In recent years, nutritional research has significantly shifted to finding alternatives to zinc oxide (ZnO) in pig farming. This shift comes in light of the EU's ban on using ZnO for therapeutic purposes in 2022 due to the environmental risks and the potential to promote antibiotic resistance. However, in this new context where ZnO is no longer available, and there is tighter control over antibiotic use, only some have paid attention to the importance of vitamin levels in piglet feed, surpassing the role of vitamins as essential nutrients.
It is well known that deficiencies in vitamins and other nutrients weaken the immune system of pigs, especially piglets. They affect innate and adaptive immune responses, leading to infectious and inflammatory disease susceptibility. Based on recent scientific findings, let us explore the roles of various vitamins at different levels of the immune response in piglets.
At the mucosal immune level, both epithelial and immune cells express receptors for vitamin A (RAR, retinoic acid receptor) and vitamin D (VDR), indicating the crucial roles of both vitamins in supporting the integrity and function of the gut barrier. In this regard, the role of vitamin A in the development of gut epithelium in suckling piglets has been confirmed in a 2020 study by Wang et al., where a high level of this vitamin in feed led to a significant increase in the expression of Lgr5+ genes, a marker of stem cells in the small intestine.
Regarding the role of vitamin D at the gut level, its main functions include reducing apoptosis or cell death in inflamed conditions – anti-inflammatory effects – (He et al., 2018), as well as increasing the expression of genes encoding peptides involved in the synthesis of antimicrobial peptides, such as β-defensin, by Paneth cells in the intestine – antibacterial effects – (Lu et al., 2018).
In the intestinal epithelium, B6 acts as a cofactor in mucin synthesis by goblet cells by synthesizing oligosaccharides and proteins (Moran, 2017). Vitamin A also participates in mucin production, although vitamin B6 plays a much more direct role (Lauridsen et al., 2021).
Inflammatory responses to intestinal diseases in non-human animals, such as diarrhea or enteritis, produce oxidative stress. Although this stress has antibacterial properties (e.g., the production of nitric oxide by macrophages with antibacterial properties), if it becomes more severe, it can cause tissue damage, prolonging both local and systemic inflammatory responses. It has been demonstrated that supplementing high levels of vitamin C in the diet of mold-contaminated suckling piglets increases overall antioxidant capacity in the liver (Shi et al., 2017).
It has been shown that the production of reactive oxygen species (ROS) increases in pigs fed diets deficient in vitamin E and selenium (Lessard et al., 1991, 1993). Therefore, vitamins C and E are primary factors in controlling oxidative stress in the context of intestinal disorders in piglets. However, another vitamin is involved in the regulation of oxidative stress: vitamin D. Therefore, the concentration of the potent endogenous antioxidant enzyme glutathione peroxidase significantly increases in suckling piglets when they are supplemented with high doses of calcidiol metabolite (25(OH)D3) in their diet, with the maximum level of this antioxidant enzyme in serum corresponding to a dose of 118 micrograms 25(OH)D3 / kg of feed (Yang et al., 2018). The role of vitamin D in regulating oxidative stress contributes to its apparent anti-inflammatory effects, as mentioned earlier.
Finally, another immune-level effect of vitamins is the positive effect of vitamin A on humoral responses. Hu et al. (2020) observed that supplementing 13500 IU of vitamin A/kg of feed in the suckling piglet diet significantly increased serum IgA and IgM concentration. IgA is the most critical immunoglobulin in pigs for mucosal immunity and is the primary immunoglobulin in piglet milk. The role of IgM is crucial as it is the first line of defense in humoral responses. Additionally, IgM is particularly effective against many Gram-negative bacteria (Sánchez-Vizcaino, 2010).
In summary, recent studies on the response to various vitamin levels in the feed of suckling piglets demonstrate the beneficial effects of high levels on animal immune responses. In light of the current situation, with no ZnO and increasing restrictions on medication use, reconsidering the vitamin levels in piglet feed is crucial. Veterinary medicine companies are updating and enhancing their recommendations regarding vitamin levels, emphasizing this necessity in the current context.
With the development and widespread application of this knowledge, the veterinary medicine industry in Vietnam is increasingly asserting its position in providing high-quality products, contributing to the sustainable development of agriculture and veterinary medicine.
Keywords: Veterinary Medicines Vietnam, Veterinary Medicines Exporter, Veterinary Medicines Manufacture