Trace Elements in Pregnant and Non-pregnant Sheep and Goats and Their Relation to Steroid Hormones

Abstract

Background: One of the major factors affecting the physiology of pregnancy and reproductive cycle is the trace elements intake and their levels in serum of brood ewes and does. The main objective of this investigation was to study the association between serum concentration of trace elements, ovarian findings, stage of pregnancy and steroid hormones in sheep and goats. Methods: Total of 129 ewes (68 pregnant and 61 non-pregnant) and 54 does (32 pregnant and 22 non-pregnant) were examined clinically and ultrasonographically for pregnancy diagnosis and monitoring the ovarian findings. Pregnant animals were categorized according to the gestational stage into 1 to 2, greater than 2 to 3, greater than 3 to 4 and greater than 4 months. According to the ovarian findings, non-pregnant animals were categorized as having mature corpus luteum (CL), large follicle ( greater than 5 mm) and corpus luteum (CL+F), growing follicles (GF, less than 5.mm) and mature follicle (MF, greater than 5 mm). Animals were bled and serum was harvested and assayed for estrogen (E2), progesterone (P4), manganese (Mn), selenium (Se), iron (Fe) and zinc (Zn) levels. Result: Mn (P=0.01), Fe (P=0.05) and Zn (P=0.001) were lower in pregnant compared with non-pregnant ewes. Fe was significantly higher (P=0.03) in non-pregnant compared with pregnant does at any gestational stage. Ewes with MF had higher Se (P=0.02) and Fe (P=0.001) compared with other ewes. Fe (P=0.001) and Zn (P=0.000) were higher in does having MF compared with other does. A positive association between E2 and serum Fe in non-pregnant ewes (P=0.03) and does (P=0.05) was found. It can be concluded that pregnancy associated with a decrease in serum trace elements in sheep and goats.