Location: Livestock Behavior Research
Project Number: 5020-32000-014-007-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 20, 2023
End Date: Aug 19, 2024
The objective of this study is to determine relationships between stress-load and calf behavior in precision livestock farming. Measuring the combination of stress-related hormones (as measured by hair/salivary cortisol), changes in behavior (as measured by the automated feeding system [drinking speed, intake, frequency of rewarded/unrewarded visits] and accelerometers [locomotion/posture], size/growth ( as measured by body weight, hip and wither height/width), and health (as measured by clinical health scoring and treatment rate) will be indicative of variability in the stress response of calves to exposure to automated feeding systems over time (stress-load). Associations between these data and hair/salivary cortisol concentrations will ultimately form the basis for larger scale genotypic studies and lifetime productivity studies.
Two hundred and forty pre-weaned Holstein dairy calves will be housed in four groups of 60 starting on day 1 after birth. As a population health study under industry conditions, there is no control group identified, but epidemiological methods will provide guidance to test the controlled application of stressors in dairy calf experimentation. All calves will be assessed for health status using the scoring system developed and validated for use in young calves by a single observer on day 1 after birth and daily thereafter through 1-week post-weaning. Per farm protocol, all calves will be fed using an automated feeding system and will receive the same feeding protocol. Feeding behavior (daily intake, drinking speed, number of rewarded/unrewarded visits to the feeder) will be recorded for the entire study period. Hair samples will be taken at the time of grouping (day 1) and weaning (day 70) and tested for cortisol levels as a measure of stress-load. Hair will be cleaned, pulverized, and cortisol extracted via radioimmunoassay. Saliva samples will also be taken from calves (day 0, 35, and 70) to measure salivary cortisol as an indicator of stress-load. Calves will be weighed and measured (hip and wither height/width) on day 0, 35, and 70 using a portable calf scale. Calves will be fitted with a triaxial accelerometer on day 1 to measure lying behavior (total time, number/duration of lying bouts) at 1-minute increments.