EFFECT OF DEFERENT GESTATION PERIOD ON SERUM ESTROGEN, PROGESTERONE AND SOME BIOCHEMICAL PARAMETERS IN AWASSI EWES

This study was designed to investigate the influence of different gestation periods on serum estrogen, progesterone and biochemical attributes levels in Awassi ewes. Ten ewes of 2-5 years old and 35-50 kg live body weight were used currently during the period from September 2019 to February 2020. Estrogen concentration seemed to decline since 2 nd month and reached its lesser level at 4 th month and re-increased at 5 th month of gestation. The progesterone level increased (P≤0.05) at 2 nd and 3 rd months and decreased at 5 th month of gestation. Serum Cholesterol, glucose, total protein, albumin and glubulin were decreased (P≤0.05) at the last gestation period. AST, ALT, and ALP activities take similar trend being decreased at the last gestation period. In conclusion estrogen, progesterone and other blood biochemical parameters were changed obviously during different gestation periods of Awassi ewes


INTRODUCTION
The Awassi breed's adaptability to harsh environmental conditions in arid and semi-arid areas has been acknowledged (3). The changes in the physiological status of animals can definitely have significant effects on the hematological and biochemical parameters in ewes (4). Pregnancy is the one of the most important physiological events throughout life of female animals that leads to reproduce its progeny and preserve the continuity of the species (2). The evaluation of reproductive hormones during pregnancy would be useful for pregnancy detection, nutritional management to prevent pregnancy toxemia and effective flock management to know number of fetuses and the precise stages of pregnancy (33).Progesterone is often called the 'pregnancy hormone' and it's considers the key hormone for pregnancy maintenance in all animals (24). During pregnancy, low progesterone level in the ewe can lead to unfortunate development of embryo (27,30). Estrogen concentration increases during late gestation in ewes and this this increases could be refer to increase estrogen requirement during last stage of pregnancy for the rapid growth of mammary gland and to support the beginning of parturition (33). Pregnancy can affect metabolism resulting in biochemical changes. It is well known that through the pregnancy all the metabolic pathways are involved in sustaining of fetus growth (17). Therefor the present study conducted to investigate the alteration in estrogen, progesterone and some of biochemical parameters profile throughout pregnancy in Iraqi Awassi ewes.

MATERIALS AND METHODS Experimental animals
Ten Awassi ewes aged 2-5 years were used in the current study. All animals were raised in animal house belong to the College of Veterinary Medicine/Tikrit University during the period between September -2019 to Feberuary-2020. Blood samples were monthly collect throughout gestation period by jugular venipuncture. Blood serum samples were separated by centrifugation as ten minutes 3000 rpm, and all serum samples were stored under -20 o C till analysis (21).

Statistics analyses
Data were analysed using paired t-test (a Repeated Measures ANOVA ) in SPSS (Version 19; SPSS). The differences were set at p < 0.05 (6).

RESULTS AND DISCUSSION
The results of the present study ( Figure 1) revealed that the level of estrogen concentration seemed to decline since the 2 nd month of pregnancy, reaching its lesser level at the 4 th month (112.58±5.378 pg/ml), then it significantly (P<0.05) increased at the 5 th month of gestation (62.41±6.272 pg/ml). Similar trend was reported by Thompson (8) hypothesized that the expression of estrogen receptors on which tissues will rise as the pregnancy progressed. Also, the current result was in agreement with Sharma et al. (32) who noticed that the cortisol secreted from fetal adrenal gland during last three weeks of gestation stimulates estrogen production. Shwetha et al. (33) pointed out that the increasing of estradiol levels during late gestation could be attributed to estradiol demand for rapid growth of mammary gland at the late stage of gestation as well as to support the beginning of parturition.

Figure 1. Estrogen concentration during different gestation periods in Awassi ewes (Mean + SE) Maximum serum level of progesterone in
Awassi ewes in the present study reached to 16.72±1.46 ng/ml, these level was lesser than levels recorded by (7) in Iraqi ewes, (38) in Syrian Awassi ewes, (14) in Barbary sheep and (22) in Kari ewes. These differences in progesterone levels may contributed to different breed (9), Mitchell et al. (25) reported that the variation in progesterone concentration is affected by season, age of the animal, ovulation rates and the analytical method. Significantly (P≤0.05) higher progesterone levels ( Figure. 2) were observed in serum of pregnant ewes as pregnancy advanced in 2 nd and 3 rd months of gestation being 16.72±1.46 and 16.61± 2.88 ng/ml respectively compared with 1 st month of gestation (11.20± 1.43 ng/ml) then decreased (P≤0.05 ) in the last month of pregnancy (13.34± 0.43 ng/ml). These results was in line with Alwan et al. (7) and Mugerwa and Viviani (26) who reported higher progesterone levels during mid-gestation and lowered as parturition progressed. The increasing of progesterone concentration at the mid gestation period, is attributed to additional secretion from extra ovarian sources (placenta) (22,33).

Figure 2. Serum progestogen concentration during different gestation periods in Awassi ewes (Mean ± SE)
The results of present study (  (18,23,28,29) These decreasing in blood cholesterol concentration in the late pregnancy may return to the increased requirement of cholesterol to utilize steroid hormones at the last period of gestation for pregnancy maintenance and lactation development (29). Glucose level decreased (P ≤ 0.05) at late period of pregnancy (60.73 ± 2.54 mg/dl) compared to early and midgestation (68.3 ± 2.55 and 66.1 ± 2.13 mg/dl respectively). Similar results were reported by Ismaeel et al. (18) in Iraqi ewes and Waziri et al (39) in goat. This result may be caused by an increased fetus need for glucose due to increased fetal development during the last gestation period (13). In agreement with previous study (19,18) total protein concentration in the current study decreased gradually with the progression of pregnancy till it reached its lowest levels (P ≤ 0.05) at the late pregnancy (6.27 ± 0.32 g/dl). The variations reflect the maternal requirements of proteins need for milking and providing immunoglobulins (31). Serum total proteins usually decreased as parturition advanced due to the increased fetal requirements for proteins needed to build muscle in late pregnancy (19). Albumin was decreased (P ≤ 0.05) at the late pregnancy (2.91 ± 0.21 g/dl) compared with early and mid-pregnancy (3.35 ± 0.13 and 3.33 ± 0.43 g/dl respectively). The liver synthesizes 80% of all albumins and the significant decrease in the level of albumin indicates a deficiency of amino acid and proteins in the organism of pregnant ewes (12). Globulin also decreased at the late pregnancy (3.36 ± 0.21 g/dl), might associated with the production of colostrum that rich in antibodies derived from γ-globulins and other immunological changes occurred around parturition (20). The activity of ALT, AST and ALP increased significantly (P ≤ 0.05) at the late pregnancy being 39.76 ± 1.34, 122.3 ± 2.14 IU/L and 134.06 ± 2.25 IU/L in ALT, AST and ALP respectively compared with other periods. similar results were recorded by Gurgoze et al. (11) in Awassi ewes, El-Sherif and Assad, (10) in Barki ewes and Abdul-Rahaman et al. (1) in she camel. The high ALP activity noticed in pregnant ewes may return to the rising of metabolic rate or increased bone metabolism due to the lack of dietary minerals of pregnant ewes (34). The amine transporter enzymes increases in pregnancy due to increased liver weight and reaches the highest levels when there is a lack of protein concentration and fat depletion to manufacture energy (37). In addition, the increases in level of these enzymes is affected by feeding deficiency causes and negative energy balance due to increase of energy requirement at the late pregnancy period and its reached highest concentration during the last period of pregnancy (16).

CONCLUSION
The current study revealed that the gestational periods have clear effect on estrogen and progesterone concentrations and these effects are related with maintenance of pregnancy, prepare normal parturition and development of mammary gland. Blood biochemical levels changed throughout different gestation period and these changes may reflect the health status of animals.