The gut of the piglet is sterile at birth, but it is rapidly attacked by both beneficial organisms (such as lactobacilli) and potentially harmful bacteria (such as E.coli) which are all present in the farrowing house. These bacteria compete with each other to colonize the sterile gut which, in pigs, receives no passive immunity through the placenta of the sow.
If the lactic acid bacteria dominate, the piglet will develop as a healthy, thriving animal. On the other hand, if the harmful organisms become established, the piglet will start scouring very early in life. It is important, therefore, that the beneficial lactic acid bacteria grow rapidly and colonize the gut of the piglet.
At this stage and to a large extent, the dominance of any microbial population is dependant on the initial numbers of invading organisms. The establishment and proliferation of such beneficial bacteria can be ensured by the use of probiotics. This is quite a recent addition to the vocabulary of the pig keeper and to the range of medicinal products available.
Most people are more familiar with antibiotics. As the name suggests, these products act against microbes in the gut which, at best, impair the animal’s performance, or at worst, are killers. The big drawback of antibiotics is that they are not selective. While they destroy the harmful bacteria, as intended, they are also lethal to the beneficial ones. In short, they will kill off the good ones as well as the bad. By contrast, probiotics containing only organisms which are helpful to the health and performance of the animal. The classic example of their use is after an animal has been treated with antibiotics, leaving the gut virtually devoid of micro flora, good and bad alike.
Dosing the temporarily sterile animal with a suitable probiotic immediately after the period of antibiotic treatment colonizes the gut with beneficial organisms and helps it repel the inevitable invasion of harmful environmental bacteria.
It does this in two ways. Firstly, by getting there first, the beneficial organisms attach themselves to the walls of the gut and proliferate before harmful bacteria can get settled or comfortable. Secondly, it has a competitive edge over its harmful microbes by consuming most of the available nutrients they need to feed on. Briefly, probiotic organisms have a head start on the harmful bacteria and keep on top pf them by crowding them out and starving them. It is important therefore that the beneficial lactic acid bacteria are species that multiply fast so that they can colonize the gut of the new born piglet quickly.
To a large extent, at this stage, the dominance of any microbial population is dependant on the initial numbers of invading organisms. The growth and establishment of such beneficial bacteria will be ensured by the use of the probiotic which provides high numbers of the beneficial bacteria. Probiotic products are generally recognized as viable microbial cultures, usually containing members of the lactic acid bacterial species, which help to establish and/or maintain a balanced gut micro flora.
There are several key features that probiotics possess and which farmers should understand if they are to reap the maximum benefits from their use. The most important is that they are species specific. This means that the different probiotic formulae need be employed for pigs, poultry and cows. For example, a probiotic intended for poultry will have little or no effect on pigs and its use on the latter would be a waste of money.
To see how this operates, let us follow the typical processes used to develop a commercial probiotic intended solely for use on pigs. The organisms included were isolated from healthy pre-weaning and post weaning piglets which had been grown on a diet free of antibiotics and growth promoters. Nearly two hundred different organisms were originally obtained and these were screened for the suitability for inclusion. It was ensured that none of the selected organisms were pathogenic so the product is completely harmless.
The second key feature of the product is that the organisms have fast growth rates and are vigorous producers of lactic acid. This ability to grow quickly and produce copious amounts of acid in the gut enables them to compete with and, subsequently, inhibit the prolifically multiplying harmful bacteria strains due to the increase in pH.
All of the organisms in the product are resistant to bile acids and, therefore, are able to survive and grow under conditions normally prevailing in the gut.
Another important feature of the product bacteria is that they were selected on the basis of their capacity to adhere to the lining of the intestines. Each of the organisms has this capability. It is essential that probiotic organisms attach to the gut epithelial tissue to ensure that they are retained during the normal digestive processes and are not flushed through with the ingesta. Many pig diets contain antibiotics at growth promotional levels and, therefore, the resistance of the product organisms to growth promoters was tested.
The product was resistant to all the growth promoters used routinely, with the exception of Virginiamycin which exerted a bacteriostatic effect on the product organisms. Survival of the presence of wormers and manage control treatments was also tested. All of the above factors were taken into account in the final selection of the organisms for inclusion in the final product.
The stability of the four organisms finally selected (out of the originally two hundred) was tested further by screening them again after production to ensure none of the characteristics had been lost in the process.
The product is, therefore, a stable, viable product possessing the features essential for a probiotic. The success of probiotic products depends not only on research and development, but also on administration. All probiotcs should come with detailed instructions for application, and these must be followed to the letter, as the efficacy of the probiotics may be severely affected.