Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2004
Publication Date: 7/1/2004
Citation: Marchant Forde, R., Marchant Forde, J.N. Gestation induced changes in behavior and autonomic regulation of cardiac activity in gilts. Journal of Animal Science. 82(1):277.
Technical Abstract: Gestation in mammals is a time of considerable physical, physiological and behavioral change necessary for the continuance of the pregnancy. Gestating pigs are often used in behavior and well-being studies yet there is little published data describing how gestation affects normal behaviour and patterns of autonomic regulatory control of cardiac activity. The objective of this work was to evaluate gestation induced modifications in the longitudinal dynamics of behavior and autonomic regulation of cardiac activity using heart rate variability parameters in primiparous pigs. The behavior and cardiac activity of ten gilts were recorded at fixed time points over gestation as follows: 1 week before oestrus and mating (week -1, +2 weeks, +4 weeks, +6 weeks, +9 weeks, +11 weeks, +13 weeks and +15 weeks of pregnancy. Temporal changes in behavior patterns were present in all gilts over the course of gestation. Pre-test levels of general activity progressively declined between weeks -1 and 15 as indicated by a decrease in the proportion of observations spent rooting (p<0.001), walking (p<0.001) and standing (p<0.001). There was a corresponding decrease in activity (p<0.001) and the proportion of time spent sleeping, as opposed to lying alert, increased also (p<0.001). Apart from RR-min (Minimum RR Interval) and its corresponding HR-maximum (Maximum HR Interval) indices, all time domain parameters of cardiac activity were substantially influenced by stage of gestation. Specifically, mean HR increased (p<0.001) whereas RMSSD (Root Mean Square of the Successive Differences) and SD (Standard Deviation) decreased (p<0.001). Pregnancy further impacted frequency domain measures of heart rate variability. From week -1 to week 15 the absolute magnitude of Total power (p<0.001) decreased, HF (High Frequency) power decreased, (p<0.001) and LF (Low Frequency) power increased (p=0.004). In conclusion, pregnancy induced widespread changes in behavior and in sympathovagal regulation of cardiac activity in pigs that were reflected in both time and frequency domain indices of heart rate variability analysis.