10 Aug Antibiotic Use in Animal Agriculture in Australia and the Rise of Antibiotic Resistance.
A note on terminology used: the terminology used in this article is that of the animal agriculture and feedlot industry and is contained in many of their publications and reports. Terms such as ‘cattle’ are standard within the industry and do not indicate the author regards animals as property.
References are made to both antibiotics and antimicrobials. Antibiotics are drugs designed to kill bacteria and may be derived from mould or bacteria. Antimicrobials are a group of drugs that includes antibiotics, antifungals, antiprotozoals, and antivirals.
This article focuses on issues associated with the use of antibiotics and animals, and will also make reference to both antibiotic resistance and antimicrobial resistance.
Antibiotics are used widely in animal agriculture in the raising of feedlot cows, chickens and pigs for human consumption, and serve two distinct purposes. They may be administered daily as growth promoters to increase the weight of each animal, and are also prescribed by veterinarians to combat bacteria and the spreading of diseases amongst animals.
Concerns about the overuse of antibiotics and antibiotic resistance (also referred to as antimicrobial resistance) are largely unheard and are not well known.
In 2016, the Humane Society International Australia made a submission on the ‘Regulation of Agriculture Draft Report’ by the Productivity Commission to raise concerns about the routine use of antibiotics in intensive farming practices. The report cited the heavy use of antibiotics on factory farms has created a significant health issue by spawning antimicrobial-resistant superbugs that are transmitted to humans through the consumption of meat. These superbugs include resistant strains of E.coli, salmonella, and gastroenteritis. Furthermore, the World Health Organisation has recognised this as a significant global health issue and called for a reduction in the use of antibiotics on farms, and the United Nations Food and Agriculture Organisation (FAO) has also stated that ‘intensive industrial farming of livestock is now an opportunity for emerging diseases’. (1)
So how have we got here and what is the state of the issue within the Australian animal agriculture industry?
Lot feeding and issues of self-regulation
Australia imports approximately 700 tonnes of antibiotics annually; 550 tonnes are used for either veterinary therapy (to assist sick animals) or growth promotion (to enable higher yields of growth of farmed animals). Of the 33 classes of antibiotics used in animal and humans, one third are classified as of high to medium importance in human therapy. (2)
There are restrictions on the use of veterinary-prescribed antibiotics which has resulted in the reduction of certain drugs being used in food-producing animals, however, there is no licencing of feed millers. Corn, sorghum, wheat, and barley are the most used cereals in the preparation of feed for the cows, pigs, chickens and fish in animal agriculture.
In addition to oral administration and injection of antibiotics, small amounts are mixed into animal feed for weeks or months at a time. Feed dosing provides ripe conditions for the emergence of resistant strains. Surprisingly there is no national regulation of the use of growth promotants in animal feed in Australia; only self-regulated industry guidelines exist.
A number of antibiotics including Hormone Growth Promotants (HGPs) can be purchased and used without the supervision or administration by a veterinarian. (3)
In 1993, the Stock Feed Manufacturers’ Council of Australia (SFMCA) successfully argued against requiring registration of stockfeed containing antibiotics. Veterinary chemical product registration and controls are combined nationally under the National Registration Authority, later to be renamed the APVMA. (4).
It should be noted that 90% of grain-fed cattle receive an ionophore (an antimicrobial fed to animals designed to increase weight gain) through their feed according to A Survey of Antibacterial product use in the Australian Cattle industry produced by Meat and Livestock Australia in February 2013. (5)
One of the objectives that the report sought to address was the issue of the Australian cattle industry having no reliable or systematically collected data on the quantity or use patterns of antimicrobials by the industry.
The MLA report uncovered that in feedlots, a very high proportion (estimated to be in excess of 90%) of cattle are fed an ionophore for the duration of their time on feed, to promote growth. Monensin is clearly the dominant agent (again, it is estimated to be used in more than 90% of cases). The use of injectable antibiotics varies substantially between feedlots. One feedlot showed a rate of antibiotic use of less than 2%, while at another, 30-40% of animals were treated. The registrant data suggests that the average treatment rate is closer to the upper end of this estimate. Most treatments are directed at bovine respiratory disease (BRD).
According to the Australian Lot Feeders’ Association (ALFA), the majority of antibiotics used in the cattle industry are not used in human medicine.
ALFA cite that antibiotics can only be accessed via prescription from a veterinarian and are subject to the National Feedlot Accreditation System or NFAS, an independently audited quality assurance program. The industry organisation also claims that the level of hormones in beef derived from treated cattle is significantly less than the natural level of hormones found in many other products consumed every day by the general public. For instance, a serving of beer contains 7 times the level of hormones as a serving of HGP treated beef – a serving of peas 179 times and ice cream 273 times. (6)
In addition, ALFA point to various Government reports including the most authoritative report undertaken to date in Australia, the JETACAR report, and claim that it has been confirmed that antibiotic resistance in Australian cattle was nil or extremely low and concluding that resistance is due to over-prescription in human medicine.
The Joint Expert Technical Advisory Committee on Antibiotic Resistance (JETACAR) report stated that while there are strict registration procedures for veterinary antibiotics, it raised concerns about the importers and feed-millers not being licenced (with the exception of 2 licenced feed millers in Tasmania), and no clear audit process for antibiotics added to feed mixes or home users. The report cited the need for antibiotic regulation and raised concerns about the ‘off-label’ use including that by farmers who can purchase and use antibiotics without the intervention of a veterinarian. (7)
The Executive Summary of the JETACAR report outlined that in its consideration of antibiotic resistance and it’s implications in both human and veterinary medicine, that there was evidence of:
-the emergence of resistant bacteria in humans and animals following antibiotic use
-the spread of resistant animal bacteria to humans
-the transfer of antibiotic-resistant genes from animal bacteria to human pathogens
-and resistant strains of animal bacteria causing human disease.
Warnings about lack of transparency
Professor Peter Collingnon is a world-renowned infectious diseases expert and microbiologist based at the Australia National University. Professor Collingon has raised concerns for a number of years now about what he describes as a lack of transparency on the use of antibiotics in the Australian farming industry.
In May 2014, Professor Collingnon presented at a one-day symposium, hosted by Meat & Livestock Australia (MLA). The forum was designed to bring together representatives and stakeholders from the cattle industry to present the findings of their research and to further examine the issue of antimicrobial resistance in the industry. The suggestions made by Professor Collignon included the following regarding prudent antibiotic use in the production of animals:
• Do not use antibiotics as growth promoters.
• Use antibiotics for prophylaxis (prevention) sparingly and examine alternatives (diet, vaccination, etc).
• Although antibiotic therapy of sick animals is not an issue overall, do not use ‘critically important’ or ‘last line’ human antibiotics (glycopeptides, FQs, 3GCs). (8)
Some of the common vaccinations used in Australian cows raised for beef are for botulism, tick fever, Pestivirus (Bovine viral diarrhoea virus), vibriosis, Three-day sickness (Bovine ephemeral fever), Clostridial diseases (Blackleg, tetanus, and pulpy kidney) and Leptospirosis. (9)
Federal government response
Fast forward to 2015. The Australian government sought to address the overuse of antibiotics in both humans and animals, and for the first time developed a national plan to counter increasing concerns about the rate of antibiotic resistance. The then Federal Health Minister Sussan Ley said that there had been federal subsidies for some 29 million prescriptions of antibiotics, making Australia’s consumption the highest in the world. (10)
The Australian Commission on Safety and Quality in Health Care study found more than 30% of antibiotic prescriptions in 2013 were inappropriate. There was also increasing evidence that antibiotics used in agriculture are contributing to resistance rates and it was acknowledged that there is a lack of data and monitoring in this area.
Additionally, the strategy recommended nationally consistent prescription guidelines to be developed and followed in both human and animal healthcare to combat the issue.
Professor Collingnon who has been involved with a number of World Health Organisation advisory committees has stated that “There is a lack of appropriate controls in Australia for antibiotic use in food.” (11)
Professor Collingon has cautioned that in Australia it is not known which antibiotic or the quantity of it is given to which animal. By comparison, the available data from other countries show for example, that the US pork industry uses four to five times the amount of antibiotics as the industry in Denmark. In Australia currently, we do not have a mechanism with which to collect this data and manufacturers cite commercial confidence, therefore, making the development of a mechanism difficult.
A specific concern is the identification of third-generation antibiotic-resistant E.coli in the chicken supply. In Australia, those same antibiotics are being used in pigs and cattle, though it was unclear how frequently and in what quantities.
“As far as we are aware it’s not used in chickens in Australia but there isn’t a law that says it can’t be,” he said. “If a vet were to start using it tomorrow in chickens, there would be no way for me to find that out.”
Professor Collingnon has advised that in the US animal agriculture industry, Perdue chickens have moved their operations to be antibiotic-free after a significant investment of capital and improving animal husbandry. Perdue is a very large corporation and exploits twice as many chickens as the whole of Australia, so change is possible despite suggestions of the contrary from the pharmaceutical industry.
The Australian Poultry Industry decided against using a third-generation antibiotic called cephalosporin in chickens, and the level of drug resistance in human infections is 3% in Australia, compared to more than 50% in countries using the drug. (6) Cephalosporin is a wide range of antibiotics used to treat bacterial infections such as ear and skin infections, pneumonia, and gonorrhoea. (12)
Impact of hormone growth promotants on cows
Cows produce steroid sex hormones to regulate reproduction and growth. Within the animal agriculture industry, cows may have an implant containing natural and synthetic hormones placed under the skin in the back of their ear.
The purpose of HGP implants is to promote daily weight gain, conversion of feed and carcass quality. Commonly used HGPs are trenbolone acetate and estradiol benzoate (both synthetic hormones). Once the hormone has metabolised, it serves to increase the rate at which muscles grow by 10-30% (Hunter 2010), and reduces the overall feed time of the animal before it reaches slaughter weight. HGP work over an average period of around 70 days and may be reimplanted repeatedly over the growing/finishing period (on average twice according to Hunter (2010)).
The RSPCA acknowledge that there is little research about the effects of HGPs on the welfare of cows. The available research is focused on production characteristics rather than on animal welfare specifically. Feedlots pose a risk to the welfare of cows according to a study (Gaughan, 2005) that suggests that those animals with even an oestrogen implant could be adversely affected by the hot climate. Managing heat load and stress of cows in feedlots is crucial to their welfare.The majority of feedlots are based in QLD in hot conditions,
Other potential animal welfare issues relate to the place of injection of the hormonal implant which is often below the ear. This area has significant muscle movement, and there’s potential for the injection wound to become enlarged and irritated. Additional concerns are the failure to disinfect the injection site and also not injecting the implant properly.
Hormonal implants interact with the animal’s natural hormones and side effects of their use may include aggressiveness (particularly in the first few weeks after implantation), difficulty in handling, nervousness, rectal prolapse, ventral oedema (swelling) and elevated tail heads. Marin (2008) found evidence of chronic stress conditions. Although these side effects are less common, they are signs of poor animal welfare. (13)
The World Health Organisation
In September 2016 all of the 193 United Nations states formed an agreement that it should be a global priority to address the “fundamental threat” to global health; the issue of antibiotic resistance. It is estimated that drug-resistant infections kill more than 700,000 people each year. It is also acknowledged that there is no mechanism to track and monitor these deaths globally, and therefore the numbers may be much higher.
Alexander Fleming, who created the first antibiotic, penicillin in 1928 provided a warning of the potential for patients to become resistant to the drugs being used to treat them. He said in his Nobel prize acceptance speech in 1945 that, “There is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.”
The World Health Organization director-general, Dr Margaret Chan, has stated that it is imperative for consumers and medical providers to rely less on antibiotics for disease treatment.
Dr Chan has cautioned that there needs to be further innovation in antibiotic development and noted that only two new classes of antibiotics have been made available in the last 50 years. “The emergence of bacterial resistance is outpacing the world’s capacity for antibiotic discovery,” Chan said.
Concerns have been raised about the current trends indicating that common diseases like gonorrhoea may become untreatable, and gram-negative bacteria that cause infections such as pneumonia, meningitis and wound or surgical site infections in hospitals and healthcare facilities are proving to be resistant to antibiotics.
The UN has raised concerns that we are heading towards a world in which common infections (especially those caused by gram-negative bacteria) will kill, and that antibiotic developments are urgently required.
Signatories to the UN declaration have stated their commitment to increasing public awareness of the impending threat and developing the required regulatory systems to record the use of antimicrobials for humans and animals.
Antimicrobial resistance has been identified as a “fundamental threat” to global health and safety by the UN secretary-general, Ban Ki-moon and Professor Peter Collignon has warned that overprescribing antibiotics for human use is part of the problem, the use of antibiotics in the food industry was being “widely abused around the world”. (14)
Where are we now
The Antibiotics resistance in animals report by the Australian Pesticides and Veterinary Medicines Authority 2017 stated that there is increasing research from investigations to show that 3rd generational cephalosporin resistance is emerging in pigs and calves, and has shown up in dogs, cats, horses and aquaculture. (15)
The government’s report Australia’s Antimicrobial Resistance Strategy 2020 and Beyond refers to emerging research that indicates that active antimicrobials are contaminating waters, especially in areas close to human habitation and pose a risk to human health. Additionally, it was advised that consideration should be given to the various ways that antimicrobials can enter the environment and specifically, for example from sewage treatment plants into waterways, as well as in agriculture, aquaculture and in human health.
The report acknowledges that there are gaps in how monitoring, reporting, data collection and different diagnostic systems across various bodies has resulted in difficulties in getting an accurate picture of antimicrobial resistance in Australia.
There is a strong need for a unified national approach to addressing antimicrobial resistance, that includes a monitoring and evaluation framework to include stakeholder input from the human health, animal health, agriculture and environment sectors. (16)
Where to from here
The World Health Organisation has stated in its’ global plan against antimicrobial resistance that it wanted a whole new class of antibiotics in development to deal with the issue by 2019. Pharmaceutical companies make more money from the development of drugs for long term use such as heart disease or diabetes, than antibiotics that are used only for a short period of time.
As experts are now warning of the wide use of antibiotics in the current food system that uses animals is linked with the spread of antimicrobial-resistant infections in humans, there is increasing pressure to phase out the routine use of antibiotics in the meat and livestock industries.
It is difficult to see how this can happen in the current capitalist system of large-scale factoring farming and large, intensive feedlots.
Antibiotic use in animal agriculture and its links to antibiotic resistance highlights yet another negative impact of our unnecessary use of animals as food.
It has never been more critical to move away from animal agriculture to end the unjustified use of animals for food, and to curb what can only be one of the most critical looming global health threats of our time.
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