Foaling season is upon us and everyone realizes the lifesaving importance of mare’s colostrum in transferring disease-protecting antibodies to the new foal but colostrum does much more than this.
For example, colostrum contains a hexasaccharide that inhibits gram negative organisms, prevents biofilm formation and can even help reverse antibiotic resistance. PRPs in colostrum are small strings of amino acids, “proline rich peptides”. Previously known as transfer factors, PRPs in mare’s milk don’t actually transfer immunity; they stimulate it. Colostrum contains a host of immune system targeting cytokines and growth factors that stimulate the bone marrow. Colostrum is also rich in fat, protein in general and has a full spectrum of vitamins and minerals.
The mare’s body is programmed to short change its own nutrition in favor or providing adequate nutrients in the colostrum and milk but it can’t manufacture deficient nutrients out of the air. Current dietary recommendations also may not always be sufficient for highest quality milk.
It has been shown that supplementation for the last 4 weeks of pregnancy with vitamin E at 2500 IU/day (over 3X the current recommendation for late pregnancy in a 500 kg mare) resulted in higher vitamin E levels in the mares, milk and foals as well as higher antibody levels in milk and the foal’s blood.
The window of opportunity for foals to consume adequate colostrum is only about 12 hours. The colostrum provides antibodies against bacteria in the environment where the mare has been living as well as her past exposures and vaccinations. It also helps jump start the foal’s own ability to form antibodies. Colostrum is gone after 24 hours and the foal’s own immune system needs to start working.
Very young foals are capable of mounting an immune response and producing antibodies but have weaker abilities in their Th1 response. Specifically this means they have trouble identifying, targeting and destroying cells that have been invaded by organisms. This is what makes them susceptible to infections that adults easily resist, such as Rhodoccus equi.
Recent research has found that the ability to mount these sophisticated immune responses to R. equi is greatly enhanced if the foal is vaccinated by the oral route rather than injection. It had previously also been found that antibody titers in young foals were higher when the oral route was used for vaccination.
The intestinal tract is home to an extensive network of immune system cells, the GALT (gut associated lymphoid tissue). When an infection tries to enter the body by this avenue, the local immune system cells both deal with it at that level and also send out information to the immune system throughout the body, priming it to defend against the infection.
It is well known that the immune system of the GALT is also stimulated by substances that do not cause active infections. With the knowledge that foals respond best to immune challenges through the intestinal tract, this becomes an easy and appealing way to efficiently promote normal immunity in the young foal.
Even though foals lose the ability to absorb large antibody molecules (immunoglobins) in less than a day, colostrum and milk retain many immunity promoting and supporting ingredients such as growth factors, L-glutamine and Lactoferrin. Colostrum and bioactive Whey Protein are concentrated sources. Probiotic bacteria and plant components such as Mannanoligosaccharides, Arabinogalactan and Fructooligosaccharides (FOS) naturally promote a robust immune response. Vitamins B5, B1 and B12 support the high metabolic activity of immune system cells.
Combating the infectious challenges of the world is a formidable task for young foals, with the first few weeks of life being the most dangerous. You can maximize the foal’s chance of thriving by supporting high quality colostrum and making sure the foal ingests it in that critical window of the first 12 hours after birth. Beyond that, gentle support of the immune system via the oral route shows the most promise as an effective strategy.
Eleanor Kellon, VMD