Individual variation in the heart rate of piglets; evidence against stable differences

• Published in: Applied animal behaviour science Vol. 55; no. 3; pp. 269 - 278
• Main Authors: Webster, Stephen D., Jones, Alick R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1998
• Subjects: AGE; BEHAVIOUR; COMPORTAMIENTO; COMPORTEMENT; EDAD; FRECUENCIA CARDIACA; FREQUENCE CARDIAQUE; HANDLING; HEART RATE; Individual variation; LECHON; MANIPULACION; MANUTENTION; PESO; Pig-physiology; PIGLETS; POIDS; PORCELET; WEIGHT; Heart rate; Pig-physiology; Individual variation
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/S0168-1591(97)00052-X

Two hypotheses were tested, (a) that the heart rate of piglets would show consistent, ordinal differences between animals within data collection sessions and (b) that the heart rate of piglets would show consistent, ordinal differences between animals across data collection sessions, from birth to twenty-eight days of age. Heart rate was measured in 15 animals and was analysed with respect to the following variables; individual animal, behaviour (posture, locomotion, aggression and feeding), age, weight, ranked weight, experimental treatment and data collection session (from data collection session 1 at one day old to data collection session 5 at twenty eight days old). Within a general linear model all variables except ranked weight were found to be significantly related to heart rate ( p < 0.0001 in all cases). Residual heart rate values were found, on the first, second and fifth data collection sessions, to show consistent ordinal differences between animals within data collection sessions. That is, the residual heart rate of an animal in response to initial handling was correlated with that animal's baseline residual heart rate ( r = 0.80, 0.89, 0.89 on the first, second and fifth data collection sessions, respectively, p < 0.001 in all cases) and, on the first and fifth data collection sessions, with the residual heart rate in responses to subsequent handling ( r = 0.84, p < 0.001 and r = 0.71, p < 0.01, respectively). However, correlations of residual heart rate values across sequential data collection sessions were found not to be significant. That is, heart rate on data collection session n was not correlated with heart rate on data collection session n + 1. It is suggested that either the dynamic environment within which these animals existed precluded the observation of consistent, ordinal differences or that these types of differences do not exist in animals of this age.