A germplasm collection curated by the United States Department of Agriculture (USDA), Agricultural Research Service (ARS), National Animal Germplasm Program contains of over one million samples from over 55,000 animals, representing 165 livestock and poultry breeds. The collection was developed to provide genetic conservation and security for the U.S. livestock sector. Samples in the collection span 60 years, suggesting a wide range of genetic diversity and genetic change is represented for rare and major breeds. Classifying breeds into four groups based upon registration or census estimates of population size of < 1000, < 5000, < 20,000, and > 20,000 indicated that 50% of the collection is comprised of rare breeds in the < 1000 category. As anticipated, collections for breeds in the < 20,000 and > 20,000 are more complete (86% and 98%, respectively) based upon an index combining the number of germplasm samples and the number of animals. For the rarest breeds (< 1000), collection completeness was 45%. Samples from over 6000 animals in the collection have been used for adding diversity to breeds, genomic evaluation, reconstituting populations, or various research projects. Several aspects of collecting germplasm samples from rare breeds are discussed. In addition, approaches that could be used to enhance the status of rare breeds via the repository use are presented. However, given the array of obstacles confronting rare breeds, the gene bank may be the most secure prospect for the long-term conservation of rare breed genetics.

Long-term sustainability of breeds depends on having sufficient genetic diversity for adaptability to change, whether driven by climatic conditions or by priorities in breeding programs. Genetic diversity in Suffolk sheep in the United States was evaluated in four ways: 1) using genetic relationships from pedigree data [(n = 64 310 animals recorded in the US National Sheep Improvement Program (NSIP)]; 2) using molecular data (n = 304 Suffolk genotyped with the OvineHD BeadChip); 3) comparing Australian (n = 109) and Irish (n = 55) Suffolk sheep to those in the United States using molecular data; and 4) assessing genetic relationships (connectedness) among active Suffolk flocks (n = 18) in NSIP. By characterizing genetic diversity, a goal was to define the structure of a reference population for use for genomic selection strategies in this breed. Pedigree-based mean inbreeding level for the most recent year of available data was 5.5%. Ten animals defined 22.8% of the current gene pool. The effective population size (N_e) ranged from 27.5 to 244.2 based on pedigree and was 79.5 based on molecular data. Expected (H_E) and observed (H_O) heterozygosity were 0.317 and 0.306, respectively. Model-based population structure included 7 subpopulations. From Principal Component Analysis, countries separated into distinct populations. Within the US population, flocks formed genetically disconnected clusters. A decline in genetic diversity over time was observed from both pedigree and genomic-based derived measures with evidence of population substructure as measured by F_ST. Using these measures of genetic diversity, a framework for establishing a genomic reference population in US Suffolk sheep engaged in NSIP was proposed.

Lamb survivability is an important trait from both an economic and animal welfare perspective. Five breeds at the U.S. Sheep Experiment Station were evaluated for survival to weaning and included 74,448 records from 43 years. Objectives were to evaluate 1) the influence of lamb and littermate competition on lamb survivability to 3 d and 120 d (weaning); 2) the influence of within-litter competition on birth weight; 3) the relationship between within-litter birth weight deviation and lamb survivability, 4) the influence of ewe age on lamb survivability and birth weight, and 5) reasons for and timing of lamb loss. Sex of littermate(s) had an impact on lamb survivability, which was more pronounced for triplets than for twins. Although not significant, female birth weights were lighter in mixed-sex litters than all-female litters. Within-litter birth weight deviation had an impact on lamb survivability with lambs from below mean weight litters that were more than 1 kg lighter than the litter having less than a 50% chance of survival. Both young and old ewes had lower lamb survival than mid-age ewes. Reasons for lamb loss differed depending on the age of the lamb with weak and trauma categories resulting in early loss and predation resulting in later loss. This study provides insight into within-litter competition for use in future genetic evaluation.

Direct genetic selection for increased ewe longevity can improve flock profitability and animal welfare. However, longevity indicator traits are not presently evaluated by the National Sheep Improvement Program (NSIP). The primary objective of this study was, therefore, to estimate genetic parameters for 8 longevity indicator traits using data collected in NSIP Katahdin flocks. Ewes (n = 12,734) were born between 1989 and 2020 in 58 flocks across the U.S. and were daughters of 1,245 sires and 6,325 dams. Traits evaluated were age at the last lambing (ALL), length of productive life (PL; number of days between the first and last lambing), total number of litters (TNL), total number of lambs born (TNB) and weaned (TNW) over ewe lifetime, total lamb birth weight (TLB) and total lamb weight at weaning (TLW) over ewe lifetime, and TLW divided by the ewe’s 120 d adjusted body weight (TLWadj). Variance components were estimated using the AIREML method based on fitting an animal model using either a pedigree (A) or blended pedigree and genomic (H) relationship matrix. Genomic information of 10,032 animals genotyped with a 50K SNP chip was included in the analyses based on H matrix. Age at first lambing and birth-rearing type of the ewe were fitted as fixed effects, while the contemporary group (CG: flock-year-season of ewe’s birth) was fitted as either a fixed (contemporary group fitted as a fixed effect) or random (contemporary group fitted as a random effect) effect. Breeding values and their accuracies were obtained for 127,535 animals in the pedigree using either best linear unbiased prediction (BLUP) or single-step genomic BLUP. Genetic trends were evaluated based on all combinations of CG type and method for predicting breeding values. The averages of ALL, PL, TNL, TNB, TNW, TLB, TLW, and TLWadj were 1100 d, 890 d, 2.7 litters, 4.6 lambs, 4.3 lambs, 18 kg, 70 kg, and 2.8 kg/kg of ewe weight, respectively. The H matrix performed better than the A matrix, based on akaike information criterion and estimates of breeding value accuracy. Higher average accuracy values were observed when fitting CG as a random effect. The heritability estimates ranged from 0.06 ± 0.02 (TLWadj) to 0.15 ± 0.02 (TLB). All genetic and phenotypic correlations between longevity traits were greater than 0.80. Genetic trends were significant and positive for all traits, but no substantial genetic gains were observed. Considering the observed average values and the estimated genetic parameters, we recommend that longevity becomes part of the selection objectives for U.S. Katahdin sheep.

Social conflict over rangeland-use priorities, especially near protected areas, has long pitted environmental and biodiversity conservation interests against livestock livelihoods. Social–ecological conflict limits management adaptation and creativity while reinforcing social and disciplinary divisions. It can also reduce rancher access to land and negatively affect wildlife conservation. Communities increasingly expect research organizations to address complex social dynamics to improve opportunities for multiple ecosystem service delivery on rangelands. In the Greater Yellowstone Ecosystem (GYE), an area of the western US, long-standing disagreements among actors who argue for the use of the land for livestock and those who prioritize wildlife are limiting conservation and ranching livelihoods. Researchers at the USDA-ARS US Sheep Experiment Station (USSES) along with University and societal partners are responding to these challenges using a collaborative adaptive management (CAM) methodology. The USSES Rangeland Collaboratory is a living laboratory project leveraging the resources of a federal range sheep research ranch operating across sagebrush steppe ecosystems in Clark County, Idaho, and montane/subalpine landscapes in Beaverhead County, Montana. The project places stakeholders, including ranchers, conservation groups, and government land managers, in the decision-making seat for a participatory case study. This involves adaptive management planning related to grazing and livestock–wildlife management decisions for two ranch-scale rangeland management scenarios, one modeled after a traditional range sheep operation and the second, a more intensified operation with no use of summer ranges. We discuss the extent to which the CAM approach creates opportunities for multi-directional learning among participants and evaluate trade-offs among preferred management systems through participatory ranch-scale grazing research. In a complex system where the needs and goals of various actors are misaligned across spatiotemporal, disciplinary, and social–ecological scales, CAM creates a structure and methods to focus on social learning and land management knowledge creation.