240 • Technologies To Maintain Biological Diversity 



mules, and goats, needing special attention to 

 ensure their survival (26). 



Private companies also make significant con- 

 tributions to animal germplasm maintenance. 

 For example, the majority of poultry germplasm 

 is maintained by firms that operate both domes- 

 tically and internationally (6). Several maintain 

 unselected, random-bred control lines that 

 serve as reservoirs of genetic diversity. These 

 lines, however, are vulnerable to changes in 

 economic conditions, and their maintenance 

 does not currently represent public or indus- 

 try policy. 



Artificial insemination (A.I.) firms control 

 and distribute the majority of U.S. dairy cattle 

 germplasm. These companies have formed 

 pools of individual breeders involved in 

 planned matings, testing progeny of specific 

 germplasm strains, and development of im- 

 proved breeding lines (6). Companies focus 

 almost entirely on Holstein cattle because the 

 market is so large. Increased emphases on 

 planned matings among superior individuals 

 have been required to maximize genetic im- 

 provement within the dairy industry because 

 of intense competition among A.I. organi- 

 zations. 



As a result, new bulls for use in artificial in- 

 semination often represent the offspring of a 

 small sample of bulls from the previous gener- 

 ation. For example, of the 6 to 7 million dairy 

 cows bred each year in the United States, about 

 65 percent are impregnated by only 400 to 500 

 A.I. sires. In addition, of the approximately 

 1 ,000 performance-tested dairy bulls in a given 

 year, nearly half are sons of the 10 best bulls 

 of the previous generation (67). This process 

 tends to maximize rates of genetic improvement 

 and almost certainly will result in an excessive 

 narrowing of the genetic base. 



Researchers affiliated with universities and 

 Agricultural Experiment Stations help identify 

 genetic resources or help maintain and develop 

 germplasm resources, although not as much as 

 breed associations or private industries do. For 

 example, one researcher at the University of 

 Connecticut has produced an international 

 registry of poultry genetic stocks that is annu- 



ally updated and acts as an important catalog 

 of existing poultry resources (53). University 

 animal or veterinary science departments may 

 maintain small breeding populations of live- 

 stock for experimental and educational pur- 

 poses (26). 



U.S. universities with programs for domes- 

 tic animal research and utilization also play a 

 role at the international level. The International 

 Sheep and Goat Institute associated with Utah 

 State University, for example, works with re- 

 searchers and livestock operators in other coun- 

 tries to identify and propagate genotypes of 

 sheep and goats. Although the focus of the in- 

 stitute is to assist countries in the production 

 of sheep and goats best-suited to local environ- 

 ments, its members are also involved in train- 

 ing international institutions in the storage and 

 management of sheep and goat genetic re- 

 sources (29). 



Even with these various efforts, the overall 

 diversity within many domestic animal breeds i 

 is declining (6). In summary: " 



• Storage facilities do not exist for in vitro 

 maintenance of sheep, swine, or poultry 

 genetic stocks. 



• Breed associations report that although a 

 few breeds of sheep in the United States 

 have declined to very small numbers, global 

 diversity of sheep germplasm remains 

 adequate. 



• Genetic diversity in dairy and meat goats 

 does not appear to be changing signifi- 

 cantly. 



• Because relatively few competitive strains 

 of highly specialized egg and meat chickens, 

 turkeys, and waterfowl account for much 

 of the world poultry populations, there is 

 concern about maintaining adequate ge- 

 netic diversity for future needs. 



• The increasing emphasis on whole-milk 

 production dairy cattle favors the adoption 

 of Holstein breeds among milk producers, 

 causing the decline of other minor dairy 

 breeds. 



• Genetic diversity appears to be stabilized 

 or increasing slightly in beef cattle in the 

 United States. 



