Medicosnext
One of the most widely consumed products of animal origin is poultry meat, which is the second most consumed meat in the world after pork meat, according to a 2013 survey on worldwide meat consumption. Poultry meat has been found to be healthier than red meat. Demand for foodstuffs originating from animals is anticipated to increase rapidly due to the increasing human population, rising per capita income, and urbanization. Among these, poultry meat is expected to grow the most.
Growing trend of poultry industry
Nepal began commercial poultry farming in 2031 BS, and the country currently ranks 112th in the world for chicken meat production. According to a CBS (Central Bureau of Statistics) survey, more than 75% of poultry farms are profitable. Poultry farms include broiler (chicken bred and raised specifically for meat production) farms, hatcheries, and Giriraja (a breed of chicken developed by Karnataka Veterinary, Animal, and Fishery Sciences University in Bengaluru, India) and kuroiler (a hybrid breed of chicken developed by the Keggfarms Group in Gurgaon, Haryana) farms, but 93.29% of poultry farms are broiler farms.
Poultry industries are showing rapid growth across the world, both in terms of number as well as output per animal. According to a FAOSTAT (the UN’s Food and Agriculture Organization Corporate Statistical Database) survey conducted in 2016, the average carcass weight has increased by 30%, from 1.3 kg in 1961 to 1.7 kg in 2013. Several technological advancements, such as improvements in feeding technology, genetic advancement, health improvements by increased use of vaccines and antibiotics, and the development of better feed, have helped in achieving the result of increasing productivity. From FAOSTAT data, the world has over 23 billion poultry (three birds per person on the planet). The United States is the world’s largest meat producer, followed by China, the European Union, and Brazil.
History of use of antibiotics in livestock
Antibiotics date back to the 1940s, when penicillin was used to treat bovine mastitis and was added to animal feed. Antibiotics in chick feed boosted growth and weight gain. When the cost of these antibiotics started to come down, their use in livestock for different purposes increased. Then, these antibiotics started being used for chemotherapeutic and prophylactic purposes. as well as feed additives, to promote growth, improve feed efficiency, improve breeding performance, and enhance feed acceptability.
Role of antibiotics in poultry industries
Different antibiotics and drugs are administered to livestock at therapeutic, prophylactic, or sub-therapeutic concentrations.
• Disease prevention
The most common prevalent diseases in poultry are typhoid, mycotoxicosis, E. coli infections, salmonellosis, enteritis, etc. These diseases not only influence poultry growth and production, but also result in a high mortality rate and economic loss. Antibiotics prevent such diseases by controlling zoonotic pathogens, and are used in poultry to prevent and treat bacterial infections, which can be a common problem in crowded farm environments. They may be administered through feed, water, or directly to sick birds.
• Growth promotion
When antibiotics are used as growth promoters in poultry, they are typically added to the birds’ feed or water at low doses over a prolonged period. The antibiotics can help to reduce the number of harmful bacteria in the birds’ gut, which can improve the birds’ digestion and nutrient absorption. This can lead to increased weight gain and improved feed efficiency, which are desirable traits for poultry producers.
• Metabolic effects
Antibiotics can be used in poultry for metabolic effects, such as improving feed efficiency and preventing or treating bacterial infections. Some antibiotics can improve nutrient absorption, promote growth, and reduce harmful bacteria in the bird’s gut, leading to improved weight gain and lower feed costs. Additionally, antibiotics can be used to prevent or treat bacterial infections in poultry, which can cause illness and economic losses.
• Nutrient-sparing effect
Antibiotics in poultry can improve nutrient utilization by reducing the amount of energy required for digestion, leading to improved feed efficiency. This is due to changes in the microbial population in the bird’s gut, which can improve the bird’s ability to absorb nutrients from its feed. Additionally, antibiotics can reduce the incidence of bacterial infections, which can lead to a more efficient use of nutrients by the bird.
Common antibiotics used in poultry industries
There are several antibiotics commonly used in poultry industries for various purposes, such as disease prevention and treatment, growth promotion, and feed efficiency improvement. Some of the most common antibiotics used include: ionophores, tetracyclines, macrolides, sulfonamides, penicillins, etc.
Antibiotic residues in poultry meat in Nepal
A screening test of poultry meat samples collected from Kathmandu, Kaski, and Chitwan for antibiotics using ELISA technique showed that, out of 92 samples, 57 (62%) were found positive for antibiotics residue, of which 38% were positive for strepromycin residue, 15.2% for ciprofloxacin, and 8.7% for enrofloxacin. In a study on antibiotic residues in marketed meat of Kailali and Kavre districts, a total of 55 samples (41 muscle samples and 14 liver samples) were collected from different retail shops and tested for the antibiotics penicillin, tetracycline, aminoglycosides, macrolides, and sulfonamides. It was found that 22% of samples were positive for at least one of the antibiotics tested. Tetracycline was detected in a maximum of 16 samples, followed by macrolides, sulphonamides, and aminoglycosides in 13 samples, and finally, penicillin in a minimum of 7 samples. It was also found that out of 41 muscle samples and 14 liver samples, 16 (39%) muscle samples and 10 (71%) liver samples were found positive for antibiotic residues. It showed the prevalence of antibiotic residues to be higher in liver than in muscle.
Impact of misuse of antibiotics
Several researchers have demonstrated antibiotic resistance in microbes isolated from poultry. A study on antibiotic resistance of bacterial isolates of poultry collected from the postmortem unit of the National Avian Disease Investigation Laboratory, Chitwan, showed that 100% of the isolates were resistant to bacitracin, 80% to gentamycin, 79.4% to cotrimoxazole, 75.6% to cephalosporin, 57.1% to tetracycline, 54.3% to neomycin, 45.7% to doxycycline, 23.1% to azithromycin, 19.4% to ciprofloxacin, 12.5% to chloramphenicol, 6.7% to levofloxacin, and 4.3% to amikacin.
Occurrence of residues in meat
Veterinary medicines and chemicals used according to the label directions should not result in their residues at slaughtering. However, the possible reason for such residues may be due to not properly following recommended labels or dosages and other measuring or mixing errors.
Impact on consumer
Antibiotic-resistant bacteria are responsible for a huge number of deaths worldwide. Beyond those deaths, bacteria that are resistant to antibiotics cause millions of illnesses and cost billions in healthcare spending, lost wages, and lost national productivity. It is predicted that antibiotic resistance will cost the world $100 trillion and will cause a staggering 10 million deaths per year by 2050.
Impact on environment
With the increase in global consumption and production of animal products, large quantities of antibiotics are released into the environment. From 30% up to 90% of the dose consumed by the animals is found in the urine and feces as parent compounds and metabolite compounds.
Remedies to occurrence of antibiotic residues in foods from animal origin
The misuse of these antibiotics may result in the aforementioned hazards on poultry and consumers, as well as on the environment. So, it is very important to control such residues. This can be done by developing rapid screening methods for detecting antibiotics above maximum residue levels (MRLs), setting appropriate MRLs by regulatory bodies, following appropriate withdrawal periods, encouraging alternative practices, such as bio control measures and ethno-veterinary practices, promoting organic poultry farming, and using proper processing techniques to inactivate antibiotic residues.
