Thoroughbred yearlings fed a nutritional supplement of enriched cow-derived colostrum proved significantly more resilient to respiratory disease than a control group, researchers report.
North American researchers used 109 yearlings living on two central Kentucky farms for the blinded randomized clinical trial.
Some of the horses were fed a blended spray-dried bovine colostrum enriched with mannan oligosaccharides; zinc; vitamins A, C, and E; and folic acid. The others were fed a full-fat soy flour placebo.
There was no statistical difference in the incidence of respiratory issues across all the yearlings, but the average duration of illness was 1.96 weeks for the yearlings on the colostrum supplement compared to 4.39 weeks for the yearlings on the placebo.
The average duration of respiratory disease was reduced by over a half in the yearlings receiving the colostrum supplement, Clara Fenger and her colleagues reported in the Journal of Equine Veterinary Science.
“This bovine-colostrum-based product blended with other immune modulators provides an effective nonpharmacologic natural feed additive that significantly reduces the impact of respiratory disease in yearling horses,” they reported.
Bovine colostrum is the first milk produced by cows after calving. It contains immunoglobulins, other immune factors, growth factors and other nutrients necessary for optimal immunity, maturation, and support of the newborn calf.
The study team noted that it had recently become increasingly popular as a nutritional supplement in humans for immune support. In humans, it has been shown to be effective in the prevention of flu, upper respiratory tract infections in children, upper respiratory tract infections in athletes, and to improve the humoral immune response to vaccination. This effect, they noted, was not limited to humans: Bovine colostrum supplementation also enhanced the immune response in dogs to the canine distemper vaccine.
The effect of natural substances on the immune response is not limited to bovine colostrum. Mannan oligosaccharides were known to modify the cytokine response of pulmonary macrophages in pigs. Zinc had many direct and indirect effects on the immune system, via both its role as a cofactor in more than 300 enzymes, its direct effects on leukocytes and on the humoral immune response. Vitamins A, C, and E had well-described benefits on immune function in animals.
The researchers noted that equine respiratory disease was a significant cause of illness in horses, and young horses were significantly more susceptible than older horses. It was the second leading cause of missed training days in racehorses, being responsible for almost a quarter of lost training days.
Supplements that supported immune function and mitigated these infections would therefore benefit the equine industry, they said.
The colostrum used in the trial was produced under US and Canadian federal permits for commercial use as a veterinary biologic.
Excess colostrum was collected from dairy farms licensed to produce milk for human consumption and was stored frozen until processing.
The thawed colostrum was pasteurized using a proprietary method at the Saskatoon Colostrum Company in Sasketchewan, Canada. The method was designed to eliminate pathogens while maintaining the integrity of the immune factors. The colostrum was spray-dried during the process and then tested for retention of its potency. The powder was then packaged and blended with the additives to produce the supplement fed to the yearlings.
The colostrum supplement and the placebo group were each fed at a rate of 100 grams a day, representing less than 3% of the total diet of the yearlings. The feeding regime for both groups lasted about 22 weeks.
Discussing their findings, the study team said: “Any contribution of the bovine colostrum to the respiratory disease-sparing effects could be due to the direct action of colostral antimicrobial factors or to indirect effects of cytokines and growth factors potentially enhancing the innate or acquired immune response.
“Direct effects could be due to antibacterial and antiviral activities of molecules such as lactoferrin and lactoperoxidase that could directly interfere with transmission of infectious agents in the respiratory tract following oral or nasal exposure.
“Indirect effects on the immune response could be due to impacts of high levels of growth factors such as insulin-like growth factor 1 (IGF1) and epidermal growth factor (EGF) or to regulatory events from impacts of colostral cytokines (interleukin [IL]-1beta, IL-2, IL-6, IL-17, tumor necrosis factor-alpha, interferon-gamma, IL-10) on the cytokine network that regulates immune responses.”
They concluded: “A bovine-colostrum-based supplement was highly beneficial for reducing the duration of respiratory disease in thoroughbred yearlings”.
Enhanced Bovine Colostrum Supplementation Shortens the Duration of Respiratory Disease in Thoroughbred Yearlings
Clara K. Fengera, Thomas Tobin, Patrick J. Casey, Edward A. Roualdes, John L. Langemeier, Ruel Cowles, Deborah M. Haines.