Use of Antibiotics in Livestock Farming: Effect on Public Health and its Alternative
Abstract
The livestock sector contributes a lot by providing food and income source for millions of people, worldwide. In India, livestock employs 8.8% of the population. It contributes 4.11% to GDP and 25.6% of total agriculture GDP. The livestock sector is facing prodigious pressure to meet the demand of increasing the human population for animal protein (like meat, milk, egg, etc.). Antibiotics are being used in the livestock sector as growth promoters to increase animal production so that demand and supply of animal protein can be maintained.However, antibiotics have a harmful impact on public health such as antibiotic residues in animal products, the development of antibiotic-resistant bacteria, the emergence of fungal infections, immunosuppression, etc. So, there is a need to develop other alternatives that are as effective as antibiotic growth promoters to overcome the development of livestock-associated antimicrobial resistance and other health-related issues of humans without affecting growth performance and production value of the livestock.
Key Words: Antibiotics, Antimicrobial resistance, Growth promoter, Livestock farming
INTRODUCTION
The antibiotic discovery was a breakthrough in mankind’s history. Antibiotic is like a magic bullet that kills pathogenic bacteria without harming the body cell. Antibiotics have saved countless lives from infectious diseases.Antibiotics not only have the therapeutic potential against bacteria but also have growth-promoting effects on animals when it is used below the therapeutic dose. Its mechanism of growth promotion is unknown. Demand for animal protein is increasing day by day due to an increase in the human population and also a shift in the food habits of people from vegetarians to non-vegetarians, globally. So,there is prodigious pressure on animal husbandry to increase animal production to meet the increasing demand for animal food. To do so, antibiotic growth promoters (AGPs)are being used in animalfarming especially in poultry, swine, and cattle for more than five decades and still in use. In a study, it is reported that the use of antibiotics will increase by 82% by 2030 (Van Boeckel et al., 2005).For many years, the positive aspect of the use of antibiotics in food animals wasnoted withoutundermining its negative consequences. But experts in the field of microbiology and infectious diseases faced antibiotic resistance among bacteria and raised questions about their impact on human health (Levy, 2002). Many studies found that farms using AGPs had more resistant bacteria in the intestinal floras of the farmworkers and farm animals than in those for similar people and animals on farms not using AGPs. A prospective in vivo/in situ study in 1975 was performed to evaluate the effect of introducing low-dose in-feed oxytetracycline as an AGP on the intestinal floras of chickens and farm dwellers (Levy et al., 1976). The results showed not only colonization of the chickens with tetracycline-resistant and other drug-resistant Escherichia coli strains but also the acquisition of resistance in E. coli in the intestinal flora of the farm family.
LIVESTOCK FARMING AND ANTIBIOTICS
Antimicrobials are delivered to animals for a variety of reasons, including disease treatment, prevention, control, and growth promotion/feed efficiency. The use of antibiotics in livestock farming as growth promoters is common practice to meet the increasing demand for animal protein (meat, milk, egg, etc.). Antibiotic growth promoters (AGPs) were first advocated in the mid-1950s when it was discovered that small, subtherapeutic quantities of antibiotics could enhance the feed-to-weight ratio for poultry, swine, and beef cattle (Stokestad and Jukes, 1950). A variety of antibiotics growth promoters are used in animal feeds to maximize the efficiency of production, product quality, and to control diseases (Vidanarachchi et al., 2005). AGPs have been used widely in livestock production for almost 50 years. Although the modes of action of AGPs are not fully understood, the main effects are thought to be mediated via the gutassociated bacteria (Gaskins et al., 2002).Antibiotic growth promoters (AGP) enhance production by limiting the growth of pathogenic microorganisms (Arowolo and He, 2018).
Effect on public health
It is a very well established concept that the use of antibiotics has positive effects on growth promotion. Besides this positive aspect of antibiotics, it is creating a very serious public health problem of antimicrobial resistance associated with livestock.There are many studies available that support the fact that antibiotic use in food animals raises antibiotic-resistant bacteria among the farm people and to the distant people through the food chain(Fey et al., 2000). The high volume of antibiotics in food-producing animals contributes to the development of antimicrobial-resistant bacteria, particularly in settings of intensive livestock farming. In some countries, the total amount of antibiotics used in animals is 4 times larger than the amount used in humans. In many countries much of the antibiotics used in animals are for growth promotion and prevention of disease, not to treat sick animals. European Union banned the use of antibiotics as growth promoters in 2006, because of its harmful impact on public health. These antibiotic-resistant bacteria can be transmitted from animals to humans eitherthrough direct contact, food (milk, meat, or egg)or the environment (contaminated fruits, vegetables, soil, water, etc.). Sometimes, infectious caused by these bacteria in humans can cause death because of the failure of all available antibiotics to treat that infection. Also, the use of antibiotics in food animals is one of the main reasons for the emergence of new fungal diseases. Increased cases of the compromised immune system are also one of the consequences of antibiotic use in food animals. WHO recommends an overall reduction in the use of antibiotics in foodproducing animals to help preserve their effectiveness for human medicine.Currently, antimicrobial resistance associated annual death recorded as 0.7 million which may reach up to 10 million in 2050 and it is also estimated that loss to global economy may reach upto100 trillion dollars along with 3.5% reduction in the global gross domestic product (GDP) till 2050 (O’Neill, 2014). The use of antibiotics in food animals not only harm human but also the animals and the environment.
Alternative to antibiotics in animal production
According to a study,India accounts for 3% of global consumption of antibiotics in poultry, swine, and cattle in 2010 and is among the top consumers worldwide besides China, USA, Brazil, and Germany, and its consumption will increase by 82% in India by 2030. If this will continue, then it would make the situation worse.Sweden was the first country in Europe that banned the use of AGPs in 1986 followed by the European Union in 2006 because of the emergence of antibiotic-resistant bacteria. However, the ban on AGPs resulted in an increased incidence of enteric disorders in food animals. Some other countries are also trying to restrict and regulate the use of antibiotics as antibiotic growth promoters.Before the implementation of this complete ban on the use of AGPs, some experts attempted to assess possible effects on growth rate and feed conversion efficiency and discussed possible alternatives after the ban (Wenk, 2003). But, now the time has come to replace the use of AGPs in livestock farming gradually with natural growth promoters. So that menace of AMR associated with livestock can be tackled efficiently without affecting the growth and production efficiency of animals.This leads to increased demand to search for natural growth promoters which will as efficient as AGPs.The probiotics, prebiotics, and phytobiotics possess great potential to substitute AGPs. The use of plants and plant bioactive compounds for treating various human and animal diseases is as old as human civilization (Li, 2000). It is well documented that ancient Egyptians, Chinese, Indians, and Greeks (Kamel, 2000) have used plants extensively for the treatment of various ailments related to humans and animals. In recent years, there has been an increased awareness of the potential that natural plant compounds have in the prevention and treatment. Term ‘Phytobiotics’ are used for the plant-derived bioactive compounds. Many studies claim that phytobiotics can enhance growth, production potential, the performance and well being of animals.The phytobiotics have many beneficial properties like prebiotics, probiotics, antimicrobial, anti-inflammatory and prevent the binding of harmful bacteria to the intestinal mucosa. A few phytobioticswith their properties are described below- – Thyme and yarrow extracts are reported to have the potential to reduce caecal counts of Clostridium perfringens when incorporated in the broiler diets (Cross et al., 2004). – The plant extracts containing capsaicin (1.98 g/100g), carvacrol (4.95 g/100g) and cinnamic aldehyde (2.97 g/100g) reduced C. perfringens and Escherichia coli counts in colonic contents, which is comparable to birds treated with the antibiotic, avilamycin (Jamrozet al., 2003). – Plants derived bioactive agents like thymol,carvacrol, phenylpropane, geraniol, etc. have antimicrobial properties (Yang et al., 2015). – The yeast cell wall contains phosphorylated mannan oligosaccharides (MOS) that prevent the binding of harmful bacteria to GIT mucosa (Spring et al., 2000). – Guoet al. (2003) found thatwhen two mushroom species; Lentinusendodesand Tremellafuciformis, and a herb, Astragalusmembranaceus radix, was fed to chickens, then activation of innate and adaptive immunity was observed. – The phytobiotics containfructooligosaccharides residues which were claimed to leads to the upregulation of immunoglobulin A (IgA) secretion in murine Peyer’s patch cells in the intestinal mucosa (Hosonoet al., 2003) – Essential oils extracted from various plants possess anti-inflammatory like chamomile essential oil has been used traditionally for centuries as a drug in eczema, dermatitis and other irritations (Kamatou and Viljoen, 2010). Essential oils from pine, clove, and myrrh have been used in mixed formulations as antiinflammatory agents (Darsham and Doreswamug, 2004).
CONCLUSION
Besides various achievements in the animal food production of milk, meat, eggs, etc., India still facingtremendous pressure to meet the increasing demand for animal protein. The use of antibiotics is a common practice in livestock farming to increase growth performance and production potential. And, its use will increase soon, besides its harmful effect on public health which will worsen the AMR menace.To tackle the problem of development AMR associated with livestock, phytobioticscan be used as an alternative to AGPs.Many studies suggest that phytobiotics may have the potential to increase the growth performance and productivity of the food animals in a similar way as AGPs. More research efforts should be carried out to develop and marketing the nonantibiotic animal growth promoter to maintain the sustainability of animal husbandry and to meet the ever-increasing demand of animal proteins.
Compiled & Shared by- This paper is a compilation of groupwork provided by the
Team, LITD (Livestock Institute of Training & Development)
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