by Maike Rakebrandt, Senior Product Management Companion Animals (Equine & Pet), Leiber GmbH, Germany
Respiratory infections such as bronchitis or influenza, skin diseases such as eczema (sweet itch), mallenders, wound healing disorders, or the so-called “open window syndrome” after high performance demands – the immune system is constantly exposed to attacks by viruses, bacteria, fungi, or parasites. If the immune system is weakened, horses are more susceptible to infections, fall ill more often and require a longer recovery period. In severe cases, diseases can become chronic. A functional immune system is therefore the most important protective and defence mechanism for horses, and natural ways to support it are of high interest to horse owners.
Role of Beta-glucans
Beta-glucans are found in cereals, mushrooms, algae and yeast. However, due to their different chemical structures, they differ significantly in their mode of action. For example, oat glucans influence blood sugar regulation but not the immune system. Algal and fungal glucans exhibit some immune activity but this effect is relatively weak due to missing or shortened side chains. Yeast glucans, in contrast, are known for their strong immunostimulatory and immunomodulatory effects. This has been demonstrated in humans and in animals, particularly in aquaculture but data in horses are limited.
Effects on Young Horses’ Immune System
In a 35-day trial, 12 young warmblood horses were supplemented with 4 grams of beta-glucans (Leiber® Beta-S) per day for 28 days in addition to their usual diet of hay, oats, mineral feed and pasture. On day seven, all horses were vaccinated against influenza and tetanus. Blood samples were collected, serum analysed and results statistically evaluated. A more detailed description of the trial design is provided in Fig. 1.
In Leiber® Beta-S, beta-glucans are gently extracted from the yeast cell wall complex, preserving their structure and biological activity. This process ensures the efficiency of their immunostimulating and immunomodulating effects during intestinal passage.
Effect on the Non-specific Immune System
Lysozyme is produced by monocytes and found in the granules of granulocytes and macrophages. It is an enzyme with antibacterial activity, particularly against gram-positive bacteria and is primarily responsible for the initial defence against pathogens. An increase in lysozyme activity indicates enhanced non-specific immune defence. Seven days after supplementation, lysozyme activity was significantly increased and remained elevated until the end of the trial. Significantly higher lysozyme activity (p < 0.001) was observed on days 7, 14, 21 and seven days after the end of supplementation (day 28) (see Fig. 2). The immunostimulatory effect of Leiber® Beta-S on the non-specific immune system was clearly observed.
No Inflammation or Infection After Vaccination
Ceruloplasmin is an acute-phase protein that is part of the non-specific immune response and helps limit the spread of inflammation. Its concentration in serum increases during inflammation, infection or trauma.
Seven days after vaccination, higher ceruloplasmin activity was observed in the control group. In contrast, the Leiber® Beta-S group showed statistically significantly lower ceruloplasmin activity throughout the study period (see Fig. 3). Thus, horses receiving Leiber® Beta-S did not display acute inflammation after vaccination, unlike the control group.
Immunostimulatory Effect on the Specific Immune System
Immunoglobulin G (IgG) antibodies act mainly against viruses and bacteria. They are produced by B lymphocytes or plasma cells after contact with an antigen. IgG levels serve as markers for the specific immune response and an increase indicates an immunostimulatory effect.
Gammaglobulin levels were similar in both groups before vaccination. Seven days after supplementation and again seven days after vaccination, Gammaglobulin levels in the Leiber® Beta-S group increased significantly (p < 0.001). Significantly higher levels were also observed on days 14, 21 and seven days after finishing supplementation (p < 0.001) (see Fig. 4).
Improved Vaccination Response – Adjuvant Effect
Antibody titre tests measure the presence and level of specific antibodies in blood, providing information about the response to vaccination. Higher antibody titres were observed in the Leiber® Beta-S group seven days after vaccination and statistically higher levels were also seen 14 days after vaccination. Throughout the trial, the Leiber® Beta-S group showed higher specific antibody levels, even seven days after supplementation ended (see Fig. 5). An adjuvant effect was clearly observed.
Take-Home Message
Beta-glucans can support the immune system of horses. In this study, they showed a significant stimulatory effect on both non-specific and specific immune responses after vaccination. An adjuvant effect was also clear demonstrated.
