Effects of broiler feed medications on Salmonella

Impact assessment of the reduction or removal of ionophores used for controlling coccidiosis in the UK broiler industry

Coccidiosis is a complex parasitic disease ubiquitous in all types of poultry production. It can have both a direct effect on bird health and welfare with significant negative impacts on the production parameters and indirect effect as it predisposes to other pathogens. Ionophore coccidiostats have been used safely for over 45 years by poultry producers. Concerns have been raised that their use in livestock production could promote the development of antibiotic resistance, but their unique mode of action makes it unlikely. Conversely their removal can result in increased use of therapeutic antibiotics to treat disease posing a greater risk of antibiotic resistance development. Economic and environmental models examining the impact of the removal of ionophore coccidiostats from UK production suggest the annual cost to the broiler sector would be between £68.02-£109.95 million and result in an additional 84,000 tonnes CO₂ e being produced per annum. Any cost increase would make this wholesome and affordable animal protein less affordable to poorer sectors of society. Increased greenhouse gas production, demand for water and land as a result of less efficient production will impact on climate change targets.

Raised without antibiotics: impact on animal welfare and implications for food policy

This study assesses the impact of broilers raised without antibiotics and the information gap that exists between consumer perception and production methods. Specifically looking at risk of eye burns, footpad lesions, and airsacculitis, key indicators of animal welfare, bird-level data are collected on the occurrence and severity of each disease state by the type of antibiotic program: no antibiotics ever, nonmedically important antibiotics, or medically important antibiotics. Odds ratios and marginal effects are calculated to understand how the occurrence and severity change with access to medicine. Broilers never given antibiotics had a higher likelihood of disease states investigated, and with greater severity. In some cases, access to nonmedically important ionophores mitigated the risk of occurrence and severity of the conditions. The finding indicates that the growing trend of raising broilers without antibiotics may negatively affect animal welfare. This stands in contrast to existing consumer research showing that consumers purchase poultry raised without antibiotics because they believe that it promotes healthier animals. Therefore, a significant consumer information gap exists which needs to be addressed. JEL Codes: Q130, Q160, Q180

The potential impact of coinfection on antimicrobial chemotherapy and drug resistance

Across a range of pathogens, resistance to chemotherapy is a growing problem in both public health and animal health. Despite the ubiquity of coinfection, and its potential effects on within-host biology, the role played by coinfecting pathogens on the evolution of resistance and efficacy of antimicrobial chemotherapy is rarely considered. In this review, we provide an overview of the mechanisms of interaction of coinfecting pathogens, ranging from immune modulation and resource modulation, to drug interactions. We discuss their potential implications for the evolution of resistance, providing evidence in the rare cases where it is available. Overall, our review indicates that the impact of coinfection has the potential to be considerable, suggesting that this should be taken into account when designing antimicrobial drug treatments.