Reprod Dom Anim 43 (Suppl. 2), 83–88 (2008); doi: 10.1111/j.1439-0531.2008.01146.x ISSN 0936-6768 Reproductive Biotechnology and Gene Mapping: Tools for Conserving Rare Breeds of Livestock JA Long Animal Biosciences and Biotechnology Laboratory, Beltsville Agricultural Research Center, US Department of Agriculture, Beltsville, MD, USA Contents Ankole for imported breeds lost entire herds. The Today’s livestock diversity originated from the wild ancestor physiology and grazing behaviour of the imported species and was subsequently shaped through the processes of breeds typically are not adapted to the natural pastures mutation, genetic drift, and natural and human selection. Only and climate of Africa, especially when drought strikes a subset of the diversity present in the ancestral species (Kay 1997). In another example, cross-breeding has survives in the domestic counterparts. A 2007 report released almost decimated purebred populations of the East by UN Food and Agriculture Organization ‘The State of the African Red Maasai sheep, which is renowned for its World’s Animal Genetic Resources’, compiled from surveys disease resistance to gastrointestinal parasites and high conducted in 169 countries, found that nearly 70% of the world’s remaining livestock breeds live in developing countries. productivity under extremely challenging environments. The UN report was presented to more than 300 policy makers, In the mid-1970s, as a result of a subsidized dissemina- scientists, breeders, and livestock keepers at the First Interna- tion program, many farmers in Kenya cross-bred their tional Technical Conference on Animal Genetic Resources, Red Maasai flocks with the less-hardy Dorpers sheep, held in September 2007 in Interlaken, Switzerland. The which subsequently proved unsuitable in many produc- conference aims were to adopt a global plan of action for tion areas. In 1992, the International Livestock conserving animal genetic resources as its main outcome. In Research Institute (ILRI) undertook an extensive search this paper, the current and potential contributions of repro- in Kenya and northern parts of the United Republic of ductive and molecular biotechnology are considered as tools of Tanzania, and was only able to locate a very small conserving rare breeds of livestock. number of purebred animals, which later showed some levels of genetic contamination (Gibson and Candiff Introduction 2000). The extinction of a breed or population means the Of the 50 000 known mammalian and avian species, a loss of its unique adaptive attributes, which are under relatively small proportion has been domesticated. the control of many interacting genes and are the results Approximately 40 livestock species, shaped by a long of complex interactions between the genotype and the history of domestication and development, contribute to environment. Figure 1 illustrates the current status of today’s agriculture and food production. Livestock livestock breeds (FAO 2007). The regions with the breed development has been and continues to be a highest proportion of their breeds classified as at risk are dynamic process of genetic change driven by selection Europe (28% of mammalian breeds; 49% of avian pressures, including environmental factors and human breeds) and North America (20% of mammalian breeds; intervention through controlled breeding and hus- 79% of avian breeds). Europe and North America are bandry, which has resulted in a great variety of the regions that have the most highly specialized genetically distinct breeds. The livestock breeds devel- livestock industries, in which production is dominated oped over thousands of years has, until recently, caused by a small number of breeds. In recent years, many of a net increase in genetic diversity over time. During the the world’s small farmers have abandoned their tradi- past 100 years, however, there has been a net loss of tional animals in favour of higher yielding stock diversity because of an increased rate of extinction of imported from Europe and the USA. For example, in livestock breeds and varieties [UN Food and Agricul- 1994 local breeds comprised 72% of the sow population ture Organization (FAO) (2007)]. The number of breeds in northern Vietnam; within 8 years, however, this figure lost over the past 8 years is rapidly approaching the rate had dropped to just 26%. Of the country’s 14 local pig of extinction that occurred from 1900 to 1999 (Table 1). breeds, five are now listed as vulnerable, two are Losses have been accelerated by the rapid intensification considered critical state and three are facing extinction. of livestock production, a failure to evaluate local The 2007 report, ‘The State of the World’s Animal breeds, and inappropriate breed replacement or cross- Genetic Resources’, compiled by the FAO, with contri- breeding facilitated by the availability of high perform- butions by the ILRI and other research groups, ing breeds (FAO 2007). As an example of inappropriate surveyed farm animals in 169 countries. Nearly 70% breed replacement, Uganda’s indigenous, drought- of the entire world’s remaining unique livestock breeds hardy Ankole cattle could face extinction within are found in developing countries, which as described 20 years because they are being rapidly supplanted by above, are at risk from the importation and farming of Holstein-Friesians, a breed which produces much more exogenous livestock breeds. Renowned organizations milk. During a recent drought, however, farmers who such as the ILRI and FAO have spearheaded the first had Ankole cattle were able to walk them long distances important step for conservation by conducting livestock to reach water sources while those who had traded the Ó 2008 No claim to original government works 84 JA Long Table 1. Livestock breed extinction rates over time dotal and published reports of applying these technologies to conserving rare livestock breeds. The Year span Number of breeds Percent of breed Rare Breeds Program in Colonial Williamsburg, VA Before 1900 15 2 (USA) makes use of semen cryopreservation for live- 1900–1999 111 16 stock breeds dating from the 17th and 18th centuries, After 1999 62 9 a including Devon cattle, Leicester sheep, Ossabaw pigs Unspecified 502 73 and American Cream horses, although actual numbers Total 690 100 of offspring from artificial insemination with fro- aUnspecified = no year of extinction indicated. Adapted from FAO (2007). zen ⁄ thawed semen have not been documented to date. The Hamilton Rare Breeds Foundation in Hartland, VT (USA) has pioneered in the use of frozen semen in the breed surveys. These surveys are time-consuming and Poitou Donkey, an ancient breed dating back over logistically complex; however, ILRI scientists have 2000 years, and is the first group to have produced foals developed and integrated the Domestic Animal Genetic from the rarest breed of donkey in existence today. Resources Information System with the FAO’s Domes- Embryo transfer, pioneered in agricultural species in tic Animal Diversity Information System to streamline the 1930s, also has been reported in use with heritage the process. These web-based information systems livestock breeds. In collaboration with the Swiss Village provide a means for curation and dissemination of Farm (SVF) Foundation in Newport, RI (USA), valuable information that will support development of frozen ⁄ thawed embryos from the Tennessee Myotonic conservation priorities, as well as provide a database for or fainting goat breed were surgically transferred into use of reproductive and molecular biotechnologies to two surrogate Nubian does (a common domestic breed) maintain valuable genetic resources. and resulted in the birth of one healthy buck (Matsas et al. 2005). In 2006, the SVF Foundation reported a second birth from interspecies embryo transfer: an Impact of Reproductive Biotechnology on endangered Gulf Coast lamb born to a Santa Cruz Livestock Conservation ewe. The Gulf Coast sheep provides a good example for Modern reproductive biotechnologies, such as artificial the importance of preserving the unique genetic attri- insemination, embryo transfer, in vitro fertilization, butes of heritage livestock breeds, as the Gulf Coast is gamete ⁄ embryo micromanipulation, semen sexing, gen- sheep is extremely resistant to parasites and nearly ome resource banking and somatic cell nuclear transfer impervious to the foot rot that plagues many other ovine (cloning) have enormous potential for conserving rare breeds. breeds of livestock. The advent of artificial insemination One of the most promising areas of reproductive in the 1940s with cattle and semen cryopreservation in biotechnology is the creation of genetic resource banks the 1950s with poultry was instrumental in the successful as a conservation tool for rare livestock breeds. The transfer of genetic material between and among live- concept of banking gametes, embryos and DNA mate- stock populations and breeds. There are several anec- rial for conservation purposes is not new, as the idea has Risk status of the world's mammalian breeds in January 2006: absolute (table) and percentage (chart) figures by region 100% 80% 60% 40% 20% 0% International Near & middle Southwest Africa Asia Europe Latin america North america Transboundry World East pacific breeds Unknown 384 469 459 304 107 79 80 58 1940 Critical 13 23 182 9 0 12 9 7 255 Critical-maintained 0 4 51 4 0 0 0 0 59 Endangered 26 50 249 21 6 22 11 22 407 Endangered-maintained 4 3 142 9 0 1 1 0 160 Extinct 35 45 481 21 5 49 6 1 643 Not-at-risk 187 776 664 81 85 13 17 312 2135 Fig. 1. Proportion of the world’s breeds by risk status category. Adapted from FAO (2007) Ó 2008 No claim to original government works Biotechnology Methods for Preserving Rare Livestock 85 Table 2. Rare and historic breed livestock genetic resource banks Zealand’s Rare Breeds Conservation Society found fresh hoof-prints of two cattle on Enderby Island. Five Name Country months later, the world’s only surviving Enderby Island Avian Resource Center Canada ⁄ British Columbia cow and her heifer calf were captured.