Assessment of Thyroid Hormone Concentrations in Pregnant Ewes in Bauchi State, North East Nigeria

Thyroid hormones are central regulators of metabolic rate, fetal development, and reproductive physiology in small ruminants. This study determined serum triiodothyronine and thyroxine concentrations in pregnant Yankasa ewes at different gestational stages in Bauchi State, North East Nigeria. Sixty ewes were classified into three groups: early pregnancy (day 1 to 45), mid-pregnancy (day 46 to 100), and late pregnancy (day 101 to 150), with fifteen non-pregnant ewes serving as controls. Blood samples were obtained by jugular venipuncture and serum thyroid hormone levels quantified by enzyme-linked immunosorbent assay at a certified veterinary diagnostic laboratory. Serum thyroxine concentrations were significantly elevated during mid-pregnancy relative to the non-pregnant controls and early pregnancy group, reflecting increased maternal metabolic demands associated with placental and fetal development. Triiodothyronine levels showed a declining trend in late pregnancy, which may represent a physiological downregulation to conserve maternal energy. Body condition score correlated positively with thyroxine concentrations across all gestational stages, highlighting the interplay between nutritional status and thyroid function. These baseline data are relevant for guiding nutritional and health management of breeding flocks in the semi-arid conditions of North East Nigeria. Keywords: thyroid hormones, pregnancy, Yankasa ewes, Bauchi, reproductive physiology.