Influence of dietary epigallocatechin-3 gallate and L-arginine and its combination on early laying performance and physiological status of stressed Japanese quails

This study was designed to investigate the effect of dietary EGCG and L-arg supplementation to alleviate the oxidative stress induced artificially by H2O2 in drinking water by using 400 layer quails. The research lasted for 8 weeks and birds were distributed into 5 groups, each group had 4 replications. The groups were divided into G1: negative control, G2: addition 0.2% H2O2 to drinking water, G3 and G4: addition 500 mg/kg of EGCG and L-arg each. G5: addition 250 mg/kg mixture of EGCG and L-arg each. H2O2 was added to drinking water in G3, G4 and G5. The results revealed that feed intake, egg weight, egg mass and egg production were increased in G3, G4, G5 and G1 and the same groups led to decrease FCR and mortality compared to G2. The duodenal morphology was decreased in G2 as well. In plasma, high levels of (AST, ALT, uric acid, creatinine, glucose and total cholesterol) and low levels of (LOOH, SOD, catalase, GPx, FRAP and total protein) were in favor of G2. In conclusion, supplementation of EGCG and L-arg or their mixture in diet attenuated the detrimental effect of oxidative stress through improve productive and physiological aspects of layer quails. 1. Indroduction Nowdays, domesticated poultry have become more susceptible to stress induced by pro-oxidant factors which lead to minimum ability to resist the stressful conditions in commercial farms. Oxidative stress (OS), is an imbalance status when reactive oxygen species (ROS) generation exceed cellular antioxidant system which has become a major issue and the subject of productivity and related scope in the poultry industry. The OS negatively influences animal health, welfare, and performance, subsequently influencing economic feasibility and the final product [1, 2]. In normal metabolic activity, ROS are generated endogenously and they react with basic cellular components such as lipids, proteins and DNA and stimulate pathways that lead to oxidative damage and dangerous diseases [3]. The two groups of ROS are free radicals and nonradicals. Free radicals are molecules which have one or more unpaired electrons and thus give reactivity to the molecule [4]. The 3 major ROS that are critical from physiological viewpoint are superoxide anion (O2 ̅ ̇), hydroxyl radical (HO ̇), and hydrogen peroxide (H2O2) which attack biological molecules [3, 4]. 2nd International Science Conference IOP Conf. Series: Journal of Physics: Conf. Series 1294 (2019) 092014 IOP Publishing doi:10.1088/1742-6596/1294/9/092014 2 Maintaining and improving oxidative conditions is necessary for normal physiological performance in birds which is done particularly through natural nutrition by plant-derived non nutritive compounds or supplementary feed additives [5, 6, 7]. Epigallocatechin-3-gallate (EGCG) is one of 4 major catechins derived from green tea including epigallocatechin (EGC), epicatechin-gallate (ECG) and epicatechin (EC) [8]. EGCG is one of the most abundant polyphenol, which is a powerful antioxidant against lipid peroxidation and has beneficial effects on health due to its robust anti-inflammatory, antimicrobial, antiproliferative, antimutagenic, antiaging, and anticarcinogenic characteristics [8, 9, 10]. Also, the signalling pathways including the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and nuclear factor-erythroid 2-related factor 2 (Nrf2) which fuction the regulation of antioxidant and antiinflammatory responses can be modulated through EGCG [11]. L-arginine (L-arg) is a ubiquitous essential amino acid and nutritional additive which has a considerable effect on the productive and physiological performance of birds when included in their diet [12, 13]. It well known that birds are characterized by lack a functional urea cycle or absence of most of the enzymes involved in the urea cycle thus they are unable to synthesise arginine de novo. Accordingly, the absolute requirement for arginine meet their needs for protein synthesis and other functions are important and completely depended on dietary arginine [14, 15]. The magnitude of arginine requirement is highly changeable under various environmental conditions therefore the arginine needs of the poultry has been significant interest. Under normal and stressful states, arginine plays a pivotal fuction as a necessary substrate for the immune system with modulation of protective immune response [16] and increases the antioxidant defence and improve egg quality as well as bone mineralisation [5, 12]. Recently, [17] stated that trophic amino acids including arginine, threonine, and glutamine may be beneficial in birds to modulate the intestinal microbiota and mucosa and may increase the epithelial turnover rates toward improve intestinal recovery following a pathogenic insult. The mechanism of EGCG in layer quail as model for egg production is largely undiscovered and has not been previously studied yet. Although, there are many reports in literature on arginine effect in chicken broilers and layers, few studies were found in quails especially in case of layer quails. Therefore, this study was carried out to investigate the action mode by which supplemental EGCG or L-arg or its mixture in diet would improve performance, antioxidant properties and other physiological aspects of layer Japanese quails exposed artificially to OS by H2O2. 2.Materials and Methods This study was performed in Poultry Farm and Laboratories of Al-Musaib Technical College, Babylon, Iraq. A total of 400 healthy females of Japanese quails (10 wk of age) with similar body weights (171±6g) were randomly divided into 5 groups containing 4 replicates per group and 20 birds in each replicate. The birds were reared for 8 weeks in 2×2 m 2 cages. They were kept to an open daily photoperiod and controlled temperature at 23°C with free choice of feed and water (Table 1) throughout the experiment. Females were divided in to the following groups: 1 st group: negative control (G1), 2 nd group: positive control (G2) which was exposed to oxidative stress (OS) by 0.2% H2O2 by drinking water whereas 3 rd and 4 th groups were supplemented by 500 mg/kg diet for each of EGCG and L-arg powders, respectively and 5 th group was supplemented with mixture of EGCG + Larg by 250 mg/kg diet each. The same dose of 0.2% H2O2 was offered to drinking water of females for 3 rd , 4 th and 5 th groups. EGCG and L-arg (Nanjing Health Herb Bio-Tech Co., Ltd., China) purchased from local markets. Two of these extracts were used as antioxidant substances in diet as powdery form. EGCG product contained 95% natural EGCG isolated from green tea leaves, also the puririty of L-arg was 99%. Hydrogen peroxide (H2O2) solution (P.P.H Stanlab Sp.J/Poland), 30% concentration diluted to 0.2% in big plastic cans every second day to keep its purity. This solution was used as prooxidant factor to induce artificially the incidence of OS. These additive materials served daily to birds in the whole experimental period. The layer productive performance was registered daily in the whole period of 2nd International Science Conference IOP Conf. Series: Journal of Physics: Conf. Series 1294 (2019) 092014 IOP Publishing doi:10.1088/1742-6596/1294/9/092014 3 experiment and these data presented as total mean (56 days, 8 weeks) for each replicate . These traits included the number of laid eggs, egg weight, feed intake and mortality. From feed intake and egg weight, the feed conversion ratio (FCR) based on (g/g) and (g/egg) was calculated. Also, egg production was calculated on hen day egg production (HD%) or on hen house egg production (HH%) as the following formulas: