Plasma glucocorticoid concentrations and blood gas values were determined for 6 days in 47 newborn calves that had been subjected to various obstetrical procedures at term. Concentrations of glucocorticoids were uniformly high at birth (70 to 103 ng/ml). Increasing degrees of acidosis were accompanied by increasing glucocorticoid concentrations in plasma. Plasma glucocorticoid concentrations decreased sharply during the first 6 hours after delivery and reached a plateau at 48 hours after birth (14 to 21 ng/ml). The latter was taken as an indication that adaptation had been achieved. Calves subjected to severe pulling had higher glucocorticoid concentrations at birth (110.4 ng/ml) than calves requiring no assistance (88.3 ng/ml), calves requiring only slight assistance (83.8 ng/ml), or calves that had been delivered by cesarean section (82.9 ng/ml).

The effect of in-house transport on plasma corticosterone concentration and blood lymphocyte populations of laboratory mice was investigated. Mice were transported within a research facility at 0900 hours in a pattern designed to simulate that commonly used by investigators prior to experimental manipulation. Plasma corticosterone concentration and WBC count were determined at 0.25, 2, 4, 8, 12, and 24 hours after transport. A significant (P less than 0.05) increase in plasma corticosterone concentration was seen in mice immediately after transport. The normal circadian rhythm of plasma corticosterone concentration was altered for the subsequent 24-hour period. Corresponding significant (P less than 0.05) decreases in total WBC numbers, lymphocyte count, and thymus gland weight were observed. The decrease in total blood lymphocyte numbers at 4 hours was reflected in B-and T-lymphocyte populations. The subsequent acute increase in plasma corticosterone concentration was associated with alterations in the cellular components of the immune system. Results of the study indicated that routine in-house transport of laboratory mice should be considered a stressful stimulus.

Fecal samples were collected from 200 feeder-calves on farms in Tennessee, after assembly at a Tennessee auction market, and after transport to a Texas feedyard. A final fecal sample was collected from each calf after 30 days of feedyard confinement. The fecal samples were cultured for the presence of Salmonella spp. Salmonella isolates were serotyped and antimicrobial drug-resistance patterns determined. The number of calves fecal culture-positive for Salmonella spp increased from 0 on the Tennessee farms and auction market to 3/200 (1.5%) at entry into the Texas feedyard, and 16/200 (8%) after 30 days of feedyard confinement. Salmonella serotypes isolated and the number of isolates of each serotype were S reading (8), S cerro (4), S newbrunswick (3), S anatum (2), and S typhimurium (copenhagen; 2). All Salmonella isolates were resistant to 5 or more of 13 antimicrobial drugs tested. Salmonella reading isolates were resistant to 10 or 11 of 13 antimicrobial drugs. The results indicated that the calves could have been infected with Salmonella spp prior to or during the course of the study, and that marketing stress as they moved from farm through feedyard may have induced fecal excretion of salmonellae. In addition, the pattern of antimicrobial drug resistance in the Salmonella isolates was broad.