SOME FACTORS AFFECTING BLOOD PLASMA LEVELS OF THYROID HORMONES IN OSSIMI AND RAHMANI EWES DURING PREGNANCY

Abstract

The study aimed to determine plasma triiodothyronine (T3) and thyroxin (T4) during pregnancy period of 42 ewes (18 Ossimi and 24 Rahmani) aged 1.5 to 3.5 years. The effect of breed, days of estimation within breed, parity number of ewes, sex and type of feti and regression on age and body weight of ewes were also studied. It was found that Rahmani ewes had higher plasma T3 (69.07ng/dl) and T4 (5.58 mg/dl) than Ossimi ones (66.37 ng/dl and 5.40 mg/dl,respectively). Days of pregnancy significantly affected plasma T3 and T 4 level in both Ossimi and Rahmani ewes. Plasma T3 and T4 decreased with increasing ewes parity. The highest levels of T3 (94.42 ng/dl) and T 4 (5.6 mg/dl ) were found in ewes having 1 st and 3 rd parity, respectively, However, the lowest Levels of both two hormones ( 58.32 ng / dl and 5.43 mg/dl, respectively) were found in ewes having4 th parity. The highest level of plasma T3 level (73.50 ng/dl)was found in ewes having twins (male and female) feti, while in those having female andmale,it was66.50 and 63.15 ng/dl,respectively. On the other hand, ewes having male feti had the highest level of plasma T4 (5.84mg/dl) compared with female and twins 5.50 and 5.12 mg/dl,respectively. Ewes having single had higher values of T3 (69.39ng/dl) Compared with twins(66.05 ng/dl). On the contrary, T4 concentration was significantly (P< 0.001) higher (5.88 mg/dl) in ewes having twins compared with 5.10 mg/dl in ewes having single feti. The linear and quadratic of coefficients regression of T3 and T4 hormones on age of ewes and also on weight of ewe were statistically highly significant (P < 0.001).