspring tend to become more homozygous in thier genotype. This explains why inbred animals are more uniform than outbred individuals. Note that in the case of matings 1 and 6 above, when animals of the same genotype are mated the offspring are all alike.
Biography of Robert A. Long, Ph.D.
Professor Emeritus, Animal Science Department, Texas Tech University
Dr. Long was born and reared on a general livestock farm in Ohio. He received the Bachelor of Science degree from The Ohio State University and the Master of Science and Doctor of Philosophy degrees from Oklahoma State University. He held teaching and research appointments at Oklahoma State and the University of Kentucky before becoming Chairman of the Animal Science Division at the University of Georgia, a post he held for eleven years. In 1967 he joined Ankony Angus Corporation as Director of Research and Development and became Executive Vice President and Chief Operation Officer.
In 1976 Dr. Long joined the Faculty at Texas Tech University where he was chairman of the Animal Science Department. He is currently Professor Emeritus having retired as of January 1992 but remains active as a writer, lecturer and consultant to the beef industry.
Dr. Long has lectured on the breeding, feeding, management and marketing of beef cattle in beef producing countries throughout the world. He has assisted major meat packers in the United States, Argentina, Brazil and Chile by training cattle buyers; has served as consultant to various purebred and commercial breeders as well as feedyard operators and has judged beef cattle at all major national shows in the United States and Canada as well as most state fairs.
Research projects have dealt with ruminant nutrition and growth and development with particular attention to skeletal size and muscularity as they affect beef cattle performance and carcass characteristics.
Dr. Long is a member of the American Society of Animal Science, Phi Kappa Phi, Alpha Zeta, Gamma Sigma Delta and Sigma Xi. Among other honors he was the 1991 recipient of the Beef Improvement Federation's Pioneer Award and inducted in to the Angus Heritage Foundation.
In 1992 Dr. Long acted as "Delegation Leader" for the Citizen Ambassador Program by leading a group of United States beef producers on a three week tour of China's beef production industry. During September and October of 1993 he gave the keynote address at the annual convention of the Australian Beef Improvement Association. This association then sponsored Dr. Long in a tour of Australia during which he presented sixteen seminars on beef cattle improvement. In 1996 Dr. Long was sponsored by the Executive Service Corp. on a 90 day stay in Chile where he worked with a large meat packer with plants in Santiago, Timuco and Osorno improving the sanitation of "in plant" procedures and training cattle buyers in the selection of slaughter cattle on increased lean meat yield. In 2000 and 2003 Dr. Long was the featured speaker at several beef industry seminars in Argentina.
Dr. Long's column entitled "BEEF LOGIC" was carried by several national beef cattle publications and occasional columns published by journals in Australia, Canada, and New Zealand.