الفهرس 
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Abstract
An experimental feeding trial was conducted to study the impact of different Methionine sources on performance and oxidation status of broiler chickens . A total of 510 One-day-old Ross(308) chicks were randomly assigned into six equal groups with 5 replicates and fed 6 experimental three stages (starter, grower and finisher) corn and soybean based basal diets that were according to the recommendations of the breed producers for 40 days. The first group (G1) was fed on basal diets with DL-M, the second group(G2) was fed on the same diets with DL-M & BHT, the third group(G3) was fed on the same diets with MHA-FA (65% BE), the Fourth group(G4) was fed on the same diets with MHA-FA (BE 65%) & BHT, the fifth group(G5) was fed on the same diets with MHA-Ca (BE 65%) and the sixth group(G6) was fed on the same diets with MHA-Ca (BE 65%) & BHT .Growth performance parameters, mortality rates were recorded .At the end of experiment serum samples were collected to determine the Total Protein, Albumin, Globulin, Albumin / Globulin ratio, ALT, AST, Urea and Creatinine) and also samples from the homogenates hepatic tissue (liver ) and used for determination of the oxidation stress markers including reduced glutathione (GSH), malondialdehyde, MDA), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activity. Mitochondrial activity indicators were detected. Also at the end of the experiment the carcass traits including dressing%, breast muscle yield (BMY), Thigh yield, drump stick, Wing, Neck and abdominal fat yield percentages and also organ indices including liver, heart, gizzard and proventriculus indices were calculated. In addition the gut histo- morphological picture was examined . Results revealed significant (P< 0.05) positive effects of either DL-Met or MHA-Ca or in combination with BHT supplementation on most of the growth performance parameters, meanwhile the broiler chicks responded lesser to MHA-FA than DL-Met. None of serum parameters were affected except for the elevated levels of ALT of chicks in groups (G3 and G4). The highest (GSH) , (CAT), (GPx) and (GR) and lowest significant MDA levels were also observed in the birds supplemented with DL-Met+ BHT (G2) and those supplemented with DL-Met alone (G1),also Mitochondrial Oxygen Consumption test as well as Mitochondrial function alteration in livers were improved a situation that indicated the ability of both DL-Met or MHA-Ca to improve the oxidation status of the birds and confirmed the positive impact noticed in growth performance traits. The highest and significant (BMY%), were recorded in the birds supplemented with DL-Met+ BHT (G2) and those supplemented with DL-Met (G1).But the other carcass traits including organ indices seems to be not significantly altered . sour. In addition groups received DLMet or MHA-Ca with or without fortification of BHT showed an increase in villus height and villus to crypt ratios. It can be concluded that the use of both D-Met or MHA-Ca with or without BHT supplementation had a better effects not only on growth performance, serum parameters carcass traits and gut morphology but also alleviated oxidative stress in broilers chickens. knowing and understanding the relative biological value (RBV) of MHA-FA compared to DL-Met is an important precondition to costeffective purchasing, feed formulation and broiler production.