Pre-weaned Dairy Calf Management: An Investigation into Colostrum Practices and Non-Invasive Measures of Chronic Stress
Dairy calves in the preweaning period are exposed to a variety of stressors (e.g. disbudding, castration, etc.) and management practices that have the potential to influence their health and productivity later in life. Proper colostrum management at birth is the first step in ensuring calves can reach their full potential in terms of health, growth, and development, while improper management increases a calf’s risk of failed transfer of passive immunity (FTPI) which puts the calf at an increased risk of morbidity and mortality. Previous research has indicated there is a difference in colostrum management practices between dairy bull and heifer calves. Due to the marketing of dairy-beef crossbred calves as surplus animals along with dairy bull calves, there is growing interest in the treatment of these calves on farms. The first study presented here (Chapter 2) investigated the relationship between colostrum management practices on 15 farms and the prevalence of FTPI between purebred dairy and dairy-beef crossbred calves on those farms. The results of this study found no influence of calf breed (purebred dairy or dairy-beef crossbred) on the prevalence of FTPI. However, farm tended to influence FTPI. There was also a significant influence of the reported timing of the first colostrum feeding on FTPI, with calves on farms reporting feeding colostrum within 1 hour of birth having decreased odds of experiencing FTPI. In addition to colostrum management at birth, calves are exposed to several management factors during the preweaning period that can cause stressful experiences and result in negative behavioral and physiological outcomes. Early life stress, especially chronic stress, can negatively impact calves later in life. Short term stress load in calves can be quantified by measuring cortisol in the blood serum or saliva; however, these measures are not reflective of chronic stress load because they only measure circulating cortisol. The second study (Chapter 3) considered the efficacy of utilizing hair cortisol concentration (HCC) as a measure of stress load in 27 dairy calves exposed to a weekly saline injection or a weekly or biweekly repeated acute stressor (Cosyntropin injection) during the preweaning period. The results revealed no difference in HCC between the treatment groups, though salivary cortisol was increased in calves injected with Cosyntropin. Additionally, calf behavior and growth were not influenced by the treatments in this study. Overall, these studies provided insights into two areas that have not been extensively researched. First, considering dairy-beef crossbred calf management, and second investigating a method to assess chronic stress that has not been extensively researched in calves.
- Master of Science
- Animal Sciences
- West Lafayette