An economic assessment of alternative antimicrobial use scenarios on pig farms

This paper explores the theoretical economic outcome of management changes that result in different levels of antimicrobial use (AMU) in two types of UK pig farm. A static farm economic pig production model (FEPM) was used on a representative ‘Top-third’ most profitable farm and a representative ‘Mid-range’ profitable farm. Three AMU theoretical management scenarios were investigated; (a) management changes leading to a reduction of AMU by 35% (AMU35); (b) more extensive management changes leading to a reduction of AMU by 95% (AMU95); and (c) implementing depopulation of the herd (AMU Depop). A sensitivity analysis was conducted to determine the effect of increases or decreases in pig revenue and feed price on farm gross margin under these scenarios. Over a single year, the AMU35 scenario was estimated to have a small positive impact (+3%) on both farm types. The other two AMU reduction scenarios had higher AMU reduction on farms but required higher variable cost and hence they resulted in lower farm profitability. There was a substantial reduction (up to −50%) in farm gross margin under these two AMU reduction scenarios in the modeled short-term time-period. The impact of the alternative AMU scenarios was slightly higher on a farm representing the ‘Top-third’ farm type, reducing farm gross margin further by 7% compared to the ‘Mid-range’ farm. Nevertheless, both farm types stay profitable under all three AMU scenarios. The results showed that in the modeled short-term implementing management changes that result in a reduction of on-farm AMU by 35% had a good economic outcome. In practice, the other two scenarios would be considered as longer-term strategies. Although both require higher initial costs to implement, the improved biosecurity and hygiene will benefit from lower disease occurrence for a longer term. Farm gross margins were, however, found to be highly sensitive to changes on market prices especially increasing feed prices. An increase of more than 15% in feed price moved a profitable farm into a loss-making farm. It will be economically challenging for uptakes of these, or similar, AMU reduction scenarios on farms if the market prices become un-favorable to pig farmers

Exposure to environmental stressors result in increased viral load and further reduction of production parameters in pigs experimentally infected with PCV2b

Porcine circovirus type 2 (PCV2) has been identified as the essential, but not sole, underlying infectious component for PCV-associated diseases (PCVAD). Several co-factors have been suggested to convert an infection with PCV2 into the clinical signs of PCVAD, including co-infection with a secondary pathogen and the genetic background of the pig. In the present study, we investigated the role of environmental stressors in the form of changes in environmental temperature and increased stocking-density on viral load in serum and tissue, average daily weight gain (ADG) and food conversion rate (FCR) of pigs experimentally infected with a defined PCV2b strain over an eight week period. These stressors were identified recently as risk factors leading to the occurrence of severe PCVAD on a farm level. In the current study, PCV2-free pigs were housed in separate, environmentally controlled rooms, and the experiment was performed in a 2 × 2 factorial design. In general, PCV2b infection reduced ADG and increased FCR, and these were further impacted on by the environmental stressors. Furthermore, all stressors led to an increased viral load in serum and tissue as assessed by qPCR, although levels did not reach statistical significance. Our data suggest that there is no need for an additional pathogen to develop PCVAD in conventional status pigs, and growth retardation and clinical signs can be induced in PCV2 infected pigs that are exposed to environmental stressors alone