When cows are exposed to shifting light schedules before birth, their daily body temperature and hormone patterns change — and those changes are connected to them carrying their calves longer than usual.

Scientific Claim

In late-pregnant dairy cows, phase-shifting the light-dark cycle is associated with altered daily oscillations of body temperature and hormones (except cortisol), and this alteration is linked to longer gestation periods.

Original Statement

“Daily oscillations in temperature and hormones, except CORT, were affected by PS treatment in the prepartum and were associated with longer gestation”

From study:Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle.

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 abstract uses 'associated with' and does not imply causation. The study design is observational, so the verb strength is correctly conservative.

Evidence from Studies

Supporting (1)

Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle.

Cohort Study

Animal

2022 Mar

When scientists changed the light and dark schedule for pregnant cows near their due date, it messed up their body’s daily rhythms for temperature and some hormones—except cortisol—and those cows ended up being pregnant longer than usual.

Contradicting (0)

No contradicting evidence found

Source Study

Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle.

Score: 10

DOI: 10.3168/jds.2021-20691

Similar Assertions

When cows are kept on a changing schedule of light and dark before giving birth, their bodies produce less serotonin and more melatonin, which might affect how their internal clocks work.

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Before giving birth, cows have daily rhythms in body temperature and key hormones, but after birth, these daily patterns disappear, no matter if their light schedule was changed or not.

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The daily changes in body temperature and hormones in pregnant cows aren’t controlled by just one clock — they’re shaped by at least two different timing systems working together.

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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.

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