The effect of supplementing organic and inorganic trace minerals in flushing ration on hormonal profile, antioxidant status, and blood biochemical parameters of Ghezel ewes during breeding season.

ABSTRACT
The present study was designed to compare the efficacy of organic and inorganic sources of trace minerals (TM) in the flushing diet on some blood biochemical parameters and hormonal profile of Ghezel ewes during breeding season. Eighty ewes (48.88±7.40 kg), age (2 to 4), with parity (1 to 4), and BCS (2 to 3.5) were assigned to the experiment. The study was conducted for a period of five weeks. The ewes were divided into 4 treatment groups included: 1 (CTM): flushing with chelated TM (Zn, Cu, Mn, Fe, Cr, Se and Co from Bonzaplex7), 2 (ITM): flushing with inorganic TM (Zn, Cu, Mn, Fe, Cr, Se and Co), 3 (NTM): flushing without trace minerals, and 4 (Control): only pasture grazed. At the end of five weeks, blood samples were collected on day 34 of the experiment to assay hormones, enzymes, and metabolites. The collected data were analyzed by GLM procedure of SAS software. The experimental diets had no effect on cholesterol, glucose, insulin, and estradiol concentrations (P>0.05). Progesterone tended to be higher in CTM group (P=0.07). However, the lowest triglyceride and total protein were observed in ITM group (P<0.05). Also, serum urea concentration was the highest in the control group (P<0.05). Concentrations of T3 and T4 were affected by treatments (P<0.01) and were higher in the CTM group as compared with other groups. However, the ratio of T3/T4 was higher in the NTM and control groups as compared with supplemented ewes (P<0.01). Although superoxide dismutase, alkaline phosphatase, choline-esterase, and hemoglobin were not affected by treatments (P>0.05), malondialdehyde (P=0.09) and glutathione peroxidase (P=0.07) tended to be lower in CTM group, and total antioxidant capacity was lower in CTM group (P<0.01). Therefore, the current study demonstrated that the flushing ration with TM chelate could not affect biochemical parameters, antioxidant status and sex hormones, but thyroid hormones improved in ewes. So, it is suggested to use this supplement in longer period in order to evaluate these indicators.

keywords: Antioxidant status, Blood metabolites and hormones, Ewes, Flushing, Inorganic minerals, Organic minerals.

INTRODUCTION
Essential trace minerals (TM) plays an important role in reproductive performance (Vázquez-Armijo et al. 2011). Trace minerals participate in the synthesis of some reproductive hormones. For example, manganese is involved in the synthesis of cholesterol, which in turn is essential for the synthesis of steroid hormones such as progesterone, estrogen, and testosterone (Xie et al. 2014). Zinc is a component of a special type of proteins that play a role in the genetic expression of reproductive hormones (Tapiero et al. 2003), while Cu is essential in the synthesis and maintenance of the appropriate level of FSH in the serum (Vázquez-Armijo et al. 2011). The Se and Fe used for estrogen and progesterone biosynthesis (Derar et al. 2022). Changes in thyroid hormone concentration in the blood indicate indirect changes in thyroid gland function (Todini et al. 2007). The normal function of thyroid glands is based on the presence of minerals for the synthesis and metabolism of thyroid hormone (Arthur et al. 1988). Zinc, iron , copper and selenium have important role in action of enzymes involved in the action of thyroid hormone metabolism and T4 conversion to T3 (Ebrahimi et al. 2009; Yatoo et al. 2013). In addition, trace minerals are cofactors of a large number of enzymes that play a significant role in reproduction. As a result, their deficiency/imbalance exerts can lead to various disorders that ultimately lead to reduced reproductive efficiency. Mineral deficiency in livestock is often seasonal, resulting from increased demands of pregnancy, lactation or rapid growth at the same time as reduced mineral content or availability in pasture (Dar et al. 2014). Intensive production requires full coverage and proper balance of mineral elements. Meeting mineral needs at times when physiological needs are greatest will have a greater return on investment than at other times of the year. The periods of breeding, early gestation, and late gestation simultaneously rely on senescent plant communities with the lowest nutritional value for many extensively managed sheep operations. Deficiency of minerals in forages and soils has been reported, which is the main reason for reproductive failure and low animal productivity (McDowell and Valle, 2000). This deficiency in animal diets or in the uptake may decline ovulation rate, but it has a direct primary effect on basic health status (Vázquez-Armijo et al. 2011; Suttle 2022). Adequate amounts of TM supplements and their absorption are required for various metabolic functions such as reproduction, immunity, growth and development (Hackbart et al. 2010; Suttle, 2022). Traditionally, TM in diet is usually obtained from inorganic compounds: sulfate, oxide, chloride and phosphate due to the cost and availability of the commercial surface (Yaqoob et al. 2020). The bioavailability of ingested inorganic minerals may be less than 20% due to several factors, including reactions with lipids, protein, fiber, oxalic acids, oxides, and vitamins, as well as interactions with other compounds such as phosphates and phytates (Hardcastle, 1995). Several research activities conducted on different species of livestock showed that the use of different sources of trace minerals led to a significant improvement in the bioavailability of organic forms (OTM) compared with inorganic forms (Hardcastle, 1995; Wang et al. 2010; Yatoo et al. 2013; Xie et al. 2014; Alimohamady et al. 2019). Investigations showed that amino acids and peptides in connection with Cu, Zn, Fe and Mn elements can increase the availability of these metals. So, improve milk production, growth, reproduction and general health of livestock (Hackbart et al. 2010; Sobhanirad and Naserian, 2012; Qiu et al. 2022). Studies have reported that the presence of organic acids such as citric, lactic and malic in food materials can lead to an increase in bioavailability of copper. Organic acids can improve rumen fermentation, they sustain the rumen pH, even after consumption of carbohydrate-rich feeds through which an increased growth and fattening performance are observed (Martin, 1998). Chelate are stable complexes that preserve the minerals from engaging in chemical reactions that occur during digestion. Moreover, it has been shown that chelated trace minerals (CTM) dissociate from their carrier groups in the intestinal lumen and are then absorbed into enterocytes lining the gastrointestinal tract (Byrne et al. 2021). Recent studies have confirmed that supplementing livestock with CTM has resulted in improved production and reproductive performance. By using the flushing method and feeding vitamin E and organic selenium to ewes, reported to improve fertility, estrus and reduce non-pregnant ewes by improving the control of oxidative conditions and increasing sex hormones (Safdar et el. 2020). Earlier researchers concluded that OTMs (Fe, Mn, Se, Cu and Zn) supplement could improve hepatic Cu/Zn-SOD, ALP, and GSH-Px activities and reduce fecal Mn, Cu, and Se excretion for grower-finisher pigs when supplemented at commercially recommended levels (Liu et al. 2016).Also, ewes treated with organic phosphorus twice a week for 3 weeks at the end of breeding season had higher pregnancy rate (80 vs. 50%), shorter interval to estrus and increased number of antral follicles compared with control ewes (Senosy et al. 2018).