Periparturient stress can have long-term negative effects on both dairy cows and their calves and may contribute to lower productivity. The purpose of this study was to determine how periparturient stress is related to differences in calving difficulty and health status by measuring hair cortisol concentration in periparturient dairy cows and their calves. Calving environment (calving pen, tie stall, and group paddock), calving difficulty, calving progress, health status, and calf weight were recorded, and tail hair from 25 of the cows and their calves was collected at calving and 1 month after calving to measure hair cortisol concentration. There were no significant correlations between hair cortisol concentration and calving environment, calving difficulty, calf weight gain rate. Hair cortisol concentrations at calving were significantly higher in cows with oversized calves or twin births than in cows with normal-sized singleton calves (4.2 ± 2.2 pg/mg vs. 2.1 ± 1.5 pg/mg, P<0.05). cows with clinical disease within one month of calving had significantly higher levels of hair cortisol one month after calving compared to healthy cows (3.8 ± 1.1 pg/mg vs. 2.3 ± 1.9 pg/mg, P<0.05). calves with clinical disease within the first month after birth tended to have higher hair cortisol levels at birth than healthy calves (4.7 ± 2.4 pg/mg vs. 3.2 ± 0.9 pg/mg, P<0.1). These results suggest that calving of oversized calves and twin births and suffering clinical diseases can cause more stress for cows during the periparturient period.
