Antimicrobial Feed Additives For Animals
, PhD, South Dakota State University
Maintenance of healthy animals requires prevention of infection by pathogenic organisms. In addition, specific alteration of a hosts microflora may have beneficial effects on animal production by alteration of ruminal flora, resulting in changes in the proportions of volatile fatty acids produced during ruminal digestion. Thus, antimicrobial compounds may improve production efficiency of healthy animals fed optimal nutritional regimens.
Production-enhancing antimicrobial compounds can be classified as ionophore or nonionophore antimicrobials. This distinction is important, because ionophores have no use in human medicine and do not have any link or possible effect on antimicrobial resistance to therapeutic antimicrobials in either humans or food animals.
Antimicrobial growth promotants commonly used in production animals are detailed in Antibacterial Growth Promotants in Production Animals Antibacterial Growth Promotants in Production Animals . Antimicrobials are used in male and female animals without adverse effects on ovarian and testicular development or function because they are poorly absorbed. Unlike anabolic steroids, they do not affect carcass composition. Antimicrobials are commonly used in conjunction with estradiol, zeranol, or trenbolone acetate, and generally their combined effects are additive.
What This Means For Humans
Does this matter? How do you even get diseases or illnesses from livestock? It all starts with the colonization and transmission of antibiotic-resistant bacteria in food animals such as cattle, pork, poultry, and sheep. When the animal builds an antibiotic resistance, there is nothing to stop or minimize the bacteria from growing. Exposure sources include fecal matter, intestinal flora, and the consumption of animal products such as the meat itself. Once exposed, the individual is susceptible to infection and hospitalization, and potentially infecting others as well.
There are a number ways for a human to get infected with the antibiotic-resistant bacteria such as eating or handling the uncooked raw meat or poultry, coming in contact with the feces of the food animal, or drinking water that came into contact with animal feces. The drug resistant bacteria can remain on the meat when not handled or cooked properly and can spread to humans. Contagion, anyone?
You cannot completely stop antibiotic-resistant bacteria, but you can certainly slow it down. Antibiotic use can still prove beneficial for animal health. Subtherapeutic use of antibiotics means the dose or concentration of the drug is lower then what would usually be prescribed in order to effectively treat infections.
Diversity And Richness Estimates
Richness refers to the number of species in a microbial community while diversity relates to the number of species and evenness of distribution of the microbial species. The diversity and richness of the microbial population in the rumen, colon, and cecum samples was obtained from five control steers and five steers that were provided antibiotic feed additives, growth promoting implants and a beta-agonist during a research field study. Implants were administered during three production phases pre-weaning , backgrounding , and finishing to the AB steers. Additionally, AB steers received a beta-agonist during the final 31 days prior to harvest. Biodiversity of the human gut is reduced by both short-term and long-term use of antibiotics,. The AB steers were fed antibiotic feed additives, monensin and tylosin, which are known to cause changes in the bacterial population in the animal gut,. In the present study, we used shotgun metagenomics to study the alterations in the microbial community structure in the GIT of feedlot steers that were fed monensin and tylosin.
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Antibiotic Use In Food
Animals such as laying hens often share space with tens of thousands of animals in one location. Medically, antibiotics can be particularly useful to curb loss, both in the deaths of the chickens and money for farmers. Antibiotics in animal feed can prevent huge amounts of death and loss due to the sheer concentration of animals. Diseases can quickly spread in such an environment. Growth promotion and improvement of feed efficiency are other reasons why farmers opt for antibiotic use in animal feed.
The Food and Drug Administration has long approved antibacterial products, but they started to phase out certain types of antibiotics. The FDA is responsible for protecting the U.S. public health by ensuring safety, efficacy, and security of human and veterinary drugs, biological products, and medical devices.
They changed the way antibiotics can be utilized in food animals. The FDA along with the United States Department of Agriculture and the Environmental Protection Agency , administers the U.S. National Residue Program to prevent hazards to human health from entering the food supply.
The Food and Drug Administration approved the following uses for antibiotics in food animals:
- Disease treatment for sick animals
- Disease control for a group of sick animals
- Disease prevention for animals at risk of becoming sick
Producer Vfd Preparation Steps
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Feed Additives Can Reduce Costs And That’s Good News
Elevated feed costs may be the tallest hurdle that beef producers face in achieving greater profitability. Low supplies of hay, grains, and co-products have forced respective prices to climb to record-highs. For producers who plan to supplement cows this winter, feed additives, such as monensin, will help reduce feed costs.
Sample Collection And Genomic Dna Isolation
Samples of digesta were collected from rumen, colon, and cecum immediately after slaughter and were snap-frozen in liquid nitrogen. These samples were then transferred to 80°C and stored until use. Genomic DNA was isolated from these samples using Powersoil DNA isolation kit . Approximately 100mg of sample contents were transferred to bead tubes for DNA extraction. After adding 60µl of solution C1 to the bead tubes, samples were homogenized for 2min using Tissuelyser . Remaining steps of DNA isolation was performed according to the manufacturers protocol. The DNA was eluted in 50µL nuclease free water. The quality of isolated DNA was analyzed using NanoDrop One and DNA was stored at 20°C until use.
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Cattle Feedlots Are The Last Step In Beef Production Before Slaughter How Do You Make Sure Antibiotics Do Not End Up In Our Beef Supply
Regardless of how an animal receives antibiotics, they are entered into the computerized record keeping system. This helps administer the proper dosage, track an animals progress, and observe proper withdrawal times. Every antibiotic has its withdrawal right on the bottle. We enter it in the computer and every time an animal receives treatment, its clear date is displayed on the treatment, movement, and shipping programs. Before a pen is harvested, we check withdrawals and remove any animals if necessary.
One last question. I often get the response of Well, if you didnt have these animals in such a crowded place, they wouldnt have to receive antibiotics. How would you respond to someone saying that?
I love cattle, but they are one of the most poorly designed creatures on the face of the Earth. A vet once described them to me as a car with 4 engines and one radiator. There will be animals that get sick and require antibiotics regardless of where they are. Also, land is valuable and scarce. Around here, 160 acres goes for 1.4 million dollars. We can produce much more protein sowing that to corn or barley and feeding that to cattle than we could turning cattle out on that land.
Do you have questions about antibiotics, feed additives, or any other aspects of livestock production? Feel free to leave a comment below or send me a private message through the Contact page.
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Vitamin And Mineral Packs
These provide essential vitamins and minerals to correct deficiencies in other feed sources. Feedlot performance results are variable and may depend on vitamin and mineral status prior to arrival at the feedlot. If theres no deficiency to start with, they may not give much benefit.
Calves that are highly stressed from weaning, transportation, or poor conditioning may get an economic benefit from extra vitamin and mineral supplementation.
Products: 20-10 Plus Mineral and Availa-4
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What Is The Maximum Number Of Times An Animal Will Get Treated With Antibiotics When Do You Decide To Stop Treating The Animal
Typically, an animal will receive no more than 3 or 4 treatments . However, if we think the animal will respond and improve, we will treat as many times as necessary. When we hear consolidation and referred sounds in the lungs, an animal is determined to be chronic and treatment is either ceased or altered, depending on treatment history, condition, and amount of consolidation in the lung.
Yeast Cultures And Fermentation Products
Some yeast products have been reclassified as post-biotics, a relatively new term within ruminant nutrition. Many of these products have been on the market for quite some time, but have been classified as prebiotics. These are microbial metabolites delivered with inactivated cell or cell fragments of the microbes or yeast that produced them. Commercial products are often called cultures or extracts or described by their source . One way to differentiate between pre- and post- is by saying prebiotics act on native microbial populations and postbiotics act on the host animal. Post-biotics are often attributed with the ability to confer health-related benefits. Research with specific products has shown desirable impacts on immunity, modulation of inflammation, and toxin or pathogen binding capabilities. However, because they are not registered and regulated as drugs, companies must be very cautious about publicly making what could be considered a health claim.
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What Is A Veterinary Feed Directive
The VFD is a written statement issued by a licensed veterinarian in the course of the veterinarians professional practice that authorizes the use of a VFD drug or combination VFD drugs in or on an animal feed. This written statement authorizes the client to obtain and use animal feed bearing or containing a VFD drug or combination VFD drugs to treat the clients animals only in accordance with the conditions for use approved, conditionally approved, or indexed by the FDA. A Veterinary Feed Directive is also referred to as an VFD order.
When Do Feedlot Cattle Receive Antibiotic Treatments For Sickness
The last way we use antibiotics is for individual animal treatment. This could be for anything from BRD to footrot or acidosis. In our yard, sick cattle are pulled by cowboys and brought to the hospital, where we use a thermometer, stethoscope, and visual assessment to diagnose and determine the severity of an animals illness.
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The New Rules Of Feed Antibiotics
After decades of discussions, proposals, and threats, its finally happened: There are new rules for including antibiotics in animal feeds.
As of January 1, 2017, a new regulation from the U.S. Food and Drug Administration requires that a prescription from your veterinarian a veterinary feed directive be in place for all medically important antibiotics administered in feed and water.
Tom Peters, a consulting nutritionist to beef producers for Superior Attitude Livestock Technologies in Oregon, Illinois, answers seven questions about the new law.
Is There Something Good That Can Come From This For The Beef Industry
Peters: Consumers are telling us they want less antibiotic use in animals that become food products. It doesnt make any difference if there is science behind it or not. If its what they want, well provide it. Well get more judicious use of antibiotics, and thats good. Maybe some producers have overused antibiotics, and that will end.
Now, we need to follow the new rule to the letter. We can have no violations. None! If we violate the rule, it will surely bring even more regulation.
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Phytochemicals And The Digestive Microbiota
The mammalian gastrointestinal tract harbors a dense and diverse microbial community, which is composed primarily of bacteria but also includes fungi, Archaea and viruses. Collectively, these are referred to as intestinal microbiota. These microorganisms are environmentally acquired, and their metabolic functions can shape host physiology. Many vertebrates consume a diet rich in complex nutrients that are indigestible by their own intestinal enzymes, relying on the diverse biochemical catabolic activities of the microbiota. Available evidence strongly suggests that the gut microbiota plays important roles in host energy harvest, storage and expenditure, as well as overall nutritional status . It must be highlighted that germ-free animals that lack any microbiota weigh less and have less fat than conventional animals , pointing out a key role of the microbiota in weight gain. Gut microbiota may affect weight gain through regulating nutrient extraction, and modulating the immune system and metabolic signaling pathways .
In ruminants, tannins modify the digestive processes not only by binding dietary protein , but also through modulation of rumen microbiota and improvement of the growth of certain bacterial populations . The effects of tannins on rumen microbiota may vary depending on the molecular nature of these polyphenols . The understanding of in vivo interactions between rumen bacteria and sources of plant tannins are limited.
Resistome Composition Of The Gut
The presence of antibiotic resistance genes in the pathogenic bacteria has been a threat to human and animal health. Microbiome of livestock could act as a potential reservoir for AMR genes for the pathogens. Antibiotic resistome of the GIT is composed of all the AMR genes present in pathogenic and non-pathogenic bacteria. The use of antibiotics as feed additives in livestock farming has been a controversial subject because of the possibility of gut microbiome gaining AMR determinants and expanding the antibiotic resistome. Functional metagenomics provides a potential resource for detecting the existence of AMR genes and antibiotic resistome composition in the gut microbial community.
Figure 7
Heatmap showing the resistome profile in the GI tract of feedlot steers. Steers were fed Monensin and Tylosin as feed additives or control animals were not given any treatments . Samples were collected from rumen, colon, and cecum and DNA was subjected to metagenome sequencing using Illumina platform. The raw files were de novo assembled and antibiotic resistance genes were identified searching the assembled contigs against a local copy of ResFinder database using BLAST. The yellow color represents absence of the antibiotic resistance genes and orange color indicates the presence. The macrolide resistance genes erm and erm were detected only in rumen of 3 AB steers.
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Use And Regulation By Country
The use of medicines to treat disease in food-producing animals is regulated in nearly all countries, although some countries prescription-control their antibiotics, meaning only qualified veterinary surgeons can prescribe and in some cases dispense them. Historically, the restrictions have existed to prevent contamination of mainly meat, milk, eggs and honey with chemicals that are in any way harmful to humans. Treating a sick animal with medicines may lead the animal product containing some of those medicines when the animal is slaughtered, milked, lays eggs or produces honey, unless withdrawal periods are adhered to which stipulate a period of time to ensure the medicines have left the animal’s system sufficiently to avoid any risk. Scientific experiments provide data for each medicine in each application, showing how long it is present in the body of an animal and what the animal’s body does to metabolise the medicine. By the use of ‘drug withdrawal periods’ before slaughter or the use of milk or eggs from treated animals, veterinarians and animal owners ensure that the meat, milk and eggs is safe and free of any contamination. However, some countries have also banned or heavily controlled routine use of antibiotics for growth stimulation or the preventative control of disease arising from deficiencies in management or facilities. This is not over concerns about residues, but about the growth of antibiotic resistance.
Effect Of Tetracycline Feeding On Animal Therapy
Poultry And Swine
Cattle
Cattle in commercial feedlots should be studied that have not received antibiotics have received a high level of antibiotic during the first 3 to 4 weeks, followed by a low level during the remainder of the period on feed and have received a high level of antibiotic during the first 3 to 4 weeks, followed by withdrawal of the drug. Comparisons should be made of tetracycline therapy on sick animals from the lots on the various treatments. Response to therapy should also be monitored by the number of animals treated, the length of stay in the sick pens, and mortality. Measurements should also include antibiotic susceptibility of organisms in treated animals and samples of healthy animals from all lots at periodic intervals.
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Growth Promotion In Food Animals
There is a lot of controversy out there regarding the use of antibiotics to promote development in food-producing animals. The use of growth promoters and improvement of feed efficiency was introduced decades ago without much testing. Growth-promoting antibiotics, particularly in poultry production, can be associated with economic losses.
In 2017, the World Health Organization recommended stopping using antibiotics to promote growth and prevent infections in healthy animals, which was directed to farmers and the food industry as a whole. The World Health Organization stated that high volume of antibiotics in food-producing animals contributes to the development of antimicrobial-resistant bacteria.
Use Of Phytonutrients In Ruminants
AGPs are efficient in shifting rumen fermentation towards more efficient energy and nitrogen utilization pathways , improving productivity in dairy and beef diets . Therefore, industry is searching for alternative feeding strategies and/or additives that will allow it to maintain the current level of production without increasing the cost.
Most phytonutrients of interest in animal feeding are classified into three main groups: saponins, tannins and EOs. Saponins and sarsaponins are the main active components of several phytochemicals, including yucca, quillaja, alfalfa and fenugreek. Saponins exhibit antibacterial and antiprotozoal activity, resulting in a reduction in ammonia nitrogen concentration. Tannins are phenolic compounds found in almost every plant part, and are divided into two groups, hydrolysable and condensed tannins. Condensed tannins have the ability to bind and precipitate proteins and may be useful in the control of protein utilization by ruminants , but at high levels may interfere with dry matter intake and digestibility of nutrients , and may decrease the incidence of bloating . EOs are secondary plant metabolites present in many plants and may have a wide range of effects. In this section, we review recent research on the use of EOs as feed additives in ruminants.
Essential oils as modifiers of rumen fermentation
Essential oils as modifiers of metabolic activities
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