|STEWART, WHITNEY - University Of Wyoming|
|SCASTA, JOHN - University Of Wyoming|
|Taylor, Joshua - Bret|
|Murphy, Thomas - Tom|
|JULIAN, ALEXIS - University Of Wyoming|
Submitted to: Applied Animal Science
Publication Type: Review Article
Publication Acceptance Date: 4/15/2021
Publication Date: 5/20/2021
Citation: Stewart, W.C., Scasta, J.D., Taylor, J.B., Murphy Jr, T.W., Julian, A.A. 2021. Invited Review: Sheep mineral nutrition considerations for extensive production systems. Applied Animal Science. 37(3):256-272. https://doi.org/10.15232/aas.2021-02143.
Technical Abstract: PURPOSE: Discuss contemporary and pertinent considerations related to mineral supplementation strategies for sheep grazing marginal rangelands in extensively managed production systems. Considerations include complex interactions of soil geochemistry, plant type and phenology, mineral intake variation, trace mineral interactions, and sheep breed and productivity changes through time that influence animal requirements. SOURCES: Information was gathered from the gray literature, peer-reviewed literature, and data from co-authors (both published and unpublished) to illustrate concepts and examples from extensive sheep production environments of the western United States with applications globally. SYNTHESIS: Precision trace mineral nutrition of sheep that are managed in extensive production systems requires a comprehensive understanding of the sheep and the grazing environment. Generally, extensive sheep production systems are found in remote geographical regions comprised of marginal rangelands not suitable for cultivated crop farming or improved forages. Sheep production is subject to the accessibility, availability or quantity, and quality of grazable forage on marginal lands, which may vary greatly within and across years. Contemporary sheep common to extensive production systems include mostly wool-, meat-, and some hair-type sheep. Furthermore, traditional wool-type breeds that still dominate most enterprises have changed considerably with regard to mature body weight, dietary intake, and prolificacy due to improvements in genetic selection. Accordingly, it is important to simultaneously consider both landscape and animal challenges when developing effective trace-mineral nutrition programs. CONCLUSIONS AND APPLICATIONS: Mineral heterogeneity of sheep diets from grazing marginal rangelands has persistently made precision mineral supplementation challenging. Knowledge of rangeland plant species differences, temporal changes in plant phenology, metabolic/digestive mineral antagonism, and to a lesser extent soil geochemical mapping can facilitate prediction of site-specific mineral shortfalls. Furthermore, an appreciation of the diversity of sheep breeds and recent genetic improvement of breeds common in extensive production systems can enable producers to accurately estimate specific mineral requirements respective of breed and production stage. Future research efforts that utilize contemporary sheep genotypes and emerging trace-mineral sources with site-specific environmental data are critical to further refine mineral nutrition management of sheep managed in extensive production systems.