This is an early access version, the complete PDF, HTML, and XML versions will be available soon.
Oxidative Stress and Blood Parameters During Shearing in Sheep Treated with Melatonin
by
, , ,
Vincenzo Carcangiu
,
Sebastiano Luridiana
,
Raffaella Cocco
,
Othmane Trimasse
,
Imane Bennaghmouch
,
Mortadha Ouadday
and
Maria Consuelo Mura
*
Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
*
Author to whom correspondence should be addressed.
Animals 2026, 16(11), 1699; https://doi.org/10.3390/ani16111699
Submission received: 23 April 2026
/
Revised: 25 May 2026
/
Accepted: 29 May 2026
/
Published: 1 June 2026
(This article belongs to the Special Issue Potential Role of Antioxidants and Advanced Management Strategies to Improve Animal Production, Reproduction, Health, and Welfare)
Simple Summary
Shearing is a necessary practice for sheep welfare, but it causes stress due to restraint, isolation, and the shearing procedure itself. Stress can lead to the production of harmful free radicals, a condition known as oxidative stress, which may negatively affect animal health. Melatonin is a natural hormone known for its antioxidant properties and its ability to regulate sleep and seasonal rhythms. This study investigated whether treating sheep with melatonin before shearing could reduce their stress response and oxidative stress. Forty ewes were divided into four groups: some received a melatonin implant and were either shorn or left unshorn, while others remained untreated and were either shorn or left unshorn. Blood samples were collected before, during, and after shearing to measure stress hormones, energy levels, and markers of oxidative stress. The results showed that melatonin-treated sheep had lower stress hormone levels and better antioxidant capacity compared to untreated animals, both during and after shearing. These findings suggest that melatonin administration can help sheep cope with the stress of shearing, reducing physiological indicators associated with stress during this routine management practice. Melatonin administration may represent a useful approach to modulating physiological stress responses during routine handling procedures in sheep.
Abstract
Shearing is a stressful procedure for sheep, combining isolation, restraint, and the mechanical action of shearing, which activates the hypothalamic–pituitary–adrenal axis and induces oxidative stress. This study investigated whether melatonin—a pleiotropic hormone with well-documented antioxidant properties—administration could modulate the stress response and oxidative stress in Sarda sheep during shearing. Forty lactating ewes (aged 3–5 years, mean body weight 41 ± 1.1 kg) were randomly assigned to four groups (n = 10 each): two groups received a subcutaneous melatonin implant (18 mg); two remained untreated as controls. Within each category, one group was shorn and the other subjected only to restraint. Blood samples were collected before, during, and after shearing to measure cortisol, glucose, reactive oxygen metabolites (ROMs), biological antioxidant potential (BAP), and oxidative stress index (OSI). Procedures elevated cortisol, glucose, ROMs, and OSI in all groups, but melatonin treatment significantly reduced these parameters and increased BAP relative to untreated animals at all sampling points (p < 0.05). No significant differences were observed between shorn and unshorn animals within the same treatment, suggesting that the handling, restraint, and isolation associated with the shearing procedure represent the major sources of stress, rather than the mechanical act of shearing itself. In conclusion, melatonin administration blunts the stress response and reduces oxidative stress in sheep during routine shearing-related handling procedures, suggesting its potential as a practical tool to improve animal welfare during routine management practices.
Keywords:
sheep; melatonin; shearing; stress; oxidative stress
