Soy Protein Isolate-Stachyose Emulsion Gel for the Delivery of Vitamin D3: Effect on the Humoral Immune Response in Dairy Goats Under Heat Stress

Small ruminant production is a significant sector of agricultural industry in Texas, USA. Heat stress has a negative effect on productivity and animal health. Cholecalciferol, a form of vitamin D3, may enhance the function of immune cells and help ensure healthy immune function in farm animals exposed to heat stress. Practical applications of vitamin D3 against infectious diseases can benefit from the protective effects of a delivery system comprised of soy protein isolate and stachyose in emulsion gel. The prebiotic oligosaccharide stachyose has shown to have a great potential as a substrate for beneficial intestinal bacteria, which are thought to modulate the immune system. Cellular and humoral immunity are both impaired in dairy animals under heat stress. The delivery of vitamin D3 embedded within the soy protein isolate-stachyose emulsion gel resulted in a marked increase in 25-hydroxyvitamin D3 [25-(OH)-D3] concentration in blood serum. Chicken egg albumin (OVA)-immunized goats produced low anti-OVA immunoglobulin G (IgG) responses. In contrast, OVA-immunized goats fed vitamin D3 within the soy protein isolate-stachyose emulsion gel diet strongly stimulated antibody production. These results show that anti-OVA IgG responses can be modulated in dairy goats using vitamin D3, particularly if this vitamin is delivered in the form of emulsion gel. The results seem to depend on the highly hydrated gel matrix of soy protein isolate-stachyose at the low pH of the stomach as monitored by oxygen-17 (17O) and proton (1H) nuclear magnetic resonance (NMR). In addition, the prebiotic nature of stachyose may boost beneficial gut bacteria, most notably for immune health and reducing the risk of infectious diseases.