Changes of thyroid hormone levels in periparturient Holstein cows

• Published in: Journal of the Japan Veterinary Medical Association Vol. 54; no. 3; pp. 172 - 176
• Main Authors: Aruga, T. (Obihiro Univ. of Agriculture and Veterinary Medicine, Hokkaido (Japan)), Tanabe, S, Uzuka, Y, Sarashina, T
• Format: Journal Article
• Language: Japanese
• Published: Japan Veterinary Medical Association 20.03.2001
• Subjects: cow; DAIRY COWS; PERINATAL PERIOD; postpartum recovery times; T4/T3ratio; THYROXINE; thyroxine (T4); TRIIODOTHYRONINE; triiodothyronine (T3)
• ISSN: 0446-6454; 2186-0211
• DOI: 10.12935/jvma1951.54.172

Thyroid hormone levels change markedly during the periparturient period. In order to clarify their post-partum recovery times, changes in serum thyroxine (T4), serum triiodothyronine (T3), serum nonesterified fatty acid (NEFA), and plasma glucose levels were measured in 6 clinically healthy Holstein cows. The measurements were carried out over a period of 3 months in the Tokachi District of Hokkaido. Serum T4 and T4/T3 ratio started decreasing 2 weeks before parturition and reached minimum values (0.9 micro g/dl and 13.1, respectively) 3 days after parturition. Levels recovered gradually thereafter. Serum T3 (49 ng/dl) reached the minimum 5 days after parturition and plasma glucose levels (38.6 mg/dl) 3 days after parturition. Thereafter, those levels also increased gradually. Serum NEFA levels started to increase 3 weeks before parturition; thereafter they decreased. These findings show that in healthy cows it takes about 2 postpartum months for thyroid hormone levels to recover.