The Value Of Probiotics In The Prevention Of Digestive Problems
And Associated Mortalities Of Birds
By Prof S. J. Schoeman, Stellenbosch

Many finch breeders, and particularly those who keep their birds in large, planted aviaries with sand floors, have had to deal with a variety of digestive problems and resulting losses amongst their birds from time to time. These breeders know only too well about finches that become ill, even though they eat well, gradually lose weight and eventually die.

Symptoms of these birds, apart from the first signs of sitting puffed up, which can be more easily seen in colder weather, are mainly a light chronic diarrhoea to begin with which is not easily seen but which develops into a condition in which undigested seeds can be seen in the droppings. Often these afflicted birds try to and do take in large amounts of grit. Although there may be a great number of reasons for these symptoms, there are two that are of particular significance.

  • The first can be attributed to the intake of mycotoxins that occur mainly on food that has been infested with fungi or mould,
  • The second and most probably the most important cause of this affliction is the existence of a microbial imbalance in the digestive tract of the bird which can very likely be induced by stress. It is this second cause which will receive attention in this article.

The microbial population in the digestive system of birds. Under normal conditions both positive micro organisms (e.g.. Lactobacilli, streptococci) as well as negative micro organisms (e.g.. pathogens such as E. coli, coccidia, etc.) are found in the digestive tract of a healthy bird. These two groups occur in a fairly specific and balanced quantities. If this balance is disturbed, for whatever reason, so that the pathogens increase in number at the cost of the positive micro organisms, it has a suppressive effect on the normal digestive function. In aviaries that have a reasonably high bird population density, such a build up of pathogens can happen fairly easily.

A healthy population of positive micro organisms in the digestive tract suppresses or inhibits the build-up of large populations of pathogens by the formation of, amongst other things, lactic acid. If the positive micro organisms should decrease for a reason, production of lactic acid decreases and causes an increase in the population of pathogens, which results in a sick bird.

On the surface of the intestinal lining there are limited sites available for microbial colonisation. If their is a high concentration of pathogens in the intestinal tract, they will, according to the principle of competitive exclusion, colonise the available sites, to the exclusion of the positive microbes, who then have no "room" left to colonise and are therefore excreted. Obviously the opposite is also true, namely that if the positive micro organisms adhere to the sites in large numbers, colonise and multiply, the pathogens will be excreted. As a result of the limited life span of these organisms, these sites become available regularly and the ratio between pathogens and positive micro organisms determines which ones will colonise the available sites. It is therefore important that the ratio must always be in favor of the positive organisms. The principle is based on the creation of a favorable- micro organism ecosystem so that a healthy digestive function may be maintained.

Apart from the increase in production of lactic acids, as mentioned earlier, such a healthy system also creates a condition in which more short chain fatty acids, a product of the metabolism of these organisms, are formed, and to which the pathogens are more sensitive than the positive micro organisms. This would the help to further suppress the pathogens.

The general procedure for treating sick birds is to use an antibiotic. Apart from the fact that the pathogens are able to build up resistance after repeated use of antibiotics, the antibiotics also destroy the positive micro organisms. This occurs particularly when broad spectrum antibiotics are used. A specific antibiotic is only suitable for a certain spectrum of pathogens. The use of sub-therapeutic levels on a regular basis is fairly common amongst some bird keepers, but it has definite disadvantages and is also dangerous. As mentioned before, the actual cause and reason for the high incidence of these kinds of problems is the high level of stress to which aviary birds are exposed.

Reasons for stress in birds:
Birds that are kept in aviaries are in highly unnatural surroundings that cause various levels of stress. Species do differ in their ability to cope with stress. The most important reasons for stress are e.g..:

  • competition as a result of limited space
  • unsuitable or unbalanced diet. The diet in an aviary is always very different from the diet (great variety of food sources) eaten in the wild, and deficiencies of certain essential nutritional elements occur in an imbalanced diet.
  • species that are fairly incompatible with others or are dominated by others - environmental disturbances, especially in towns and cities, e.g.. noise
  • temperatures that are too high or too low and a climate that is different from the one the birds come from originally, so they have to adapt.

Results of high stress levels:
There are direct and indirect consequences to the stress levels to which birds in captivity are exposed. The most important are a decrease in food intake, a greater degree of nutritional imbalance, decrease in fertility, and lower resistance to diseases. To be more specific, the following are results of stress:

  • a change in the pH of the lower gastro intestinal tract
  • the balance in the ecosystem of the digestive tract is disturbed by a decrease in the positive micro organisms such as lactobacilli and streptococci (e.g.. L. casei, L. fermentuni, S. faecium) in the favor of pathogens (e.g.. E. coli)
  • the bird becomes highly sensitive to coccidia (eimeria) which increase quickly in the gastro intestinal tract.
  • From this follows a suppression of the digestive function, diarrhoea, undigested seeds in the droppings, general unwellness or "going light" and eventually the bird dies.

These problems can partly be prevented by the addition of probiotics to the feed for birds.

What are probiotics?
Probiotics can be broadly defined as any product that is able to create or maintain the micro population in the gastro intestinal tract of a bird, so that digestion can occur more efficiently. As such, these products would include the great variety of vitamin, amino acid and electrolyte supplements that are readily available commercially.

To be more specific however, probiotics are those products which contain a great variety of positive bacteria and which are added to the birds' feed in order to create and maintain a balance in the population of bacteria in the gastro intestinal tract. Several bacteria that are mostly obtained via the process of fermentation - some of which have been named already - as well as certain yeast cells, possess bioregulatory properties. As discussed, the bacteria attach themselves to the epithelium cells of the gastro intestinal tract to create a biofilm that protects it from the pathogens from the environment. This further stimulates the production of natural antibiotics such as nycin, as well as peroxidase enzymes, which play an important role in the immune system.

The use of these products often occurs as treatment for sick birds rather than as a preventative medicine. It is particularly valuable after antibiotic treatment. Probiotics can however be administered on a more continuous and preventative basis without any negative side effects, especially where digestive problems occur readily. Because the success thereof depends on the number of living organisms that the birds take in, it would be advisable to follow the directions given by the manufacturers very meticulously.

This above article is published here with kind permission from Chairman, Rowan Dickerson of The Gouldian Finch Society of South Africa. Visit their web site at: www.gfs.org.za . Thank you Mr. Dickerson. Don Perez

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