By Jordan Johnson (Advisor: Dr. Abbott)
Summary: This paper aims to review the relationship between micronutrients and the immune system of beef cattle. The integrity of immune health is important for animal performance, disease resistance, and producer profitability. The beef cattle industry is also a large part in food security, and the topic of health and sustainability should be considered paramount. This review addresses the major layers of the bovine immune system and focuses specifically on the roles of micronutrients, including zinc, copper, selenium, chromium, vitamin A, vitamin D, and vitamin E. The role of these micronutrients within the immune system is addressed, and the consequences of deficiency are explored throughout the paper. By analyzing these micronutrients, there can be a new appreciation into the intricacies of micronutrients and the immune system. There is also an emphasis on the practical implications for producers and the supplementation strategies that may be applied within beef cattle production systems. The goal of this paper is to address the role that micronutrients play in a well-rounded beef production system. Although micronutrients do not replace good husbandry and management, they can support herd health and contribute to overall production efficiency.
Conclusions: The immune system is the foundation of health in beef cattle production systems. Physical barriers such as the skin and the mucociliary escalator prevent penetration of pathogens, the innate immune response acts to quickly respond to insult and the adaptive creates a protective future immunity. Micronutrients play an important role in supporting these immune functions. The physical barriers, the innate and adaptive immune responses rely on adequate levels of vitamins and minerals to ensure that immune defenses can protect the animal. While all minerals contribute to overall homeostasis and health, zinc, copper, and selenium have specific roles within the immune system that are of note. These minerals, along with vitamins A, D, and E, contribute to immune cell function, regulation of inflammatory responses, mucosal barrier function, antioxidant production, system regulation and overall resistance to pathogens. Although the specific mechanisms of many of these processes are not yet entirely understood, the currently available evidence supports the importance of maintaining adequate micronutrient status.
The goal for the producer should be to support herd health while increasing productivity. Throughout the beef cattle production system, multiple unique stressors are placed on the herd, increasing the strain on the immune system. The supplementation of vitamins and minerals can be costly upfront, but evidence-based supplementation should decrease economic loss. This reduction may be due to the decreased treatment cost, decreased morbidity and increased herd performance associated with stronger immune function. Targeted nutrient programs can take many forms, such as free mineral, injectable or a mixture of the the two. These programs should be a collaborative effort between veterinarians, nutritionists, extension offices and producers to best support cattle health and performance. Ultimatly, the proudcer must be willing and able to make long-term changes to their production systems. When properly used, these programs can be a practical management tool used to support immune function and improve the profitability of beef cattle production systems.
By Hanna Sihler (Advisor: Dr. McConnel)
Summary: This Caseous lymphadenitis (CLA), caused by Corynebacterium pseudotuberculosis, is a chronic, contagious disease of small ruminants that impacts animal health and economic concerns globally. This retrospective study analyzed 10 years (May 1, 2015–May 1, 2025) of domestic sheep and goat diagnostic data from the Washington Animal Disease Diagnostic Laboratory (WADDL) to characterize CLA prevalence using synergistic hemolysin inhibition (SHI) and CLA-targeted aerobic cultures. Data from 139,238 sample submissions (120,958 individual animals; 20,492 herds) were standardized and analyzed at the sample, individual, and herd level. Herd-level prevalence exceeded individual prevalence and the number of animals tested per herd was associated with herd-level positivity for both species. The prevalence of CLA in goat samples tested by SHI (3.7%; 4,452/120,213) was lower than in sheep samples tested by SHI (9.9%; 1,779/17,990). However, the prevalence of CLA in goat samples tested by CLA-targeted aerobic culture (33.3%; 269/808) exceeded that from sheep samples tested by aerobic culture (32.2%; 73/227). Prevalence increased with animal age and was found to be higher in females of the combined species (SHI 4.9% (2,281/46,268); aerobic culture 35.7% (251/704)) than in males (SHI 3.9% (450/11,561); aerobic culture 25.6% (61/238)). Geographic variation was observed, with lower prevalence in WA compared to other regions in the United States and Canada. These findings underscore the importance of surveillance to inform epidemiological studies and herd-level control strategies aimed at reducing the burden of CLA across diverse production systems.
Conclusions: This retrospective analysis highlights the complex interconnections of biological, environmental, and management factors that shape the epidemiology of CLA in small ruminants. Prevalence differences between SHI antibody detection and direct bacterial culture highlight the strengths and limitations of each test. Geographical and seasonal patterns are likely a reflection of regional differences in herd mobility, housing, grazing systems, cultural practices, and timing of management activities. Species-level differences reinforce the significance of considering both animal behavior and targeted testing practices when interpreting prevalence. Higher rates among females and older animals may result from management decisions and increased exposure to risk factors, whereas breed-level comparisons were constrained by uneven submission counts and scarce data on housing, herd information, and biosecurity. The possibility of within-herd transmission suggested by this study calls attention to the need for herd-level interventions, especially given the limitations of treatment, current diagnostic tools, and the absence of a DIVA vaccine. Sustained vaccination programs partnered with targeted culling and monitoring of new introductions remain a fundamental component of CLA control overall. These findings taken together provide a framework for refining surveillance strategies and designing targeted, context-specific interventions aimed at reducing the burden of CLA across diverse production systems.