- Monensin interacts with the parasite during the motile stage (sporozoites and merozoites) and does not penetrate the intestinal cells.
- Nicarbazin interacts later during the lifecycle of the parasite and can penetrate the intestinal cells (1st and 2nd generation schizonts).
The different modes of action of monensin and nicarbazin work synergistically, resulting in a high performing product that gives optimal efficacy.
Synergy of two strong, active compounds
An anticoccidial sensitivity test (AST) has demonstrated this synergistic effect between nicarbazin and monensin: the combination of both products performed better than the products individually.
Monensin included in the diet at 40 ppm did not reduce lesions for any of the Eimeria species. Nicarbazin included in the diet at 40 ppm significantly reduced the lesions for E. tenella but the other Eimeria species were not significantly affected. The combination of nicarbazin and monensin (both at 40 ppm) significantly reduced the lesions for all Eimeria species (Table 1), proving the synergistic effect of the two active ingredients.
Although Monimax® is a new product, the active compounds have been on the market for many years, so development of resistance is a legitimate concern. Recent feedback from the field suggests reduced efficacy of the frequently used nicarbazin/narasin combination product currently on the market.
For this reason, a meta-analysis was performed to evaluate the effectiveness of Monimax® against recent Eimeria field strains in comparison to a nicarbazin/narasin product. The meta-analysis was performed using the data from 27 different ASTs conducted over a 7-year period (2013-2019). The Eimeria isolates were collected from commercial farms from 13 different countries with different anticoccidial control programs.
The sensitivity trials were conducted in two different research institutes, using a comparible, standardized AST protocol (Figure 2). In short, groups of cage-reared birds were supplemented with Monimax® or nicarbazin/narasin starting 2 days before oral inoculation with different Eimeria field strains. Approximately 6 days after inoculation, the severity of lesion scores (according to Johnson and Reid, 1970) and other performance parameter measurements were collected and compared to an uninfected, untreated control group (UUC), and an infected, untreated control group (IUC). All coccidiostats were used at their current registered European dosages.
Average daily gain (ADG), average daily feed intake (ADI) and feed conversion ratio (FCR) were collected over the course of one week and compared in a meta-analysis from 27 standardized sensitivity trials (Table 2). The in-feed application of Monimax® was compared to both control groups and to the inclusion of a nicarbazin/narasin combination product.
Monimax® resulted in significantly higher values for all measured parameters (ADG, ADI and FCR) compared to the IUC. Although the difference was not statistically significant, Monimax® resulted in a numerically better performance compared to the nicarbazin/narasin combination.
Lesion scores were determined according to the Johnson and Reid (1970) scoring system. The least square mean (LSM) per Eimeria species is shown in Table 3.
The nicarbazin/narasin combination product did not deliver a significant reduction of E. acervulina, whereas Monimax® resulted in a significant reduction for all species (E. acervulina, E. maxima and E. tenella) compared to the IUC. Monimax® inclusion resulted in significantly lower lesions both for E. acervulina and E. maxima compared to nicarbazin/narasin.
Control of E. acervulina is very important as prevalence data, collected using Aviapp® demonstrates that E. acervulina is the most frequently diagnosed Eimeria spp. when monitoring broilers in Europe, followed by E. maxima and E. tenella. When plotting out lesion scoring data from more than 4,000 flocks over a 3-year period by age of the birds, E. acervulina is the main driver of the total mean lesion score (Figure 3).
Monimax® is a new anticoccidial product registered for use in Europe. The combination of nicarbazin and monensin results in a product with proven efficacy due to the synergistic effect of the two active compounds.
Monimax® has proven to significantly improve zootechnical and parasitological parameters in an extensive study including data from 27 standardized sensitivity trials. The birds that received Monimax® showed improvements in comparison to birds receiving the nicarbazin/narasin combination product due to significantly better control of E. acervulina and E. maxima. From a practical point of view, this is especially important as E. acervulina is the most prevalent Eimeria species in Europe.