Title: A resource for broadening the genetic base of livestock populations Author
Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: September 1, 2012
Publication Date: September 28, 2012
Citation: Blackburn, H.D. 2012. A resource for broadening the genetic base of livestock populations. Popular Publication. 29:4-5. Interpretive Summary: Over the last century there has been a contraction in livestock genetic diversity. Gene banking is one mechanism that can be used to capture genetic diversity for future use. The National Animal Germplasm Program (NAGP) has developed such a gene bank for livestock over the past decade and it currently contains over 800,000 samples. Livestock breeders have used the collection to introduction of genetic variability into livestock populations. In 2008 and 2009 Cantagree Milking Shorthorns submitted a request to NAGP to use semen from two Milking Shorthorn bulls, Borgs Dairy King 5th (born 1959) and Floyd Crest Dairymaster (born 1954). Upon receiving the semen Cantagree artificially inseminated their selected cows with semen from the two bulls and nine calves were born. Of these calves there were several bulls which have been raised, sent to an AI stud where they could be collected and the semen cryopreserved. A portion of these collections were then sent back to NAGP to replenish and add to the Milking Shorthorn collection. This example of using semen from the repository underscores the utility of developing and maintaining a national gene bank with a collection that is publically available.
Technical Abstract: For the past decade the National Animal Germplasm Program (NAGP) has been acquiring semen, embryos and blood samples from U.S. livestock. To date more than 800,000 samples from over 18,000 animals have entered the repository. A substantial portion of these samples were derived from rare and minor livestock breeds. In total, samples from 48 rare and minor breeds of cattle, sheep, goats, pigs and chickens have been acquired. Originally the intent in developing the collection was to have a collection of “last resort”; in-other-words to use the samples if and when a breed was in critical danger. However, since the collection’s initiation it has become clear that the collection can be used for more routine uses. For example, to date samples from over 3,300 animals have been released from the repository for: reconstituting populations, adding genetic variation to populations, and DNA studies. This article will detail how the collection has been used by several breeders that raise rare or minor breeds of livestock. In 2008 and 2009 Cantagree Milking Shorthorns submitted a request to NAGP to use semen from two Milking Shorthorn bulls, Borgs Dairy King 5th (born 1959) and Floyd Crest Dairymaster (born 1954). They believed these two bulls would add needed and useful genetic diversity to their herd and subsequently benefit the breed. For the Milking Shorthorn breed it has been estimated that the average inbreeding level is 6% (AIPL website). In comparison these two bulls are lowly related to the current population and it was estimated that their expected future daughter inbreeding would be 1.4% for each bull. The request was reviewed by the NAGP Dairy Species Committee (which included the CEO of the Milking Shorthorn Association) and they recommended that the semen be released. Upon receiving the semen Cantagree artificially inseminated their selected cows with semen from the two bulls and nine calves were born. Of these calves there were several bulls which have been raised, sent to an AI stud where they could be collected and the semen cryopreserved. A portion of these collections were then sent back to NAGP to replenish and add to the Milking Shorthorn collection. A different type of repository use has been to assist breeders with adoption or development of new technologies, in addition to facilitating the formation of different genetic combinations. For several years NAGP has worked with Ken and Oogie McGuire in evaluating nonsurgical AI with Black Welsh Mountain sheep. Semen samples from their Black Welsh Mountain rams have been collected and cryopreserved as part of developing the Black Welsh Mountain sheep collection in the repository. Sufficient quantities of semen have been collected so that the repository samples could be used to test and evaluate transcervical AI approaches in sheep. While the results to date are inconclusive the project has enabled the breeder to generate lambs from desired matings and with the subsequent collection of semen samples from those progeny new genetic combinations were entered into the repository. The germplasm collection is maintained as a public good. Therefore, samples are distributed at no cost. With the assistance of our species committees, the livestock industry, and ALBC a process has been developed for accessing the germplasm in the collection. This involves: • looking up the animals in the collection of the breed of interest on the internet or contacting us about animals of interest, • submitting a germplasm request form, which can be obtained from our website, • review of the request and development of a recommendation by the appropriate NAGP species committee, and • making a final determination about the request. Once a request is approved the shipment is coordinated with the requester. There are conditions which prohibit us from distributing germplasm. For example, there has to be sufficient number of semen units in the repository to be able to release material without compromising the breed reconstitution element of this program. Second, the requested material can be obtained directly from the breeder. In-other-words, a potential users first step should be to obtain the germplasm from the original source or from other practicing breeders that may have similar genetic backgrounds. Third, the requestor is asked how the germplasm will be handled (e.g., inseminated) and if they have prior experience using the technique, or if they are working with some person or entity that does routinely do matings with cryopreserved semen. If this element cannot be met the request will be denied. The example of using semen from the repository underscores the utility of developing and maintaining a national gene bank with a collection that is publically available. While a substantial collection has been developed there is still a need to further enhance the collection particularly for the rarer breeds. Therefore, we will continue to seek additional animals from which samples can be collected, cryopreserved and utilized by breeders.