The last chance for antibiotics as growth promoters

Global situation of antibiotic growth promoters

Meat is increasingly consumed globally so that the farming industry is constantly improving animal production. In poultry, genetics and nutrition for broilers are continuously selected to answer this demand, improving animals’ performance and final weight. As an example, the National Chicken Council published statistics about chicken consumption and performance in the US in the last years, indicating +39% in broiler production (ready-to-cook meat), +20% in human consumption, +25% in broilers’ final weight at 47 days of life and a reduction by 0.13 in FCR, between 2000 and 2018. The use of antibiotics at low dosages as growth promoters (AGP) is widespread to help animals modulating gut microflora, mildly suppressing harmful bacteria. China is the first country in the world for AGP use. India introduced limits for antibiotics’ residues in meat only in 2011 and AGP are currently widely used. In Brazil, Mexico, and other countries of the Latin America antibiotics are currently used both for therapeutic purposes and as growth promoters. There are only few exceptions worldwide: AGP in animal productions were banned a few years ago in Chile, Turkey, European Union, South Korea, and US but they were largely used in the past.

Why are agp a problem?

The continuous use of sub-therapeutic dosages of antibiotics in animals’ productions killed bacteria sensible to these molecules while selecting resistant strains. Thus, pathogens important both for animals and humans acquired more and more resistance to different antibiotics, they are widely spread in the environment, and are also included in meat and animal products: this is one of the most relevant sources of infection for humans. Multi-drug resistant bacteria cause several infections very difficult to treat, resulting in prolonged illness, and disability. This means severe health problems, but also a huge loss of money for treatments and medical care both in human and veterinary medicine. Nevertheless, the global mortality after the infection by resistant bacteria is 700’000 people per year worldwide. Antimicrobial resistance is a complex problem with many interconnected factors, but, for sure, AGP is among the most important causes.

The new global trend

All countries are adopting several measures to face this increasing problem, among which the reduction of the use of antibiotics as growth promoters. For example, the Chinese government decided to control antibiotic resistance in bacteria of animal origin within 2020, implementing a strict regulation of registration, market, and surveillance of drugs, the reduction of AGP with national plans and models, and doing tests for antimicrobial residues in animal products. In 2012 the FDA promoted a voluntary program to reduce unsupervised use of AGP in the US and during the next years, several acts were promulgated to preserve the effectiveness of antibiotic treatments, with the ban of AGP in 2017 with the VFD. The New Zealand Veterinary Association wants to completely eliminate antibiotics in managing animal health and welfare within 2030. Because of the strict interconnection of many factors in animal production, the reduction and elimination of AGP need several measures to be put in place.

Possible tools to reduce AGP in poultry production

If we reduce the sub-therapeutic administration of antibiotics, we need to be sure that animals will find an environmental commensurate pathogenic pressure and that they will be able to face it. This is related to 4 fundamental topics: animal density, biosecurity, preventive measures, and nutrition.

Since pathogen is spread in the environment with feces, the fewer chickens in the flock, the cleaner the litter, and the fewer health problems arise. The all-in-all-out rearing protocol, effective disinfection at the end of the cycle, clean litter, and strong biosecurity measures during animal rearing are extremely important to overthrow the microbial load and prevent bacterial infections and shedding. A main topic of prevention is vaccines to improve chickens’ immune response to pathogens and reduce clinical signs of infections. Last but not least, nutrition is a very important tool to deal with resistant bacteria. Nutritional deficiency can affect the immune system and response of poultry, and feed additives can help to balance poultry diets. At the same time, feed additives can improve animal growth and performance with better intestinal health. For example, organic acids and nature identical compounds (NIC) can have strong antimicrobial activity against different intestinal pathogens. When in combination, these molecules have a synergistic mode of action: organic acids pass the bacterial membrane causing cells’ death by energy starvation, while NIC are pore-forming agents that disrupt cells’ integrity, causing cell death and increasing organic acid entrance and activity. This synergy results in a strong antimicrobial activity against a number of pathogens included multi-drug resistant bacteria. These qualities are at the base of AviPlus®P that is proved to enhance chickens’ live performance (body weight and FCR) and to modulate intestinal microflora. This microencapsulated product contains a specific blend of organic acids and NIC. In a study conducted at North Carolina State University, these ingredients demonstrated to have an anti-inflammatory activity on the intestinal mucosa, thereby improving the barrier function against toxins and bacteria, allowing better nutrients absorption. Our research proved that the combination of AviPlus®P ingredients can eliminate different important pathogens in a very effective way. Last data, presented at PSA Latin American Scientific Conference, confirmed that the combination between sorbic acid and thymol can eliminate E. coli strains resistant to different conventional antibiotics, isolated from broilers with colibacillosis.

The next step

In a global context of reduction of AGP, because of the increasing antibiotic resistance and animal and human infections difficult to treat, a multifactorial approach is needed. We certainly should improve management, biosecurity, and prevention in poultry production, but nutrition plays a key role in animal health. Feed additives are an effective tool to balance the diet, improving poultry performance, and overthrow harmful pathogen load during the entire rearing cycle.For more information: