Sheep Industry News August 2022

will aff ct lamb survival, ewe longevity and reproduction, and overall productivity. Breeding more robust and climatic resilient animals will ensure the long-term sustain ability of sheep farming in the U.S.” A proposed outcome of Sheep GEMS is to provide sheep producers with genomic enhanced estimated breeding values, or GEBV, for a suite of traits. What are GEBV? “Accurately identifying the best individuals to become the parents of the next generation is not a trivial task. Fortunate ly, the integration of perfor mance records, pedigree and genomic data is a powerful

Distribution and number of NSIP and USDA/ARS location flock by breed.

although current traits evaluated in NSIP are economically important, they are limited in scope to what can be collected on farm or ranch, or by a qualifi d technician. "While performance in many other health, longevity and effici cy traits impacts fl ock productivity, specialized equipment or increased labor may be required to accurately collect them. Th resources needed to do so are available at USDA/ARS locations. "We are collecting the same information on our ewes in our refer ence fl cks as the Sheep GEMS participants are in their fl cks, along with many other novel traits. Th is will allow NSIP breeders to select for these novel traits without having to record them all in their own opera tions.” What are examples of novel traits? “Udder health is one of them,” Murphy replied. “Recent surveys have estimated that about half of ewes are culled in the U.S. before they reach the end of a ‘normal’ productive life, say at 6 or 7 years of age. Udder health also aff cts ewe longevity as approximately 15 percent of ewes are culled for mastitis or hard bag. Subclinical mastitis – the form of the disease we cannot diagnose without testing ewe milk – is also common and negatively impacts ewe productivity.” At USMARC, we are evaluating 10 traits associated with udder health and conformation on ewes at lambing and at weaning. We are also collecting milk samples to quantify subclinical mastitis. Since these measures are labor intensive, we have selected only a subset of these traits – udder depth and teat placement – for other Sheep GEMS fl cks to collect.” An important element of Sheep GEMS is genomics, with more than 10,000 sheep to be genotyped. Dr. Brad Freking – also a research ge neticist at USMARC – is contributing his expertise in molecular genet ics to the team. Among the information participating fl ock owners will

tool to help sheep producers with this undertaking. By combining this information, geneticists can calculate GEBV, which predict the genetic potential of an animal for each trait evaluated based on thousands of genomic markers.” What do they off er beyond what is already available to sheep pro ducers? “GEBV tend to be more accurate for young animals than traditional EBV, especially for traits that are diffic ult or expensive to measure, such as robustness and climatic resilience. GEBV also allow us to evaluate and diff erentiate lambs from the same litter even before they them selves have been measured. Th is allows us to make selection decisions earlier and make more progress.” Why is the project using Katahdin, Polypay, Rambouillet and Su ff olk breeds? “Th y were selected because they are among the largest – in terms of total number of records – of NSIP breeds and they are each reared at one or more USDA/ARS locations," said Dr. TomMurphy, a research geneticist at the U.S. Meat Animal Research Center in Clay Center, Neb. "Th Katahdin is reared at all three locations, Polypay and Su ff olk at USMARC and the U.S. Sheep Experiment Station, and Rambouillet at the USSES. We have been exchanging rams and ewes of common breeds to strengthen genetic connectedness across USDA/ARS sites.” Murphy is leading eff orts to establish reference populations in each of the breeds involved in Sheep GEMS by connecting genetically fl cks at USDA/ARS centers with those in industry. But why is this necessary? “Th basic concept of the USDA/ARS Genetic Reference Flocks is to bring in genetically representative rams from industry NSIP fl cks and collect standard and novel traits on their progeny," Murphy said. "First ly, this will help us ‘work the kinks out’ of potential new NSIP traits before we ask industry breeders to begin recording them. Secondly,

See GEMS PROJECT on Page 26

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