Acceptable daily intake (ADI)

An estimate of the amount of a substance in food or drinking water that can be consumed over a lifetime without presenting an appreciable risk to health. It is usually expressed as milligrams of the substance per kilogram of body weight and applies to chemical substances such as food additives, pesticide residues and veterinary drugs.


A substance that acts to accelerate, prolong, or decrease antigen dosage, or to enhance the antigen-specific immune response when used as part of a vaccine formulation.


Requiring oxygen.


Antibody affinity refers to the tendency of an antibody to bind to a specific epitope at the surface of an antigen, ie, to the strength of the interaction.


Substance which changes the properties of cells via receptors at the cell membranes.


The egg-white of a bird’s egg (Latin:albus = white).

All-in all-out method

A single age group of animals enter and leave a farm at the same time.

Amino acids

The "building blocks" from which protein are constructed.


The sac that envelops the embryo from about 3 days of incubation (Greek: amnos = a lamb).


Requiring the absence of oxygen


Describes a substance that acts in opposition to another substance, thus cancelling out its effect; for example, a hormone that, when released in the body, prevents another hormone from working.


An agent or substance that is produced from microorganisms that can act against another living microorganism. Antimicrobial substances that are synthetic, semisynthetic, or those derived from plants or animals, are therefore, by strict definition, not considered antibiotics. 


Proteins of the immunoglobulin family, present on the surface of B lymphocytes, secreted in response to stimulation, that neutralize antigens by binding specifically to their surface.


Any substance that stimulates an immune response by the body. The immune system recognizes such substances as being foreign, and produces cellular antibodies to fight them. Antigen/antibody response is an important part of a person's immunity to disease.

Antimicrobial resistance

The ability of microbes to grow in the presence of substances specifically designed to kill them; for example, some human infections are now resistant to antibiotics, raising concerns about their widespread use.


Drugs, chemicals, or other substances - synthetic or naturally produced by other microorganisms - that either kill or slow the growth of microbes. They are most commonly used to prevent or treat disease and infections due to micro-organisms. Antimicrobial agents include antibacterials, antibiotics, antivirals, antifungals, and antiparasitic drugs.


A quantitative or qualitative evaluation, or test, of a substance.  Frequently used to describe tests of the presence or concentration of infectious agents, antibodies, etc.


An attenuated vaccine is one that has been weakened by chemicals, or other processes (passages) so that it will produce an adequate immune response without causing the serious effects of an infection.


The area under the concentration-time curve at steady-state over 24 h unless otherwise stated. It is equivalent to a single dose AUC 0-∞


Autogenous vaccine

Autogenous vaccines for veterinary use are defined as any immunological veterinary medicinal products manufactured for the purpose of producing active immunity from pathogenic organisms obtained from an animal or animals from the same herd that have been inactivated and used for the treatment of this animal or of animals from this herd.



Bacteria that are rod-shaped.


Tiny microorganisms that reproduce by cell division and usually have a cell wall. Bacteria can be shaped like a sphere, rod, or spiral and can be found in virtually any environment.


A virus that infects and multiplies within a bacterium, which it can also kill.

Beak trimming

Removal of part of the upper and sometimes also lower mandible of the beak.

Bioavailability (F)

The fraction of administered drug that reaches the systemic circulation.


A preparation of one or more active substances (see definition) designed to use chemicals or other means to kill or halt the actions of harmful organisms such as plant diseases or animal infections.


Decomposition or breakdown of a substance through the action of microorganisms (such as bacteria or fungi) or other natural physical processes (such as sunlight).


A community of microorganisms (either single or multiple species) developed on or associated with a surface.


The study of the factors influencing the bioavailability of a drug in man and animals and the use of this information to optimize pharmacological and therapeutic activity of drug products. 


Administration of an additional vaccination to help increase or speed the immune response to a previous vaccination.

Breeding flock

A flock that is composed of stock that has been developed for commercial egg or meat production and is maintained for the principal purpose of producing chicks for the ultimate production of eggs or meat for human consumption.



Capsid proteins

Proteins that make up the shell of a virus particle that contains the genetic material.


A substance that causes cancer.


A person or animal that harbors a specific infectious agent without visible symptoms of the disease.  A carrier acts as a potential source of infection.

CAS Number

A CAS (Chemical Abstracts Service) Registry Numberis a unique identifier of a chemical. Each CAS Registry Number, is a unique numeric identifier, designates only one substance, has no chemical significance and is a link to a wealth of information about a specific chemical substance.

CAS Registry

The largest and most current database of chemical substance information in the world containing more than 32 million organic and inorganic substances and 59 million sequences.


Colony Forming Units. A measure of viable microbial populations. A count of colony forming units estimates the number of viable cells in a sample. It assumes that each colony of cells growing on a standard sized petri dish plate is separate and has arisen from a single cell. 


One of the two spring-like structures projecting from the equatorial region of the vitelline membrane of the laid egg. The chalazae are thought to act as ‘‘balancers’’, helping the yolk to float in the albumen (Greek: chalaza = lump).


The process of infecting an animal with a disease agent to test for protective immunity.


Small secreted proteins that function as chemoattractants, recruiting cells that express the corresponding chemok ine receptors at their surface and thus migrate toward higher concentrations of chemokines.


A process that removes contaminants including dust, soil, large numbers of micro-organisms and the organic matter that protects them.


Genetically identical biological entities derived from a single parental entity.


Increase above the number of expected cases in a place or time period.

Cmax (level, concentration)

The highest concentration reached or estimated in the compartment of reference.

Conformational epitopes

Antigenic determinants that are only present when the antigen is in a specific (usually native) conformation.

Conjugated vaccine

A conjugated vaccine is produced by covalently binding an antigen to a carrier protein with the intention of improving the immunogenicity of the attached antigen. This technique is most often applied to bacterial polysaccharides for the prevention of invasive bacterial disease.


A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful (adverse) health effects.

Cross contamination

The process by which microbes are unintentionally transferred from one substance or object to another, with harmful effect.


Proteins manufactured by cells of various lineages that, when secreted, drive specific responses (e.g., proliferation, growth, or maturation) in other susceptible cells.

Cytotoxic T lymphocyte (CTL)

A sub-type of T lymphocyte (CD8) that has been activated by an antigen and can target and kill a cell that presents that antigen.



A general term for the destruction or removal of microbial contamination to render an item safe.

Dendritic cells

Cells derived from bone marrow that play a major role in presenting processed antigen to T cells.

Deoxyribonucleic acid (DNA)

The chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms.


Removal of the dew and somtimes also pivot claw from the feet of breeder males to prevent damage to females during natural mating.


Persistent, chlorine-containing organic pollutant which occurs as by-product of industrial processes. It can accumulate in the food chain and pose a serious public and environmental health risk.


A process used to reduce the number of micro-organisms.


The amount of a substance to which a person/animal is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time).

Dose-response relationship

The relationship between the amount of exposure (dose) to a substance and the resulting changes in body function or health (response).


Removal of all, or part, of the male comb.



The European Food Safety Authority (EFSA), an agency of the European Union. Its permanent home is in Parma, Italy. Its primary responsibility is to provide independent scientific advice on all matters concerning Food Safety.


Substances that dissociate in water to form a cation (positively charged ion) and and anion (negatively charged ion).

ELISA (enzyme-linked-immunosorbent serologic assay)

A technique that relies on an enzymatic conversion reaction. It is used to detect the presence of specific substances, such as enzymes, viruses, antibodies or bacteria.


EMA stands for the European Medicines Agency. This is a government agency which approves and licenses medicines, allowing them to be prescribed in European countries.


A dispersion of a liquid called the dispersed phase in a second liquid called the continuous phase with which the first one is not miscible. In vaccine formulations, these phases are water (antigenic media) and oil.


Disease that is widespread in a given population. Infection that is maintained at a baseline level in a geographic area; the infectious agent is always present in the population.


A disease which is constantly present in the animal community, but only occurs in a small number of cases.


Specialized proteins that act as catalysts for virtually all necessary chemical reactions that take place within the body. Like all catalysts, enzymes unchanged by the reactions they promote, and will initiate many reactions until they are degraded (usually by another enzyme).


The occurrence of cases of an illness in a community or region which is in excess of the number of cases normally expected for that disease in that area at that time.


The branch of medical science that deals with the incidence, distribution, and control of disease in a population.


A molecular region on the surface of an antigen capable of eliciting an immune response and of combining with the specific antibody produced by such a response.


An outbreak or epidemic of disease in animal populations.


Causal association of a disease with an agent. The study of the cause of diseases.

Extra-label use

The administration of a therapeutic drug in a way that differs from its approved use (i.e., the “label use”).



The Food and Agriculture Organization of the United Nations (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate agreements and debate policy. FAO was founded on 16 October 1945 in Canada. The headquarters


Food and Drug Administration. The American drug regulatory authority.

Feed additive

Product intentionally added to animal feed to improve: i) the quality of the feeds ii) the quality of the food products obtained from animals; iii) animal performance and health.

Feed Conversion Rate (FCR)

The amount of feed consumed (in Kg) divided by the weight gained (in Kg).


A cell derived from connective tissue.


An object that is not harmful in itself but which can harbor pathogenic organisms and thus may be involved in transmission of an infection.

Foodborne disease

An illness caused by foods or drinks which have been contaminated by toxins or harmful microbes (e.g. bacteria, viruses).


A combination of both active and inactive constituents to form the end use product.

Functio laesa

Loss of function; one of the cardinal signs of inflammation.



Good distribution practice (GDP) requires that medicines are obtained from the licensed supply chain and are consistently stored, transported and handled under suitable conditions, as required by the product specification.


The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.


An organism with one or more genes removed from the genome to render it nonpathogenic so it can be used as a vaccine.

Genetically modified (GM) vaccine

A vaccine that is produced using genetic modification. Examples are recombinant antigen(s), (self-amplifying) DNA/RNA and vaccines that consist of genetically modified organisms.

Genetically modified organism (GMO)

An organism of which the genome has been altered genetically by non-natural means in order to modify its phenotype.


The entire amount of genetic material found in the cells of living organisms.


A substance that damages DNA. A genotoxin can cause mutations in DNA - mutagen, it can trigger cancer - carcinogen, or it can cause a birth defect - teratogen. 

Geographic information system (GIS)

 mapping system that uses computers to collect, store, manipulate, analyze, and display data.


Good laboratory practice (GLP) is a standardised way of planning, performing and reporting laboratory-based studies to ensure a high standard of quality and reliability.


A biomolecule composed of a protein and a carbohydrate.


Good Manufacturing Practices: The part of quality assurance which ensures that products are consistently produced and controlled to the quality standards appropriate to their intended use and as required by the marketing authorization.



Hazard analysis critical control points. The process by which food safety hazards occurring within the operations of a business are assessed and managed. The aim of HACCP is to ensure product is safe by identifying microbial, chemical and physical hazards, establishing controls for the hazards, monitoring the controls and regularly verifying that the system is functioning correctly.

Half Life

The period of time required for the concentration or amount of drug in the body to be reduced to exactly one-half of a given concentration or amount.

Hemagglutination (HA)

Agglutination of erythrocytes usually by either antibodies, viruses or certain bacteria.



Related to an abnormal state or condition produced in a patient through inadvertant or erroneous treatment.


Denoting a disease of unknown cause.


IgA antibodies are found in areas of the body such the nose, breathing passages, digestive tract, ears, and eyes. IgA antibodies protect body surfaces that are exposed to outside foreign substances. This type of antibody is also found in saliva and tears. IgA activity is essentially related to the mucosa immunity.


One of many antibodies present in blood serum which is usually indicative of a recent or remote infection. IgG is most prevalent about 3 weeks after an infection begins. It is the most important antibody in the secondary response.


One of many antibodies present in blood serum which is usually indicative of an acute infection. It is the first immunoglobulin to be produced after the immune response takes place. IgM is the  predominant isotype in the primary response. 

Immune system

All the organs, cells, biological substances and cell functions which, together, are responsible for defending the body from extraneous elements.

In vitro

In an artificial environment outside a living organism or body.

In vivo

Within a living organism or body.


The number of new cases of disease in a defined population over a specific time period.


The entry and development of an infectious agent in the body of a person or animal.


A substance that kills insects.


A class of antimicrobial substances used to treat coccidiosis, a protozoal disease of poultry.



The Joint Expert Committee on Feed Additives. It is an international body of scientists supported by the UN’s Food and Agriculture Organisation and World Health Organisation. JECFA has the ability to set MRLs.


Kilobase (kb)

A measure of the size of a nucleic acid molecule. One kilobase = 1000 nucleotides. Animal virus DNAs range in size from less than 2 kilobases (Circoviruses) up to several hundred (Poxviruses).


Latency (virus)

Latency describes the phase when viruses remain within cells in an inactive state and there are no clinical symptoms in the individual harboring the viruses.

Live vaccine

A vaccine that contains a living, yet weakened organism or virus.


The lowest observed adverse effect level (LOAEL) is the lowest level of a substance that has been observed to cause harm in an exposed population.


A limit of detection (LOD) is the lowest concentration of a substance that can be detected using standard tests but which is too small to be measured with certainty.

LOQ (Limit of Quantification)

The smallest analyte concentration for which a method has been validated with specified accuracy and precision to enable quantification. If the analyte is detected at levels above the LOD, but below the LOQ, it can be detected, but not quantified. i.e. we know it’s there, but not exactly how much of it.



A large white blood cell that kills invading microbes and takes the antigens of those cells to helper T cells, so that they can identify and kill the infection.

Marker vaccine

A recombinant organism containing a foreign gene in which, when used as a vaccine, the foreign gene or antibodies to the expressed protein from the foreign gene can be detected. Marker vaccines or animals receiving marker vaccines can be detected with specific diagnostic tests.

MCR genes

Colistin resistance genes that are on plasmids and thus mobile so can be readily transferred between bacteria. They confer resistance to colistin, which is a polymyxin.


The conversion or breakdown of a substance from one form to another by a living organism.


Substance formed as a consequence of metabolism in an organism.

MHC (Major Histocompatability Complex)

MHC is the name given to a cluster of genes on chromosome 16 that influence immune response.


The minimum inhibitory concentration (MIC) of an antibacterial is defined as the maximum dilution of the product that will still inhibit the growth of a test microorganism.


The minimum lethal concentration (MLC) of an antibacterial is defined as the maximum dilution of the product that will kill a test organism.

Monoclonal antibodies (mAbs)

Antibodies produced by a single clone of identical B cells or hybridoma cells.


The maximum residue limit (MRL) is defined as the maximum concentration of a residue that is legally permitted or acceptable in or on a food.


A microbe’s ability to survive and grow despite the presence of multiple antimicrobial drugs, making infections from such microbes particularly challenging to treat.


A substance that causes mutations (genetic damage).


A change (damage) to the DNA, genes, or chromosomes of living organisms.



Any disease of the kidneys.


Destructive to kidney cells.


The no observed adverse effect level (NOAEL) is the greatest concentration or amount of a substance at which no detectable adverse effects occur in an exposed population.

Nosocomial infection

An infection occurring in a patient which is acquired at a hospital or other healthcare facility. Commonly called a cross infection.



A linear nucleic acid fragment consisting of 2-10 nucleotides joined by phosphodiester bonds.


Egg stage of the coccidian parasite.


A sudden appearance of a disease in a specific geographic area. Greater-than-anticipated increase in the number of cases of an endemic illness; if not quickly controlled, an outbreak can become an epidemic.



An outbreak of disease that spreads throughout the world.

Pathogen organisms

A pathogen is a biological agent that can cause a disease.


The ability to cause disease.


Characteristic or indicative of a disease, denoting especially one or more typical symptoms, pathological lesions.

PCR (polymerase chain reaction)

A method for copying (‘amplifying’) specific sequences of nucleotides in DNA; a modified form of the process is used for copying sequences in RNA.


Substance used to kill or control pests, including disease-carrying organisms and undesirable insects, animals and plants.

Peyer’s patches (gut-associated lymphatic tissue)

Lymphatic tissues in the gut that allow antigenic proteins and pathogens to interact directly with the immune system.


Pulsed-field gel electrophoresis: a technique used for the separation of fragments of a genome / large (DNA) molecules, by applying to a gel matrix an electric field that periodically changes direction.


The study of absorption, distribution, metabolism and excretion (ADME) of drugs and their corresponding pharmacologic, therapeutic, or toxic responses in man and animals.


The quantitative relationship between a pharmacokinetic parameter (such as AUC, peak level) and a microbiological parameter (such as MIC) is labelled as a PK/PD index (PDI).

Plaque Forming Unit (=PFU)

A measure of infectious virus particles. One plaque forming unit is equivalent to one infectious virus particle.


The fluid portion of the blood, rich in soluble proteins with a wide range of functions.

Positive predective value

The number of truly positive cases in a population adjusted positive by a specific test procedure.


Parts per billion.


Parts per million.


Non-digestible food ingredients that benefically affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improve host health.


The number of cases at a given time in a population at risk of exposure.


A short oligonucleotide sequence used in a polymerase chain reaction.


An infectious agent, prions are abnormal proteins that can be transferred between species attacking cellular proteins found mostly in the brain.


A probiotic is a culture of one or more micro-organisms, which benefit the host by stimulating the positive properties of its natural occuring microflora in the gut. A probiotic is manufactured by fermentation technology.


A type of molecule composed of complex strings of amino acids (protein building blocks).


A young female domestic chicken that has not yet reached sexual maturity (i.e. begun to lay eggs).



Isolation or restriction of free movement imposed to prevent the spread of contagious disease.



The creation by a process of intramolecular exchange, of chromosomes combining genetic information from different sources, typically two genomes of a given species.


The measure of consistent reproducibility of a test result under identical conditions.


Any person, animal, arthropod, plant, soil or substance in which an infective agent normally lives and multiplies. The infectious agent primarily depends on the reservoir for its survival.

Rigor mortis

Postmortem state 6–24 hours after death in which muscles stiffen and become less extensible; onset of rigor mortis correlates with depletion of ATP in the slaughtered animal.

Risk assessment

A specialised field of applied science that involves reviewing scientific data and studies in order to evaluate risks associated with certain hazards. It involves four steps: hazard identification, hazard characterisation, exposure assessment and risk characterisation.


(reverse transcriptase polymerase chain reaction) Powerful technique for producing millions of copies of specific parts of the genetic code of an organism so that it may be readily analyzed.  More specifically, RT-PCR produces copies of a specific region of complementary DNA that has been converted from RNA.  The technique is often used to help in the identificat



A cancer developing from fibriblast.


The ability of a test to detect a disease or pathogen. High sensitive tests may generate false positive results.


The ability of a test to differentiate between the disease or pathogen of significance and other agents. High specific tests may generate false positive results.

Stability of vaccines

Stability is the ability of a vaccine to retain its chemical, physical, microbiological and biological properties within specified limits throughout its shelf-life.

Standard operating procedures (SOP)

The detailed written instructions that specify how a test or administrative procedure is to be performed, or how a piece of equipment is operated, maintained and calibrated.


A process used to render an object free from all living organisms.


Proteins produced by pathogens, including bacteria, mycoplasma and viruses that are capable of simulating large numbers of T cells.

Synergistic effect

The combined effect of the substances acting together is greater than the sum of the effects of the substances acting by themselves.


The time required for 50% of a substance present in an individual, population or ecosystem to break down or be eliminated naturally. The half-life, or t½, is often used to describe the disappearance of potentially harmful substances such as chemical toxins.

Table-egg layer

A domesticated chicken grown for the primary purpose of producing eggs for human consumption.


A substance that causes defects in development between conception and birth. A teratogen is a substance that causes a structural or functional birth defect.


The concentration of a substance in a solution, or the strength of such a substance detected by titration. The term is most likely to refer to antibody titer, which is a measure of the concentration of specific antibodies to selected microbes that are circulating in an individual's bloodstream.


The capacity of a substance to confer morbidity or mortality.


The study of the movement of toxins through the body.


The ability to locate an animal, commodity, food product or ingredient and follow its history in the supply chain forward or backword.



United States Pharmacopeia



Validation is defined as the establishing of documented evidence which provides a high degree of assurance that a planned process will consistently perform according to the intended specified outcomes.


A carrier which transmits infective agent from one host to another. In recombinant DNA technology, it can be (1) a self-replicating molecule of DNA that serves to transfer a gene of forgeign DNA fragment from one organism to another (usually bacteria) or (2) a virus or bacteria containing a foreign gene thet is used to vaccinate an animal.


The degree or ability of a disease-causing organism (e.g. a bacterium, virus or parasite) to cause disease.


A virus is a minuscule cell parasite. Incapable of living independently, a virus penetrates a cell and takes control of the cell’s machinery to reproduce itself, and, later, contaminate other cells.

Virus-like particles (VLPs)

Self-assembling, nonreplicating particles similar in size to natural virions, which result after expression of certain proteins in bacterial, insect, or mammalian cell culture.


Organic substances, which are necessary for the proper operation of vital functions in humans and animals. Vitamins must be provided in the diet, since the animal body is generally incapable of synthesising its own vitamins in sufficient quantities.



World Health Organization. Agency of the United Nations, the aim of which is to promote health. Founded in 1947 and based in Geneva.

Withdrawal period

The period necessary between the last administration of the veterinary medicinal product to animals, under normal conditions of use, and the production of foodstuffs from such animals, in order to protect public health by ensuring that such foodstuffs do not contain residues in quantities in excess of the maximum residue limits for active substance.



Derived or obtained from an organism of a different species.



Unicellular fungi belonging mainly to the Ascomycetes that usually multiply by budding. Their commercial significance lies in their ability to secrete enzymes.



Relating to a disease that is communicable from animals to humans under natural conditions.