Study finds decreasing morbidity on calf rearing farms can lower antibiotic usage

As food production animals continue to receive antibiotics, concern over antibiotic-resistant bacteria grows. Antimicrobial resistance is a global health threat that occurs when microbes evolve to protect themselves from drugs designed to kill them. This process happens naturally and can affect anyone, but antibiotic overuse in both humans and animals accelerates the process.

Reports of livestock-associated antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus) causing human infections continue to emerge. New methods to reduce antibiotic consumption are needed because of the known association between antibiotic use in cattle herds and the presence of antibiotic resistance

One way to reduce the use of antibiotics in food production without affecting animal welfare is to decrease morbidity in beef herds. Investigators from Finland performed a retrospective observational study on calf rearing farms to identify factors that help lower overall morbidity and antibiotic usage. These researchers also sought to determine the overall treatment incidence of calves.

Calf rearing farms care for calves until they are slaughtered for beef production. Commonly, calves are less than a month old when they are transported to a calf rearing farm. Group housing and calves arriving from various origin farms facilitate the spread of infectious disease. The stress of transportation and comingling of calves also weakens immunological responses.

Calves that arrived at an older age were associated with decreased morbidity and a lower treatment incidence. In contrast, greater age variation between calves as well as larger batches of calves were factors associated with increased morbidity and an increased treatment incidence. Greater age variation can increase morbidity through uneven competition between the older and younger calves. Additionally, older calves can carry infection to the younger, more immunologically susceptible calves.

Results from the study also showed that calves reared on farms with fewer caretakers in relation to the number of calves were more likely to be medicated. Fewer caretakers could mean that time is too limited to provide substantial attention to disease prevention.

Farms that didn’t use temperature to measure sickness in calves also were less likely to give medications recurrently. A likely explanation could be that the number of sick calves were underestimated. Farms with mechanical ventilation were associated with an increased treatment incidence compared to farms with natural ventilation. Mechanical ventilation can possibly cause barn drafts; that may explain why calves from this type of barn had more observable nasal discharge than calves from farms with natural ventilation.

Investigators concluded that decreasing morbidity on calf rearing farms can increase profitability, improve animal welfare, and reduce antibiotic usage. This study identified factors associated with high morbidity and treatment incidence for the purpose of lowering antibiotic usage without compromising animal welfare. Additional research is necessary to determine more factors associated with high morbidity and treatment incidence, and also find causal relationships.

Isabella L. Bean is a 2022 PharmD Candidate at the University of Connecticut in Storrs.

Reference

Sandelin A, Hälli O, Härtel H, et al. Effect of Farm Management Practices on Morbidity and Antibiotic Usage on Calf Rearing Farms. Antibiotics (Basel). 2022;11(2):270. Published February 18, 2022. doi:10.3390/antibiotics11020270