PROBIOTICS AND THE HORSE
Thesis by Bridgett Hannigan, Warwickshire College of Agriculture
Selected Abstracts

Antibiotic Therapy

Broad-spectrum antibiotics and some anti-parasitic chemicals periodically introduced into the system devastate the beneficial microbial population as well as target pathogens. Chlorine in the water, added by authorities to act as a purifying, antibacterial agent, will also have a detrimental effect on the horse's beneficial gut flora.

Frequent occurrence of disease following antibiotic treatment suggests a protective suppressing effect from the normal resident population. The gut flora acts as an important barrier to pathogenic colonization by monopolizing all available nutrients and residential sites. Some are also able to produce their own antibodies against other species. For example, various lactobacillus strains produce lactic and acetic acids and hydrogen peroxide which inhibit the growth of Eshcerichia coli and other gas producing coliforms which cause disease when their numbers become excessive.

Stress is also a major factor in the horse's life, which will disrupt the gut flora. Stress can be generated by any drastic change in the physical or emotional environment, birth, weaning, traveling or even fear.

The optimum pH for the growth of the beneficial bacterial species (pH 6) is different from that of pathogens (pH 8-9). The imposition of stress on the horse can result in an increase in intestinal pH and therefore favors the development of pathogens. When this occurs, the number of
Lactobacilli decreases while the number of coliform increase.

The effects of feeding probiotics
Test results

Extensive work by Dr, Michael Glade in America has shown some incredible results:

If probiotics are added to the diets of pregnant mares six weeks prior to their foaling dates and then on into lactation until the foal is eight weeks old, the volume and composition of her milk will alter in: gross energy, sugar concentrates, total lipids as well as increased levels ofamino acids and proteins. This means more nutrients available to the foal.

Consequently, the foals involved in this research grew faster than those nursing mares that had not received the probiotic supplementation. A significant difference was noted from four weeks of age and by the end of the eight-week study period, those foals were 11 cms taller and 21 kgs heavier than their counterparts.

Fecal samples taken from the mares before, during and after probiotic supplementation have shown probiotics will enhance fiber digestion in the hind gut, increasing digestibility of dry matter of 15, crude protein by 11-14% and phosphorus by 22%.

In conclusion Dr. Glade says the greater efficiency of feed conversion by the mare into foal body weight is 24% greater if there is probiotic supplementation.

Higher foal growth rates can be attributed to both increased quantity of nutrients and the nature of the nutrients consumed.

Dr. Glade has also investigated probiotic supplementation in growing horses:

It is important that a protein source be digestible, but equally critical is the horse's ability to retain the nitrogen it provides and incorporates into the body tissues.

Tests have shown that youngsters given probiotics have increased levels of plasma lysine (most likely to be deficient in growing horses), argenine and methionine. This results in stimulation of growth hormone secretion, increased muscle strength and bone development.

Experiments conducted by Dr. Hoe Pagan have led to the conclusion that probiotics increase the fermentation process in the hind gut and enable the horse to digest phosphorus more efficiently.

Dr Pagan's results have shown that with the use of probiotics fiber digestibility is increased by 7.5% and absorption of phosphorus is 22% greater. By including probiotics, the horse utilizes the phosphorus that is already in the diet more efficiently. This is a far cheaper alternative to additional phosphorus supplementation. Information that was not expected from these experiments was that probiotics also increase calcium digestion.

In conclusion, the fact probiotics improve the fermentation process in the hind gut would also indicate that they can be beneficial in stabilizing digestive disturbances. These result from carbohydrate overload when the horse is fed concentrate ration. Such overloads can bring out colic and laminitis.

The institute of Probiotic Studies in studs and racing stables, in the UK, has carried our research.

Probiotics were fed to five hundred racehorses in flat training, twenty eventers and other competitive horses. All stables reported probiotic fed horses appeared less susceptible to digestive upset, did not seem to suffer the detrimental affects of stress and an improvement in their general health and well being.

On studs, the growth rate and general condition of eight thorough bred foals was improved and scouring was also effectively controlled. Probiotic fed mares showed less stress during parturition and were noted to be in consistently better condition than the controls.

Work at Warwick College had shown that the inclusion of probiotics in the diet resulted in quicker weight gain. Probiotics also helped in rapid recovery from weight loss after strenuous activity.

When yeast was removed from the ration, horses lost between ten and thirty kilograms within the following six weeks, even though their ration stayed exactly the same in all other respects.

All researchers reported an improvement in the general health and well-being and even an improvement in the temperament of horses supplied with probiotics.

Summary:

Scientific evidence suggests that probiotic supplementation will:

• Improve the composition of the mare's milk
• Increase early milk production
• Increase the availability of nutrients to foals, thereby enhancing growth
• Improve fiber digestion by approximately 7.5%
• Improve crude protein digestion by 11-14%
• Improve phosphorus digestion by approximately 22%
• Improve calcium digestion
• Increase feed conversion efficiency by up to 24%
• Increase nitrogen retention, thereby improving growth rates
• Stabilize the digestive system, reducing the risk of colitis and laminitis
• Stabilize weight and speed up any weight loss recovery after strenuous exercise
• Maintain health and condition of the animal

Stimulation of Immunity:

Laboratory experiments have shown germ free animals have much weaker immune systems than those with a normal collection of gut flora. This has been shown by phagocytic activity and lowered immunoglobulin levels.

Recent findings that Lactobacilli given orally can stimulate immunity in a nonspecific way, which creates many more areas of potential benefit, derived from probiotics. Not only do they have the ability to affect the balance of gut flora, but they could also influence diseases, which occur in tissues other than the intestinal tract.

The use of probiotics is more for preventative medicine rather than for use in disease therapy. Pathogens that cause disorders are usually well established by the time the symptoms show, and providing an abundance of beneficial microorganisms at this stage is consequently unlikely to be as effective as present antibiotic strategies.