Prenatal transportation stress alters temperament and serum cortisol concentrations in suckling Brahman calves.
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abstract
This experiment examined the relationship between prenatal stress and subsequent calf temperament through weaning. The prenatal stressor used was repeated transportation of pregnant Brahman cows for 2 h at 60 5, 80 5, 100 5, 120 5, and 140 5 d of gestation. Prenatally stressed calves ( = 41) were compared with controls ( = 44; dams did not undergo transportation during pregnancy) from 2 wk of age until weaning (average age at weaning = 174.8 1.3 d). Temperament was defined by pen score (PS; 1 = calm and 5 = excitable), exit velocity (EV; m/sec), and temperament score (TS; (PS + EV)/2) and was recorded for each calf on d -168, -140, -112, -84, -56, -28, and 0 relative to weaning (d 0 = weaning). Cortisol concentrations were determined in serum samples obtained on d -168, -140, -28, and 0 relative to weaning. Birth weight and weaning weight were not different between treatment groups ( > 0.1). Pen score was greater ( = 0.03) in prenatally stressed calves (2.84 0.21) relative to controls (2.31 0.21). Exit velocity was greater ( < 0.01) in prenatally stressed calves (2.1 0.14 m/sec) than in controls (1.61 0.14 m/sec). Exit velocity was affected by a treatment calf sex interaction ( = 0.04) and was greater in prenatally stressed females. Exit velocity was also affected by day ( < 0.0001). Temperament score was greater ( = 0.01) in prenatally stressed calves (2.45 0.16) than in controls (1.95 0.16). Temperament score was affected by day ( < 0.01). Basal cortisol concentrations were greater ( = 0.04) in prenatally stressed calves (15.87 1.04 ng/mL) than in controls (13.42 1.03 ng/mL). Basal cortisol concentrations were greater ( < 0.01) in females (16.61 1.06 ng/mL) than in males (12.68 1.02 ng/mL). Cortisol concentrations were positively correlated ( < 0.01) with PS ( = 0.55, < 0.01), EV ( = 0.4, < 0.01), and TS ( = 0.55, < 0.01). Overall, suckling Brahman calves that were prenatally stressed were more temperamental and had greater circulating serum concentrations of cortisol than control calves.
