Coccidiosis in chickens: Current situation in the USA
Coccidiosis is one of the most important diseases in the US because of its direct consequences, which include diarrhea, growth retardation and poor feed conversion, and because it makes animal more susceptible to suffer from other infections, such as necrotic enteritis.It is an endemic disease since the parasite is universally present and can resist for quite a long time in the environment. It affects all types of production, but especially broilers and broiler breeders, because they are more often raised on the floor.
Coccidiosis is one of the most important diseases in the US because of its direct consequences, which include diarrhea, growth retardation and poor feed conversion, and because it makes animal more susceptible to suffer from other infections, such as necrotic enteritis.
It is an endemic disease since the parasite is universally present and can resist for quite a long time in the environment. It affects all types of production, but especially broilers and broiler breeders, because they are more often raised on the floor.
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Etiology, cycle, and pathogenesis
Coccidiosis is caused by coccidia, unicellular protozoa of the genus Eimeria that parasite the enterocytes (cells of the digestive mucosa). Seven species of Eimeria can infest chickens: E. acervulina, E. maxima, E. necatrix, E. brunetti, E. mitis, E. praecox, and E. tenella. Each species affects a specific part of the digestive tract and causes lesions of different severity.
The disease is transmitted feco-orally when chickens ingest infective oocysts. In the gut, sporozoites are released, invade the enterocytes, and start the reproductive cycle. The replication stages cause the destruction of the mucosa, the clinical signs and the lesions observed in animals. Epithelial integrity decreases and chickens become prone to suffer infections. This is the reason why diseases such as necrotic enteritis is tightly related to coccidiosis.
Once the reproductive stages are completed, oocysts are excreted in the feces and sporulate to become infective and restart another cycle.
Species of importance in the USA
The most prevalent coccidian species in US farms using anticoccidian programs are E. praecox, E. acervulina, E. maxima and E. tenella.
maxima and E. tenella are the ones having a greatest impact. The first affects the mid-small intestine and develops in the deeper mucosa, for it impairs nutrient absorption and is tightly related to necrotic enteritis outbreaks. E. tenella is the only species that affect the ceca, and it is of importance because of the severe lesions and high mortality it causes in chicken farms.
Economic importance of coccidiosis in the USA
Coccidiosis is one of the most costly diseases in poultry worldwide. It is estimated to cost over 2 billion dollars to the poultry production industry worldwide (Dalloul & Lillehoj, 2006). The inversion associated with prevention of coccidiosis represents an important cost too, of around 3 million dollars every year in the US.
Main prevention methods used in the US: coccidiostats and vaccines
Most poultry farms in the US use coccidiostats, especially in broiler production. There are many products available, which are called chemical and ionophore coccidiostats. Despite this, the development of resistances and the growth of antibiotic-free (ABF) and no antibiotic ever (NAE) production systems have accelerated the search of other solutions to prevent coccidiosis, such as vaccines and natural additives.
Chemical coccidiostats have lost efficacy in the recent years. Nowadays, nicarbazin is the most used one, despite medicated birds are more likely to suffer from heat stress in hot weather.
Among the ionophores, monensin is the most widely used. Ionophores have different mechanisms of action, so it is harder for coccidia to develop resistances. Some ionophores may depress feed consumption if used at higher doses than the recommended ones.
To slow down the appearance of new resistances, shuttle and rotation programs should be applied when using coccidiostats with products of a different type and with different mechanism of action.
The second most used mechanism to prevent coccidiosis, which has been available in the USA since 1952, are non-attenuated coccidiosis vaccines. For many years, the use of these tools was restricted to broiler breeder, but, because of the new types of production (ABF, NAE), they have gained importance.
These vaccines are administered to poultry in the first day of live or during hatchery. They seem to work quite well, but they have several limitations:
- Selective protection: they only protect against the Eimeria strains present in the vaccine. If there is a different wild strain, birds will get infected despite the vaccine.
- Late-cycle infestations: farms that raise heavy broilers (over 60-day-old chickens) sometimes suffer from late-cycling coccidiosis, despite the birds were vaccinated on day 1 of age.
- Mild infestation: vaccines cause a mild infestation and, therefore, vaccinated birds may have reduced growth performance during the first stages.
Natural additives to prevent coccidiosis: Alquernat Zycox as a promising strategy
A natural solution based on intestinal optimizer pronutrients, called Alquernat Zycox, was developed several years ago to prevent coccidiosis in a different way. These pronutrients have recently become available for the US market and are gaining importance in the area.
This technology is based on a metagenetic mechanism of action described by the R&D department of Biovet, S.A., with a positive effect on the gut immunity of the animal, which, in turn, improves productivity.
How does it work?
Pronutrients are active molecules of a plant origin that stimulate cell physiology. They target the immune cells of the digestive tract (local immune system) and act as a stimulus so that they start reading certain genes of their DNA related to the functions of the organs.
Does it create resistances?
Thanks to this mechanism of action, based on the physiologic stimulation of the local immune system, these molecules do not cause the development of resistances (they do not target the parasites).
Is it effective against all Eimeria strains?
Again, due to the mechanism of action, it is not selective against specific strains: any Eimeria that comes across the gut will be eliminated by the immune system, which will be ready to fight any protozoan.
Can it be combined with other prevention methods?
Alquernat Zycox can be used as the only prevention method for coccidiosis, because it is effective to protect the birds. The product can also be combined with coccidiostats (whether ionophores or chemicals) and coccidiosis vaccinations: it can be added on top during challenging periods or in shuttle and rotation programs.
In combination with vaccinations, it boosts the immunity achieved with these biological products. Therefore, it increases the protection achieved by the vaccines (synergistic effect).
Is it available for ABF, NAE and organic production?
Alquernat Zycox is a natural feed additive that can be used in ABF and NAE production systems. It is also available for conventional and organic production (ECO certified).
In what presentations is it available?
It is available in premix and liquid presentations. The former is intended to be mixed with the feed, while the latter is mainly intended to be added to the drinking water, whether continuously or in challenging periods.
Is there any similar product to Alquernat Zycox in the market?
Alquernat Zycox is the one and only natural product for the prevention of coccidiosis with a patented technology and a mechanism of action described with molecular (in vitro) and field (in vivo) trials.
Thanks to this, the function and homogeneity of the product is always the same in all the production batches. In addition, a patent protects this technology, developed by Biovet, S.A., so that it remains as a unique solution in the market.
Coccidiosis is an important disease to consider in poultry production because it affects productive performance and increases the susceptibility to suffer other infections, such as necrotic enteritis.
There are different tools to prevent it, such as coccidiostats, vaccination and pronutrients. Coccidiostats are becoming obsolete, so it is important for producers to get used to the other tools.
Alquernat Zycox is a promising strategy, based on intestinal optimizer pronutrients, that can be used alone or combined with vaccinations in farms facing hard coccidiosis challenges.
MV. Júlia Pié Orpí
Veterinary Technical support to the area of Latin America at Biovet S.A. Laboratories Official Veterinary Services (SVO) in poultry slaughterhouse