The role of selenium in small ruminants: implications for haematopoiesis and supplementation strategies – a review

Selenium is a pivotal micronutrient for microorganisms, humans, and animals, playing essential roles in antioxidant defence, endocrine function, immune response, muscle function and reproduction. Haematopoiesis, the process of blood cell formation in the bone marrow, is a tightly regulated process to ensure the continuous formation of mature blood cells. However, the bone marrow is highly responsive to a wide range of substances, including selenium. As a result, supplementation with this micronutrient has gained attention for its potential impact on haematopoietic activity of the ruminant bone marrow. This review aims to provide an overview of the reasons and forms of selenium supplementation in small ruminants with a particular focus on its impact on caprine and ovine haematopoiesis in the bone marrow. Despite its significance, research on selenium influence on haematopoiesis in small ruminants remains limited. Studies conducted so far have varied in enrolled species, animal age, supplementation type, and material studied. Recent findings suggest that selenium supplementation may enhance overall bone marrow haematopoietic efficiency especially in terms of erythropoiesis, and thrombopoiesis. However, differences in the selenium bioavailability from various supplements, regional variations in supplementation practices, and interactions with other micronutrients underscore the complexity of maximising selenium benefits. These factors highlight the need for further research to optimise selenium supplementation strategies for improved small ruminant health and productivity.