The Study
Relationship between weaning and secretion of luteinizing hormone, cortisol and transcortin in beef cows.
This study watched two groups of cows—one that kept nursing their babies and one that got separated—and saw how their body chemicals changed. It didn't prove that stopping nursing caused the changes, just that they happened together.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
When baby cows stop nursing, their moms’ bodies start making more of a hormone that helps them get ready to have another baby.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 510 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This matters because it shows that stopping nursing helps cows restart reproduction — not because they get stressed, but because nursing itself blocks a key hormone signal.
- 2After weaning, moms made more LH pulses (but each pulse was the same size).
- 3Cortisol levels didn’t change.
- 4A protein that carries cortisol in the blood started holding more of it, but didn’t hold it tighter.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of animal science
Year
1987
Authors
G. Faltys, E. Convey, R. Short, C. Keech, R. Fogwell
Related Content
Claims (5)
Higher levels of the stress hormone cortisol cause the pituitary gland to release less luteinizing hormone, which results in lower testosterone production by the testes.
In postpartum beef cows, weaning is linked to a higher ability of the protein transcortin to bind cortisol, but the strength of that binding does not change, suggesting cortisol transport can change without changes in binding strength.
In postpartum beef cows, the difference in luteinizing hormone levels between cows that nurse their calves and those that do not is not caused by differences in cortisol levels, and nursing does not change how much cortisol is bound to transcortin or how much is free in the bloodstream.
In postpartum beef cows that are not ovulating and are fed enough energy, stopping suckling is linked to more frequent luteinizing hormone pulses and higher baseline levels of the hormone, with no change in the size of each pulse.
In postpartum beef cows, total cortisol levels in the blood do not change after weaning during the first three days, and they remain the same before, during, and after suckling events.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.