Physiological effects of repeated transport in pregnant goats and their offspring

Although pregnant farm animals can encounter different stressors on numerous occasions, studies on the physiological effects of repeated stress during gestation on females and their offspring are quite recent and still scarce. The present experiment was performed to study the effects of repeated transportations on some physiological parameters in pregnant goats and to determine whether repeated exposure to prenatal stress resulted in alterations in the hypothalamic-pituitary-adrenocortical (HPA) axis and the sympatho-adrenomedullary (SAM) system of their offspring. Twenty-six goats were assigned to one of two treatments during the last five weeks of gestation: 9 series of 55 min of transport (n = 13) or no transport (n = 13). During transport, the goats were physically and visually isolated from their congeners. Transport in isolation induced a large increase in plasma concentrations of cortisol, glucose and non-esterified fatty acids, which confirms that it is a very stressful situation for goats. Moreover, the goats did not become accustomed to the stressor. Gestation length, birth weight, litter weight and growth of the kids were not modified by treatment. Cortisol concentrations tended to be higher in prenatally stressed kids than in control kids 1 h after birth ( P < 0.10) and the opposite was observed at 48 h of age ( P < 0.10). Indeed, the decrease in cortisol concentrations between 1 and 48 h was greater in prenatally stressed kids than in control kids ( time x treatment interaction, P < 0.01). The effect of prenatal stress on the HPA axis did not persist, since in older kids cortisol concentrations were not modified by treatment. At one month of age, prenatally stressed kids showed a higher medulla weight ( P < 0.05) and tended to show a higher phenylethanolamine N-methyl transferase activity ( P < 0.10) than control kids. Therefore, repeated transport in isolation is an important stressor in pregnant goats and can affect the HPA axis and the SAM system of their offspring.