Weaning is a natural process and can induce stress in both the calf and the dam. Norepinephrine and epinephrine, major neurotransmitters of the sympathetic autonomic nervous system, are both affected by stress. Norepinephrine concentrations increase in calves while epinephrine concentrations increase in both calves and dams during separation, but decrease again after reunion [14]. However, weaning calves at day 89 compared to day 300 has been shown to increase the tolerance of these calves to transport and feedlot entry stress. Acutephase proteins, haptoglobin and ceruloplasmin, as part of the innate immune system, were measured as an estimate of stress. While haptoglobin concentrations were increased in both groups of calves, calves weaned at day 89 showed lesser ceruloplasmin concentrations when compared to calves weaned at day 300 as well as improved feed to gain ratios [15]. Transportation is a managerial necessity that can cause stress on cattle. Adrenocorticotropin (ACTH), a hormone secreted by the anterior pituitary in response to stressful stimuli such as transportation, causes the release of glucocorticoids from the adrenal glands. This results in immunosuppression and changes in the regulation of glucose homeostasis. It has also been found that peripheral lymphocytes secrete ACTH during times of stress. Lymphocytic ACTH secretion was significantly increased in cattle transported for 14 hours and remained at elevated when animals rested on the transportation trailer. However, lymphocytic ACTH levels returned to pre-transport levels when the cattle were offloaded and rested in stalls [16].