Reducing Veterinary Drug Residues in Animal Products: A Review

Md Shohel Rana1,, Seung Yun Lee1,, Hae Jin Kang1, Sun Jin Hur1,*
Author Information & Copyright
1Department of Animal Science and Technology, Chung-Ang University, Anseong 17546, Korea
*Corresponding author: Sun Jin Hur, Department of Animal Science and Technology, Chung-Ang University, Anseong 17546, Korea, Tel. +82-31-670-4673, Fax: +82-31-675-3108, E-mail:

† These authors contributed equally to this work.

© Korean Society for Food Science of Animal Resources. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Jul 05, 2019 ; Revised: Aug 20, 2019 ; Accepted: Sep 16, 2019

Published Online: Oct 31, 2019


A survey we conducted suggests that the ingestion of veterinary drug residues in edible animal parts constitutes a potential health hazard for its consumers, including, specifically, the possibility of developing multidrug resistance, carcinogenicity, and disruption of intestinal normal microflora. The survey results indicated that antibiotics, parasitic drugs, anticoccidial, or nonsteroidal anti-inflammatory drugs (NSAIDs) are broadly used, and this use in livestock is associated with the appearance of residues in various animal products such as milk, meat, and eggs. We observed that different cooking procedures, heating temperatures, storage times, fermentation, and pH have the potential to decrease drug residues in animal products. Several studies have reported the use of thermal treatments and sterilization to decrease the quantity of antibiotics such as tetracycline, oxytetracycline, macrolides, and sulfonamides, in animal products. Fermentation treatments also decreased levels of penicillin and pesticides such as dimethoate, malathion, Dichlorodiphenyldichloroethylene, and lindane. pH, known to influence decreases in cloxacillin and oxacillin levels, reportedly enhanced the dissolution of antimicrobial drug residues. Pressure cooking also reduced aldrin, dieldrin, and endosulfan in animal products. Therefore, this review provides updated information on the control of drug residues in animal products, which is of significance to veterinarians, livestock producers, and consumer health.

Keywords: veterinary drugs; residue; effect; withdrawal period; reduction


Human beings consume protein-rich foods, mainly of animal origin (milk, meat, and eggs), to fulfill their nutritional requirements, and their health has been associated with the nature and quality of the food consumed (Rokka et al., 2005). Nevertheless, the quality of animal-based products is of great concern with regard to consumer health globally. Veterinary drugs such as antibiotics are generally used to enhance production, improve the feed conversion ratio, and treat diseases in food-producing animals (Beyene, 2016). However, the benefits of drug administration to farm animals used for food production are also accompanied by the risks associated with drug residues in the edible parts of treated animals (Boeckman and Carlson, 1995). Antimicrobial drugs, growth promoters, sedative drugs, anticoccidials, nonsteroidal anti-inflammatory drugs (NSAIDS), and anti-helminthics are the main veterinary drugs that potentially contaminate food-stuff (Beyene, 2016). Therefore, veterinary drug residues have been considered as a global food contamination challenge. Residues are defined as chemical substances or metabolites of medicinal products that may accumulate within the tissues or edible parts of treated animals (EC-European Commission, 2012). These residues may result from inappropriate or extra-label drug usage, failure to maintain drug withdrawal periods, or poor livestock production practices (Tajick and Shohreh, 2006). The treated animals may rapidly and efficiently metabolize some drugs while slowly and poorly metabolizing others; thus, the residues accumulate in the edible portion of the animals. Subsequently, consumers are exposed to these residues, resulting in health hazards (Babapour et al., 2012). Different cooking procedures, temperatures, and storage times, as well as the fermentation processes, have the potential to reduce veterinary drug residues (Heshmati, 2015). Hence, this paper aimed to review the potential sources of veterinary drug residues and their effects on the health of the public and highlight prevention, control, and reduction measures of drug residues in food producing animals.

Veterinary Drug Residues and Their Sources in Animal Products

Residues and chemical food contaminants arise from a variety of sources, including ingredients from natural toxins, industrial contaminants, agrochemicals/veterinary drugs, food processing, and packaging. Residues may also accumulate in animal tissues, depending on the drug’s physicochemical properties and pharmacokinetic parameters. The major causes of drug residue accumulation in food-producing animals include improper observation of withdrawal periods, failure to maintain treatment records, overdose, or using prohibited drugs for economic animal treatment (Beyene, 2016). Contaminated animal feedstuffs also act as an important source of drug residues (Peeters et al., 2016) (Table 1).

Table 1. Stability of veterinary drug residues of animal origin
Veterinary drugs Residue stability References
Antibacterial Aminoglycosides - Neomycin and streptomycin are stable in milk with approximately 40% reduced by boiling. Laszlo et al., 2018
- Gentamicin residues are stable in chicken muscle. Li et al., 2017
Amphenicols - Florfenicol is heat-labile in eggs and degraded (approximately 78%) via frying and boiling. Filazi et al., 2015
- Thermal treatment of meat degraded thiamphenicol by approximately 66%-82% in meat. Franje et al., 2010
Lactams - Cloxacillin is the most heat-stable in milk and degraded by <10% after boiling. Laszlo et al., 2018
- Ampicillin was degraded by roughly 25% in milk during boiling and penicillin-G reduced by >40%.
- Cephalexin reduced by approximately 40% in milk post thermal treatment.
Quinolones - Quinolone residues in milk were degraded by <10% when stored at 20°C.
- Quinolones are very stable during thermal procedures and decreased by only 10% in milk.
Rozanska and Osek, 2013
- Ciprofloxacin and norfloxacin were decreased by 12.71% and 12.01%, respectively, during thermal treatment of milk. Roca et al., 2010
Sulfonamides - Sulfadiazine showed approximately 10% loss during milk boiling.
- Sulfonamide residues are stable in animal tissues when frozen.
Laszlo et al., 2018
Tetracyclines - Pasteurization of milk decreased oxytetracycline and tetracycline residues by 40% and 30%, respectively. Kellnerova et al., 2015
Macrolides - Lincomycin and tylosin are more heat stable in milk. Heshmati, 2015
Adrenergic agonists Clenbuterol - Clenbuterol has a tendency not to degrade during storage. Pinheiro et al., 2009
- Different cooking procedures have no net effect on clenbuterol residues in incurred tissues. Parr et al., 2016
Sedatives Azaperone and azaperol - Azaperone and azaperol residues are stable in pig kidney and liver under frozen conditions. Aoki et al., 2009
Antihelminthics Albendazole - During milk storage, albendazole’s concentration was barely affected. Desmarchelier et al., 2018
Levamisole - Levamisole residues were decreased by 11% in fried muscle. Cooper et al., 2011
Rafoxanide - Decreased by only 17%-18% in cooked muscle.
Carbadox - Carbadox was stable in muscle. Zhang et al., 2018
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Antibiotics are very important, hence, widely used as veterinary medicine for therapeutic purposes as well as for prophylaxis and growth promotion. These substances inhibit DNA topoisomerases, protein synthesis, cell division and development, and/or cell wall synthesis of disease-causing or infectious microorganisms (Kohanski et al., 2010). Presently, approximately 80% of food animals receive antibiotics for part or most of their lifetime (Kibruyesfa and Naol, 2017), which may lead to residue accumulation in animal products. The presence of unexpected residues in foodstuff like meat, milk, and eggs may be attributable to unintentional or cross-contaminated feed in the pasture or feed mills, recirculation through manure and bedding materials, and antimicrobial-contaminated feed ingredients or water provided to the animal (Alebachew et al., 2016). However, antibiotic residue violation incidence has been observed globally. In Madagascar, the highest incidence rate of antibiotic drug residues was 37.2% in pork (Rakotoharinome et al., 2014). The residue violation rates of quinolone and penicillin increased in Korea, and the overall antimicrobial residue violation rate for different animal species was 0.5% (Kim et al., 2013). According to the Vietnamese antibiotic residues monitoring program, an average residue violation rate of 11.9% occurred in chicken, pork, and beef (Yamaguchi et al., 2015). In Malaysia, drug residues in chicken, swine, and cattle were monitored and the average violation rate was observed to be 2.7% (Marni et al., 2017). Meanwhile, Japan revealed that approximately 0.8% of antimicrobial drug residues were violated in 2012 (Yamaguchi et al., 2015) (Table 2).

Table 2. Violation status of antibiotic residues in animal products
Antibiotic Animal food source Residue level (µg/kg) References
Tetracycline Milk 16–134.5 Gaurav et al., 2014
Cattle tissue 176.3 Abbasi et al., 2012
Kidney 672.40
Liver 651.30
Doxycycline Poultry muscle 847.7 Jank et al., 2017
Sulfonamides Milk 2.5 Kang et al., 2016
Gentamicin 90 Zeina et al., 2013
Streptomycin 80
Penicillin 0–28 Abebew et al., 2014
Flumequine 2.58 Han et al., 2015
Enrofloxacin Poultry (liver) 10–10,690 Sultan et al., 2014
Cattle (liver) 30–3,610
Sheep (liver) 20–1,320
Sulfonamides Milk 13.5–147.9 Elizabeta et al., 2011
Sulfapyridine 1.77 Han et al., 2015
Sulfamethoxazole 4.2
Lincomycin 11.25
Quinolone Chicken 30.81 Kim et al., 2013
Beef 6.64
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Owing to parasitic infections-induced economic losses, antihelmintic drugs are frequently used in livestock and, thus, have been associated with the appearance of residues in edible animal products. Illustratively, ivermectin is extensively used for the prevention and treatment of parasites in food-producing animals. Ivermectin is lipophilic, implying a long withdrawal period and presence in the edible parts of the treated animals, specifically those with high fat content (Baynes et al., 2000). In Ireland, bovine samples were screened and found positive for benzimidazole and avermectin (including ivermectin) residues (Teagasc, 2011). Furthermore, following dairy cattle antihelmintic treatment against gastrointestinal nematodes, antihelmintic drug residues were observed in cattle in Ireland, UK, Sweden, Belgium, and Germany (Bennema et al., 2010). However, residue exposure was higher in countries with a wider use of antihelmintic drugs and more locally consumed cattle products (Table 3). Interestingly, animals also absorb pesticides through a variety of routes; ingestion, inhalation, and dermal absorption. For instance, biotransformation of organochlorine pesticides into milk (via transfer of the absorbed active ingredient through the blood-milk barrier in the mammary gland) or measures for the prevention of pest infestation (spraying pesticide solutions on animals and their accommodation) contribute to bioaccumulation of persistent pesticides in animal-derived food (LeDoux, 2011) (Table 4).

Table 3. Violation status of antihelmintic residues in animal products
Antihelmintic Animal food source Residue level (µg/kg) References
Ivermectin Cattle (liver) 48 Escribano et al., 2012
Sheep (liver) 43.7
Pig (liver) 23
Rabbit (liver) 15.8
Milk 2
Pigeon liver 58.5 Mestorino et al., 2017
Levamisole Egg 599 Hossain et al., 2017
Oxyclozanide Milk 130 Whelan et al., 2010
Levamisole 108
Oxyclozanide Soft cheese 5.6
Levamisole 52
Rafoxanide Beef 28.6 Cooper et al., 2012
Doramectin 13.8
Closantel Milk (incurred) 41 Whelan et al., 2010
Benzimidazole Bovine tissue 252.464 da Silva et al., 2017
Avermectin 100.025
Moxidectin Lamb (incurred) 20.95 Michelle Del Bianchi et al., 2018
Mebendazole Pork 16.4 Lee et al., 2017
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Table 4. Violation status of pesticide residues in animal products
Pesticide Animal food source Residue level (µg/kg) References
Malathion Milk 48 Kara et al., 2016
Lindane 80 Richhariya et al., 2017
2,2-Bis(4-chlorophenyl)-1,1-dichloroethylene dichlorodiphenyldichloroethylene 0.51 Fischer et al., 2011
Dieldrin 0.2
Fluvalinate 1.82
Endosulfan sulfate 0.22
Diphenylamine 0.19
Bifenthrin 0.1
Cyfluthrin 1
Diazinon 0.005–0.586 Salas et al., 2003
Chlorpyrifos 0.059
Malathion 0.110
Dichlorodiphenyldichloroethylene Egg 2.5–4.4 LeDoux M, 2011
Milk 1.3
Simazine Egg 30.1–59.5
Atrazine 52.2
Dichlorodiphenyldichloroethylene Pork 1.2–3.4
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Coccidiostats are compounds extensively used as additives or drugs for the prevention and treatment of livestock coccidiosis (Peek and Landman, 2011; Pura, 2013). Specifically, these drugs are used to treat or control the disease caused by organisms of the genus Eimeria, known to damage the intestinal mucosa of the host animal (Zhao et al., 2018). However, coccidiostats are also potent, causing residue accumulation in edible animal products and, consequently, posing serious health risks to the consumer (Kadykalo et al., 2018). Animals have been shown to rapidly metabolize anticoccidials, leading to harmful consequences; for example, metabolism of dimetridazole causes the release of the main metabolite, 2-hydroxydimetridazole, which accumulates highly in tissues and eggs (Mortier et al., 2005). The incidence of anticoccidial residues in edible animal products is very common. For instance, in Northern Ireland, the detectable concentrations of lasalocid ranged from 1.5–19 µg/kg (Matus et al., 2016). In the UK, eggs were monitored for the presence of different anticoccidials and proved positive for the corresponding residues such as robenidine (16 µg/kg), monensin (10 µg/kg), salinomycin (8 µg/kg), and lasalocid (129 µg/kg) (Mortier et al., 2005) (Table 5).

Table 5. Violation status of anticoccidial residues in animal products
Anticoccidial Animal food source Residue level (µg/kg) Reference
Salinomycin Beef 7.35 Zhao et al., 2018
Toltrazuril Milk 27 Clarke et al., 2013
Dinitrocarbanilide Chicken breast 13 Bacila et al., 2017
Lasalocid Chicken 1.5–19 Matus et al., 2016
Monensin 1.7–27
Ractopamine 2.1–32
Lasalocid Egg 129 Mortier et al., 2005
Nicarbazin 342
Narasin 11
Robenidine 16
Monensin 10
Salinomycin 8
Dinitrocarbanilide 10
Diclazuril Chicken (liver) 161–469 Kang et al., 2015
Toltrazuril 104–525
Amprolium 195–196
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Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

In veterinary practice, NSAIDs are widely used (singly or in combination with antibiotics) for treating inflammation, pain, respiratory diseases, fever, and musculoskeletal disorders (Gallo et al., 2010). They are equally used for improving animal production, and their secondary pharmacological effects enhance meat quality. However, after administration, these drugs bind to plasma proteins, are absorbed and distributed through tissues and fluids, and excreted as glucuronic conjugates (Rocca et al., 2017). NSAIDs are also frequently used for treating mastitis in pigs and milking cows, and the residues are excreted through milk (Jedziniak et al., 2012). Therefore, only few NSAIDs are approved for use in dairy cows. In the EU, MRLs have been established in milk; flunixin (40 µg/kg), meloxicam (15 µg/kg), tolfenamic acid (50 µg/kg), metamizole (50 µg/kg), and diclofenac (0.1 µg/kg). Nevertheless, some of these residues such as meloxicam (15.2 µg/kg), tolfenamic acid (54 µg/kg), and diclofenac (0.13 µg/kg) have been shown to exceed the maximum limit (Jedziniak et al., 2012). To maintain these residues within acceptable limits, they must be withheld with MRLs and legislation compliance adequately monitored (Table 6).

Table 6. Violation status of NSAID residues in animal products
NSAIDs Animal food source Residue level (µg/kg) Reference
Acetyl salicylic acid Pig 12–576 Kang et al., 2015
Chicken 50–53
Paracetamol Pig 28–381
Phenylbutazone Chicken 247
Oxyphenbutazone 15
Flunixin Milk 77 Feely et al., 2002
Meloxicam 15.2 Jedziniak et al., 2012
Tolfenamic acid 54
Diclofenac 0.13
Carprofen 4 Gallo et al., 2010
Flurbiprofen 2
Vedaprofen 4
Niflumic acid 20
Mefenamic acid 10
Naproxen 2
Phenylbutazone Bovine muscle 153.9 Asea et al., 2004

NSAIDs, nonsteroidal anti-inflammatory drugs.

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Decreasing Drug Residues in Animal Food Products

Proper drug use and good veterinary practices may lead to healthy and fresh edible animal products. However, the negative consequences of drug use, such as drug residues, continue to affect food; the levels of these residues sometimes exceed the limits of safe consumer levels. However, several drug-related factors such as drug formulation type, site, and route of administration, dose, and animal-related factors such as breed, age, sex, and body condition, have potential effects on the pharmacokinetics and drug residue levels in milk, meat, eggs, and other edible tissues (Moreno and Lanusse, 2017). Drug residue concentration in tissues depends on the physicochemical properties of the drug, such as acidic or basic properties and lipid solubility, which regulate the passive diffusion of drugs through cell membranes. Highly lipid-soluble drugs readily enter the intra and extracellular tissue compartments through passive diffusion, whereas drugs with poor lipid solubility remain in the extracellular compartment (Lees and Toutain, 2012). Drug transport modulation (such as several pharmacological approaches) delays bile or intestinal secretions, prolonging the macrocyclic lactone recycling time in the host, leading to transport protein (P-gp) efflux, which may be related to pharmacokinetic disposition and drug residue profiles (Lespine et al., 2012; Lifschitz et al., 2012). When this occurs, P-gp modulating agents change tissue residue patterns (Lespine et al., 2008). Interestingly, drug administration through animal ears helps prevent drug residue accumulation in edible animal tissues (Brown, 2000). However, most animal products are not consumed raw; hence, different heat treatments (pasteurization, sterilization, steaming, boiling, frying, or roasting) can cause drug residue loss through evaporation, co-distillation, and/or thermal degradation (Dordevic and Durovic-Pejcev, 2016). Furthermore, fermentation, different pH levels, and storage times also have a considerable impact on the reduction of drug residues in different edible products (Table 7).

Table 7. Thermal reduction of antibiotic residues in animal food products as reported in literature
Antibiotic Compound Processing method Matrix Reduction (%) References
β-Lactam Oxacillin/dicloxacillin/cloxacillin Boiling Milk 8–64 Grunwald and Petz, 2003
Ampicillin Grilling/roasting Meat 2.3–100 O’Brien et al., 1981
Cephalonium/cephapirin/cefoperazoe/amoxycillin/ampicillin/penicillinG/cloxacillin Boiling Milk 0.1–100 Roca et al., 2011
Tetracycline Tetracycline/oxytetracycline/doxycycline/chlortetracycline Boiling/roasting/microwave Meat 42–100 Abou-Raya et al., 2013
Tetracycline Frying/ boiling Egg 58–69 Alaboudi et al., 2013
Macrolide Erythromycin/spiramycin/tylosin Ivermectin Boiling Milk 0–93 Zorraquino et al., 2011
Ivermectin Boiling/frying Meat 45–50 Slanina et al., 1989
Aminoglycoside Gentamicin/kanamycin/neomycin/streptomycin Boiling Milk 17–9 Zorraquino et al., 2009
Amphenicol Chloramphenicol/florfenicol/thiamphenicol Boiling/microwave Meat 100 Franje et al., 2010
Quinolones Ciprofloxacin/norfloxacin/flumequine/oxolinic acid/enrofloxacin Boiling Milk 0.01–12.71 Roca et al., 2010
Enrofloxacin Frying/ boiling Egg 47–52 Alaboudi et al., 2013
Sulfonamides Sulfamethazine/sulfachloropyridazine/sulfadiazine/sulfadimethoxine/sulfamerazine/sulfapyridine/sulfathiazole/sulfaquinoxaline Boiling Milk 0–85.1 Roca et al., 2013
Lincosamide Lincomycin Boiling Milk 0–5 Zorraquino et al., 2011
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Reduction of Drug Residues in Milk and Milk Products

Veterinary drug residues in milk remain a paramount concern to farmers, processors, milk regulatory agencies, and consumers because milk is widely consumed by people of all ages (Shaker and Elsharkawy, 2015). Veterinary drugs are broadly used to treat several cattle diseases or increase milk production. Consequently, drug residues are accumulated and secreted alongside milk (Han et al., 2015). However, before consumption, a majority of animal products undergo thermal treatment that leads to water loss, fat degradation, and protein denaturation, as well as an altered pH, which helps change drug residue quantity and chemical structure and, hence, the pharmacological and toxicological effects (Hsieh et al., 2011). For instance, heating milk via pasteurization, ultra-heat treatment (UHT), or sterilization, helps decrease drug residues in milk. The UHT, was shown to decrease oxytetracycline and tetracycline concentrations by >40% and 30%, respectively, and the sterilization process degraded tetracycline in milk by approximately 98% (Kellnerova et al., 2015). Furthermore, thermal treatment degrades macrolides in milk by approximately 93% and is mostly responsible for erythromycin susceptibility (Zorraquino et al., 2011). A majority of aminoglycosides are very unstable in milk, when boiled at 120°C for 20 min, leading to elimination of approximately 95% aminoglycoside residues (Zorraquino et al., 2009).

During yoghurt production by heat treatment, precipitated proteins promote reduction of penicillin residues, and lactic acid slightly helps degrade cloxacillin, oxacillin, dicloxacillin, and nafcillin (Grunwald and Petz, 2003). Furthermore, yogurt cultures and low pH affect the decrease in drug residue concentration by occlusion in the coagulated protein matrix, decomposition, adsorption, and covalent binding to the proteins. During lactic acid-induced milk coagulation (pH 4), penillic acid concentration was shown to increase to 60%-90% and the residues comprised intact penicillin and penillic acid. At lower pH values (pH 2), further degradation occurred and unidentified products were observed after totaling penicillin G and penillic acid. It was also reported that heat treatment (pasteurization and sterilization) and fermentation helped to decrease organophosphorus pesticide residues in yoghurt (Zhang et al., 2006). Pasteurization helped to degrade pesticide dimethoate by as much as 73.42%, and, by fermentation, dimethoate and malathion concentrations decreased by 86.50% and 97.17%, respectively (Abd-Rabo et al., 2016). Moreover, when two starter cultures were added during yoghurt preparation, dimethoate, fenthion, and trichlorfon concentrations readily decreased (Regueiro et al., 2015).

  • - Thermal treatments: reduced tetracycline and oxytetracycline by 30% and 40%, respectively. Sterilization helped to degrade tetracycline by approximately 98%, reduce macrolides by 93%, reduce aminoglycosides residues by >95%, and degrade sulfonamides within a range of 0%-99%.

  • - Fermentation: reduced penicillin by 35%-40% and pesticide-like dimethoate and malathion by 86.5% and 97.17%, respectively.

  • - Altered pH: lactic acid (pH 4) at room temperature reduced cloxacillin and oxacillin residues by 20%-25%.

Reduction of Drug Residues in Eggs

When drugs are administered to laying hens, their metabolites may accumulate as residues in egg components (yolk and albumen) (EC-European Commission, 2012). These drugs are absorbed in the intestine, carried through blood/plasma to the ovary, and deposited in the inner yolk to the magnum of the oviduct for accumulation in the albumen, uterus, and the oviduct; and finally, during plumping of the eggs, drug residues are accumulated in the eggs (Donoghue and Myers, 2000). Drugs that quickly disappear from the body of the laying hen are also excreted rapidly from the egg component a few days post-withdrawal or treatment termination. Moreover, the biological half-life (drug residues reducing time) of the used drug is essential for drug residue clearance from egg components (Goetting et al., 2011).

Raw eggs are usually not consumed, unless refrigerated and subjected to heat. Heat treatment promotes dehydration, protein denaturation, and pH changes that can help reduce residue quantity, chemical formulation, as well as alter residue solubility. Consequently, frying and boiling eggs reduced the concentration of enrofloxacin and tetracycline residues by 69% and 58%, and 52% and 47%, respectively (Fath El-Bab, 2012). Furthermore, the residues of antimicrobials such as ciprofloxacin, enrofloxacin, and chlortetracycline, were reduced after eggs were boiled at 100°C for 15 min, by approximately 87%, 93%, and 61%, respectively (Alaboudi et al., 2013). However, chlorinated pesticides can diffuse into laying hens via feed, leading to residue excretion in eggs (Hashemy-Tonkabony and Mossofian, 1979). Effects of hard boiling and scrambling decreased the residue of chlorpyriphos in egg yolks by 38% (Bajwa and Sandhu, 2014). Adoption of best management practices in the poultry farms, feed quality monitoring, and breeding in confined areas can help decrease pesticide residues in eggs (Hamid et al., 2017). However, pH may differ in the albumen and yolk of fresh eggs (albumen; 7.6–7.9, yolk; 6.0), resulting to fading drug capabilities (Kan and Petz, 2000). High pH increases the fading capabilities of drugs with a naturally low pH value. For instance, the pH value of chlortetracycline is 2.3–3.3; hence, it has a relatively high binding affinity to the alkaline albumen than the acidic egg yolk (Alaboudi et al., 2013).

Egg refrigeration and storage also contributes to reducing antimicrobial residues in eggs. For instance, enrofloxacin and ciprofloxacin in eggs showed instability as refrigeration time increased, resulting in a 44%-50% reduction after 4 weeks of storage. Eggs refrigerated at 10°C for 4 weeks led to a decrease in the concentration of sulfanilamide and chlortetracycline residues by 44%-49% and 20%-22%, respectively (Alaboudi et al., 2013).

Mycotoxins such as aflatoxins and zearalenone are carried over in eggs; prolonged exposure in laying hens may result in residue deposition in eggs. Incorporating the Bacillus subtilis biodegradation products in the diet may decrease aflatoxins residue levels, causing specific toxin biotransformation and aiding inhibition of toxin absorption via the gastrointestinal tract; hence, decreasing the toxin residues in eggs (Jia et al., 2016). However, heating milk and dairy products with this quantity of aflatoxins M1 (AFM1) is obscure, and some treatments such as pasteurization and sterilization have very little effects on their concentration in the processed animal product. Conversely, milk processing such as evaporation, concentration, or drying, largely affect AFM1 concentration (Flores-Flores et al., 2015).

  • - Thermal treatments: reduced enrofloxacin and tetracycline residues by 52% and 47% and ciprofloxacin, enrofloxacin, and sulfanilamide residues by 87%, 93%, and 89%-91%, respectively, and chlorpyriphos residue by 38%.

  • - Storage: sulfanilamide reduced by 44%-49%, chlortetracycline by 20%-22%, and enrofloxacin and ciprofloxacin by 44%-50%.

  • - pH treatments: pH enhances the dissolution of antibiotic residues in egg components.

Reduction of Drug Residues in Meat

Uncontrolled usage of veterinary drugs and poor biosafety measures for drug withdrawal may result in drug residues, as well as decrease meat quality (Mehtabuddin et al., 2012). A majority of meat and meat products may not be an obvious part of the human food chain but are frequently stored or processed. Before consuming raw edible animal products and byproducts, some heat treatment or cooking is required. These processes lead to protein denaturation, water and fat loss, and change in the pH, thus, help in altering residue concentration, chemical structure, or solubility.

Doxycycline residue concentrations have been shown to reduce after meat cooking, and residues were excreted from muscle tissues into cooking fluid (Javadi, 2011). The biological activity of oxytetracycline, ampicillin, and chloramphenicol in beef also decreased by 12% to 50% after roasting at 50°C-90°C for 20 min. Moreover, beef cooking contributed to a substantial decrease (35% to 94%) in oxytetracycline’s net concentration (Gratacos-Cubarsí et al., 2007). Different cooking methods with different pH levels have a potential reduction effect on oxytetracycline. For instance, the muscle concentration of oxytetracycline was significantly reduced after roasting and boiling by 53.6% and 69.6%, respectively, and roasting, microwaving, and boiling at pH 6.0 and 7.2, decreased oxytetracycline levels by 34.3%, 53.2%, and 67.7%, respectively (Vivienne et al., 2018). In chicken and pork, different thermal treatments have potent degradation effects on oxytetracycline and produce oxytetracycline degradation products. Residual concentrations of oxytetracycline degrade as the sum of the corresponding epimeric forms (OTCs=OTC+4epi-OTC and apo-OTCs=α-apo-OTC+β-apo-OTC). After tissue thermal treatment, the concentrations of apo-OTCs increased whereas the OTC residues decreased (Nguyen et al., 2015). Therefore, the four epimers and anhydro forms of tetracycline may degrade under different conditions. The pathways associated with degradation of different tetracycline isoforms are mainly pH dependent, with the degradation of 4eTCs and anhydro-TCs being favored in dilute acidic medium, whereas in strong acidic medium, anhydro-TCs get cleaved and lactonized to generate apo derivatives (Xuan et al., 2009). Chicken meat boiling and roasting for 12 min decreased sulfonamide residues by 45%-61% and 38%-40%, respectively (Furusawa and Hanabusa, 2002).

pressure cooking accelerate pesticide degradation (aldrin; 93.75%, dieldrin; 93.77%, and endosulfan; 78.70%) in beef (Singh, 2017). Chemical and biological degradation occur during fermentation, and help decrease pesticide levels significantly (Azizi, 2011). For instance, the pesticide residues of DDT and lindane were reduced by approximately 10% and 18%, respectively, 72 h post-fermentation in fermented sausage (Abou-Arab, 2002). However, thermal treatment also helped to reduce antihelmintic residues: nitroxynil, by 78% and 96% in fried and roasted muscle; levamisole, by 11% and 42% in fried muscle and liver; rafoxanide, by 17% and 18% in fried and roasted muscle; and triclabendazole, by 23% and 47% in fried liver and roasted muscle, respectively (Cooper et al., 2011).

  • - Thermal treatments: oxytetracycline, ampicillin, and chloramphenicol residues were decreased by 12%-50%, sulfonamide residues by 45%-61%, and antihelmintic residues by 11%-96%.

  • - Pressure cooking: aldrin, dieldrin, and endosulfan were reduced by 79%-94%.

  • - Fermentation treatments: DDT was reduced by 10% and lindane by 18%.


The use of veterinary drugs for disease prevention or treatment and/or production enhancement, leads to residue accumulation in animal products. Drug residues in animal products are influenced by many factors such as the physicochemical properties of drugs, biological processes of animals, and their products. These residues can cause significant public health hazards such as hypersensitivity reactions, cancer, mutagenicity, reproduction challenges, bacterial resistance, and disruption of intestinal normal flora. Therefore, it is the responsibility of veterinarians and livestock producers to observe the relevant drug withdrawal period before animal slaughter and ensure that undesirable residues do not accumulate in edible products. Veterinarians should be updated with the latest information, to create awareness among producers and employees, as well as the general public. Moreover, avoiding unapproved or illegal drugs and practicing proper drug use and best farm and livestock management can lead to the control of drug residues. Moreover, different cooking conditions (temperature and time), fermentation, and pH, play a major role in decreasing veterinary drug residues. Generally, cooking and other processes do not ensure full drug residue degradation, but can contribute to a marked decrease in concentration. Although some veterinary drug residues are reduced and degraded by processing, it is essential to perform toxicology experiments to monitor the potential adverse effects of drug residues on consumer health.


Conflict of Interest

The authors declare no potential conflict of interest.


This work was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET) through Agri-Bio industry Technology Development Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) (316029-03-2-HD050).


Author Contributions

Investigation: Rana MS. Writing original draft: Rana MS, Hur SJ. Writing review & editing: Rana MS, Lee SY, Kang HJ, Hur SJ.


Ethics Approval

This article does not require IRB/IACUC approval because there are no human and animal participants.



Abbasi MM, Nemati M, Babaei H, Ansarin M, Nourdadgar AOS. 2012; Solid-phase extraction and simultaneous determination of tetracycline residues in edible cattle tissues using an HPLC-FL method. Iran J Pharma Res. 11:781-787.


Abd-Rabo FH, Elsalamony H, Sakr SS. 2016; Reduction of pesticide residues in Egyptian buffalo milk by some processing treatments. Int J Dairy Sci. 11:75-80


Abebew D, Belihu K, Zewde G. 2014; Detection and determination of oxytetracycline and penicillin G antibiotic residue levels in bovine bulk milk from Nazareth dairy farms, Ethiopia. Ethiop Vet J. 18:1-15.


Abou-Arab AAK. 2002; Degradation of organochlorine pesticides by meat starter in liquid media and fermented sausage. Food Chem Toxicol. 40:33-41


Abou-Raya SH, Shalaby AR, Salama NA, Emam WH, Mehaya FM. 2013; Effect of ordinary cooking procedures on tetracycline residues in chicken meat. J Food Drug Anal. 21:80-86.


Alaboudi A, Basha EA, Musallam I. 2013; Chlortetracycline and sulfanilamide residues in table eggs: Prevalence, distribution between yolk and white and effect of refrigeration and heat treatment. Food Control. 33:281-286


Alebachew T, Lamessa J, Ayichew T, Abebaw G. 2016; Review on chemical and drug residue in meat. World J Agric Sci. 12:196-204.


Aoki Y, Hakamata H, Igarashi Y, Uchida K, Kobayashi H, Hirayama N, Kotani A, Kusu F. 2009; Simultaneous determination of azaperone and azaperol in animal tissues by HPLC with confirmation by electrospray ionization mass spectrometry. J Chromatogr B. 877:166-172


Asea PEA, Souster KD, Salisbury CDC, Boison JO. 2004; Development and validation of a method for the determination of phenylbutazone drug residues in bovine, equine, and porcine muscle tissues using HPLC with UV detection. J Liq Chromatogr Relat Technol. 27:3013-3027


Azizi A. 2011; Bacterial-degradation of pesticides residue in vegetables during fermentation. In Pesticides-formulations, effects, fate. In: Stoycheva M, editor.(ed)InTech. Rijeka, Croatia: pp p. 651-660


Babapour A, Azami L, Fartashmehr J. 2012; Overview of antibiotic residues in beef and mutton in Ardebil, North West of Iran. World Appl Sci J. 19:1417-1422.


Bacila DM, Feddern V, Mafra LI, Scheuermann GN, Molognoni L, Daguer H. 2017; Current research, regulation, risk, analytical methods and monitoring results for nicarbazin in chicken meat: A perspective review. Food Res Int. 99:31-40


Bajwa U, Sandhu KS. 2014; Effect of handling and processing on pesticide residues in food: A review. J Food Sci Technol. 51:201-220


Baynes RE, Payne M, Martin-Jimenez T, Abdullah AR, Anderson KL, Webb AI, Craigmill A, Riviere JE. 2000; Extralabel use of ivermectin and moxidectin in food animals. J Am Vet Med Assoc. 217:668-671


Bennema SC, Vercruysse J, Morgan E, Stafford K, Hoglund J, Demeler J, von Samson-Himmelstjerna G, Charlier J. 2010; Epidemiology and risk factors for exposure to gastrointestinal nematodes in dairy herds in northwestern Europe. Vet Parasitol. 173:247-254


Beyene T. 2016; Veterinary drug residues in food-animal products: Its risk factors and potential effects on public health. J Vet Sci Technol. 7:1-7.


Boeckman S, Carlson KR. 1995 Milk and dairy beef residue prevention protocol: 1996 producer manual. Available from at Jan 16, 2019


Brown SA. 2000 Administration of an injectable antibiotic in the ear of an animal. US Patent 6,074,657.


Clarke L, Moloney M, O’Mahony J, O’Kennedy R, Danaher M. 2013; Determination of 20 coccidiostats in milk, duck muscle and non-avian muscle tissue using UHPLC-MS/MS. Food Addit Contam Part A. 30:958-969


Cooper KM, Whelan M, Danaher M, Kennedy DG. 2011; Stability during cooking of anthelmintic veterinary drug residues in beef. Food Addit Contam. 28:155-165


Cooper KM, Whelan M, Kennedy DG, Trigueros G, Cannavan A, Boon PE, Wapperom D, Danaher M. 2012; Anthelmintic drug residues in beef: UPLC-MS/MS method validation, European retail beef survey, and associated exposure and risk assessments. Food Addit Contam Part A. 29:746-760


Da Silva GR, Lima JA, de Souza LF, Santos FA, Lana MAG, de Assis DCS, de Vasconcelos Cancado S. 2017; Multiresidue method for identification and quantification of avermectins, benzimidazoles and nitroimidazoles residues in bovine muscle tissue by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using a QuEChERS approach. Talanta. 171:307-320


Desmarchelier A, Feuerrigel P, Fathi Ahmed H, Moulin J, Beck A, Mujahid C, Bessaire T, Savoy MC, Mottier P. 2018; Stability study of veterinary drugs in standard solutions for LC-MS/MS screening in food. Food Addit Contam Part A. 35:695-705


Donoghue DJ, Myers K. 2000; Imaging residue transfer into egg yolks. J Agric Food Chem. 48:6428-6430


Dordevic T, Durovic-Pejcev R. 2016; Food processing as a means for pesticide residue dissipation. Pestic Fitomed. 31:89-105


EC-European Commission. 2012 Commission staff working document on the implementation of national residue monitoring plans in the member states in 2009 (Council Directive 96/23/EC). Available from at Mar 30, 2019.


Elizabeta DS, Zehra HM, Biljana SD, Pavle S, Risto U. 2011; Screening of veterinary drug residues in milk from individual farms in Macedonia. Mac Vet Rev. 34:5-13.


Escribano M, San Andres MI, de Lucas JJ, Gonzalez-Canga A. 2012; Ivermectin residue depletion in food producing species and its presence in animal foodstuffs with a view to human safety. Curr Pharma Biotechnol. 13:987-998


Fath El-Bab GFA. 2012; Residues of some antibiotics in table eggs in some private farms. J Egypts Med Assoc. 72:69-80.


Feely WF, Chester-Yansen C, Thompson K, Campbell JW, Boner PL, Liu DD, Crouch LS. 2002; Flunixin residues in milk after intravenous treatment of dairy cattle with 14C-flunixin. J Agric Food Chem. 50:7308-7313


Filazi A, Sireli UT, Dikmen BY, Aydin FG, Kucukosmanoglu AG. 2015; The effect of cooking and storage on florfenicol and florfenicol amine residues in eggs. Ital J Food Sci. 27:351-356.


Fischer WJ, Schilter B, Tritscher A, Stadler RH. 2011; Contaminants of milk and dairy products: Contamination resulting from farm and dairy practices. Encycl Dairy Sci. 2:887-897


Flores-Flores ME, Lizarraga E, de Cerain AL, Gonzalez-Penas E. 2015; Presence of mycotoxins in animal milk: A review. Food Control. 53:163-176


Franje CA, Chang SK, Shyu CL, Davis JL, Lee YW, Lee RJ, Chang CC, Chou CC. 2010; Differential heat stability of amphenicols characterized by structural degradation, mass spectrometry and antimicrobial activity. J Pharmaceut Biomed. 53:869-877


Furusawa N, Hanabusa R. 2002; Cooking effects on sulfonamide residues in chicken thigh muscle. Food Res Int. 35:37-42


Gallo P, Fabbrocino S, Dowling G, Salini M, Fiori M, Perretta G, Serpe L. 2010; Confirmatory analysis of non-steroidal anti-inflammatory drugs in bovine milk by high-performance liquid chromatography with fluorescence detection. J Chromatogr A. 1217:2832-2839


Gaurav A, Gill JPS, Aulakh RS, Bedi JS. 2014; ELISA based monitoring and analysis of tetracycline residues in cattle milk in various districts of Punjab. Vet World. 7:26-29


Goetting V, Lee KA, Tell LA. 2011; Pharmacokinetics of veterinary drugs in laying hens and residues in eggs: A review of the literature. J Vet Pharmacol Ther. 34:521-556


Gratacos-Cubarsi M, Fernandez-Garcia A, Picouet P, Valero-Pamplona A, Garcia-Regueiro JA, Castellari M. 2007; Formation of tetracycline degradation products in chicken and pig meat under different thermal processing conditions. J Agric Food Chem. 55:4610-4616


Grunwald L, Petz M. 2003; Food processing effects on residues: Penicillins in milk and yoghurt. Anal Chim Acta. 483:73-79


Hamid A, Yaqub G, Ahmed SR, Aziz N. 2017; Assessment of human health risk associated with the presence of pesticides in chicken eggs. Food Sci Technol. 37:378-382


Han RW, Zheng N, Yu ZN, Wang J, Xu XM, Qu XY, Li SL, Zhang YD, Wang JQ. 2015; Simultaneous determination of 38 veterinary antibiotic residues in raw milk by UPLC-MS/MS. Food Chem. 181:119-126


Hashemy-Tonkabony SE, Mosstofian B. 1979; Chlorinated pesticide residues in chicken egg. Poult Sci. 58:1432-1434


Heshmati A. 2015; Impact of cooking procedures on antibacterial drug residues in foods: A review. J Food Qual Hazards Control. 2:33-37.


Hossain MK, Nahar K, Mazumder MEH, Wahiduzzaman M, Alqahtani AS, Gestier T, Hamid K. 2017; Development and validation of a bioanalytical method for the determination of levamisole residue in backyard poultry egg. Res J Pharm Technol. 10:2249-2254


Hsieh MK, Shyu CL, Liao JW, Franje CA, Huang YJ, Chang SK, Shih PY, Chou CC. 2011; Correlation analysis of heat stability of veterinary antibiotics by structural degradation, changes in antimicrobial activity and genotoxicity. Vet Med. 56:274-285


Jank L, Martins MT, Arsand JB, Motta TMC, Feijo TC, dos Santos Castilhos T, Hoff RB, Barreto F, Pizzolato TM. 2017; Liquid chromatography-tandem mass spectrometry multiclass method for 46 antibiotics residues in milk and meat: Development and validation. Food Anal Methods. 10:2152-2164


Javadi A. 2011; Effect of roasting, boiling and microwaving cooking method on doxycline residues in edible tissues of poultry by microbial method. Afr J Pharm Pharmaco. 5:1034-1037


Jedziniak P, Szprengier-Juszkiewicz T, Pietruk K, Sledzinska E, Zmudzki J. 2012; Determination of non-steroidal anti-inflammatory drugs and their metabolites in milk by liquid chromatography-tandem mass spectrometry. Anal Bioanal Chem. 403:2955-2963


Jia R, Ma Q, Fan Y, Ji C, Zhang J, Liu T, Zhao L. 2016; The toxic effects of combined aflatoxins and zearalenone in naturally contaminated diets on laying performance, egg quality and mycotoxins residues in eggs of layers and the protective effect of Bacillus subtilis biodegradation product. Food Chem Toxicol. 90:142-150


Kadykalo S, Roberts T, Thompson M, Wilson J, Lang M, Espeisse O. 2018; The value of anticoccidials for sustainable global poultry production. Int J Antimicrob Ag. 51:304-310


Kan CA, Petz M. 2000; Residues of veterinary drugs in eggs and their distribution between yolk and white. J Agric Food Chem. 48:6397-6403


Kang J, Park HC, Gedi V, Park SJ, Kim MA, Kim MK, Kwon HJ, Cho BH, Kim TW, Lee KJ, Lim CM. 2015; Veterinary drug residues in domestic and imported foods of animal origin in the Republic of Korea. Food Addit Contam Part B. 8:106-112


Kang J, Park SJ, Park HC, Hossain MA, Kim MA, Son SW, Lim CM, Kim TW, Cho BH. 2016; Multiresidue screening of veterinary drugs in meat, milk, egg, and fish using liquid chromatography coupled with ion trap time-of-flight mass spectrometry. Biotechnol Appl Biochem. 182:635-652


Kara R, Ince S. 2016; Evaluation of malathion and malaoxon contamination in buffalo and cow milk from Afyonkarahisar region, Turkey, using liquid chromatography/tandem mass spectrometry-a short report. Pol J Food Nutr Sci. 66:57-60


Kellnerova E, Navratilova P, Borkovcova I. 2014; Effect of pasteurization on the residues of tetracyclines in milk. Acta Vet Brno. 83:21-26


Kibruyesfa B, Naol H. 2017; Review on antibiotic residues in food of animal origin: Economic and public health impacts. Appl J Hyg. 6:1-8.


Kim M, Cho BH, Lim CM, Kim DG, Yune SY, Shin JY, Bong YH, Kang J, Kim MA, Son SW. 2013; Chemical residues and contaminants in foods of animal origin in Korea during the past decade. J Agric Food Chem. 61:2293-2298


Kohanski MA, Dwyer DJ, Collins JJ. 2010; How antibiotics kill bacteria: From targets to networks. Nat Rev Microbiol. 8:423-435


Laszlo N, Lanyi K, Laczay P. 2018; LC-MS study of the heat degradation of veterinary antibiotics in raw milk after boiling. Food Chem. 267:178-186


LeDoux M. 2011; Analytical methods applied to the determination of pesticide residues in foods of animal origin. A review of the past two decades. J Chromatogr A. 1218:1021-1036


Lee JS, Cho SH, Lim CM, Chang MI, Joo HJ, Bae H, Park HJ. 2017; A liquid chromatography-tandem mass spectrometry approach for the identification of mebendazole residue in pork, chicken, and horse. PLOS ONE. 12:e0169597


Lees P, Toutain PL. 2012; The role of pharmacokinetics in veterinary drug residues. Drug Test Anal. 4:34-39


Lespine A, Alvinerie M, Vercruysse J, Prichard RK, Geldhof P. 2008; ABC transporter modulation: A strategy to enhance the activity of macrocyclic lactone anthelmintics. Trends Parasitol. 24:293-298


Lespine A, Menez C, Bourguinat C, Prichard RK. 2012; P-glycoproteins and other multidrug resistance transporters in the pharmacology of anthelmintics: Prospects for reversing transport-dependent anthelmintic resistance. Int J Parasitol Drugs Drug Resist. 2:58-75


Li C, Zhang Y, Eremin SA, Yakup O, Yao G, Zhang X. 2017; Detection of kanamycin and gentamicin residues in animal-derived food using IgY antibody based ic-ELISA and FPIA. Food Chem. 227:48-54


Lifschitz A, Ballent M, Lanusse C. 2012; Macrocyclic lactones and cellular transport-related drug interactions: A perspective from in vitro assays to nematode control in the field. Curr Pharm Biotechnol. 13:912-923


Marni S, Marzura MR, Eddy AA, Suliana AK. 2017; Veterinary drug residues in chicken, pork and beef in peninsular Malaysia in the period 2010-2016. Malaysian J Vet Res. 8:71-77.


Matus JL, Boison JO. 2016; A multi-residue method for 17 anticoccidial drugs and ractopamine in animal tissues by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry. Drug Test Anal. 8:465-476


Mehtabuddin A, Ahmad T, Nadeem S, Tanveer Z, Arshad J. 2012; Sulfonamide residues determination in commercial poultry meat and eggs. J Anim Plant Sci. 22:473-478.


Mestorino N, Buldain D, Buchamer A, Gortari L, Daniele M, Marchetti ML. 2017; Residue depletion of ivermectin in broiler poultry. Food Addit Contam Part A. 34:624-631


Michelle DelBianchi AC, Fernandes MA, Braga PADC, Monteiro AL, Daniel D, Reyes FG. 2018; Moxidectin residues in lamb tissues: Development and validation of analytical method by UHPLC-MS/MS. J Chromatogr B. 1072:390-396


Moreno L, Lanusse C. 2017; Veterinary drug residues in meat-related edible tissues. In New aspects of meat quality. In: Purslow PP, editor.(ed.)Woodhead. Duxford, UK: pp p. 581-603


Mortier L, Huet AC, Charlier C, Daeseleire E, Delahaut P, Van Peteghem C. 2005; Incidence of residues of nine anticoccidials in eggs. Food Addit Contam. 22:1120-1125


Nguyen V, Nguyen V, Li C, Zhou G. 2015; The degradation of oxytetracycline during thermal treatments of chicken and pig meat and the toxic effects of degradation products of oxytetracycline on rats. J Food Sci Technol. 52:2842-2850


O’Brien JJ, Campbell N, Conaghan T. 1981; Effect of cooking and cold storage on biologically active antibiotic residues in meat. J Hyg. 87:511-523


Parr MK, Blokland MH, Liebetrau F, Schmidt AH, Meijer T, Stanic M, Sterk SS. 2016; Distinction of clenbuterol intake from drug or contaminated food of animal origin in a controlled administration trial - The potential of enantiomeric separation for doping control analysis. Food Addit Contam Part A. 34:525-535


Peek HW, Landman WJM. 2011; Coccidiosis in poultry: Anticoccidial products, vaccines and other prevention strategies. Vet Q. 31:143-161


Peeters LE, Daeseleire E, Devreese M, Rasschaert G, Smet A, Dewulf J, Heyndrickx M, Imberechts H, Haesebrouck F, Butaye P, Croubels S. 2016; Residues of chlortetracycline, doxycycline and sulfadiazine-trimethoprim in intestinal content and feces of pigs due to cross-contamination of feed. BMC Vet Res. 12:209


Pinheiro I, Jesuino B, Barbosa J, Ferreira H, Ramos F, Matos J, da Silveira MIN. 2009; Clenbuterol storage stability in the bovine urine and liver samples used for European official control in the Azores Islands (Portugal). J Agric Food Chem. 57:910-914


Pura RS. 2013; Anticoccidial drugs used in the poultry: An overview. Sci Int. 1:261-265


Rakotoharinome M, Pognon D, Randriamparany T, Ming JC, Idoumbin JP, Cardinale E Porphyre V. 2014; Prevalence of antimicrobial residues in pork meat in Madagascar. Trop Anim Health Prod. 46:49-55


Regueiro J, Lopez-Fernandez O, Rial-Otero R, Cancho-Grande B, Simal-Gandara J. 2015; A review on the fermentation of foods and the residues of pesticides-biotransformation of pesticides and effects on fermentation and food quality. Crit Rev Food Sci Nutr. 55:839-863


Richhariya N, Mishra S, Thakur LK, Rani R. 2017; Pesticide residues contamination of liquid milk in India-A review. World J Pharm Pharm Sci. 6:549-562


Roca M, Althaus RL, Molina MP. 2013; Thermodynamic analysis of the thermal stability of sulphonamides in milk using liquid chromatography tandem mass spectrometry detection. Food Chem. 136:376-383


Roca M, Castillo M, Marti P, Althaus RL, Molina MP. 2010; Effect of heating on the stability of quinolones in milk. J Agric Food Chem. 58:5427-5431


Roca M, Villegas L, Kortabitarte ML, Althaus RL, Molina MP. 2011; Effect of heat treatments on stability of β-lactams in milk. J Dairy Sci. 94:1155-1164


Rocca LM, Gentili A, Perez-Fernandez V, Tomai P. 2017; Veterinary drugs residues: A review of the latest analytical research on sample preparation and LC-MS based methods. Food Addit Contam Part A. 34:766-784.


Rokka M, Eerola S, Perttila U, Rossow L, Venalainen E, Valkonen E, Peltonen K. 2005; The residue levels of narasin in eggs of laying hens fed with unmedicated and medicated feed. Mol Nutr Food Res. 49:38-42


Rozanska H, Osek J. 2013; Stability of antibiotics in milk samples during storage. Bull Vet Inst Pulawy. 57:347-349


Salas JH, Gonzalez MM, Noa M, Perez NA, Diaz G, Gutierrez R, Zazueta H, Osuna I. 2003; Organophosphorus pesticide residues in Mexican commercial pasteurized milk. J Agric Food Chem. 51:4468-4471


Shaker EM, Elsharkawy EE. 2015; Organochlorine and organophosphorus pesticide residues in raw buffalo milk from agroindustrial areas in Assiut, Egypt. Environ Toxicol Pharmacol. 39:433-440


Singh S. 2017 Studies on the effect of different processing methods on the levels of pesticide residues in milk, meat and their products. Ph.D. dissertationP.V. Narsimha Rao Telangana Veterinary Univ. Telangana, India: .


Slanina P, Kuivinen J, Ohlsen C, Ekstrom LG. 1989; Ivermectin residues in the edible tissues of swine and cattle: Effect of cooking and toxicological evaluation. Food Addit Contam. 6:475-481


Sultan IA. 2014; Detection of enrofloxacin residue in livers of livestock animals obtained from a slaughterhouse in Mosul City. J Vet Sci Technol. 5:168


Tajick MA, Shohreh B. 2006; Detection of antibiotics residue in chicken meat using TLC. Int J Poult Sci. 5:611-612


Teagasc. 2011 National food residue database. Available fromhttp://nfrd.teagasc.ieAccessed at Jan 16, 2019


Vivienne EE, Josephine OKO, Anaelom NJ. 2018; Effect of temperature (cooking and freezing) on the concentration of oxytetracycline residue in experimentally induced birds. Vet World. 11:167-171


Whelan M, Chirollo C, Furey A, Cortesi ML, Anastasio A, Danaher M. 2010; Investigation of the persistence of levamisole and oxyclozanide in milk and fate in cheese. J Agric Food Chem. 58:12204-12209


Xuan R, Arisi L, Wang Q, Yates SR, Biswas KC. 2010; Hydrolysis and photolysis of oxytetracycline in aqueous solution. J Environ Sci Health Part B. 45:73-81


Yamaguchi T, Okihashi M, Harada K, Konishi Y, Uchida K, Do MHN, Bui HD, Nguyen TD, Nguyen PD, Chau VV, Dao KTV, Nguyen HT, Kajimura K, Kumeda Y, Bui CT, Vien MQ, Le NH, Hirata K, Yamamoto Y. 2015; Antibiotic residue monitoring results for pork, chicken, and beef samples in Vietnam in 2012-2013. J Agric Food Chem. 63:5141-5145


Zeina K, Pamela AK, Fawwak S. 2013; Quantification of antibiotic residues and determination of antimicrobial resistance profiles of microorganisms isolated from bovine milk in Lebanon. Food Nutr Sci. 4:1-9


Zhang H, Chai ZF, Sun HB, Zhang JL. 2006; A survey of extractable persistent organochlorine pollutants in Chinese commercial yogurt. J Dairy Sci. 89:1413-1419


Zhang H, Qu W, Tao Y, Chen D, Xie S, Huang L, Liu Z, Pan Y, Yuan Z. 2018; A convenient and sensitive LC-MS/MS method for simultaneous determination of carbadox-and olaquindox-related residues in swine muscle and liver tissues. J Anal Methods Chem. 2018:2834049


Zhao X, Wang B, Xie K, Liu J, Zhang Y, Wang Y, Wang J. 2018; Development and comparison of HPLC-MS/MS and UPLC-MS/MS methods for determining eight coccidiostats in beef. J Chromatogr B. 1087-1088:98-107


Zorraquino MA, Althaus RL, Roca M, Molina MP. 2009; Effect of heat treatments on aminoglycosides in milk. J Food Prot. 72:1338-1341


Zorraquino MA, Althaus RL, Roca M, Molina MP. 2011; Heat treatment effects on the antimicrobial activity of macrolide and lincosamide antibiotics in milk. J Food Prot. 74:311-315