Location: Range Sheep Production Efficiency Research
2022 Annual Report
Objectives
The ARS Grand Challenge calls for a transformation in U.S. agriculture that results in 20% more quality products, with a 20% reduction in environmental resource impacts by 2025. At the Range Sheep Production Efficiency Research Unit (RSPER), also known as the U.S. Sheep Experiment Station, our objectives are based on the premise that the rangeland ecosystem is the environmental resource base and that stakeholder products are quality meat and fiber from sheep and multi-use resilient rangelands. Accordingly, objectives were developed to reflect that food-animal production and rangeland management must be compatible and complementary.
Research objectives are long-term, leveraging former and historic experimental accomplishments to achieve goals of increasing production efficiency, while simultaneously generating ecological benefits. RSPER’s extensive and historic databases of sheep production and genetic endpoints, rangeland vegetation variables, climate measures, and wildlife records were critical in developing project plan objectives. Consistent with the Grand Challenge, our purpose is to equip rangeland sheep producers with research-based tools, solutions, and data necessary to increase the annual weight of quality lamb and wool from ewes at a positive return to the rangeland resource base. Specifically, during the next five years we will focus on:
Objective 1: Increase lifetime reproduction efficiency, net production yield, and product quality of range-type wool flocks. Subobjective 1.A (experimental): Evaluate Suffolk, Siremax, and RSPER terminal-composite (TSC) for ability to increase quantity and value of lamb. Subobjective 1.B (initiative): Establish genetic linkages between experimental and industry flocks to support industry-wide genetic evaluations and development of comprehensive breeding objectives. Subobjective 1.C (experimental): Determine the utility of chlorate salts to mitigate production losses due to postpartum diseases. Objective 2: Estimate ecological value of rangeland management practices in accomplishing Objective 1. Subobjective 2.A (experimental): Determine the sheep-production and ecological value of using sheep grazing to improve sage grouse-nesting habitat in recently-burned mountain big sagebrush steppe.
Objectives are presented as either “experimental” or “initiative.” Experimental objectives are hypothesis driven and accomplished by controlled experimental designs with treatment replication. Initiative objectives are goal driven and aimed at coordinating large datasets or creating opportunities that can be used by others immediately or in the future for discovery-, development-, or solution-oriented research.
Approach
The hypothesis of Obj. 1.A is: “The main factors influencing the value of individual lambs and the lamb-crop as a whole, such as lamb survival, growth rate, and carcass yield and quality, differ between lambs sired by the new Siremax composite and Terminal Sire Composite (TSC) breeds and the industry standard Suffolk breed.” In-house TSC rams and a nation-wide sampling of Suffolk and Siremax rams will be mated to wool-type ewes. Offspring will be reared in a rangeland production system, subsequently weaned, finished, and slaughtered. Lamb pre-weaning and finishing health and performance and carcass yield and quality will be measured, and data will be analyzed to determine sire breeds and sires that excel at the traits of interest.
The goals of Obj. 1.B are to: “Migrate Range Sheep Production Efficiency Research Unit (RSPER) genetics database to the National Sheep Improvement Program (NSIP)” and “Create NSIP-relevant linkages of RSPER flocks to the U.S. sheep industry.” The RSPER genetics database for Rambouillet, Targhee, Polypay, and Suffolk breeds will be uploaded to the Nat'l Sheep Improvement Prog. (NSIP) database. In order to develop NSIP-relevant linkages, a nation-wide sampling of NSIP Rambouillet, Targhee, Merino, and Merino-composite rams across the nation will be purchased from the industry and mated to RSPER Rambouillet and Targhee ewes. Ewe offspring will be retained in the RSPER flock and lifetime production data will be uploaded to NSIP.
The hypothesis of Obj. 1.C is: “Ewe consumption of chlorate salts during early lactation will alter incidences of lamb diarrhea and ewe mastitis and weight-of-lamb weaned from ewes.” Ewes, beginning as yearlings, will be treated with chlorate or no chlorate (control) via drinking water for 4 days immediately after lambing. This treatment regimen will be repeated annually. Four-year cumulative ewe health and production performance will be calculated based on annual health measurements of lamb diarrhea and ewe mastitis morbidity, total count lambs birthed and weaned, and total weight of lambs birthed and weaned. Data will be analyzed to determine efficacy of chlorate to reduce mastitis and diarrhea morbidity in shed-lambing systems and improve lifetime production of range-type ewes.
The hypothesis of Obj. 2.A is: “Post-burn recovery rate of sagebrush canopy cover, a critical factor of sage grouse-nesting habitat, and ewe productivity will be altered based on the season and intensity of grazing management.” Sixteen recently-burned pastures that are in the exponential shrub recovery phase will be assigned to 1 of 4 annual sheep grazing treatments of no spring or fall grazing, moderate spring and fall grazing, light spring and moderate fall grazing, and no spring and heavy fall grazing. The responses of plant community, dominant shrubs, forage production, and sage grouse-nesting habitat suitability will be measured annually. Sheep production will be measured, and dietary selection of sagebrush will be determined by near-infrared spectroscopy of ewe fecal samples. Data will be analyzed to determine the effect of timing of sheep grazing on sage grouse habitat sustainability and sheep production.
Progress Report
This is the final report for project 2056-31610-006-000D, Enhancing Sheep Enterprises and Developing Rangeland Management Strategies to Improve Rangeland Health and Conserve Ecology, which has been replaced by the new project 2056-31610-007-000D, Agroecological Approach to Enhance U.S. Sheep Industry Viability and Rangeland Ecosystem Conservation.
Substantial results were realized over the five years of the project. In Objective 1, “Increase lifetime reproduction efficiency, net production yield, and product quality of range-type wool flocks,” a new terminal sire composite sheep breed, enhanced for use in the U.S. West, was developed and released to the public. The new breed either outperformed or was equivalent to performance of standard terminal-sire breeds used by the industry. Initial response from the public that adopted the new breed was positive, with favorable comments about the hardiness and longevity in extensive, range-based sheep production systems of the U.S. West. Over 70,000 sheep genetics records were submitted to the National Sheep Improvement Program (NSIP). The NSIP is the U.S. sheep industry’s genetics database for development of breeding estimates (genetic merit estimates for important traits). Strength and ultimately the value of NSIP breeding estimates is based on genetic connectivity across U.S. flocks. Over 48 sires, mostly from NSIP-enrolled flocks of Rambouillet and Targhee breeds, were imported and mated to the location’s corresponding sheep flocks. Performance data originating from these flocks were uploaded to NSIP, which in turn enhanced the accuracy of NSIP breeding estimates for overall improvement of the U.S. wool sheep industry. Concomitantly, algorithm-based adjustments were created that facilitate the use of sheep cross-bred offspring performance data to estimate the genetic merit of pure-bred parents, something formerly not possible worldwide.
Use of chlorate salts, added to the drinking water, was demonstrated to drastically reduce fecal Escherichia coli shed in a commercial-scale lambing environment. Pathogenic E. coli is a leading cause of neonatal diarrhea in lambs and mastitis in lactating ewes soon after parturition. Safe and effective strategies about the use of chlorate salts in lambing systems were developed for application in the industry. The progress gained under Objective 1 of the expiring plan provided the genetics and disease mitigation foundation for the new project plan.
In Objective 2, “Estimate ecological value of rangeland management practices in accomplishing Objective 1,” post-fire sheep grazing solutions were developed that facilitate prompt vegetation recovery after fire. Catastrophic wildfire poses the greatest threat to sagebrush steppe ecosystems and the livestock enterprises and wildlife dependent upon on these ecosystems. Traditional range-management practices call for a cessation of grazing for at least two years following fire with the assumption that temporary absence of livestock grazing will facilitate vegetation recovery. Such management is problematic and costly for livestock enterprises dependent upon yearly access to the range. Immediate return of sheep grazing during the fall season following the fire (e.g., one year after a fall fire or five months after a spring fire) was demonstrated to improve perennial grass recovery compared to deferred grazing treatments. Perennial grasses are an important component of the sagebrush steppe, facilitating proper recovery of shrubs and mitigating risk of invasive weeds.
In an initial attempt to understand herbivory of sheep grazing sagebrush ecosystems, a procedure was developed to classify sheep as having either a tolerance for or aversion to bitter flavor added to drinking water. The procedure enabled identification of both phenotypic traits and genotypes of sheep that either tasted or did not taste bitter flavors. The progress gained under Objective 2 of the expiring project plan provided the foundation for further relating quantified taste preferences of sheep with herbivory choices in the grazing system under the new project plan, as well as grazing solutions to be applied in the upcoming (2023) new National Program 215 project plan.
Accomplishments
Review Publications
Davenport, K.M., Taylor, J.B., Henslee, D., Southerland, C., Yelich, J., Ellison, M.J., Murdoch, B.M. 2021. Variation in type two taste receptor genes is associated with bitter tasting phenylthiocarbamide consumption in mature Targhee and Rambouillet rams. Translational Animal Science. 5(3):1-8. https://doi.org/10.1093/tas/txab142.
Vargas Jurado, N., Notter, D.R., Taylor, J.B., Brown, D.J., Mousel, M.R., Lewis, R.M. 2022. Model definition for genetic evaluation of purebred and crossbred lambs including heterosis. Journal of Animal Science. 100:1-14. https://doi.org/10.1093/jas/skac188.
Mousel, M.R., White, S.N., Herndon, M.K., Herndon, D.R., Taylor, J.B., Becker, G.M., Murdoch, B.M. 2021. Genes involved in immune, gene translation and chromatin organization pathways associated with Mycoplasma ovipneumoniae presence in nasal secretions of domestic sheep. PLoS ONE. 16(7). Article e0247209. https://doi.org/10.1371/journal.pone.0247209.
Massa, A.T., Mousel, M.R., Durfee, C.J., Herndon, M.K., Hemmerling, K.M., Taylor, J.B., Neibergs, H.L., White, S.N. 2021. A DNA regulatory element haplotype at zinc finger genes is associated with host resilience to small ruminant lentivirus in two sheep populations. Animals. 11(7). Article 1907. https://doi.org/10.3390/ani11071907.
Sprinkle, J., Sagers, J., Hall, J., Ellison, M., Yelich, J., Brennan, J., Taylor, J.B., Lamb, J. 2021. Protein supplementation and grazing behavior for cows on differing late-season rangeland grazing systems. Animals. 11(11). Article 3219. https://doi.org/10.3390/ani11113219.
Oliveira, R.D., Mousel, M.R., Gonzalez, M.V., Durfee, C.J., Davenport, K.M., Murdoch, B.M., Taylor, J.B., Neibergs, H.L., White, S.N. 2022. A high-density genome-wide association with absolute blood monocyte count in domestic sheep identifies novel loci. PLoS ONE. 17(5). Article e0266748. https://doi.org/10.1371/journal.pone.0266748.
Page, C.M., Knuth, R.M., Murphy, T.W., Rule, D.C., Bisha, B., Taylor, J.B., Stewart, W.C. 2022. Effects of increasing dietary zinc sulfate fed to gestating ewes: II. Milk somatic cell count, microbial populations, and fatty acid composition. Applied Animal Science. 38(3):285-295. https://doi.org/10.15232/aas.2022-02268.
