Interpretive Summary: Characterizing the effect of incrementally increasing dry bulb temperature on linear and nonlinear measures of heart rate variability in nonpregnant, mid-gestation, and late-gestation sows

By: Christopher J. Byrd, Betty R. McConn, Brianna N. Gaskill, Allan P. Schinckel, Angela R. Green-Miller, Donald C. Lay Jr., and Jay S. Johnson

Pregnant pigs may be at a higher risk of poor physiological outcomes due to heat exposure compared to mature female pigs that are not pregnant. The purpose of this study was to evaluate the stress response of pregnant pigs to increasing environmental temperatures using heart rate variability, a noninvasive measure commonly used to evaluate the physiological stress response. Our findings show that pregnant pigs, particularly those who are closer to giving birth, exhibit greater evidence of physiological stress compared to pigs who are not pregnant. However, we did not find evidence that increasing environmental temperature throughout the experimental period was a primary reason for the increased stress exhibited by pregnant pigs. It is possible that the physiological changes that normally occur during pregnancy may have masked the physiological stress response typically associated with increased heat exposure. 

Th original article can be found in the Journal of Animal Science.