پديد آورندگان :
موسوي، اسماء دانشگاه صنعتي اصفهان - دانشكده كشاورزي - گروه علوم دامي , مهدوي، اميرحسين دانشگاه صنعتي اصفهان - دانشكده كشاورزي - گروه علوم دامي , رياسي، احمد دانشگاه صنعتي اصفهان - دانشكده كشاورزي - گروه علوم دامي , حسيني، حسين شركت داروسازي باريج اسانس - گروه تحقيقات كشاورزي
كليدواژه :
اسيدهاي چرب , پاسخ هاي ايمني , پسماند گياهان دارويي , فراسنجه ها خوني , كيفيت تخم مرغ , مرغ تخمگذار
چكيده لاتين :
Introduction: It has been demonstrated that an enhancement in n-3 polyunsaturated fatty acids of the eggs can suppress the saturated fatty acids, and therefore it causes to production of eggs with better lipid profile as well as nutritional contents (Hayat et al., 2010); however, the eggs containing higher levels of omega-3 polyunsaturated fatty acids make them more susceptible to lipid peroxidation (Baucells et al., 2000). Nowadays, the scientists utilize the medicinal plants or theirs byproductsas beneficial natural antioxidants (Jirovetz et al., 2006). Therefore, the current study was carried out to assess the effect of different levels of herbal by-product mixture on some blood parameters, immunological responses and egg quality of laying hens received different omega-6 to omega-3 ratios.
Material and methods: A total of 120 laying hens, 40 weeks of age, were assigned to 6 experimental diets with 4 replicates and 5 birds in each replication. Dietary treatments consisted of three levels of medicinal plants’ by-product (0, 2.5 and 5%) and two omega-6 to omega-3 ratios (15.12 and 1.65) in a 2×3 factorial arrangement based on completely randomized design. The experiment lasted for a total of 80-d including 10 d for adaptation and 70 d as main recording period.Birds were housed in a windowless hall containing battery cages (45 × 50 cm2) with the light program of 16L: 8D. Hens had free access to water and to the experimental diets. Body weights were recorded at the beginning and at the end of the experimental period. Three eggs were collected from each replicate on days 35 and 70, and egg quality indices including shape index, yolk index, Haugh unit, yolk color, eggshell weight, eggshell thickness, and eggshell breaking strength were measured. Yolk cholesterol of three eggs per replicate was extracted by the Folch method, with consideration of the modifications done by Washburn and Nix (1974) at the end of study and estimated by the colorimetric Libermann-Burchard method. Blood samples of two hens per replicate were collected at the final trial day and centrifuged (3000×g for 15 min). Sera samples were harvested and stored (−20°C) until further analysis for concentrations of serum cholesterol, triglycerides and HDL, and also the enzymatic activity of serum glutamic pyruvic transaminase, serum glutamic-oxaloacetic transaminase, and alkaline phosphatase by using turbidometric method as described by Hosseini-Vashan et al. (2012). The concentration of malondialdehyde(MDA) was assessed by the method of Badraoui et al. (2009) with minor modifications. On d 70 of trial, 500 μl of serum was mixed by 3.75 ml of 0.44 mol/l phosphoric acid, 1.25 ml 0.67% thiobarbiotic acid, and 2.5 ml distilled water. The mixture was incubated at 100 °C for 1 h. After cooling, it was centrifuged at 4,000×g for 10 min and the absorbance was measured at 532 nm using an automated spectrophotometer. On d 41 of the trial, Newcastle vaccine was sprayed and three hens of each cage were randomly selected after one week and bled from wing vein. Sera were separated by centrifugation (5000 × g for 10 min) and antibody titers against Newcastle disease virus were measured by Hemagglutination halter test using commercially available V-form ELISA plates according to the manufacturer’s instructions.Two randomly selected birds 70 days of age from each pen were bled and differential counts of leukocytes were performed by screening a Gimsa-stained slide. The different subpopulations of leukocytes were enumerated and the heterophil:lymphocyte ratio was calculated as described by Stedman et al. (2001).
Results and discussion: Feeding low dietary ratio of omega-6 to omega-3 led to a significant increase in serum malondialdehyde concentration (P<0.05) and egg colour index (P<0.05), and also a remarkable decrease in serum alkaline phosphatase enzyme activity (P<0.05), serum triglyceride, (P<0.05) and yolk cholesterol concentrations (P<0.01). As indicated by Al-Daraji et al. (2010), serum enzymes activities were decreased in laying quail received supplemental fish oil; however, Alparslan and Zdogan (2006) showed that serum glutamic-oxaloacetic transaminase was higher in broilers fed fish oil. Moreover, herbal by-product mixture caused an improvement in antibody titer against Newcastle disease virus (P<0.05) and lymphocytes percentage (P<0.05) as well as egg yolk colour index (P<0.01), eggshell hardness (P<0.05) and Haugh unit (P<0.05). Improvement in humoral immune responses by medicinal plants, such as rosemary, thyme, oregano and clove bud (Nadia et al. 2008; Taheri Gandomani et al. 2014) in layers has been seen due to the remarkable antioxidant activities of these bioactive compounds (Labban, 2014). In addition, level of 5% herbal by-product mixture in diet was led to a reduction in heterophil percentage (P<0.05), blood cholesterol and triglyceride concentrations (P<0.05), and alkaline phosphatase and serum glutamic pyruvic transaminase enzyme activities (P<0.05). A decrease in serum cholesterol concentration could be related to hypocholesteromic activity of herbal essential oils via hepatic 3- hydroxyl -3-methyl-glutaryl-coenzyme A reductase inhibition, the rate-limiting enzyme of cholesterol biosynthesis in smooth endoplasmic reticulum (Srinivasan, 2004), and also stimulation of hepatic cholesterol-7- hydroxylase converting cholesterol to bile acids leading to facilitate the biliary cholesterol extraction (Babu and Srinivasan, 1997).
Conclusion: Our results indicated that though feeding low dietary ratio of omega-6 to omega-3 decreased serum triglyceride and cholesterol concentrations, yolk cholesterol content and liver enzymes activities, it increased the probability of lipid peroxidation. Furthermore, supplementation of the highest level of herbal by-product blend could improve the liver health indexes, cellular immunity responses and eggshell hardness.
