As cows get closer to giving birth, their bodies start showing stronger daily patterns in stress hormones, pregnancy hormones, and mood-related chemicals — but only if they’re on a steady light schedule.
Scientific Claim
In late-pregnant dairy cows under control lighting, circadian rhythms of cortisol and progesterone emerge by 9 days before calving, and serotonin rhythm appears by 9 days before calving, indicating increasing circadian organization near parturition.
Original Statement
“Both treatments exhibited circadian rhythms of CORT at 9 BEC, CON cows also exhibited circadian rhythms in P4 at 23 BEC, and 5HT at 9 BEC”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim reflects exact observations from the abstract without inferring causation. The study design does not allow for causal claims, so 'association' is appropriate.
Evidence from Studies
Supporting (1)
In cows that weren’t disturbed by changing light schedules, their body clocks started showing regular daily patterns for stress and pregnancy hormones about 9 days before giving birth, which means their bodies were getting ready for labor in a timed, organized way.