Hormonas tiroideas en ganado vacuno de aptitud lechera: relación con la actividad reproductiva (Thyroid hormones in bovine cattle: relation with reproductive activity)
Resumen Se determinaron los niveles séricos de triiodotironina (T3) y Tiroxina (T4) en 29 hembras bovinas, en tres momentos del ciclo productivo. Estos fueron: en la Toma 1(7-8 semanas anteparto) T3:125,27 ng/dl y T4: 5,36 hg/dl en la Toma 11 (0¬6díías postparto) T3: 127,25 ng/dl y T4: 2,8 µg/dl en la Toma III (40-53 días postparto) T3: 177,96 ng/dl yy T4: 3,35 µg/dl. Se observaron correlaciones significativas entre los niveles de T3 y de T4 y algunos de los parámetros reproductivos considerados (Indice de fecundidad, Intervalo PartoConcepción e Intervalo Interpartos). Abstract Serum levels of Triiodothyronine (T3) and Thyroxin (T4) in three moments of productive cycle of 29 female bovines were analysed. The results were: in Sample I (7-8 weeks before parturition) T3: 125,27 ng/dl and T4:5,36 pg/dl in Sample 11 (0-16 days after parturition) T3:1 27,25 ng/dl and T4: 2,8 jig/dl and in Sample III (40-53 days after parturition) T3:177,96 ng/dI and T4: 3,35 pg/dI. Significative correlations between levels of T3 and T4 and reproductive parameters studied (Rate of Fertility, Conception calving Interval and calving interval) were also found.