Figure 1

Weaning and maternal separation (WMS) increases mortality following a secondary bacterial respiratory infection. (A) Serum cortisol levels were measured prior to (Day 0) and for 4 days following BHV-1 infection. Data presented are median cortisol values for each group and WMS and pre-adapted calves (PA) were compared to non-transported (Control) calves. *p < 0.05. (B) Percent survival of WMS (n = 10) and PA (n = 10) calves following primary BHV-1 infection (Day 0) and secondary M. haemolytica infection (black arrow) four days later (Experiment #1). **p < 0.01. (C) Percent survival of PA (n = 20) calves following a primary BHV-1 infection (Day 0) and secondary M. haemolytica infection (black arrow) four days later. Percent survival of WMS calves following a primary BHV-1 infection (Day 0) and secondary M. haemolytica infection (black arrows) four days (n = 10) and 12 days (n = 10) later (Experiment #2). ***p < 0.001. (D) The percent lung damage correlated significantly (r² = 0.53, p < 0.01) with increased time to death following secondary bacterial challenge Values presented are for individual animals that died in both the WMS and PA groups.