اثرات استفاده از سطوح مختلف پودر سماق در جیره مرغ‌های تخمگذار بر عملکرد تولید و صفات کیفی تخم مرغ تحت شرایط مختلف نگهداری

Introduction: Natural sources of antioxidants have been gained an intense interest in poultry nutrition studies due to their potential impacts on birds’ performance, blood parameters, and immune system (Peschel et al., 2006). These beneficial impacts, which have mainly been addressed to the improvements in the health and function of the gastrointestinal tract and nutrients digestion, are attributed to the bioactive compounds found in herbal plants (Simitzis et al., 2008). Sumac (Rhus coriaria) which belongs to the Anacardiaceae family is an herbal plant that contains a vast range of beneficial compounds, including myricetin, phenolic acids, quercetin, L-ascorbic acid, benzoic acid, gallic acid, and other organic acids (Kheiri et al., 2015, Özcan and Haciseferogullari, 2004). Also, Sumac fruit has also been reported to contain high fiber (14.6%, fresh content) (Ozcan and Haciseferogullari, 2004) and fat (18.74% dry matter (DM)) accompanied by low levels of crude protein (4.69% DM) and ash (2.93%) (Raodah et al., 2014). The internal quality of an egg, the most potential, safe, and accessible source of protein worldwide, losses over the storage time. Thus, it is assumed that Sumac fruit powder (SFP) may help to improve egg quality for long storage duration. It has been proven that storing eggs at high ambient temperature reduces their internal quality by accelerating CO2 emission through the eggshell (Chukwuka et al. 2011). Moreover, it has been shown that the CO2 emission increases the albumin pH significantly, which subsequently decreases the internal quality traits of the egg by weakening the protein bonds between lysozyme and ovomucin (Ahn et al. 1999). The effects of non-herbal antioxidants and, in some cases, the inorganic antioxidants, such as selenium, on these parameters have been well studied. However, there are limited studies that have investigated the effects of herbal antioxidants, especially Sumac fruit powder.
Material and Methods: One hundred-twenty laying hens (Hy-line W-36), 53 weeks of age, were distributed in three experimental groups with five replicates, and eight birds per replicate with similar body weights (1394 ± 42g) by employing a completely randomized design. Corn-soybean meal-based diets were formulated according to Hy-line W-36 nutritional management guide (2020) and fed for eight weeks. Experimental diets included a) zero sumac (control), b) 0.25% sumac, and c) 0.5% sumac supplemented treatments. Performance parameters, including egg yield, egg weight, egg mass, feed conversion ratio, and feed intake, were recorded throughout the experiment. Egg quality traits were evaluated in two experiments (the first phase, at the end of the experiment, and the second phase, after being stored in different conditions). In the first experiment, internal and external quality traits, were evaluated after storing the eggs under different conditions. Total phenolic compounds were measured using Gallic acid as the standard by a spectrophotometer (model M501; Unicosh Co, China) in a wavelength of 765 nm light absorbance as described by (Golzadeh et al., 2012). Total phenolic compounds were determined using collected supernatants in the colorimetric method by sodium carbonate (Na2CO3) 20% in Folin-Ciocalteau reagent (Merck Co. Germany) and measuring wavelength absorbance at 720 nm. The results showed that SFP used in the present study contained 45.61 mg/g total phenolic compounds. The data obtained at the present study were statistically analyzed using GLM PROC of SAS software Ver. 9.2 (SAS, 2009). The significance of the differences among means were also determined by Tukey test, where the P-Values below 0.05 were considered as significant. A completely randomized design one, and a 3×2×2 factorial arrangements was used for experiment one and two, respectively.
Results and Discussion: The results indicated that egg production (EP) and egg mass (EM) were decreased in the groups of birds fed with SFP supplemented diets (P<0.05), however, feed conversion ratio (FCR) increased significantly (P<0.05). These responses were in line with the previous studies where the researchers believed that a monocyclic monoterpene component and polyphenolic compounds found in sumac fruit contents are responsible for low lipid absorption and biliary acid reabsorption from the gut, respectively (Gumus et al., 2018, Ikeda et al., 1992). Evaluating of internal and external quality egg traits in experiment one showed that Haugh unit (HU) and egg density (ED) decreased (P<0.05); while, the yolk height (YH), yolk index (YI), yolk pH (YpH), and albumen pH (ApH) significantly increased by SFP supplementation (P<0.05). These responses are generally attributed to the impacts of polyphenolic compounds, since previous studies have found a strong relationship between these compounds and the protein bonds of egg white, and therefore, ApH, HU, egg density (ED), YH, etc. (Ahn et al., 1999). These results were in agreement with previous studies (Arpášová et al., 2014). Regarding the internal quality traits of the eggs stored in different conditions, the main effects of SFP supplementation on HU and ApH of the stored eggs were significant (P<0.05 and increased HU and reduced ApH. Moreover, the main effects of storage time and temperature on the internal quality traits of the eggs were significant in all measured parameters, except for YpH (P<0.05). A significant interaction was found between the SFP levels and storage time on YI and YH (P<0.05). Furthermore, significant interactions were observed between SFP levels and storage temperature on ApH and YpH (P<0.05). The storage time and the storage temperature interactions on HU and YpH were also significant (P<0.05); briefly, the results indicated that the more storage time and temperature increased, HU unit and YpH decreased. These observations confirmed previous findings (Mirghelenj et al., 2017b) regarding capability of natural sources of antioxidants in preventing internal quality reduction of eggs under different storage conditions; probably by inhibiting lipid peroxidation in the vitelline membrane of yolk, and therefore, pH alteration (Ahn et al., 1999). Finally, no significant interactions were detected among all three independent variables in internal quality traits of the egg.
Conclusion: According to the results obtained in this study, SFP supplementation in laying hens' diet significantly reduced production performance and egg quality traits throughout the experiment; however, it was capable of maintaining the internal quality of the eggs during different storage conditions.
Keywords: Natural antioxidant, egg quality, sumac, production performance, laying hen, herbal plant.