Trial 35: Comparative experimentation in relation to the efficacy of probiotics in animal nutrition

P. Susmel, B. Stefanon. - University of Udine (Italy) Department of Animal Production.

Introduction: probiotics and antibiotics

The increased sensitivity in regards to natural products and the necessity, imposed by norms and economical needs, to diminish the "medicalization" of breeding farms, make it obligatory, on the part of the research sectors working on the exploitation of feeds for zootechnical use and animal production, to conduct a careful scientific examination of the physiological and biological behavior of the microorganisms commonly called probiotics.

In fact, the appearance and the increase in bacteria strains dangerous for man and animals and resistant to therapies has been widely attributed to a widespread use of antibiotics as dietary additives. This negative secondary effect has pushed the legislator to set more and more restrictive limits on the utilization of these substances and impose research to study experimental protocols that also consider companies' needs to contain costs, which have often become excessive for a rational economic budget, due precisely to the use of these antibiotic substances.

Probiotics are vital microorganisms able to give benefit to its host through the re-balancing of the intestinal microflora. This definition, given by R. Fuller regarding human medicine, is most certainly extensible to the zootechnical sector. Probiotics are often commonly called "lactic yeasts" and their positive properties in the diet of animals and humans have been known for a long time, even though only recently their physiological action has begun to be scientifically evaluated and analyzed.

In fact, it has been long noted that the positive characteristics of these microorganisms, which favor the well-being and health of animals, are closely connected with the capacity of fermentation of organic substrata, with the production of various metabolites, among which acetic acid and, better yet, lactic acid.

The Department of Animal Production Sciences, having determined the interest of further scientific investigation on the physiological and biological processes of probiotics and of the economical aspects of the market for the use of commercial products which contain these organisms, tested a number of probiotics in commerce, comparing them with one another and with brewer's yeast, traditionally used for animals because it's a low cost supplement and derived from the brewing industry.

Objective - evaluation of the efficacy of probiotics

The study of digestive and metabolic processes in vivo (directly on the animals) is not easily interpreted, due to the numerous factors that characterize the gastric and intestinal digestive process including the diversity of species and breeds, the ingredients of the diet, the chemical and nutritional characteristics of the ration and the method of breeding. The same factors interfere with the secretion activity of the enzymes and on the motility of the intestine, and, therefore, influence the fermentation activity of the microorganisms. For these motives, it was estimated to be more useful, for the aim of comparison between products, to test the probiotics in vitro, analyzing the fermentative potential and the capacity of the microorganisms to produce metabolites contained in the products compared, rather than using the in vivo method, based on the “final” results obtained in animals.

In order to reduce the dietary and breeding variables and to be able to describe the phenomena of interest, laboratory methods were developed in vitro, which represent simplified but more exemplary models of what happens in vivo.

Conclusions - Scientific results

The results of the laboratory tests indicate a considerable variation of probiotic activity in vitro and a substantial modification of their fermentation capacities after gastric digestion. The probiotics Turval 6, Turval Swine and Yea-Sacc1026 have nonetheless maintained a good overall fermentation potential, which should allow for a better regulating activity of the intestinal microflora than the other products.

In order to evaluate the mechanisms of action of probiotics, without incurring variables found in experimentation on live animals, a method of examination in vitro was developed , able to simulate, and simplifying, the microenvironmental conditions of the gastro-intestinal apparatus of the animal host in which the microorganisms contained in the commercial products are found.

The parameters measured give an indication of the microbiotic activity before and after gastric digestion, from which scientific hypotheses can be drawn regarding the effects found on animals in campo.

The results of the laboratory tests indicate a considerable variation of probiotic activity in vitro and a substantial modification of their fermentation capacities after gastric digestion. The probiotics Turval 6, Turval Swine and Yea-Sacc1026 have nonetheless maintained a good overall fermentation potential, which should allow for a better regulating activity of the intestinal microflora than the other products

Lastly, it should be noted that the laboratory method of evaluation in vitro developed, because it can be standardized and repeated, represents an innovative system of evaluation of the microbiological activity of a product, which could also be utilized for analyses on other products on the market with similar characteristics of action.

It should also be pointed out that in eventual other experimentations , it would be opportune to re- calibrate the quantity of product to use for each sample.