Influence of Pregnancy Stages on Thyroid Status and Blood Metabolites in Desert Ewes Raised under Range Conditions in West Kordufan State, Sudan

Abstract

This study aimed to evaluate the influence of the stages of pregnancy in two ecotypes of sheep, located in different grazing areas on thyroid status and certain blood metabolites. Eighty clinically healthy ewes (40 Hamari and 40 Kabashi ecotype) aged 2-5 years were used in the study. For each ecotype, the ewes were divided into four groups according to the reproductive status. Group (A): 10 ewes non-pregnant non-lactating (dry) served as the control. Group (B): 10 ewes in the early stage of pregnancy (first trimester). Group (C): 10 ewes in mid-stage of pregnancy (second trimester). Group (D): 10 ewes in the late stage of pregnancy (third trimester). Blood samples were used to measure serum levels of thyroid stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3), plasma glucose concentration and serum triglyceride levels. The study detected that Hamari ecotype was supplied with salt and minerals block during watering by its owners. The results showed that in both ecotypes, the serum TSH levels were significantly (P<0.05) higher during the early stage of pregnancy then, it decreased significantly (P<0.01) as the pregnancy advanced. While serum T4 levels were higher during the early stage of pregnancy, then it decreased significantly (P<0.01) during the late pregnancy in both ecotypes. Serum T3 level was significantly (P<0.001) higher in both ecotypes during early and mid-pregnancy, then declined to the lowest value during the late stage. The plasma glucose level was significantly (P<0.001) lower during mid and late pregnancy in both ecotypes. There was a significant (P<0.05) decrease in serum triglyceride level when pregnancy advanced in both ecotypes. Kabashi ecotype showed significantly higher serum triglyceride levels in the control group (P<0.001) during early pregnancy stage (P<0.01) and mid pregnancy stage (P<0.05) compared to the values of serum triglyceride levels in Hamari ecotypes. This study indicated that pregnancy altered thyroid status in both ecotypes, however, the influence of pregnancy on the thyroid status was less in the Hamary ecotype which supplemented by mineral and salt blocks. Therefore, supplementation with minerals during pregnancy might enhance the metabolic profile on the natural pasture grazing.