Results of an extensive literature survey
Diseases in poultry flocks can lead to substantial economic losses through reduced revenues, for example, from reduced volume or quality of meat or eggs produced, and increased costs of inputs such as feed and labour. However, although this fact is understood, there is little consensus about the level of the economic losses resulting from individual production diseases. In addition, while the costs of prevention measures and treatments may be known, the economic savings they make are often not well understood. Consequently, large numbers of poultry producers may not be implementing economically optimal disease prevention and treatment measures. This problem is likely to become more acute as pressure to reduce the use of antimicrobials in the treatment of poultry diseases increases.
Survey of recent studies
To explore the full economic impacts of poultry production diseases the PROHEALTH project carried out an extensive survey of recent studies, collecting information on the costs of uncontrolled disease, and the benefits resulting from various prevention or treatment measures. Data for a number of production diseases were available from studies relevant for modern, commercial poultry production. The studies varied considerably in terms of scale, from a few birds in a single pen, to tens of thousands of birds across multiple farms. Here we report estimated costs for seven different poultry diseases.
The cost of poultry diseases
The economic risks from production diseases are related to the level of incidence and severity. The incidence of the production diseases recoded in the studies reviewed is shown in Figure 1. Here, incidence is based on the percentage of birds in flocks that have a sufficiently severe form of a disease to have negative economic impacts. The most prevalent diseases in reviewed studies were enteric diseases, i.e. coccidiosis and clostridiosis. While clinical forms of diseases obviously have more severe symptoms, including mortality, sub-clinical forms can also lead to substantial economic losses, for example, in the form of impaired feed conversion ratio, leading to higher feed requirements for growth in broilers and egg output in laying hens.
The costs of production diseases vary with the disease causing the infection and the severity of each disease. For each of the reviewed diseases, costs were assessed for broilers (Figure 2) and laying hens (Figure 3). Economic losses per bird in laying hens appear larger than for broilers, because the disease is impacting over a far longer production period in laying hens than in broilers. Total economic losses from uncontrolled keel bone damage average around €4 over the life of a laying hen, while losses from uncontrolled Infectious bronchitis reach €3.2 per laying hen. Losses on this scale would, in most years, make the affected flock unprofitable. Among the reviewed diseases affecting broiler flocks, uncontrolled clostridiosis incurred the greatest losses at around €1 per broiler bird (slaughtered at 2kg liveweight), while losses from uncontrolled coccidiosis amounted to €0.21 per broiler.
Figures 2 and 3 also reveal that some disease losses can be reduced by prevention or treatment measures. For example, interventions for Salpingoperitonitis, ascites and clostridiosis can go a long way to reducing losses. However, in the cases of coccidiosis and keel bone damage, studied interventions were much less effective.
The results highlight the fact that farms suffering from production diseases can make substantially less profit than disease-free farms. However, these losses can often be reduced by a range of interventions, such as vaccinations, better litter management, or improved nutrition and hygiene. The economic benefit of interventions to control production diseases varies greatly according to disease and the particular intervention chosen. As some of these interventions have been observed to reduce disease incidence or severity of multiple diseases, the next step in the PROHEALTH project is therefore a broader investigation into the most useful interventions for reducing disease-related economic losses in poultry farming, especially where these interventions have the potential to reduce the use of antimicrobials.