CYCLIC VARIATIONS OF CORTISOL, TRIIODOTYRONINE (T3) AND TYROXINE (T4) ON BEFORE AND AFTER PARTURITION OF QUARTER HORSE MARES

• Autor(a) principal: Teixeira, Pedrinho Paes
• Data de Publicação: 2008
• Outros Autores: Meirinhos, Maria Lúcia Gambarini, Pádua, João Teodoro, Vieira, Dirson
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Ciência animal brasileira (Online)
• Texto Completo: https://revistas.ufg.br/vet/article/view/539
• topic: Sanidade Animal; Pordução e Reprodução

This study was designed to evaluate changes in plasma concentrations of cortisol (Cs), triiodothyronine (T3) and thyroxine (T4), as well as their circadian rhythm during peripartal period of Quarter Horse mares. Eighteen clinically healthy mares, with age between 60 and 96 months and alive weight (AW) between 350 and 420 Kg were divided in three groups (n=6) according the reproductive status, that means: no pregnant (TE), Pregnant (GE) and after parturition (PA).The blood samples were taken during 24 hours in intervals of two hours.There was no differences between cortisol levels regarding the reproductive status and periods of blood samples collections. This hormone showed a circadian rhythm, with accentuated oscillation in TE, but small for GE and PA. For T3 and T4 there was difference between reproductive status (P<0.05 and P<0.01), respectively, as well as for the periods (P<0.01 and P<0.05), respectively. It was possible to characterize the circadian rhythm for both hormones, verifying great oscillation for T3 in PA in the morning. It was possible to conclude that the final phase of pregnancy alter cortisol , T3 and T4 secretion standards, keeping, however, the rhythm, suggesting an organism adaptation along the peripartal period. KEY WORDS: Equine, reproductive status, hormones, circadian rhythm.