Avian coccidiosis: current situation in Southeast Asia and natural control methods
Coccidiosis is recognized as the parasitic disease with the greatest economic impact in the poultry industry worldwide. The losses are estimated at 1.5 trillion dollars per year, represented by a decrease in productive efficiency and anticoccidial treatments. The etiological agent is classified within the genus Eimeria, a group of protozoa that multiply in the intestinal tract and damages the tissue, which causes malabsorption of nutrients, diarrhoea, dehydration, bleeding and mortality.
There are seven species of coccidia that affect avian production: E. acervulina, E. maxima, E. tenella, E. mitis, E. necatrix, E. praecox and E. brunetti. Non-sporulated oocysts are released in the feces and sporulate when adequate temperature and humidity conditions occur. Sporulation gives rise to the infective forms of Eimeria spp. (see figure 1). The temperature range for sporulation to happen is 12ºC to 39ºC, the optimum being from 28ºC to 31ºC. If these sporulated oocysts are ingested by an animal, they hatch in the intestine and give rise to parasite forms that will infect the enterocytes.
Coccidiosis in Southeast Asia
The process of transformation of the poultry industry in Southeast Asia shows a greater investment in the incorporation of technology, mechanization of processes to achieve greater productive efficiency, application of measures related to biosecurity and animal welfare. However, these innovations are not enough to eradicate coccidiosis from farms, being necessary the application of treatments to control its prevalence. In a study conducted in the region, a higher prevalence of E. tenella, E. maxima and the concomitant infestation of these two species was found – “Investigation on the Prevalence of Coccidiosis of Chickens in Luang Prabang“, Bounmy Keohavong, 2016.
Southeast Asia has a tropical climate (15ºC-35ºC) with high rainfall presence. High temperatures and humidity are two predisposing factors that exacerbate coccidiosis’ pathogenicity. For this reason, there is a high infective pressure due to coccidiosis in the farms located in that area.
Natural tool to fight coccidiosis: the pronutrients
Worldwide trend of banning prophylactic chemotherapy in poultry production has led to new research focusing on the immune control of coccidiosis.
In this sense, intestinal optimizer pronutrients (POI) are an effective tool for the immunological control of coccidiosis. These have immune boosting properties that act on the intestinal mucosa, thanks to which they stimulate the expression of interleukins (IL-1, IL-12, IL-18) by intestinal polymorphonuclear cells (PMNs). The interleukins are proteins that act as chemical mediators in the cellular immune reaction, therefore they play a fundamental role in the prevention of coccidiosis.
Field trial: intestinal optimizer pronutrients efficacy test versus a chemical coccidiostat in fattening chickens
The following is a trial conducted in Bangladesh to measure the efficacy of these pronutrient intestinal optimizers. The aim of the study, carried out at the Bangladesh University of Agriculture (BUA), is to evaluate the effect of intestinal optimizer pronutrients on growth and conversion rate, and compare their effectiveness against a chemical coccidiostat.
Broilers (Cobb 500) were used for the trial, during a period of 35 days:
Three lots were bred separately with the same environmental and management conditions, food and water were supplied ad libitum. At 16 days of age, an artificial infliction of Eimeria tenella 2.5×10⁴ oocysts / bird was conducted. Potassium dichromate (2.5%) was used to generate the sporulation of the oocysts, causing the infective capacity.
Feed Conversion Rate
According to the results, a better Feed Conversion Rate (FCR) is obtained in the batch treated with intestinal optimizer pronutrients compared to the other two batches (figure 2) ) – control batch in red, coccidiostat-treated batch in green.
It is important to note that the FCR and mortality rate of the batch treated with intestinal optimizer pronutrients was better both in the pre-infection and post-infection periods compared to the other batches (figure 3).
Feces clinical evaluation
The clinical evaluation of the feces was carried out according to coccidiosis-presence signs. The POI batch showed better results than the other two. Although there was an increase in signs of coccidiosis in feces at day 8 of post-infection, there also was a marked decrease in the severity of the lesions – greater recovery.
Similar results were observed regarding cecal lesions: the batch treated with pronutrients showed an increase in the intensity of lesions until day 8 and then descended. Despite of this phenomena, the POI batch showed fewer lesions and experimented better recovery during the trial (figure 4).
Cecal lesions’ histopathology was graded from 0 to 4 considering inflammatory cells by focus, villus damage, lamina propria exudation and luminal accumulation. Histological sections were analyzed at 6, 8, 10 and 14 days post-infection, showing a lower score from day 8 of post-infection in the pronutrient-treated batch when compared to the other two.
The oocyte count was lower in the POI batch compared to the other batches. On day 6 after infection an average of 11500 oocysts per gram of fecal content was counted, descending to 6000 oocysts at day 14 of post-infection.
In view of the results, we can conclude that the batch treated with intestinal optimizer pronutrients (POI) obtained better parameters of HF and mortality in comparison to the other batches. The improvement of the parameters had a direct correlation with the clinical observation of the feces, the cecal lesions and the oocyte count. Weight gain was similar in all batches.
Intestinal optimizer pronutrients are an effective tool for the immunological control of avian coccidiosis. The immune-boosting they generate prevent coccidium from invading the intestinal epithelial cells.
The prevalence of coccidiosis in Southeast Asia is favoured by region climatic conditions, allowing Eimeria spp. oocytes reach their infective form throughout the year. Therefore, the use of pronutrients is key for a systematic control of such parasitosis.
The intestinal optimizer pronutrients produced by BIOVET S.A are marketed under the Alquernat Zycox trademark.