Review: Vitamin A supply in swine production: Current science and practical considerations
Yauheni Shastak, Wolf Pelletier
Abstract
This paper aims to present a comprehensive overview of vitamin A metabolism in pigs and the effects of retinol supplementation on pig production, including immune function, reproductive performance, hematopoiesis, and antioxidant capacity. Furthermore, this review highlights crucial factors that need to be considered to ensure adequate vitamin A supply to pigs. The primary source of information reviewed was independent, published scientific peer-reviewed literature. Vitamin A, also known as retinol, plays a crucial role in growth, cellular metabolism, bone development, and reproduction. The amount of retinol supplementation in commercial animal production has been a topic of contention in recent discussions. Although the physiological function of vitamin A is a key factor, the cost and stability of pure commercial products, along with their stability in premix and feed formulations, are also important considerations. Failure to provide adequate levels of vitamin A to swine can lead to decreased performance, increased susceptibility to diseases, and reproductive disorders. Determining the optimal amount of vitamin A for swine is not a simple task, as it depends on various factors such as age, health, nutritional status, and physiological state. Scientific committees such as the Gesellschaft für Ernährungsphysiologie (GfE) and the National Academies of Sciences, Engineering, and Medicine (NASEM) provide requirement estimates (NASEM) or allowances (GfE) based on the needs of healthy animals under optimal environmental conditions, serving as a foundation for practical considerations. However, when extrapolated to real-world conditions, requirement estimates and allowances derived on controlled research settings may have inherent limitations. Therefore, it becomes imperative to comprehend the effects of supplemental vitamin A on swine metabolism and health to formulate well-balanced diets and attain optimal performance in practical circumstances. Retinol is crucial in pig nutrition, and synthetic retinyl acetate supplementation is necessary to meet dietary requirements, as plant feedstuffs are deficient in vitamin A. Dietary supplementation and injection of retinol have demonstrated positive effects on swine reproduction, performance, immunity, and health. To ensure a well-balanced pig diet, it is crucial to have insights into the appropriate stages for increased retinol supplementation and its interactions with other fat-soluble bioactive substances. Updates to scientific committees’ recommendations on vitamin A are recommended, to reflect the current state of knowledge on the role of vitamin A, genetics, and current pig farming practices.