Optimizing strategies to manage coccidiosis in poultry

Anticoccidial drugs have been used for decades, but new regulations, consumer preferences and resistance concerns are changing coccidiosis management. Rotation, shuttle, and bio-shuttle coccidiosis programs have become more widely used. A strategic and comprehensive approach can help achieve optimal coccidiosis management.

Shelby Ramirez
Global Poultry Technical Manager

The estimated cost of coccidiosis globally is between USD 9.2 and 15.6 billion, or approximately USD 0.2 per chicken (Blake et al., 2020). This estimate is derived not only from the cost of prophylactics and therapeutics, but also the associated performance and mortality loss. Additional losses due to secondary challenges associated with coccidiosis may also increase the overall economic impact. Many protozoa plague the livestock industry but, in poultry, there are seven Eimeria species of the protozoal parasite coccidia that infect different regions in the intestinal tract (Shirley et al., 1986). Regardless of the site of infection, Eimeria have a complex life cycle that includes stages within the bird and environment. Depending on the Eimeria species, site of infection and life cycle stage, certain prevention strategies may be more effective than others (Chapman and Rathinam, 2022).

For more than 50 years, synthetic chemicals, ionophores and the combination of the two have been available for coccidiosis control; however, no new anticoccidial drugs have been developed for many years (Novak et al., 2019). This makes optimizing the currently available coccidiosis strategies even more critical. Not all synthetic chemicals have known modes of action but, in general, chemicals disrupt Eimeria by altering their metabolism during their intracellular life cycle stages, and ionophores disrupt Eimeria by altering osmotic balance during their extracellular life cycle stages (Chapman and Rathinam, 2022). These two anticoccidial drugs have often been used in combination because of their complimentary modes of action and the additional coverage ionophores have on Gram-positive bacteria. This is advantageous because coccidiosis can predispose birds to clostridial enteritis resulting in high mortality rates and production losses. Thus, using chemicals with ionophores or ionophores alone can provide coverage for both coccidiosis and clostridial enteritis. Although combinations of chemicals and ionophores have been used successfully for several decades to combat coccidiosis, development of resistance has been reported (Glorieux et al., 2022).

Chemical anticoccidials tend to induce resistance more rapidly compared with ionophores because of their mode of action during the intracellular life cycle of Eimeria. However, this resistance may be masked while using chemical and ionophore blends as Eimeria that are resistant to chemical may still have susceptibility to the ionophore making the overall prophylactic use effective. However, the challenge with ionophores is that they have a very narrow range for safety, can contribute to reduced performance and may impact heat tolerance. Many producers have implemented programs that rotate anticoccidials between flocks (rotation programs) or use different anticoccidials in starter, grower and finisher rations (shuttle programs) to maintain or improve Eimeria drug sensitivity.

Figure 1. Rotation, shuttle, and bio-shuttle program examples used in commercial production*
*Figure highlights an example of programs, descriptors used may vary by country and product category regulation.

Another strategy to improve drug sensitivity has been to switch from anticoccidial drugs to using a coccidia vaccine. Coccidia vaccines are based on specific Eimeria species and induce immunity three to four weeks after vaccination (Tewari and Maharana, 2011). Introducing non-resistant Eimeria via vaccination can repopulate the environment to restore drug sensitivity. However, the effectiveness of this strategy to restore environmental Eimeria drug sensitivity may be impacted by litter management strategies (i.e., raising birds on fresh litter for each cycle or using re-used litter for several cycles). One challenge with coccidia vaccines is that they tend to impact performance during the time the birds are acquiring immunity. This associated performance loss is more challenging to overcome when birds are marketed at a younger age compared to those marketed at an older age because there is limited time to regain that lost performance. Recovering performance loss associated with vaccination is one area in which feed additives can be used as part of a coccidiosis management strategy.

Feed additives such as probiotics, prebiotics and phytogenics have become part of many coccidiosis management strategies because of their compliance with programs like no antibiotics ever or antibiotic-free and for their unique modes of action that compliment different rotation and shuttle programs. For example, Eimeria disrupt the intestine and nutrients are leaked into the lumen; live probiotics can help overcome this by improving intestinal integrity whereas microbial metabolic modulators can redirect those leaked nutrients towards beneficial microbial metabolism. If resistance is becoming a concern or you are seeking an alternative, using phytogenic-saponin blends may be a way to give a break to stronger chemicals which could keep those anticoccidials effective long-term. Incorporating feed additives into rotation, shuttle or bio-shuttle programs can help keep current anticoccidial drugs effective while keeping performance at the expected level when other strategies are implemented.

*Not all products and services are available in every region
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About Shelby Ramirez
Shelby Ramirez is the Global Poultry Technical Manager at DSM Animal Nutrition & Health. She holds a PhD (Iowa State University) and MS (University of Illinois) in nutritional physiology and applied nutrition, respectively. She continued in research as postdoctoral research at USDA and research manager at Biomin before her current role where she enjoys communicating science into application.