Avian coccidiosis and its economic impact

Avian coccidiosis is a parasitic disease of global impact in poultry due to its negative effects on performance and the difficulty in controlling and preventing it. This pathology is caused by different species of protozoa from the genus Eimeria, which are obligate intracellular microorganisms that replicate in the intestinal epithelium of birds. In this location, they cause lesions in the mucosa and alter nutrient absorption. The different Eimeria species also produce enteritis and diarrhoea of different degrees, as well as a marked decrease in production.

There are seven species of Eimeria that can affect both chickens and laying hens in poultry farming. Some of the most common in farms in Peru are E. acervulina and E. maxima, both affecting the small intestine, and E. tenella which affects the caecal region. The prevalence of this disease is remarkably high in the country, especially in the coastal region, where the humidity and temperature conditions favour the growth of coccidia, as well as its vector, Alphitobious.

Clinical coccidiosis is one of the main causes of growth retardation, poor feed conversion, and high mortality in intensive broiler, pullet, and breeder farms. In addition, subclinical infestations increase the economic impact of the disease, since the diagnosis is complicated and is often confused with other pathologies. Besides, coccidiosis acts as a predisposing factor for other diseases such as necrotic enteritis [1].

Prevention and control programs

Since coccidiosis affects almost all farms at certain times of the year and has a great economic impact, it is common to routinely use anticoccidial programs to control this disease.

More than six decades ago, the first coccidiosis prevention programs were developed. They were based on coccidiostats, both synthetic and ionophores, included in the diet of birds. These products inhibit the development of coccidia by interrupting their reproductive cycle, and thus, prevent damage to the intestinal mucosa.

Therefore, these substances act directly on the coccidia, so that these parasites develop resistances, and, consequently, these preventive programs have lost their effectiveness over time. To reduce the occurrence of resistances, it is common to implement complete or dual (shuttle) rotation programs. In the complete rotation programs, at the end of each productive cycle the coccidiostat is replaced by another, and, in the dual or shuttle programs, a coccidiostat is administered in the starter phase, and a different one in the grower diet, and they are alternated [1].

In addition to the development of resistances, there are other disadvantages derived from the use of coccidiostats. Most of them cannot be used until slaughter, as they require a withdrawal period. Besides, hepatotoxicity problems have also been reported, as in the case of nicarbazin, associated with problems in growth and egg quality in the case of laying hens.

Improvement of the physiology of the intestinal immune cells using natural molecules

Both the loss of efficacy of traditional anticoccidial programs and many legal limitations have led to the development of natural alternatives to control coccidiosis. Biovet’s R&D department has developed and patented a technology based on intestinal optimizer pronutrients, which prevents the consequences derived from the coccidia multiplication in the gut.

Intestinal optimizer pronutrients are active molecules that promote the activity of the gut local immune system. These molecules induce the expression of genes related to the synthesis of interleukins considered essential in anti-Eimeria reactions, such as IL-1, IL-12, and IL-18. This increase in the synthesis of interleukins enhances the local immunity of the intestine, and makes it difficult for the sporozoites to complete their cycle. Thus, these molecules prevent the symptoms of the disease and the related consequences [2] [3].

As these molecules do not act directly on the parasite, but stimulate the bird physiology , they do not create resistances and can be administered in continuous programs. In addition, they do not leave residues on animal products and do not require a withdrawal period.

Sometimes, chemical or ionophore coccidiostats are used in dual programs together with intestinal optimizer pronutrients, and it is usual that the latter are finally administered alone after progressively reducing the chemicals.

Field trials support the efficacy of intestinal optimizer pronutrients

The positive effect of intestinal optimizer pronutrients on the gut immunity and, therefore, on the control of coccidiosis, has been tested in several trials worldwide, always following scientific methodology. In these studies, intestinal optimizer pronutrients provided birds with greater local immunological capacity in the intestine that avoids the consequences of coccidiosis.

In a trial carried out in Asia [4], the effect of pronutrients was compared to chemical and ionophore coccidiostats (maduramycin and nicarbazin), by analysing the productive performance, lesions and oocyst counts in birds that were artificially infested with oocysts. of E. tenella at 16 day of life.

In the results, we can see that the group supplemented with intestinal optimizer pronutrients obtained better weight gain compared to the group with coccidiostats, and a better feed conversion rate compared to both the control group and the group with coccidiostats. In addition, the caecal lesions were significantly milder and disappeared faster than in the other two batches, and the oocyst count was lower and decreased more markedly in the group supplemented with pronutrients.

This means that pronutrients achieve greater protection against coccidiosis than coccidiostats, since the birds had less injuries and less capacity to spread the infestation as they excrete fewer oocysts.

Conclusion

Coccidiosis is one of the most prevalent poultry diseases, and its control is very difficult since there are many predisposing factors that favour it. In Peru, the coastal zone has high prevalence of this disease, where the main species involved are E. acervulina, E. maxima and E. tenella.

Traditional prevention programs based on both chemical and ionophore coccidiostats have shown very limited efficacy. In addition, they generate resistances quickly, so they require the implementation of rotation programs in order to minimize them, moreover, the current global trend is to reduce the use of this type of substances in animal feed.

For this reasons, natural alternatives, such as intestinal optimizer pronutrients, are very important developments for the poultry industry. Several studies, under different field conditions, support the beneficial effects of the addition of pronutrients in the diet, which significantly improve the local immunity of the intestine. This helps to avoid the negative effects of coccidiosis and, since they just act at physiological levels, they do not generate residues nor generate resistances.

In conclusion, intestinal optimizer pronutrients are an effective solution for the control of coccidiosis in poultry, as they notably reduced coccidial lesions and oocyst counts, and simultaneously improved feed conversion by 1.35%, and weight by 2.88%.

Intestinal optimizer pronutrients are developed and manufactured by Biovet S.A. and marketed under the name Alquernat Zycox.

Bibliography

• [1] Cervantes HM. Control de la coccidiosis en la avicultura comercial. In: XIV Seminario Internacional Patología y Producción Aviar. Athens, Georgia; 2018. p. 126–50.
• [2] Borrell J. Uso de pronutrientes de origen natural en veterinaria. RACVE (Real Acad Ciencias Vet España). 2005;
• [3] Borrell J, Domenech C, Martin N, Tesouro A. Pronutrients use in poultry nutrition (S11-0224). In: XXV World’s Poultry Congress [Internet]. Beijing, China; 2016. p. 97. Disponible en: http://www.wpsa.com/images/downloads/tables_of_contents/The Proceedings of WPC2016-Abstracts-20160920.pdf
• [4] Estudio de la eficacia de pronutrientes optimizadores intestinales frente a un coccidiostato químico en pollos de engorde [Internet]. 2018. Disponible en: https://www.veterinariadigital.com/post_blog/estudio-de-la-eficacia-de-pronutrientes-optimizadores-intestinales-frente-a-un-coccidiostato-quimico-en-pollos-de-engorde/