THE EFFECT OF USING DIFFERENT LEVELS OF VITAMIN E ON THE ANTIOXIDANTS STATUS OF BROILER CHICKENS

: This study was conducted at the Poultry Research Station of the Live-stock Research Department in the Agricultural Research Department. 126 One-day-old chicks were used in the study, with an average starting weight of 38 g from Ross 308 strain. The chicks were distributed randomly into 3 treatments, and each treatment contained three replicates. 14 chicks for each replicate, where the first treatment was control, and the chickens in the second and third treatments were given vitamin E at a level of 350 and 600 mg / kg feed, respectively, as the continuous lighting system was followed (24 hours / day) in the hall until the end of the experiment, which reached 42 days and the temperature was 35 m throughout the study. The results of the study showed a significant (P<0.01) in fat oxidation in liver tissue in vitamin E treatments (350 and 600 mg/kg feed) decreased significantly (P<0.05) in the level of malondialdehyde, the level of free fatty acids and the peroxide value compared with the control treatment, which indicates the role of the additives used in protecting against infection and effect of exposure to high temperature and its ability to improve the studied traits.


Introduction
High temperatures are dangerous for broiler chickens and make them uncomfortable and lead to an increase in the breathing rate immediately when exposed to broiler chickens [1]. In addition to that, water consumption increases and feed consumption decreases, and accordingly, a rise in the body temperature of chickens occurs to reach more than 43 ° C, and the birds become uncomfortable and unable to breathe normally and then leads to the destruction of broiler chicken [2]. The high temperature leads to a decrease in the antioxidant defense system in the body [3], which leads to an increase in the level of free radicals, which causes an increase in oxidative stress, oxidative stress, and a decrease in immunity [4].
High temperatures weaken antioxidant status through a decrease in feed consumption and feed conversion factor, and then a decrease in live body weight [5], and high temperatures cause the release of corticosterone hormone, which causes disturbances in endocrine function and a decrease in the rate of metabolism with oxidation [6]. Unsaturated fats in the body then weaken the immune response, which makes the body more susceptible to disease [7]. Therefore, it was necessary to use many means and methods in order to reduce the severity of the high temperatures on the birds [8], such as adding aspirin or vitamin E, C, and E is one of the most powerful natural antioxidants because it works to protect unsaturated fatty acids inside and outside the cells of the body from free radicals and also prevents the reactions of the formation of free radicals resulting from respiratory processes [9]. These reactive chemicals are essential in the host-pathogen interaction because they cause pathogen detection, host defense system activation, and gene expression [10]. Organisms have specific antioxidant defense mechanisms that include enzymatic and non-enzymatic substances like catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GSH), glutathione (GSH), thioredoxin, melatonin, carotenoids, Vitamin E, and Vitamin C to lessen ROS-and RNS-induced alterations [11]. By boosting the synthesis of reactive chemicals, the RNA virus known as the ND virus is known to cause oxidative stress [12].
However, only vitamin E supplementation at 120 mg/kg was shown to increase GSH-Px activity in plasma, while at 160 mg/kg vitamin E supplementation was associated with decreased malondialdehyde (MDA) and reactive oxygen species (ROS) in plasma measured fluorometrically by using 2′,7′-Dichlorofluorescin Diacetate as a reactive agent [13]. Furthermore, increased dietary vitamin E levels (from 30 to 60 mg/kg) for 10 wk was shown to be responsible for significant increase in antioxidant defense indexes evidenced by increased serum α-tocopherol concentrations, SOD activity, and the antioxidant capacity of serum measured by FRAP assay based on reduction of Fe3+ to Fe2+ by antioxidants present in the serum with the following formation of a colored complex with 2,4,6 tripyridyltriazine present in the solution [14]. In practically relevant stress conditions of industrial poultry production, antioxidant defense mechanisms are in charge of preventing the negative effects of free radical overproduction and oxidative stress [15]. The principal chain-breaking antioxidant in the cell, found in biological membranes, is thought to be vitamin E, which has been shown to be a key factor in antioxidant defense. In reality, studies have shown that vitamin E is necessary for both male and female reproduction, immune function, efficient growth and development, high-quality eggs and meat, and strong resilience to a variety of stresses [16].
Therefore, this study aimed to find out the effect of adding different levels of vitamin E to the diet on the MDA, free fatty acids, lipid profile and antioxidant status of broiler chickens under heat stress.

Materials and Methods
This study was conducted at the Poultry Research Station in the Livestock Research Department of the Agricultural Research Department, as (126) one-day-old chicks were used in the study, with an average starting weight of 38 g of Ross 308 strain. The chicks were distributed randomly to 3 treatments, and each treatment contained three Replicates of 14 chicks for each replicate, where the first treatment (T1) was control, and the chickens in the second (T2) and third treatments (T3) were given vitamin E at the level of 350 and 600 mg/kg feed, respectively, as the continuous lighting system was followed (24 hours/day) in the hall until the end of the experiment, which reached 42 days and was a degree The temperature was 35 C throughout the study, and the birds feeding as ad libitum from the diet used in the study, whose components, percentages, and chemical composition are shown in Table (1), and water was also provided to the birds freely. Vitamin E manufactured by the United Company for Veterinary Pharmaceutical Industry Ltd. (Jordanian Yovidco) was used, which could be obtained from the local markets, as it was added on the basis of the active substance (α-Tochopherol acetate), which was at a level of 50%, so the addition was doubled in the diets to reach The active substance was reduced to 100%, and the idea of doubling the additives was for the purpose of in- The water used in the chemical analysis was ultra-purified [18].
The Statistical Analysis System-SAS [19] was used to analyze the data of the study to find out the effect of different coefficients on the studied traits according to a completely randomized design (CRD). Significant differences between the means were compared with the Duncan [20] multinomial test. Table (2) shows a significant (P<0.01) superiority of the two vitamin E treatments mg/kg feed over the control treatment in fat oxidation in liver tissue in vitamin E treatments (350 and 600 mg/kg feed) decreased significantly (P<0.05) in the level of malondialdehyde, the level of free fatty acids and the peroxide value compared with the control treatment the two experimental treatments compared with the control treatment. The reason for the superiority of the additional treatments in antioxidants status over the control treatment is due to the effect of the additions that contributed to reducing the intensity of heat stress on the chickens [21]. Vitamin E is one of the most powerful antioxidants in the body, as it prevents the formation of free radical peroxide in fat cells by hindering the formation of free radicals, and thus provides an important cover in the protection of unsaturated fatty acids [22].

Results and Discussion
The main function of vitamin E is as an antioxidant, as it inhibits the reactions of the formation of free radicals resulting from a high respiratory rate when exposed to a high temperature or from imbalance and irregular [23], and thus it performs an important function which is to protect unsaturated fatty acids in the body from oxidation and then maintains all body tissues [24]. The reason for the superiority in antioxidants status may be attributed to the effect of additives that worked to reduce high temperatures on chicken, as vitamin E is one of the most powerful natural antioxidants, as it protects unsaturated fatty acids in the body [25]. Vitamin E works to prevent the reactions that form free radicals resulting from the increase in respiratory processes as a result of the entry of large amounts of oxygen in order to cool the body of the bird during exposure to high temperatures. It was found that the oxidation process affects broilers, which leads to a rise in body temperature [26], as it has been proven that vitamin E works to strengthen the antioxidant systems in the body, which reduces the oxidation processes occurring in the body, and this leads to maintaining the temperature of the chickens [27]. Vitamin E breaks the chain of lipid oxidation reactions by donating a hydrogen atom to the peroxyl radical, and this leads to a reduction in the formation of hydroperoxide [28]. As for vitamin C, it controls all active oxygen species, which are hydrogen peroxide radical, negative peroxide, single oxygen, hydroxyl radical, and others. It also has a protective effect against the inhibition of antioxidant enzymes in the body, which causes their concentrations to rise, and this leads to a rise in immunity in chickens [22].   [29]. Recent research, however, has produced conflicting findings on the effects of vitamin E on broiler chicken development performance, particularly in relation to the size of the vitamin E response in accordance with the quantity of supplementation used [30]. As an antioxidant, vitamin E lessens the pathology caused by free radicals in both inflammatory and regular metabolic conditions [31]. Vitamin E modifies the expression of genes that are regulated by free radical signaling by regulating free radical synthesis, which in turn impacts free radical-mediated signal transduction processes [30].

Conclusions
In conclusion that adding different levels of vitamin E in the diets as appetite stimulants in the antioxidants status of broiler chickens under heat stress conditions. led to a significant improvement in the Malondialdehyde, Peroxide, and Free Fatty Acids in (1-42) days, and improvement in the VLDL, LDL HDL especially in the treatments T2 and T3 compared with the control treatment in (1-42) days of broiler chickens.

Funding:
This research received no external funding.

Institutional Review Board Statement:
The study was conducted in accordance with the protocol authorized by the Animal Science and Food Technology Faculty, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Ethics Committee, Iran in cooperation with Universiti Pendidikan Sultan Idris, Perak Malaysia, from a commercial farm, fertile eggs from Ross (308) strain broiler breeder hens were obtained.

Informed Consent Statement:
No Informed Consent Statement.

Data Availability Statement:
No Data Availability Statement.

Conflicts of Interest:
The authors declare no conflict of interest.