Intestinal functions in animals : an experimental study on horses, pigs, cows and fish

Animals and humans live in symbiosis with an active gastrointestinal ecosystem. The balance of the system is maintained by the main actors, the macroorganism, the microflora and the environment, in concert. Microflora-associated characteristics (MACs), defined as the recording of any anatomical structure, physiological, biochemical or immunological function in the host (macroorganism) that has been influenced by the intestinal microflora, are parameters reflecting the ecosystem. By utilizing six MAC-parameters the intestinal ecosystems in healthy horses, cows, pigs, salmons and cods have been studied and compared with previous results found in man, rats and mice. The following MACs were studied.. conversion of bilirubin to urobilins, conversion of cholesterol to coprostanol, degradation of mucin, inactivation of tryptic activity, degradation of beta-asparty1glycine and formation of short-chain fatty acids.

The found baselines for these MACs in faecal samples, as well as in different sections of the equine gastrointestinal tract and in rumen of cows, are comparative to baselines found in samples from healthy animals of other species. As the microflora in growing mammals undergoes environmental assimilation and maturation, changes of MACs were found in piglets related to ages.

The antibiotic zinc-bacitracin was found to influence upon three MAC-parameters in horses and four MACs in weaned piglets. Antibiotic treatment of salmon did also lead to different MAC-values. Four MAC-parameters in piglets at weaning were influenced by the probiotic preparation Alcare®, which contains Bacillus licheniformis. Different values of MACs were found in different breedings of salmons and in ecologically vs. conventionally raised piglets, which demonstrate influences of the environment on the ecosystems. Some of these parameters were found to be influenced by exogenous factors, such as physical effort of horses, as well as the diet to horses and piglets. The disease diarrhoea did also influence on MAC-values.

These results demonstrate that MAC-parameters used in these studies are applicable tools to measurements of actual complex intestinal state in horses, cows, pigs and other species.

The baselines in these species are more similar within the herbivores and within the omnivores than between these categories. When more baselines are established in more species, the concept can be of increasingly importance for studies of both general and specific factors influencing on microbial intestinal interactions with the host. As the gastrointestinal ecosystem represent a corner-stone for animal health and welfare, increased knowledge of the system creates possibilities for future strategies in animal husbandry - including fish farming.

List of scientific papers

I. Collinder E, Lindholm A, Midtvedt T, Norin E (2000). "Six intestinal microflora-associated characteristics in sport horses. " Equine Vet J 32(3): 222-7
https://pubmed.ncbi.nlm.nih.gov/10836477

II. Collinder E, Berge GN, Gronvold B, Lindholm A, Midtved T, Norin E (2000). "Influence of bacitracin on microbial functions in the gastrointestinal tract of horses. " Equine Vet J 32(4): 345-50
https://pubmed.ncbi.nlm.nih.gov/10952385

III. Collinder E, Cardona ME, Kozakova H, Norin E, Stern S, Midtvedt T (2001). "Biochemical intestinal parameters in pigs reared outdoors and indoors, and in germfree pigs." (Accepted)

IV. Collinder E, Cardona ME, Berge GN, Norin E, Stern S, Midtvedt T (2001). "Influence of zinc bacitracin and Bacillus licheniformis on intestinal functions in weaned piglets." (Submitted)