Farm-economic analysis of reducing antimicrobial use whilst adopting good management strategies on farrow-to-finish pig farms

Pig farming employs high amounts of antimicrobials (Dunlop et al., 1998; Callens et al., 2012; European Medicines Agency, 2013; MARAN, 2014; Rushton et al., 2014). A significant fraction of those are also administered in human medicine (Laxminarayan et al., 2013). Their extensive use in pig husbandry, as suggested by relevant studies, is linked to the selection and spread of resistant bacteria, which may be transferred interspecies through direct or indirect contact (Schwarz et al., 2001; Aarestrup, 2005; Chantziaras et al., 2014).
According to the most recent ESVAC report (European Medicines Agency, 2014), in 2012 Belgium was ranked 6th, out of 25 countries in the EU, in terms of the volume of sales of antimicrobials for food producing animals, the majority in pig production (Filippitzi et al., 2014). Unfortunately, more recent reports of antimicrobial surveillance in Belgium have shown that after a declining trend of the antimicrobial usage in food production animals, the consumption of such agents has increased by 1.3% in 2014 with respect to 2013 (BelVet-SAC, 2011, 2012, 2013, 2014). This is despite the efforts of the Center of Expertise on Antimicrobial Consumption and Resistance in Animals (AMCRA), whose guidelines are encouraged to be used by Belgian veterinarians to aid their judicious prescription of antimicrobial agents. These guidelines state, amongst others, that antibiotics cannot be used as substitutes for good hygiene, housing and appropriate feed. However, standard prophylactic antimicrobial treatments are often considered by farmers as an easier, cheaper and less labor-intensive way to prevent bad health conditions and to avoid repercussions on the productivity and, indirectly, on the farm-financial situation, compared to therapeutic treatments (Callens et al., 2012), or investments in infrastructure or disinfection on the farm (Filippitzi et al., 2014).
The relation between the use of antimicrobials and higher productivity is described in literature since the early 50’s. However, it was already acknowledged that the farming conditions were inversely related to the productivity response to antimicrobials (Coates et al., 1951; Hill et al., 1953). Recent studies post 2000 demonstrate that the effect of antibiotics on productivity were lower than those from the early trials. Current production conditions in Europe, and most of the developed countries, have substantially improved in the last decades, consequently it is questionable whether the effect of antimicrobials on productivity will remain high (Rushton et al., 2015).
The adoption of general herd management strategies (e.g. biosecurity practices or specific vaccinations) can be noted as a more sustainable alternative to prophylactic antimicrobials (Postma et al., 2015). Moreover, higher levels of biosecurity are associated with improved average daily weight gain, feed conversion ratio and a decreased consumption of antibiotics (Laanen et al., 2013). As such, financial concerns seem to become a dominant factor for considering the adoption of biosecurity strategies (Visschers et al., 2015). On the one hand, veterinarians feel the need to give information about the economic impact of advised interventions (Gunn et al., 2008) while on the other hand, farmers have shown an inverse relationship between the willingness to adopt biosecurity practices and their estimated costs (Fraser et al., 2010). Farmers have shown interest in knowing the costs of biosecurity measures, as well as its benefits entailed (Laanen et al., 2014), but the lack of such insight still represents a limit, while such detailed information could foster awareness. To date, few studies have evaluated the economics of biosecurity compared to antibiotics. Two studies estimated the direct costs associated to the use of preventive strategies (Siekkinen et al., 2012; Miller and Dorn, 1990). Two cross-sectional studies, which also accounted for the indirect economic impact due to changes in technical parameters, found that farrow-to-finish pig farms who exhibited a higher biosecurity and health status were correlated with improved technical parameters and a higher economic margin (Corrégé et al., 2011; 2012) than the farms with lowest biosecurity status. The methodological weakness of these studies are the lack of a control group and their cross sectional nature, which may have caused an overestimation of the effect. This could be controlled with a longitudinal study.
This study aims to use a quasi-experimental longitudinal approach for assessing economic impacts of antimicrobial substitution for good management practices, in particular biosecurity strategies.