Individual behavioral and physiological strategies in pigs.
Previous experiments demonstrated consistent individual behavioral differences in pigs. Some showed a more active behavioral response (so-called A/R pigs), others a more passive behavioral response (so-called NA/NR pigs). In the present study we selected 32 A/R and 32 NA/NR individuals and tested them individually in an open field at 3 (OF1) and 8 weeks of age (OF2). Individual response patterns were remarkably consistent between OF1 and OF2. While more A/R than NA/NR pigs made escape attempts, the A/R ones vocalized less, and were less inhibited to approach novel objects in OF1 and OF2, although they spent less time in exploring these objects than NA/NR pigs. Cortisol (CS) level after OF1 increased in A/R pigs but did not change in NA/NR ones, while CS level in OF2 remained constant in A/R pigs but decreased in NA/NR pigs. CS response to ACTH1-39 was measured at 3 and 8 weeks of age but did not differ between types. Basal CS level was higher in NA/NR than in A/R pigs and accompanied by adrenal hypertrophy. Mean heart rate (HR) was higher of A/R pigs compared to NA/NR ones in two backtests. HR of A/R pigs substantially increased (23.9 bpm = 15.5%) in reaction to the novel object in OF2, while HR of NA/NR ones only slightly increased (4.5 bpm = 2.9%), or even decreased (bradycardia). A/R pigs had more often heart deviations than NA/NR ones. The present study demonstrates that the two behavioral strategies of pigs are characterized by consistent differences in behavioral, physiological, and endocrine responses to conflict situations.
Hessing
M J
MJ
Department of Animal Husbandry, Agricultural University Wageningen, The Netherlands.
Hagelsø
A M
AM
Schouten
W G
WG
Wiepkema
P R
PR
van Beek
J A
JA
D000223:Adaptation, Psychological / Q000502:physiology*; D000311:Adrenal Glands / Q000473:pathology; D000324:Adrenocorticotropic Hormone / Q000502:physiology; D000374:Aggression / Q000502:physiology; D000818:Animals; D001143:Arousal / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006854:Hydrocortisone / Q000097:blood; D007206:Individuality; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009206:Myocardium / Q000473:pathology; D009929:Organ Size / Q000502:physiology; D010275:Parasympathetic Nervous System / Q000502:physiology; D012931:Social Environment; D013315:Stress, Psychological / Q000150:complications; D013552:Swine; D013564:Sympathetic Nervous System / Q000502:physiology
D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone