Probiotics alternative to antibiotic growth promoters -

The proper use of antibiotics can prevent death loss in animals. However, the indiscriminate use of antibiotics has become a problem in both humans and in animals.

Vijay Sasidharan

Overuse of antibiotics causes some bacteria to become resistant to the very antibiotic that would normally kill it. This becomes a real problem when nothing can be used to treat animal infections and, even more important, when the antibiotic does not work in human infections. The problem started when it was discovered that antibiotics can help animals grow rapidly, and antibiotics were then being added to feed and water, even when the animals were not sick. We now know that when used at subtherapeutic levels as growth promoters, antibiotics can lead to drug resistance, which means that critical antibiotics can no longer be as effective in treating infections.

The U.S. uses far more antibiotics in livestock than many other nations. According to the Food and Drug Administration (FDA), the amount of antibiotics sold for use in livestock has risen substantially in recent years. This can lead to antibiotic resistance in humans as well as animals.

Due to increasing fear of antibiotic resistance and public awareness, the FDA has started curbing the use of antibiotics and is implementing a voluntary plan with industry to phase out the use of certain antibiotics to enhance food production. The FDA has now asked the drug companies to change the label directions. Those changes mean that food animal producers would no longer be able to use antibiotics to make the animals grow faster. If food animal producers wanted to give the drugs to a sick animal, they would need to get a prescription from a veterinarian.

United Nations forecasts that the world's population will increase from 7.2 billion today to 8.1 billion in 2025, and by 2050, it will reach 9.6 billion. If producers can no longer use subtherapeutic levels of antibiotics as growth promoters, how are they going to meet the growing need for milk, meat and eggs? This question has sparked a lot of research for alternatives to antibiotics as growth promotors.

Several alternatives are currently being used, including probiotics, prebiotics, organic acids and essential oils, to improve feed efficiency. Probiotics are by far the most recognized alternative to antibiotic growth promoters.

The words "probiotics" and "antibiotics" originate from Greek and respectively mean "for life" and "against life." These terms clearly denote the crucial difference in their effect. Whereas the antibiotics suppress and kill the harmful bacteria as well as the beneficial bacteria in the gut, probiotics are living organisms that are capable of colonizing the intestines after being ingested.

What are the characteristics of a good probiotic?

It should be non-pathogenic.
The organism should be able to survive the rigors of manufacturing, shipping and storage, and be viable until final use.
It should be able to survive the low pH of the gastric environment and successfully colonize the gut.
It should provide a health benefit to the host animal.
It should be cost effective.

The FDA has approved a list of bacteria that are safe and, when given as directed, will provide benefits to the animals. These bacteria are "generally recognized as safe” (GRAS). These include several species of lactobacillus, bifidobacterium, bacillus and several species of yeast.

Modes of action

The following are research-proven modes of action of probiotics:

Modification of the gut microflora
- Supplementing probiotics helps keep the number of beneficial bacteria high in the gut.
Competitive exclusion of pathogens
- Beneficial bacteria out-compete pathogens for nutrients and adhesion sites in the gut, thereby preventing infections.
Production of B vitamins and enzymes
- This helps maintain normal appetite and digestion.
Production of natural antimicrobial substances
- This keeps the pathogenic bacteria low.
Ability to modulate immune system
- Probiotics are in intimate contact with gut- associated lymphoid tissue (GALT). GALT is the largest lymphoid tissue in the body and plays a crucial role in the functioning of the immune system.

Even with all the research-proven benefits of probiotics, it is very difficult to make any claims. Unlike antibiotics, probiotics manufacturers are not allowed to make any label claims related to prevention or treatment of infections, growth promotion, improving feed efficiency or reducing morbidity or mortality. This is due to the regulatory environment that surrounds the use of probiotics, even though probiotics are efficacious. So it can be a challenge to explain the benefits of a probiotic product to producers.

Educating the veterinarians, nutritionists, producers and general public is the key to success. With the growing concern for antibiotic resistance in both humans and animals, combined with increased demand for quality food products, the potential for probiotics is enormous.

Because probiotics are not drugs, they are not regulated by the FDA. It is critical that producers, nutritionists and veterinarians choose products from reputed manufacturers with adequate research so that they get a quality product for their animals.

Antibiotics will always play a crucial role in livestock management. Probiotics are not the best alternative to antibiotics when it comes to treating or preventing acute infections, but probiotics certainly provide an alternative to antibiotics for improving health and profitability of farm operations.