National Office of Animal Health
...for the welfare of all animals

Bookmark and Share
 

HOME | NEWS | MEDICINES TOPICS | ABOUT NOAH | BOOKS | CODE | NCAH | LINKS | CONTACT | JOBS | COMPENDIUM | RESPONSIBLE

Topics and Briefing Documents

ANTIBIOTICS
General Overview
Resistance
Fluoroquinolones
Anticoccidials
In-Feed
Growth promoters
MRSA
Cephalosporins

HEALTH AND WELFARE

CONTROLS ON ANIMAL MEDICINES

ANIMALS IN RESEARCH

ORGANOPHOSPHATES

SAFETY OF FOOD & RESIDUES

VACCINES

ADVERTISING

ADVERSE REACTIONS

ENVIRONMENT


CONSUMER ATTITUDES

VETERINARY LEGISLATIVE REVIEW

Anticoccidials

Introduction

Coccidiosis is an infection of the intestinal tract caused by a single cell parasite. All livestock species, as well as wild animals, can be infected and it is especially prevalent when animals or birds are grouped together in significant numbers. However it can occur in less intensively managed situations, including outdoor flocks and herds. Each species of livestock has a species-specific coccidia that causes infections in that species. Generally, there is not cross-infection between species.

The disease is characterised by an invasion of the intestinal wall by the parasite. The parasite then undergoes several stages of growth and multiplication, during which there is damage to the mucosal and submucosal tissues. Severe haemorrhage may result and mortality in an unprotected poultry flock may be extensive.

Although cattle, sheep and pigs can become infected causing significant depression of performance, it is usually in poultry species that the parasite can cause the most devastating losses. For this reason, it is essential in most poultry rearing situations to use an anticoccidial agent period to prevent illness and control infections.

The production of affordable, quality poultry meat owes much to the development of effective anticoccidial products used in the prevention, control and treatment of coccidiosis.

The Development of Anticoccidials

Chemical Agents

The development of the chicken meat industry in the 1950s required the urgent availability of anticoccidial compounds. Intensive screening activities by several companies soon produced a range of chemicals that were effective in the control of coccidia. Unfortunately, they often became ineffective after a relatively short period of use due to the parasite’s ability to build up resistance against them.

For this reason the development of new chemical anticoccidials proceeded apace throughout the 1960s. By carefully selecting the anticoccidial compounds, it was possible to rear chickens with only occasional disease outbreaks.

Anticoccidials since 1970

Several chemical compounds have remained to the present day and continue to provide a key role in the prevention and control of coccidiosis. A breakthrough came during the 1970s when a new class of compounds – the ionophores – was discovered and rapidly became established as the key component of coccidiosis control.

The ionophores are unique in that they permit a small “leakage” of coccidia to enable the bird to develop a certain level of immunity. This allows a greater degree of protection against the parasite and is a much more efficient method of control. Resistance to ionophores develops very slowly and there is more of a tendency for increasing levels of tolerance. This means that the chicken producer is in a position to adjust the anticoccidial medication programme before there is an acute outbreak of disease.

The Regulatory Process

Since 1970 there has been a European system for approval of anticoccidials involving scrutiny by European experts in the Commission and the European Food Safety Authority.

In the past few years all the anticoccidial products have been completely reviewed by a specialist scientific body under the European Food Safety Authority. Major new studies were conducted by pharmaceutical companies to comply with current guidelines; the review was extremely thorough, focusing mainly on human safety from both residue and microbiological aspects.

In 2006, MRLs (maximum residue levels) were published on the molecules that completed the review. In 2008, the Commission published a report on the future of the anticoccidials which, in agreement with stakeholders, including producers and practising veterinarians, recognised that the products are essential for animal health and welfare.

The authorised products are listed in a Register published in the European Official Journal. This can be found at: http://europa.eu.int/comm/food/index_en.htm

Control programmes

The anticoccidials are designed to be administered orally in strictly controlled amounts generally via animal feed. These amounts are carefully researched by the manufacturers and closely regulated by the authorities. There are a few, however, that can be supplied via the animal’s drinking water system.

In the early stages of a chick’s life, the immune system is not fully developed. It is not unusual for protection in this early stage to be provided by a chemical anticoccidial added to the feed followed by a switch to an ionophore. Such “shuttle programmes”, as they are known, provide an adequate balance between control of infection and the development of immunity in the older bird.

In some cases, shuttle programmes may comprise two types of ionophore, but this is less common. Other specialists propose a “reverse” shuttle, where the starting anticoccidial is an ionophore followed by a chemical based product. And some manufacturers provide an anticoccidial based on a combination of an ionophore with a chemical.

Vaccines to prevent coccidiosis are available and are used in replacement layers and breeding stock. A vaccine for use in chickens for meat is also available.

Vaccines are an important tool, but they are not always the answer. It is important that there is a full range of solutions, so the best option can be chosen to prevent this disease on a particular farm.

In other livestock species, the disease is more sporadic and difficult to predict. However, effective anticoccidials are available and the disease can be kept under control to permit natural immunity to develop. These anticoccidials may be incorporated into feed, or some are administered as an oral drench.

Treatments

In the event of a disease outbreak, it is imperative that water soluble treatments are readily available that can be administered via the watering system in the case of poultry, for instance, or as a drench in the case of cattle or sheep.

Conclusion

It would not have been possible to develop the modern chicken and turkey industries without the discovery and use of anticoccidials When used in a structured and monitored programme, modern anticoccidials are extremely effective and enable the animal to achieve optimum performance by remaining free of the debilitating coccidiosis disease. No new in-feed anticoccidial has been developed since the 1980s, which is perhaps a reflection of the level of success that the ionophores and the remaining few chemicals have brought to the control of the disease.

Printer friendly version here

Updated May 2010

 

HOME | NEWS | MEDICINES TOPICS | ABOUT NOAH | BOOKS | CODE | NCAH | LINKS | CONTACT | JOBS | COMPENDIUM | RESPONSIBLE


Bookmark and Share