Influence of Deliverable Form of Dietary Vitamin D₃ on the Immune Response in Late-Lactating Dairy Goats

Mastitis-causing bacteria can establish persistent infections in the mammary glands of commercially important dairy animals despite the presence of strong specific humoral and cellular immune mechanisms. We investigated the effect of vitamin D₃ in the diet at a set level, but in two different forms (i.e., unencapsulated and encapsulated by complex coacervation with sulfur-saturated bovine lactoferrin-alginate using microbial transglutaminase-catalyzed crosslinking) on the immune response in late-lactating dairy goats. Dairy goats (n = 18) were randomly assigned to three experimental groups (n = 6). Dairy goats were orally administered 0.35 mg of vitamin D₃/day in the unencapsulated form and 0.35 mg of vitamin D₃/day in the encapsulated powder form. Another group received the basal diet. The experimental period lasted 6 weeks. The blood serum concentrations of 25-hydroxyvitamin D₃ [25-(OH)-D₃], lactoferrin, immunoglobulin A (IgA), and interferon-gamma (INF-γ) were measured. There were major differences in these parameters between dietary groups. However, the delivery of vitamin D₃ in the encapsulated powder form to dairy goats resulted in a marked increase in 25-(OH)-D₃ concentration in serum, while the serum level of lactoferrin also increased. Alternatively, the serum levels of IgA and the immunomodulatory cytokine INF-γ were elevated following supplementation with the encapsulated vitamin D₃. The observed effects suggest that the deliverable form of dietary vitamin D₃ results in differences in the immune response in late-lactating dairy goats.