The impressive feed efficiency of poultry is key to its sustainability – not to mention its affordability, both of which make it an important part of feeding a growing world. Coccidiosis, an extremely common disease caused by a widely distributed and very robust parasite, threatens that. Harming the intestinal integrity of the birds reduces their ability to efficiently convert feed into performance, and also makes them more susceptible to diseases which require antibiotics to treat, running counter to the industry’s ambition to reduce the use of antibiotics in feed.
In today’s Industry Perspectives piece, Dr. Daniel Parker, Emeritus Director Slate Hall Veterinary Practice and Independent Veterinary Consultant joins Elanco’s George Gould, Global Poultry Technical Advisor, to discuss the potential impacts that a move away from one of the most important tools for controlling coccidiosis – ionophores – would have on the economic and environmental impacts of poultry production.
[Feedinfo] Can you start us off by talking about the costs of both coccidiosis and associated bacterial enteritis on poultry production?
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George Gould |
[George Gould] It is widely recognised that coccidiosis represents one of the greatest threats to broiler production in terms of both bird health, as well as feed efficiency and performance aspects. The reasons for this are firstly because coccidia are a highly successful parasite of chickens and as such are ubiquitous – in short, wherever we are growing chickens in the world, we will face some burden and challenge of coccidia. The damage and cost related to these parasites are partly a direct impact of coccidia infection, because every parasite completing its life cycle will destroy intestinal epithelial cells lining the gut of the chicken – the cells directly responsible for absorption of nutrients from the feed. |
Additionally, the presence of coccidia, or more specifically the damage and immune response to it, act as a trigger and create conditions where bacterial enteritis is more likely. Therefore, in flocks where coccidiosis is poorly managed, it would not be uncommon to see some degree of bacterial enteritis as well. When considered together, the impact of coccidiosis and bacterial enteritis can be very significant for a broiler producer.
The impact of coccidiosis has long been studied, and in 1999 a paper by Williams estimated the cost to broiler producers to be in excess of £38 million annually in 1999. More recently an analysis published by Blake used an updated model to demonstrate the impact in the UK alone now stands at £99.2M, and globally, coccidiosis may cost around £10 Billion or equivalent to £0.16 per chicken.
[Feedinfo] What role does the intestinal damage caused by coccidiosis play in this story? What impacts are coccidia-induced intestinal lesions having on feed conversion, growth, susceptibility to bacterial infections, etc.?
[George Gould] As mentioned earlier, all of the coccidia species we are concerned with in broilers invade and then replicate within host intestinal epithelial cells which are lining the gut. In completing their life cycles the infected cells, and often those around them, will be destroyed. This destruction of the intestinal epithelium has direct consequences on feed efficiency since the intestinal epithelium is responsible for absorption of nutrients from the feed. In severe infections, we see clinical signs of the disease as well as performance impacts, but even in subclinical cases we would expect to see a reduction in feed efficiency and reduced weight gain. Additionally, damage from coccidiosis results in inflammation and an immune response from the bird. This makes the birds far more susceptible to secondary bacterial infections; indeed, the mucogenesis upregulation in response to Eimeria infection provides conditions suitable for Clostridium perfringens replication, increasing the risk of necrotic enteritis – a severe disease causing acute depression and sudden mortality.
[Feedinfo] The ADAS study looked at the additional interventions that would be required (and the associated costs incurred) if ionophores were removed from UK production, with an optimistic scenario and two pessimistic scenarios. How big a change in the cost of production should be expected if the industry moves away from ionophore use? What are the biggest factors accounting for that increase (e.g. greater use of medication, increase in feed conversion ratios, etc.)?
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[Daniel Parker] In the ADAS study the models were developed based on expected impacts of ionophore removal from broiler diets based on a comprehensive literature review and expert opinion from specialist poultry nutritionist and veterinary surgeons. The models concluded that production costs would increase by 5.7% in the main model. ADAS modelers then applied an optimistic scenario where they considered the impacts would be less than expected and a pessimistic scenario where they considered the impacts would be more than expected. The model showed that in an optimistic scenario, production costs would increase by 3.7% but in the pessimistic scenario the costs would increase by a massive 10.7%. |
Daniel Parker |
Whilst several factors had some influence, the major factors impacting this increase in cost was the decreased feed efficiency of the broilers when ionophores were removed from the diets, a consequence of the decreased intestinal integrity in these birds.
[Feedinfo] Have such consequences been seen in production schemes which don’t use ionophores, such as RWA in the US?
[Daniel Parker] Extensive data on broiler production costs in the USA are available, and these have shown increased production costs associated with RWA programs. Meanwhile, veterinarians servicing the USA broiler sector have reported impacts on intestinal integrity, and especially the issue of necrotic enteritis in American broiler production on RWA programmes. So yes, we also see production cost increases in other countries where ionophores have been removed from broiler diets.
[Feedinfo} How would a no-ionophore production programme impact the greenhouse gas emissions per bird? Can that impact be quantified?
[Daniel Parker] As part of the study, ADAS undertook analysis using a simplified greenhouse gas (GHG) emission assessment, based on three key GHGs associated with chicken production: carbon dioxide, methane and nitrous oxide. The main sources of emissions assessed were those from energy consumption in the house, the manure produced by the birds and the embedded emissions in the feed. The methodology used for this analysis was in line with PAS 2050 (BSI 2011) and utilised IPCC methodologies and emission factors, where appropriate. The model concluded that Green House gas emissions would increase by 3.9% as a result of ionophores being withdrawn from diets. The majority of this increase was related to GHGs embedded in feed production - a result of the decreased feed efficiency.
[Feedinfo] Coccidiosis also has other impacts, including the increased risk of processing damage and the higher co-occurrence with bacterial pathogens such as Campylobacter or Salmonella. Can you talk about any other economic, environmental, or human health burdens that might increase if ionophores were removed from the industry’s coccidiosis-control toolbox?
[George Gould] We are increasingly focused on sustainability in food production and the broiler sector is no exception. Sustainability has many different aspects, and the control of coccidiosis is critical to a number of different facets of this. Broiler production with suboptimal coccidiosis control would likely result in increases in coccidiosis cycling and the inevitable consequences of this. In this sense, the role of ionophore anticoccidials in the industry’s toolbox is critical. Firstly, we know that even subclinical coccidiosis has significant impacts on the production costs related to loss of feed efficiency and decreased weight gain, but also impacts the environment through increased raw materials required, increased water intake as well as greater land usage required to grow the feed ingredients, not to mention more energy usage per broiler during longer growouts.
Another aspect of sustainability that would be affected is the health and welfare of the birds. It is logical to say that the intestinal inflammation associated with coccidiosis inherently has an impact on welfare, and in flocks with severe enteritis the mortality increase is another concern. In compromised intestinal health we also very often see the litter conditions worsen, which has consequences on the bird health, with pododermatitis and breast blisters a risk from poor litter conditions.
Finally, reducing our ability to manage coccidiosis effectively can also pose a risk in terms of human health. Coccidial infections have been shown in several papers to increase the intestinal colonization of Campylobacter jejuni as well as enhancing Salmonella infections in chickens [citations available upon request]. The damage from coccidiosis can also cause the intestinal wall to become more fragile and therefore more prone to rupture during processing. This results in a greater risk of intestinal contents contaminating the processed carcass, increasing the risk of bacterial contamination.
Produced in association with Elanco
