تاثیر سطوح مختلف ال-کارنیتین بر عملکرد رشد، صفات لاشه، سیستم ایمنی، جمعیت میکروبی روده کور، بافت شناسی روده باریک، و ترکیب اسیدهای چرب گوشت سینه جوجه های گوشتی

زمینه مطالعاتی: ال-کارنیتین برای کاهش تجمع چربی در بدن و حفظ سلامت طیور مفید است. هدف: این آزمایش به منظور بررسی امکان بهبود عملکرد رشد، صفات لاشه، فراسنجه‌های خونی و ایمنی جوجه‌های گوشتی با افزودن ال-کارنیتین به جیره، انجام شد. روش کار: آزمایش در قالب طرح کاملاً تصادفی با 3 تیمار، 4 تکرار و 10 قطعه جوجه گوشتی نر سویه راس 308 در هر تکرار به مدت 42 روز انجام شد. تیمارهای آزمایشی شامل 3 سطح ال کارنیتین (0، 200 و 400 میلی‌گرم/کیلوگرم) بودند که در ترکیب با جیره پایه مورد استفاده قرار گرفتند.. نتایج: در دوره پایانی آزمایش، جوجه‌های تغذیه شده با جیره حاوی 400 میلی‌گرم/ کیلوگرم ال-کارنیتین بطور معنی‌داری دارای خوراک مصرفی و ضریب تبدیل کمتر و افزایش وزن بیشتری (3/1 درصد) نسبت به شاهد بودند (0.05>p). افزایش سطح ال-کارنیتین بطور معنی‌داری موجب افزایش کارایی شاخص تولید اروپایی شد (0.05>p). کاربرد 400 میلی‌گرم/ کیلوگرم ال-کارنیتین بطور معنی‌داری (0.05>p) موجب کاهش چربی بطنی، کلسترول، تری‌گلیسیرید، لیپوپروتئین با دانسیته خیلی کم (vldl) و افزایش پروتئین کل و hdl شد. تیتر آنتی بادی علیه ویروس نیوکاسل، اﯾﻤﻮﻧﻮﮔﻠﻮﺑﻮﻟﯿﻦ ﮐﻞ در 35 و 42 روزگی با کاربرد ال-کارنیتین به‌طور معنی‌داری (0.05>p) افزایش یافت. ال-کارنیتین در بهبود خواص حسی گوشت سینه اثر مثبت و معنادار (0.05>p) داشت. بیشترین مقدار اولئیک اسید (18:1c) و لینولئیک اسید (18:2c) در گوشت سینه به‌ترتیب با کاربرد 200 و 400 میلی‌گرم/کیلو گرم ال-کارنیتین بدست آمد. همچنین طول پرز روده با افزایش سطح ال-کارنیتین در جیره افزایش و عمق کریپت کاهش یافت. نتیجه‌گیری نهایی: با توجه به اثر مثبت ال-کارنیتین در پژوهش حاضر، تکمیل جیره جوجه‌های گوشتی سویه راس 308 با 400 میلی‌گرم/ کیلوگرم ال-کارنیتین جهت بهبود عملکرد رشد، کاهش چربی بطنی، بهبود فراسنجه‌های خونی و ایمنی و افزایش اسیدهای چرب ضروری لاشه، قابل توصیه است.

Effect of different levels of Lcarnitine on growth performance, carcass characteristics, abdominal fat, Blood plasma components, immune system, microbial flora of the cecum, small intestinal histology, sensory properties of breast meat and profiles of fatty acids of breast meat in broilers

LCarnitine (βhydroxyγtrimethylaminobutyric) is produced in living organisms through food and the biosynthesis of the amino acids lysine and methionine in the liver, kidney, skeletal muscle and brain and then enters the bloodstream. One of the most important functions of Lcarnitine in the body is to produce energy, facilitate the entry of long chain fatty acids into the mitochondria, facilitate the exit of short and medium chain fatty acids into the mitochondria, eliminate the toxic effects of acyl groups in cells, regulate the ratio of coenzymeA versus acyl coenzymeA in the cytosol and mitochondria. Lcarnitine is a plasma lipidlowering drug that lowers cholesterol, triglycerides, free fatty acids, phospholipids and lowdensity lipoproteins, while increases highdensity lipoproteins. Supplementation of poultry diets with Lcarnitine in has been reported to be effective in controlling blood lipids, abdominal fat pad and poultry health. This study aims to investigate the effects of Lcarnitine on growth performance, carcass characteristics, abdominal fat, blood biochemical parameters, immune system, cecal microflora, histology of jejenum, taste properties of breast meat and fatty acid composition of breast meat of broilers. Material and methods: The experiment was performed in a completely randomized design with 3 treatments, 4 replicates, with 10 broiler chicks with the approximate weights of 45±2g in each pen having the dimension of 1.5×1.5m2 and a total number of 120 chicks during 42 days. The experimental treatments included 3 levels of Lcarnitine (0, 200 and 400 mg/kg) in cornsoybean meal basal diet. The effects of experimental treatments were analyzed by SAS software and the comparison of the means with Duncan’s multiplerange test at 5% significance level. Body weight gain, feed intake, and feed conversion ratio (FCR) were calculated at the end of feeding phases to evaluate the traits. European Production Efficiency Factor (Aviagen 2018), carcass characteristics (Farrokhyan et al. 2014), blood parameters (Hosseinitabar et al. 2015), immune system (Seidavi et al. 2014), breast meat fatty acid (Folch et al. 1957) cecal microbial population, histology of the small intestine were calculated at the end of experiment (42 days). Results and discussion: In the finisher period of the experiment, the chickens fed by a diet containing 400 mg/kg Lcarnitine significantly had lower feed intake and FCR as well as the highest weight gain compared to the control (p < 0.05) ). The reason for the increase in weight of the chickens fed by Lcarnitine may be due to the effect of this substance on increasing the insulinlike growth factorI and also the elevated access of chickens to the energy of feed (Kita et al. 2002). Rabie and Szilagyi (1998) reported that the effect of Lcarnitine on improving FCR is related to improving nitrogen metabolism. Elevated levels of Lcarnitine significantly increased the European Production Efficiency Factor (P <0.05) in which the highest European Production Efficiency Factor (312.75) was obtained by consuming 400 mg/kg of Lcarnitine. The application of Lcarnitine significantly reduced abdominal fat pad (p < 0.05) and the lowest was obtained by consuming 400 mg/kg Lcarnitine. Lcarnitine reduces fat accumulation in tissues by altering fat metabolism (Burtle et al. 1994). Heart weight increased and the weight of duodenum decreased with the supplemntation of Lcarnitine (p < 0.05). The level of cholesterol, triglycerides, and very lowdensity lipoprotein (VLDL) decreased with Lcarnitine compared to the control (P <0.05). Lcarnitine also increased total protein and HDL compared to the control. The effect of Lcarnitine on albumin and glucose levels was not significant (P≥0.05). Zhang et al. (2010) reported that Lcarnitine reduces blood triglycerides in broilers by increasing the catabolism of fatty acids. On the other hand, Cartwright (1986) believes that Lcarnitine reduces the serum triglyceride by increasing the activity of lipase enzyme. The weight of the immune system organs (spleen, thymus, and bursa of Fabricius) were not affected by Lcarnitine supplemntation (P≥0.05). The antibody titer against the Newcastle virus and the level of total immunoglobulin against SRBC was significantly increased at 35 and 42 days of age with the use of Lcarnitine (p < 0.05). A group of researchers stated that Lcarnitine improves the humoral response to vaccination and boosts the immune system in broilers and laying hens by producing monoclonal antibodies and increasing the tendency of white blood cells to remove foreign agents (Mast et al. 2000, Deng et al. 2006). Lcarnitine Supplementation of broilers diet significantly (p < 0.05) reduced the population of clostridium, Escherichia coli, coliform bacteria and increased the population of Lactobacillus bacteria The health of digestive system is a necessity to increase performance and profitability in poultry farming. The balance between the grampositive and negative microbial populations plays an important role in the health of the digestive system. In a healthy digestive system, the population of grampositive bacteria is predominant (Norreh et al. 2015). LCarnitine had a positive and significant effect on improving the sensory properties of breast meat (P <0.05) and increased the flavor of breast meat. The highest amounts of oleic acid (18: 1c) and linoleic acid (18: 2c) in breast meat were obtained using 200 and 400 mg/kg Lcarnitine, respectively. Also, the length of the intestinal villi increased and the depth of the crypt decreased with increasing Lcarnitine level in the diet. Lcarnitine appears to improve intestinal histology by affecting the intestine microflora, reducing harmful bacteria, and increasing lactobacilli. Conclusion: Considering the positive effect of Lcarnitine on the traits measured in the present study, supplementing the diet of Ross 308 broiler chickens with 400 mg/kg Lcarnitine is recommended to improve growth performance, carcass characteristics, blood parameters, function of immune system, cecal microbial population, histology of the small intestine, and composition of breast meat fatty acids of broiler.