اثر مکمل سازی آرژنین و تراکم جمعیت بر عملکرد رشد، ریخت شناسی روده، شاخص های خونی و کیفیت گوشت در جوجه های گوشتی آرین و راس

مطالعه حاضر به منظور مقایسه عملکرد جوجه های گوشتی سویه آرین و راس و بررسی مکمل آرژنین بر عملکرد رشد، ریخت شناسی روده، شاخص های خونی و کیفیت گوشت در شرایط تراکم جمعیت انجام شد. در این آزمایش از 224 قطعه جوجه گوشتی یک روزه سویه آرین و 224 قطعه جوجه گوشتی یک روزه سویه راس استفاده شد. آزمایش در قالب طرح کاملاً تصادفی با آرایش فاکتوریل 2×2×2 با استفاده از دو سویه جوجه (آرین و راس) و دو سطح تراکم (12 و 16 پرنده در متر مربع) و دو سطح اسیدآمینه آرژنین (100 و 130 درصد پیشنهاد کاتالوگ آرین) با هشت تیمار و پنج تکرار اجرا شد. آثار متقابل نشان داد پرندگان هر دو سویه راس و آرین در تراکم بالا و سطح 100 درصد آرژنین، کمترین میزان افزایش وزن روزانه را داشتند (0.05>p). در دوره پایانی 1، کمترین ضریب تبدیل خوراک در گروه سویه آرین، تراکم پایین و سطح 130 درصد آرژنین مشاهده شد (0.05>p). تراکم بالا موجب کاهش غلظت آلبومین و پروتئین کل و افزایش غلظت گلوکز، کلسترول و فعالیت آنزیم آسپارتات آمینوترانسفراز شد (0.05>p). غلظت کلسترول در هر دو سویه با افزایش تراکم، بالا رفت ولی در گروهی که سطح بالای آرژنین استفاده شد، کاهش یافت (0.05>p). ارتفاع، عرض پرز و سطح جذب روده در تراکم بالای پرورش، کاهش یافت. آثار متقابل نشان داد کمترین سطح جذب پرز در سویه آرین، تراکم 16 و سطح 100 درصد آرژنین مشاهده شد (0.05>p). تراکم بالای جمعیت موجب کاهش ظرفیت نگهداری آب و افزایش افت ناشی از پخت شد و در مقابل، افزایش درصد آرژنین سبب افزایش ظرفیت نگهداری آب و کاهش افت ناشی از پخت شد (0.05>p). به طور کلی، نتایج نشان داد سویه راس نسبت به آرین، افزایش وزن روزانه و مصرف خوراک روزانه بالاتری نشان داد. تراکم بالای جمعیت در هر دو سویه، تاثیر منفی بر عملکرد، ریخت شناسی روده، کیفیت گوشت و بعضی از شاخص های خونی داشت.

effect of arginine supplementation and stocking density on growth performance, intestinal morphology, blood indices, and meat quality of arian and ross broiler chickens

introduction: many variables must be considered in broiler production to achieve maximum profits. the selection of an appropriate broiler strain and optimal stocking density are among the key factors for maximizing economic returns. today, several strains such as ross, arian, cobb, and arbor acres are available in the iranian market, each with specific rearing guidelines based on their genetic modifications. maintaining an optimal stocking density throughout the production cycle is economically important. the study therefore compared the iranian arian strain and the ross strain with different stocking densities (12 and 16 birds per square metre, respectively). higher density can lead to stress, and arginine plays a critical role in the urea cycle and protein synthesis. it serves as a precursor for the production of polyamines, creatine, and especially nitric oxide (no). in conditions of environmental stress, such as heat or oxidative stress, the role of arginine is even more important because of its role in the formation of no. therefore, in addition to broiler strain and stocking density, the study included the use of arginine.materials and methods: a total of 448 one-day-old chicks (224 arian and 224 ross) of both sexes were used in a 42-day feeding trial. the experiment was conducted in a completely randomized design in a 2×2×2 factorial arrangement with two broiler strains (arian and ross), two stocking densities (12 and 16 birds/ square metre), and two levels of dietary arginine (100 and 130% of the arian catalog recommendation). there were eight treatments with five replicates. experimental diets were formulated for four phases: starter, grower, finisher 1, and finisher 2. feed intake and body weight gain were recorded during the starter, grower, finisher 1, and finisher 2 periods. the feed conversion ratio (fcr) was calculated. at the end of the experiment (42 days), two birds were randomly selected from each replicate for blood sampling from the wing vein to measure blood parameters. to evaluate intestinal morphology, two birds from each pen were slaughtered at 42 days. a 4-cm section was taken from the jejunum (10 cm before meckel’s diverticulum) and fixed in 10% formalin after washing with physiological saline. to measure meat quality traits including water holding capacity (whc), ph, drip loss (dl), and cooking loss (cl), two birds were randomly selected from each replicate at 42 days, and the left thigh muscle was collected. data were analyzed using minitab 16 software. data were analyzed using the general linear model (glm), and treatment means were compared using tukey’s test at p<0.05.results and discussion: the results showed that the ross strain had a higher feed intake than the arian strain (p<0.05). high stocking density significantly reduced feed intake throughout the entire period (p<0.05). in the starter phase, the use of 130% of the recommended arginine level increased feed intake compared to the 100% level (p<0.05). ross strain chicks receiving 130% arginine also had a higher feed intake. the average daily weight gain of the ross strain was significantly higher than that of the arian strain during the grower phase and over the entire period (p<0.05). stocking density reduced the average daily weight gain in the finisher 1, finisher 2, and entire periods (p<0.05). the use of 130% arginine improved daily weight gain in these phases (p<0.05). ross broilers reared at a density of 12 birds per square meter exhibited the highest daily weight gain during the finisher 2 phase compared to the ross and arian strains at 16 birds per square meter (p<0.05). ross chicks receiving 130% arginine had higher daily weight gains than those receiving 100% arginine (p<0.05). in the finisher 2 and overall periods, broilers raised at a density of 16 birds per square meter and fed 100% arginine had the lowest daily weight gain compared to other treatments (p<0.05). both ross and arian broilers reared at high stocking density and fed 100% arginine had the lowest daily weight gain. the fcr of the arian strain in the starter phase was lower than that of the ross strain. high stocking density improved fcr in the starter phase, but it increased fcr in the finisher 2 and overall periods (p<0.05). the use of 130% arginine significantly improved fcr in broilers (p<0.05). in the finisher 1 and overall periods, arian broilers reared at low stocking density had better fcr than those at high density. in the finisher 2 phase, ross broilers reared at low stocking density had better fcr than those at high density. the results indicated that rearing both ross and arian strains at low stocking density improved fcr. in the finisher 1 phase, the lowest fcr was observed in the ross strain fed 100% arginine and the arian strain fed 130% arginine. over the entire period, arian broilers fed 100% arginine had the highest fcr compared to other levels. the interaction of stocking density × arginine showed that the highest fcr was observed in birds reared at 16 birds per square meter and fed 100% arginine. the interaction of strain × stocking density × arginine had a significant effect on fcr in the finisher 1 phase (p<0.05), with the lowest fcr observed in the arian strain, reared at 12 birds per square meter, and fed 130% arginine. increased stocking density reduced albumin and total protein concentrations and increased blood glucose concentration (p<0.05). higher stocking density significantly reduced albumin concentration in both ross and arian strains compared to arian birds reared at lower density. the interaction of strain × stocking density × arginine significantly affected total protein concentration (p<0.05), with the highest level observed in the ross strain reared at 12 birds per square meter and fed 130% arginine. high stocking density increased cholesterol concentration (p<0.05). the 130% arginine level reduced cholesterol concentration compared to 100% arginine (p<0.05). increased stocking density also raised ast concentration (p<0.05). ross broilers had greater villus width and absorption surface area (p<0.05). high stocking density reduced villus length, width, and absorption surface area (p<0.05). the highest absorption surface area was observed in the ross strain reared at 12 birds per square meter and fed 100% arginine, while the lowest was in the arian strain reared at 16 birds per square meter and fed 100% arginine (p<0.05). higher stocking density reduced water-holding capacity and increased cooking loss (p<0.05). increased arginine levels improved water-holding capacity and reduced cooking loss (p<0.05).conclusions: overall, the results of this study indicated that the ross strain had higher feed intake and daily weight gain compared to the arian strain, though their feed conversion ratios did not significantly differ. stocking density harmed performance indices during the late and overall phases of the trial. the ross strain showed a better response to arginine supplementation at high stocking densities than the arian strain. the use of arginine supplementation can mitigate the negative effects of high stocking density and improve broiler performance.