Effect on Gilt Behavior and Postures when Selected for Residual Feed Intake Selection in Response to a Lipopolysaccharide Challenge

and Implications The objective of this study was to determine low and high-RFI gilt sickness behavior when challenged with lipopolysaccharide (LPS). This work was conducted with seven low residual feed intake gilts (RFI) and eight high RFI gilts (63±4 kg BW) from the 8th generation of the ISU Yorkshire RFI selection lines. Gilts were challenged intramuscularly with 30 µg/kg BW Escherichia coli O5:B55 LPS at 1000±1 hour. Gilts were video recorded one day before the LPS challenge (baseline) and on the treatment day (LPS challenge). Video was analyzed for lying, sitting, standing, eating and drinking using a 1-minute scan sample at two time points on the baseline and treatment days; 1) 1000 to 1200 hour and 2) 1700 to 1800 hour. There were no line by treatment interactions for behaviors and postures in response to the LPS challenge (P ≥ 0.32). There were no RFI selection line differences in behavioral and postural responses to the LPS challenge (P ≥ 0.45). Regardless of the RFI selection line, after the LPS challenge gilts laid more (P < 0.0001) and stood less (P < 0.0001). However, there were no differences observed in the percent of time engaged in sitting, eating and drinking (P ≥ 0.16). Regardless of the RFI selection line, gilts laid more (P = 0.0004) and stood and ate less (P < 0.0001) during the first (AM) compared to the second time point (PM). In conclusion, gilts from both RFI selection lines similarly expressed classical sickness behaviors and postures when challenged with LPS. Introduction Feed has been estimated to cost 50 to 85% of operating costs. Additionally, competition between animal agriculture, human food, and biofuel industries has resulted in an increased demand for grain. Consequently, grain prices and swine production cost have increased. By decreasing the amount of feed needed per pig for the same rate of growth, we can ultimately lower swine production costs. Residual