دانشگاه تبریزپژوهش های علوم دامی (دانش کشاورزی)2008-512536120260522The effect of selenium and whole cottonseed on milk yield, milk composition and blood parameters in lactating Holstein dairy cowsاثر سلنیوم و پنبه دانه بر تولید، ترکیبات شیر وپارامترهای خونی درگاوهای شیری هلشتاین1112185410.22034/as.2022.23498.1402FAکریمالطافیگروه علوم دامی دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایراناکبرتقی زادهگروه علوم دامی دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایران0000-0002-9120-1662غلامعلیمقدمگروه علوم دامی دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایرانسیدعباس رأفتگروه علوم دامی دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایرانشهرامشیرمحمدیگروه علوم دامی دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایرانسمیرادهقانیگروه علوم دامی دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایرانJournal Article20171017Introduction: Selenium has a special place in the natural antioxidants and prevents the oxidation of cell structures. Se supplementation may also improve the efficiency of the antioxidant system; enhance the disease resistance and nutritional quality of the livestock product. Selenium is recognized as an essential trace element for domestic animals. It is a powerful catalytic element constituting the active centre of about 20 selenoproteins. As a component of these selenoproteins, Selenium displays metabolic function related to maintenance of integrity and defenses of the organism. Se supplementation may be required to improve the performance and health of dairy cow. Furthermore, Se supplementation may enhance the nutritional quality of the milk product. Two principle forms of Se, inorganic Se (sodium selenite or selenate) and organic Se (selenium-yeast [SY]), can be supplemented to cattle diets. Most studies reported that organic Se is less toxic than inorganic Se. Bioavailability of selenium-yeast has been found to be higher than that of inorganic Se sources. Most trials in dairy cattle have demonstrated that selenium-yeast leads to higher Se content in milk and in blood but also show higher Se blood levels in beef cattle. Results of selenium-yeast on milk yields and milk components from literature are inconclusive. Several studies observed that Se source and dietary Se concentration had no effect on milk yields and milk components. In contrast, other studies found that selenium may exert an effect on milk fat. These contrasting results could be due to differences in the composition of the diet and/or to the dose of selenium-yeast and lactation period of dairy cow.<br />This experiment was conducted in order to investigate the effects of selenium and whole cottonseed on milk yield, milk composition and blood parameters in lactating Holstein dairy cows.<br />Materials and Methods: In order to study effect of adding selenium source to the diets containing height levels of whole cottonseed 12 lactating Holstein dairy cows with average milk production of 25±4kg were used in complete randomized design with 2 treatments and 6 repeat for each treat. The experiment was conducted in a periods of 28 days including 21 day adaptation and 7 day sampling. Two treatments including; 1) basal diet containing 10% cottonseed, without selenium supplement and 2) basal diet + 0.3 ppm organic selenium. The cows were fed three times a day (morning, noon, and noon) with a diet that was completely mixed with appetite. Fresh water was freely available during the experimental period. The milk produced per day was recorded per meal. Production of milk for experimental animals at the beginning of the experiment and measured for seven days at the end of each experimental period. On the last day of the course, 2 hours after the morning feeding, blood samples were collected from each vetiver vein of the cow. After the clot, it was centrifuged to separate the serum. Milk production and composition were measure In the first and the last days of each period and hematologic parameters were measured at the last day of experimental period. Protein, fat, lactose and milk solids-non-fat are measured with the milkoscan machine. All statistical analyses were performed using PROC MIXED of SAS.<br />Results and Discussion: Statistical analysis showed that there were significantly effect of treatments on milk yield and 4%FCM (P<0.05). Milk yield of cows fed diets 1, 2 was 30.19, 33.98 kg/d respectively, and FCM4% were 27.70, 29.83 respectively for 2 experimental treatments. Adding selenium source to the basal diet has not any significant effects on milk composition. However selenium supplement numerically decreased the somatic cell counts (SCC) in treatments (P>0.05). The obtained data showed that selenium supplementation to diet did not have significant effect on the concentrations of serum glucose, urea-N, cratenin, Triglyceride, Cholesterol, High density lipoprotein (HDL) and Low density lipoprotein (LDL) of dairy cows, but in contrast adding of selenium to the diet significantly increased the concentration of blood glutathione peroxidase activity (P<0.05).<br />CONCLUSIONS: Finally the results indicate that supplement organic selenium to diets with high level of cottonseed Increase milk production protection effects on milk secretion cells with against oxidants and free radicals of dairy cattle. present study showed that selenium supplementation increased antioxidant capacity of serum which is reflected in improved milk production of the cows.زمینه مطالعاتی: سلنیوم یکی از آنتی اکسیدان های طبیعی میباشد که مانع اکسیداسیون ساختارهای سلولی میشود. هدف: مطالعه حاضر جهت بررسی اثر سلنیوم و پنبه دانه بر تولید، ترکیبات شیر و پارامترهای خونی در گاوهای شیری هلشتاین انجام شد. روش کار: 12 رأس گاو شیرده هلشتاین در اوایل دوره شیردهی وبا میانگین تولید 4 ± 25کیلوگرم در قالب طرح کامل تصادفی با 2 تیمار و6 تکرار برای هر تیمار مورد استفاده قرار گرفتند. آزمایش در یک دوره 28 روزه شامل 21 روز عادت دهی و 7 روز نمونه برداری اجرا شد. تیمارها شامل: تیمار اول جیره پایه محتوی 10درصد پنبه دانه بدون مکمل سلنیوم(شاهد) و تیمار دوم جیره شاهد + 3/0 پیپیام سلنیوم آلی بود. نمونهگیری از شیر و ترکیبات شیر هر دام در ابتدا و انتهای دوره و نمونه گیری خون درروز آخر دوره از ورید وداجی انجام شد. نتایج: نتایج حاصل نشان داد که افزودن سلنیوم آلی به جیره پایه حاوی سطح بالای پنبه دانه، موجب افزایش معنیدار میانگین تولید شیر و تولید شیر تصحیح شده بر اساس 4 درصد چربی شد(05/0>P) اما تاثیری بر مقدار و درصد پروتئین ، چربی، لاکتوز و مواد جامد بدون چربی شیر نداشت. همینطور تاثیر معنی داری برروی گلوگز ازت اوره ای، کراتنین و کلسترول و تری گلیسیرید و HDL و LDL نداشت. اما به طور معنی داری موجب افزایش فعالیت گلوتاتیون پراکسیداز در تیمار حاوی سلنیوم نسبت به تیمار شاهد شد.<br />نتیجه گیری نهایی: به طور کلی نتایج این مطالعه نشان داد که افزودن 3/0 پی پی ام سلنیوم آلی، به جیره های حاوی منابع چربی غیر اشباع باعث افزایش تولید شیر و ظرفیت آنتی اکسیدانی شده که موجب بهبود توان تولیدی گاوهای مورد آزمایش شد.https://animalscience.tabrizu.ac.ir/article_21854_d44524d5ae6b360fc2b88cf4f1121e23.pdfدانشگاه تبریزپژوهش های علوم دامی (دانش کشاورزی)2008-512536120260522Effect of different levels of Condensed Molasses Soluble (Vinasse) Mixed with Straw on Fattening Performance, Carcass Traits and Meat Chemical Composition in Lori Lambsاستفاده از سطوح مختلف پساب تقطیری حاصل ازکارخانه الکل سازی با بسترملاس(ویناس) مخلوط با کاه بر عملکرد پرواری، صفات لاشه و ترکیب شیمیایی گوشت بره های نژاد لری13282072010.22034/as.2025.63464.1751FAبهروزیاراحمدیبخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی لرستان ، سازمان تحقیقات، آموزش و ترویج کشاورزی، ایرانسعیدویسکرمیبخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی ،لرستان ،سازمان تحقیقات ، آموزش و ترویج کشاورزیمحسنمحمدی ساعیبخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی لرستان ، سازمان تحقیقات، آموزش و ترویج کشاورزی،Journal Article20240911Introduction: Concentrated molasses distiller condenses soluble (Vinasse) was one of the by-products of processing industries that can be used in animal feeding.Vinasse has high palatability and is considered a nutritious liquid feed for ruminants. If used in animal diets, it increases forage consumption. Vinasse due to having a high amount of degradable protein in the rumen, it increases the digestibility and increases the consumption of low-protein fiber feeds ( Moeini et al 2008). This feed contains 56% dry matter, 24.4% crude protein, 2% crude fat, 17% neutral detergent insoluble fiber (NDF), 21% starch and 12% sugar (Yarahamdi et al 2011). In order to reduce humidity, solve transportation problems, allow it to be used more easily in animal feeding, better storage for longer and more palatability, it is mixed and dried with straw, and it has a positive effect on the nutritional value of straw(Moeini et al 2014). According to the mentioned materials, the purpose of this research is to use straw mixed with molasses distiller condenses soluble (vinasse) in the sheep diet and replace part of the forage with straw mixed with molasses distiller condenses soluble (vinasse) on growth performance, carcass traits and chemical composition of meat of fattening lambs of Lori breeds.<br />Materials and methods: Seventy two Lori male lambs were selected with three months of age and average body weight 30±0.52 kg. Wheat straw was added to 700 liters of condenced molasses soluble and air dried. Experimental diets include: 1- control (straw was mixed with the basal diet without any process), 2- 2- Processing and mixing straw with 5% of vinasse, 3- 3- Processing and mixing straw with 10% vinasse, and 4- Processing and mixing straw with 15% vinasse (). Diets were formulated based on the nutritional requirements tables of small ruminants (NRC, 2007) and were prepared as total mixed ration. Average daily gain, final body weight and feed intake were measured and feed conversion ratio was calculated. At the end of experiment, three lambs of each treatment were slaughtered and carcass weight and different parts of carcass were weighted. Carcass characteristics,meat chemical composition were measured and of and cost of each kilogram of weight gain, carcass and lean meat was calculated. Data was analysed in a completely randomized design with four treatments and three replications with 6 lamb in each treatment. Initial body weight of - lambs was considered as a covariate. Data was analyzed by SAS program and mean compared with Tukey test.<br />Results and discussion: The effect of different levels of vinasse mixed with straw in the diet on the final weight and avarage gain daily (ADG) of lambs was significant. The highest ADG was related to lambs fed with 15% vinasse mixed with straw (239 gr) and the lowest daily weight gain was in lambs fed with control diet (191gr). The effect of different levels of effluent in the ration on the consumed feed was not significant, but the feed conversion coefficient was significant. By increasing the level of vinasse mixed with straw in the diet, the amount of feed consumed in lambs that received higher levels of wastewater decreased and tended to be significant. Due to the higher weight gain in the 15% vinasse mixed with straw (239gr) and the lower feed intake (1428gr), it has made it possible to achieve the appropriate final weight. The effect of different levels of vinasse mixed with straw in the diet on the feed conversion ratio (FCR) was significant. In this experiment, the weight of hot and cold carcasses in the control diet was lower than the rest of the treatments and had a significant difference with them. At the same time, with the increase of different vinasse levels, fat-tail weight, fat-tail percentage compared to cold carcass and fat percentage of the whole carcass decreased. Based on this, it can be concluded that the lambs fed with 15% of vinasse had a lower percentage of total carcass fat and total fat compared to other treatments Different levels of vinasse had a significant effect on the amount of dry matter, protein, ether extract and meat ash. Zali et al (2017) reported that in fattening calves, the weight of visceral fat decreased significantly with the increase of vinasse in the diet, and in the diet with 15% of vinasse, there was the lowest carcass fat, which is according to the findings of this research. is Also, Potter et al (1979) and Yalcin et al (2010) observed a significant reduction in carcass internal fat using vinasse. In terms of the economic value of the vinasse 15% treatment of 24.3% the price per kilogram of weight gain was lower than the control and had a higher economic value.According to the mentioned cases, lambs fed vinasse mixed with straw to the level of 15% diet due to higher ADG (239 gr), more suitable FCR (5.97) in terms of fattening status It was preferable to other lambs. Too, in terms of carcass characteristics and composition, vinas treatment with 15% reduced carcass fat percentage (6.81%), increased carcass efficiency (2.58%) and lean meat percentage (6.6%), and finally increased carcass quality.This has made the cost of producing one kilogram of live weight gain per feed consumption lower (24.3) in the treatment of 15% vinasse, and the cost of producing each kilogram of carcass and meat has a good price reduction compared to other treatments. <br />Conclusion: This study demonstrates that incorporating vinasse-straw mixtures into Lori lambs diets significantly enhances fattening performance and carcass quality, with the 15% inclusion level proving most effective. The treatment improved growth rates, feed efficiency, and lean meat yield while reducing undesirable fat deposition. Economically, it lowered production costs, highlighting vinasse as a viable feed supplement. These findings underscore the potential of vinasse-straw blends to optimize lamb production systems sustainably. Further research could explore its long-term impacts and applicability across diverse farming conditions.زمینه مطالعاتی: پساب تقطیری حاصل ازکارخانه الکل سازی با بسترملاس (ویناس) ازجمله فرآوردههای جانبی کارخانههای صنایع تبدیلی است که میتواند در تغذیه دام مورداستفاده قرار گیرد. هدف: هدف از مطالعه حاضر، بررسی اثرات استفاده از پساب الکل سازی (ویناس) مخلوط با کاه بر عملکرد پرواری، صفات لاشه و ترکیب شیمایی گوشت بره های نژاد لری بود. روش کار: برای انجام آزمایش، تعداد 72 رأس بره پرواری با میانگین وزنی 52/0±30 کیلوگرم و سن سه ماهگی در قالب طرح کاملاً تصادفی با چهار تیمار و سه تکرار با شش رأس در هر تکرار بود. وزن شروع پروار بهعنوان عامل کوواریت در نظر گرفته شد به همین دلیل از روش تجزیه کوواریانس استفاده شد. گروههای آزمایشی شامل الف- تیمار شاهد ب- تیمار کاه مخلوط شده با 5 درصد پساب الکل ج- تیمار کاه مخلوط شده با10 درصد پساب الکل د- تیمار کاه مخلوط شده با 15 درصد پساب الکل بود. نتایج: نتایج نشان داد میزان خوراک مصرفی، اضافهوزن روزانه و ضریب تبدیل خوراک تحت تأثیر سطوح مختلف ویناس درکل دوره پرورش بود و تیمار 15 درصد پساب عملکرد پرواری بالاتری داشت. اثر سطوح مختلف پساب الکل سازی روی وزن لاشه گرم و سرد، گوشت لخم، درصد چربی لاشه و عضله راسته معنیدار بود و تیمار 15 درصد پساب نسبت به سایر تیمارها برتر بود(05/0P<). سطوح مختلف ویناس تأثیر معنیداری بر میزان ماده خشک، پروتئین، عصاره اتری و خاکستر گوشت داشت و تیمار برتر 15 درصد پساب بود (05/0P<). همچنین میانگین وزن لاشه تیمار 15درصد نسبت به سایر تیمارها بیشتر بوده، علاوه بر این موجب کاهش درصد چربی لاشه، افزایش راندمان لاشه و درصد گوشت لخم و درنهایت افزایش کیفیت و ترکیب لاشه شد. نتیجهگیری نهایی: نتیجه کلی نشان داد که استفاده از 15 درصد پساب الکل مخلوط با کاه تأثیر مثبتی بر عملکرد برههای پرواری داشته و موجب درصد چربی لاشه کمتر، گوشت لخم بیشتر و درنهایت هزینههای تولید لاشه و گوشت لخم پائین تری نسبت به سایر تیمارها شد.https://animalscience.tabrizu.ac.ir/article_20720_2f7ce7ab120d974aea92e5080b2001b8.pdfدانشگاه تبریزپژوهش های علوم دامی (دانش کشاورزی)2008-512536120260522Effects of feeding of colostrum with different storages on performance, Serum immunoglobulin, hematology, diarrhea condition and colostrum microbial population in Simmental calvesاثرات تغذیه آغوز با روشهای مختلف نگهداری بر عملکرد، ایمنوگلوبولین سرم، هماتولوژی، وضعیت اسهال و جمعیت میکروبی آغوز در گوساله های سیمنتال29432039010.22034/as.2025.64456.1762FAسید حسینحسینی سابقیگروه تغذیه دام و طیور، دانشکده علوم دامی، دانشگاه علوم کشاورزی و منابع طبیعی گرگانتقیقورچیدانشگاه علوم کشاورزی و منابع طبیعی گرگانعبدالحکیمتوغدریگروه تغذیه دام و طیور، دانشکده علوم دامی، دانشگاه علوم کشاورزی و منابع طبیعی گرگان0000-0002-5198-1940محمداسدیگروه تغذیه دام و طیور - دانشکده علوم دامی -دانشگاه علوم کشاورزی و منا بع طبیعی گرگان-گرگان-ایرانJournal Article20241111Abstract<br />Introduction: Colostrum is essential for the growth and development of the calf, not only as a food but also as a passive immunity transmitter. Feeding the calf with colostrum is one of the first and important steps in calf nursing. This happens when the calf is less than a week old. Colostrum is rich in nutrients that are needed for the growth of the body and includes sufficient and required amounts of proteins, fats, carbohydrates, trace elements and vitamins. In dairy cattle management, the calf receives colostrum during the first 4 days of life, and then the colostrum is replaced by milk. The protein digestion system of the calf remains immature from birth to three weeks of age, so it is not able to break down proteins other than milk. It is necessary for the calf to receive a sufficient amount of colostrum, which is considered both in terms of immunoglobulin concentration and in terms of reducing intestinal permeability to immunoglobulin during the first 24 hours after calving (Godden et al., 2019). The colostrum received also affects the metabolism, endocrine system and nutritional status of the newborn calf. Colostrum also stimulates the development and function of the digestive tract. One of the problems and issues that most livestock farmers face is the lack of adequate intake of good quality colostrum by newborn calves (Gomez & Chamorro, 2017). Among the most important causes of calf mortality during infancy are infectious diseases such as pneumonia and diarrhea. Since the main reason for the occurrence of these diseases is the insufficient level of immunity in the calf due to insufficient intake of quality colostrum, and the calf's low ability to produce immune factors, storing sufficient amounts of colostrum in livestock for consumption in times when the newborn calf does not have access to quality colostrum is essential for its survival. Excess colostrum, which is rich in protein and fat and is produced in large quantities by cows, may be a promising alternative for calf consumption (McGrath et al., 2016). Although most farmers are aware of the importance of its storage and consumption during milk feeding, the difficulty of its storage makes it uninteresting to store and use it in various production systems. Also, there is not much information about colostrum storage methods for feeding calves in the country. This study was conducted to investigate the effect of using colostrum with different storage methods on performance, serum immunoglobulin, hematology, diarrhea status, and colostrum microbial population in Simmental calves (Robbers et al., 2021).<br />Materials and Methods: This experiment was conducted to investigate the effects of different colostrum storage methods on the performance, health indicators, colostrum nutrient absorption, dry matter digestibility and blood factors of Simmental breed calves. The number of 32 male Simmental calves with an average weight of 39.5 ± 3.2 were divided into 4 groups in a completely random design for a period of 60 days, which included newborn calves that 1- received colostrum fresh from Mothers 2- received Fermented colostrum without any additives, 3- received Fermented colostrum with the addition of low-fat yogurt, and 4- received colostrum that was kept frozen in the freezer and heated to 37 degrees before use. Eight Simmental male calves were allocated to each group the calves were completely dried at birth, then weighed and the first blood sampling was done, which included two blood samples of 5 cc in vacuum tubes containing anticoagulant for hematological tests and without anticoagulant for Biochemical tests were done from calf vein. The second blood sampling was 24 hours after birth and the last sampling was on the 30th day. The next weighing was on the 30th and 60th days. Before starting the project, a sufficient amount of colostrum was stored and after the storage was completed, colostrum was prepared and divided into simple fermentation, fermentation with yogurt groups, and frozen colostrum group. 8 samples were taken from each group of colostrum after the fermentation process, to measure pH and microbial contamination. On the 27th to 30th days from the start of the project, stool samples were collected to measure apparent digestibility.<br />Results and Discussion: The results of tests and investigations showed that consumption of colostrum with different storage methods had no significant effect on weight gain of calves. Also, no significant difference in feed consumption and digestibility was observed among the experimental groups. The amount of blood immunoglobulin in all treatments did not differ significantly from the control group. No significant changes were observed in the comparison of hematology indicators including the number of red blood cells, hematocrit percentage and blood hemoglobin level among the groups. The mean feces score, number of animals, and days of diarrhea did not show significant differences among the different treatments. No significant difference was observed in the comparison of physical indices. In this project, the quality indicators of colostrum were also examined, and it was shown that the total bacteria count in frozen colostrum group was higher than other groups (P<0.05). Also, the amount of E. coli bacteria was higher in the control and frozen groups than the two fermented groups (P<0.05). The amount of coliforms was higher in the frozen colostrum group than the others (P<0.05), followed by the control group and the fermentation group with yogurt and simple fermentation, respectively. The pH value was significantly higher in the control group, then in the frozen group and finally in the fermented groups (P<0.05).<br />Conclusion: The results of this research showed that if fresh colostrum is not available, frozen or fermented colostrum can be used for newborn calves.یکی از مسائل و مشکلاتی که اغلب دامداران با آن مواجه هستند عدم دریافت کافی آغوز با کیفیت مناسب توسط گوسالههای تازه متولد شده میباشد. ذخیرهسازی مقادیر کافی از آغوز در دامداری بهمنظور مصرف آن در مواقعی که گوساله تازه متولد شده دسترسی به آغوز با کیفیت ندارد برای بقاء آن بسیار ضروری است. هدف: این پژوهش بهمنظور بررسی تأثیر استفاده از آغوز با روشهای مختلف نگهداری بر عملکرد، ایمونوگلوبین سرم، هماتولوژی، وضعیت اسهال و جمعیت میکروبی آغوز در گوساله های سیمنتال صورت گرفت. روش کار: جهت اجرای این آزمایش از عداد 32 راس گوساله نر نژاد سمینتال با میانگین وزن 2/3 ± 5/39 در قالب طرح کاملا تصادفی برای مدت 60 روز و در 4 گروه تقسیم شدند: 1- دریافت آغوز تازه از مادر 2- دریافت آغوز تخمیر شده بدون هیچگونه افزودنی 3- دریافت آغوز تخمیر شده با افزودن ماست کم چرب و 4- دریافت آغوزی که به روش منجمد در فریزر نگهداری شده و قبل از مصرف تا دمای 37 درجه گرم شد. نتایج: نتایج نشان داد که مصرف آغوز با روشهای مختلف نگهداری اثر معنیداری بر افزایش وزن گوسالهها نداشت. همچنین در بین گروهها آزمایشی هیچ تفاوت معنی-داری در مصرف خوراک و قابلیت هضم مشاهده نگردید. ایمنوگلوبولین خون در تمامی تیمارها با گروه شاهد تفاوت معنیداری نداشت. در مقایسه میزان شاخصهای هماتولوژی شامل تعداد گلبولهای قرمز، درصد هماتوکریت و میزان هموگلوبین خون در بین گروهها تغییر معنیداری مشاهده نگردید. میانگین اسکور مدفوع، تعداد دام و روزهای ابتلا به اسهال در بین تیمارها تفاوت معنیداری نشان نداد. بررسی شاخصهای کیفیتی آغوزها نشان داد که میزان شمارش کلی باکتری در گروه آغوز منجمد بیشتر از سایر گروهها بود (05/0P˂). نتیجهگیری نهایی: نتایج این پژوهش نشان داد در صورت عدم دسترسی به آغوز تازه میتوان از آغوز منجمد و یا تخمیر شده برای گوساله تازه-متولد شده استفاده نمود.https://animalscience.tabrizu.ac.ir/article_20390_4a956900b6efa3e8ff93e4bc89f16fdd.pdfدانشگاه تبریزپژوهش های علوم دامی (دانش کشاورزی)2008-512536120260522Starch Source Digestibility and Its Effects on Production Performance and Health Parameters in Dairy Cattle: A Case Study in West Azerbaijan, Iranبررسی ارتباط بین گوارشپذیری منابع نشاستهای با شاخصهای تولید و سلامت در گاوداریهای شیری استان آذربایجان غربی45582079110.22034/as.2025.67725.1782FAبهزاداسدنژادگروه علوم دامی دانشکده کشاورزی دانشگاه ارومیهاحمدعلیصابریگروه علوم دامی دانشکده کشاورزی دانشگاه ارومیهرسولپیرمحمدیگروه علوم دامی دانشکده کشاورزی دانشگاه ارومیه. ارومیه- ایرانحامدخلیلوندی بهروزیارگروه علوم دامی دانشکده کشاورزی دانشگاه ارومیه- ارومیه-ایرانمهدیمخبرگروه علوم دامی دانشکده کشاورزی دانشگاه ارومیه- ارومیه-ایران0000-0002-7184-8426Journal Article20250606Introduction:<br />Starch stands as one of the most critical nutritional components in dairy cattle diets, serving as a primary energy source that directly influences metabolic functions, milk synthesis, and overall herd health. In typical feeding systems, common starch sources such as corn silage, corn grain, barley, and wheat are incorporated; however, these ingredients differ considerably in terms of their chemical structure, ruminal degradation kinetics, and total-tract digestibility. Such variations lead to marked differences in their effects on milk production, reproductive efficiency, and the prevalence of health disorders including dystocia, mastitis, and lameness. West Azerbaijan Province, a leading region in Iran’s dairy sector, relies heavily on locally produced starch sources like barley and corn. Despite this, there remains a notable lack of scientific data regarding the efficiency and suitability of these feedstuffs across different farm scales—small, medium, and large. This gap is particularly relevant given that farm size often correlates with differences in management capacity, feeding infrastructure, and access to technical support. Accordingly, this study was conceived to systematically evaluate the relationships between starch source utilization and key performance metrics across a range of dairy operations in West Azerbaijan. The specific objectives were threefold: (1) to analyze and compare the chemical composition and in vivo digestibility of the most commonly used starch sources—corn silage, corn grain, barley, and wheat; (2) to examine how each source relates to milk production traits, reproductive indices, and metabolic health parameters; and (3) to formulate herd-size–specific nutritional guidelines that can support enhanced productivity, welfare, and economic sustainability in the region’s diverse dairy farming systems.<br /><br />Materials and Methods:<br />A total of 31 industrial dairy farms located throughout West Azerbaijan Province were enrolled in this study. These were strategically classified according to herd size into three distinct categories: small (maintaining 15–30 milking cows, n=5), medium (31–60 cows, n=20), and large (61–150 cows, n=6). A comprehensive, multi-method data collection protocol was implemented over three consecutive months (June, July, and August) to capture seasonal variations. This included: (i) the administration of detailed, pre-tested questionnaires designed to record farm management practices, precise feed ingredient profiles, health event logs (e.g., dystocia, clinical mastitis, lameness, and metabolic issues), and reproductive performance indicators; (ii) systematic monthly sampling of all major starch-based feeds—corn silage, corn grain, barley, and wheat—as well as representative bulk-tank milk samples from each farm; and (iii) extensive laboratory analyses conducted on collected samples. Feed analyses determined dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and ether extract (EE) following established procedures outlined by the AOAC (2003). To estimate total-tract digestibility coefficients for DM, organic matter (OM), and CP, acid-insoluble ash was employed as a reliable internal marker. Milk composition parameters—specifically fat, protein, and lactose percentages—were accurately measured using a Fourier-transform infrared spectroscopy-based Milkoscan instrument. All statistical evaluations were carried out with SAS software (version 9.4). Continuous response variables (such as milk yield, composition, and digestibility values) were analyzed using mixed-effect models that accounted for repeated measures, while health incidence data (binomial outcomes) were assessed via logistic regression procedures. A probability level of P<0.05 was considered statistically significant for all tests.<br /><br />Results and Discussion:<br />The analysis revealed pronounced differences in starch source selection patterns across the three farm size categories. Smaller-scale farms demonstrated a heavy reliance on commercially formulated concentrates, which constituted approximately 75% of the starch input. In contrast, larger farms utilized significantly higher proportions of barley (55.6% of dietary starch) and corn grain (75%), reflecting greater on-farm mixing capacity and procurement flexibility. Use of wheat declined progressively as herd size increased, from 50% in small herds to 33.3% in large herds. Corn silage was a dietary staple across all systems, present in 75–88.9% of rations, though its dry matter content varied, with medium farms recording significantly higher DM (32.3%) compared to large farms (26.0%, P<0.05). Production outcomes indicated that larger farms achieved higher overall milk yields (P<0.05), although milk components—specifically fat (ranging 3.50–3.63%) and protein (3.13–3.19%)—remained statistically similar across groups. A notable temporal effect was observed in lactose content, which peaked significantly in small herds during August (4.72%, P<0.05), potentially indicating less effective heat-abatement strategies and subsequent shifts in rumen fermentation patterns during hot weather. Health monitoring data highlighted a higher incidence of dystocia in smaller herds (4.43% of calvings), possibly linked to suboptimal pre-partum nutrition. Meanwhile, larger herds reported elevated rates of metabolic disturbances, specifically acidosis (1.20%) and clinical mastitis (1.60%), likely resulting from high-concentrate feeding regimes. Reproductive performance was generally subpar across all farm types, with an average interval to first observed estrus of 68.95 days and 1.65 artificial insemination services required per conception. Most importantly, apparent total-tract digestibility estimates were consistently and significantly superior in larger herds across multiple metrics: DM (56.02% in large vs. 46.98% in small), OM (57.58% vs. 51.01%), and CP (61.60% vs. 53.47%) (P<0.05 for all). This digestibility advantage underscores the role of advanced ration balancing, consistent feed delivery, and professional nutritional oversight commonly available in larger, more resource-endowed operations.<br /><br />Conclusion:<br />This study underscores the profound influence of farm scale and associated management factors on starch utilization efficiency, milk output, and herd health under practical conditions in West Azerbaijan. Smaller farms, often constrained by limited technical expertise and feeding infrastructure, exhibited clear nutritional imbalances—including overreliance on commercial concentrates—and elevated perinatal challenges such as dystocia. Larger farms, while achieving higher milk yields and superior starch digestibility (reinforcing the nutritional superiority of corn over barley in high-yielding cows), simultaneously faced greater risks of diet-related metabolic disorders due to intensive concentrate inclusion. Seasonal fluctuations in milk lactose percentage highlighted critical gaps in environmental management, particularly heat stress mitigation, among smallholder producers. These findings collectively suggest that future feeding strategies must be tailored to herd capacity and available resources. For smaller farms, practical recommendations include dietary diversification, reduced dependence on purchased concentrates, and basic training in ration formulation. In larger, more intensive systems, focus should shift toward optimizing dietary starch-to-fiber ratios, adopting precision feeding technologies, and implementing more robust metabolic health screening protocols. At a broader level, policy interventions—such as the creation of open-access regional feed composition databases, financial incentives for high-quality forage production, and subsidized extension services—could significantly improve sustainability and animal welfare across the dairy sector. By aligning nutritional management with operational scale, producers can simultaneously enhance productivity, reduce veterinary costs, and improve overall farm resilience, thereby contributing to a more competitive and evidence-based dairy industry in Iran.چکیده<br />زمینه مطالعاتی: نشاسته بهعنوان یکی از اصلیترین منابع انرژی در جیره گاوهای شیری، نقش حیاتی در تأمین نیازهای متابولیکی، افزایش تولید شیر و حفظ سلامت دام ایفا میکند. منابع نشاستهای رایج مانند سیلوی ذرت، دانه ذرت، جو و گندم بهدلیل تفاوت در ترکیب شیمیایی، سرعت تجزیه در شکمبه و قابلیت هضم، اثرات متفاوتی بر عملکرد تولیدی و سلامت گله دارند. هدف: این مطالعه با هدف بررسی ترکیب شیمیایی و قابلیت گوارش منابع نشاستهای رایج در جیرهی گاوهای شیری (شامل سیلوی ذرت، دانه ذرت، جو و گندم) و ارزیابی ارتباط آنها با شاخصهای تولید و سلامت دام در برخی گاوداریهای صنعتی استان آذربایجان غربی انجام شد.<br />روش کار: بدین منظور، گاوداریهای مورد بررسی براساس ظرفیت به سه گروه 30-15 راس (گروه اول)، 60-31 راس (گروه دوم) و 150-61 راس (گروه سوم) تقسیم شدند: برای گردآوری دادهها، از پرسشنامهای ساختارمند استفاده شد و نمونهبرداری از خوراک و شیر در سه بازه زمانی (خرداد، تیر و مرداد) انجام گرفت. <br />نتایج: استفاده از کنسانتره آماده در گاوداریهای کوچکتر رایجتر بود (۷۵٪ در گروه اول، ۵۰٪ در گروه دوم و ۳۳/۳٪ در گروه سوم). با افزایش ظرفیت دامداری، مصرف جو و دانه ذرت بیشتر شد، در حالیکه مصرف گندم روندی کاهشی داشت. ترکیب شیمیایی منابع نشاستهای تفاوت معنیداری نشان نداد (P>0.05)، اما ماده خشک سیلوی ذرت بین گروهها اختلاف داشت و بیشترین مقدار در گروه دوم مشاهده شد. تولید شیر در واحدهای بزرگتر بیشتر بود، اما درصد چربی و پروتئین شیر تفاوت معنیداری بین گروهها و در ماههای مختلف نداشت. در مردادماه، میزان لاکتوز شیر در گاوداریهای کوچکتر بهطور معنیداری بیشتر بود (P<0.05). شاخصهای تولیدمثلی نشان دادند که میانگین اولین فحلی پس از زایش ۶۸/۹۵ روز و میانگین سرویس به ازای آبستنی ۱/۶۵ بود. سختزایی در گاوداریهای کوچکتر بیشتر دیده شد، در حالی که اسیدوز، کتوز، لنگش و ورم پستان در واحدهای بزرگتر شیوع بیشتری داشتند. همچنین قابلیت هضم ماده خشک، ماده آلی، پروتئین خام و دیواره سلولی در گاوداریهای بزرگتر بهطور معنیداری بالاتر بود (P<0.05).<br />نتیجهگیری نهایی: به طور خلاصه، یافتههای این پژوهش نشان میدهد که سطح مدیریت، بهویژه در حیطه تغذیه، عامل تعیینکننده اصلی در عملکرد، سلامت و بازده اقتصادی گاوداریهای شیری در استان آذربایجان غربی است. تمرکز بر آموزش دامداران، استفاده از آنالیز خوراک برای تنظیم جیرههای دقیق، مدیریت استرس گرمایی و پیشگیری از بیماریهای متابولیک از طریق کنترل علمی جیره، راهکارهای اساسی برای کاهش شکاف بهرهوری بین واحدهای مختلف و دستیابی به تولید پایدار و اقتصادی شیر هستند.https://animalscience.tabrizu.ac.ir/article_20791_2cf40fb4743e97f15c81b309ba503b7c.pdfدانشگاه تبریزپژوهش های علوم دامی (دانش کشاورزی)2008-512536120260522Effects of inbreeding depression for growth traits in Iranian sheep: A meta-analysis studyاثرات ناشی از هم خونی در صفات مربوط به رشد در گوسفندان ایران : مطالعه فراتحلیلی59752141810.22034/as.2026.69876.1793FAفاطمهقباخلوگروه علوم دامی، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایرانسعیدزره دارانگروه علوم دامی، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایران0000-0001-8979-9653علیجوادمنشگروه علوم دامی، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایرانJournal Article20251028Introduction: Inbreeding depression indicates a decrease in mean phenotypic value with increase in inbreeding level (Doekes et al 2021). The conventional method of livestock selection, in which animals are selected based on estimated breeding values, leads to increase in genetic achievement but also in inbreeding rates (Selvaggi et al 2010). Inbreeding is caused by increased homozygosity, which reduces the expression of dominance effects. When dominance effects are favorable (i.e., when dominance is in the desired direction), reducing the expression of dominant effects leads to a decrease in the mean phenotypic value. The degree of inbreeding may vary among traits (Doekes et al 2021). Loss of diversity and consequent increase in homozygosity may lead to reduced production in inbred animals. Furthermore, decreased inbreeding in domestic animals can lead to reduced selection response and genetic potential gains in economic traits. Therefore, it is important to estimate the effect of inbreeding on these traits in order to determine the magnitude of changes associated with increased inbreeding (Selvaggi et al 2010). The rate of inbreeding should be limited to maintain the genetic diversity at an acceptable level which is necessary for proper response to environmental changes and selection in the future (Van Wy ketal 2009). The effect of inbreeding depression on economic traits have been studied in many research studies. The results of these studies are not reliable because they come from special experimental conditions and limited sample size (Roger St-Pierrer 2007). In many cases, even contradictory results are observed from similar published studies. In such cases, meta-analysis with the nature of aggregating the results of individual studies could be used as a tool to achieve an overall result with higher reliability (Roger St-Pierrer 2007). In present study, meta-analysis was used to investigate the effect of inbreeding depression on weight at different ages in Iranian sheep based on the results of individual studies. By increasing the sample size, it is possible to comment with greater confidence on the effect of inbreeding on growth traits in Iranian sheep.<br />Materials and methods: Information related to inbreeding depression on body weight of Iranian sheep at different ages in 31 papers published in scientific journals, was used. Studied traits were birth weight, weaning weight and weights at six, nine and twelve months of age. To access these articles, a comprehensive search was conducted in Persian and English databases and journals using the keywords inbreeding, inbreeding loss, production traits, and sheep in Persian and English. The extracted data consisted of sample size and the regression coefficient between rate of inbreeding and the average of studied traits called inbreeding depression. Studies with absence of these information were removed from list of studies. Each study consisted of author name, year of publication, journal title, sample size, race, and regression coefficient presenting inbreeding depression and standard error or standard deviation. Inbreeding depressions were expressed in the form of regression coefficient in studies. Regression coefficients were converted to correlation coefficients to be used in meta-analysis. Normally, studies with significant results take more attention and publish more easily. These kinds of studies with higher chance to be repeated are called publication bias and may confuse the researchers. Funnel plot is a tool for presenting variation of studies around average. It is assumed that effects of studies must be distributed randomly and symmetrically around meta-analysis effect. In the case of publication bias, studies have an asymmetric distribution around meta-analysis effect. Funnel plot was used to check the publication bias in this study. <br />Random effects model was applied for analyzing the collected data. The meta-analysis was performed using CMA software version 3. Using the I2 and Q indices, the heterogeneity among studies was examined. Values between 0 to 25% shows very small amounts of heterogenty, values between 25 to 50% presents small heterogenty, values between 50 to 75% considerable amount of heterogenty and values higher than 75% shows high rate of heterogeneity among studies. <br />Results and discussion: The range of I2 index for fixed model was from 82.83 to 98.54. According to high heterogeneity among studies, random effect model was used for meta-analysis. According to the funnel plot, the result of the meta-analysis was free of publication bias, and on the other hand, examining the funnel plot for growth traits in this study showed that using a fixed effect model to express the results was inappropriate. The estimated correlation coefficients for birth weight were -0.001 (with confidence interval of -0.11 to 0.009), for weaning weight was -0.02 (with confidence interval of -0.443 to 0.003), for weight at six months was -0.46 (with confidence interval of -0.99 to 0.007), for weight at nine months was -0.03% (with confidence interval of -0.76 to -0.011) and for weight at twelve months was -0.09 (with confidence interval of -13.13 to -0.041). According to the P value, the result obtained from the meta-analysis showed that the effect of inbreeding depression on birth weight, weaning weight and weight at six months of age were not significant, while it has highly significant on weights at nine and twelve months of age in Iranian sheep breeds (P < 0.01). This means that with a one percent increase in inbreeding, the average of weights at nine and twelve months of age decrease by 43 and 90 grams, respectively. Therefore, using appropriate mating strategies for Iranian sheep breeds are very important for controlling inbreeding depression at 9 and 12 months of age. Choosing appropriate mating strategies in the herd to control and reduce inbreeding is important and should be considered.زمینه مطالعاتی: انتخاب دام بر اساس ارزش اصلاحی، منجر به افزایش پیشرفت ژنتیکی میشود اما به طور هم زمان منجر به افزایش نرخ همخونی نیز میشود. در مطالعات متعدد مقادیر مختلفی برای اثر افت ناشی از همخونی بر صفات مختلف ذکر شده است، که معمولا شرایط آزمایشی و اندازه محدود نمونه، سبب کاهش اعتماد به نتایج به دست آمده میگردد. در چنین مواردی یک مطالعه فراتحلیلی با به کاربردن قواعد آماری مناسب از طریق تجمیع مطالعات پیشین، نتایج مطالعات انفرادی را به نتایجی با صحت بالاتر تبدیل میکند. هدف: پژوهش حاضر اجرای یک مطالعه فراتحلیلی به منظور بررسی افت ناشی از همخونی بر صفات رشد در نژادهای گوسفند ایرانی بود. روش کار: در پژوهش حاضر، از اطلاعات 31 مقاله علمی برای انجام فراتحلیل استفاده شد. صفات مورد بررسی شامل وزنهای تولد، شیرگیری، شش ماهگی، نه ماهگی و یک سالگی بودند. اطلاعاتی شامل تعداد نمونه و ضریب تابعیت وزن بدن در سنین مختلف با افزایش همخونی برای انجام آنالیز مورد استفاده قرار گرفتند. به منظور تجزیه و تحلیل دادههای جمعآوری شده از مدل اثرات تصادفی استفاده شد و نتایج فراتحلیل با بکار بردن نرم افزار CMA نسخه 3 گزارش گردید. نتایج: با توجه به نتایج بدست آمده، دامنه شاخص I2 برای مدل اثرات ثابت از 83/82 تا 54/98 بود که در نتیجه ، از مدل اثرات تصادفی برای بیان نتایج فراتحلیل استفاده شد. با توجه به نتایج میزان همبستگی برآورد شده بین میزان هم خونی و عملکرد برای وزن تولد 0.001- ، برای وزن شیرگیری 0.02- ، برای وزن شش ماهگی 0.046- ، برای وزن نه ماهگی 0.043- و برای وزن یک سالگی 0.09- محاسبه شد. نتیجهگیری: نتایج این پژوهش نشان داد که افت ناشی از همخونی بر صفات وزن تولد، شیرگیری و شش ماهگی اثر معناداری نبود، در صورتی که به طور بسیار معنیداری سبب افت در صفات وزن نه ماهگی و یک سالگی در گوسفندان ایرانی میشود. بنابراین انتخاب راهبردهای آمیزشی مناسب در گله جهت کنترل هم خونی و جلوگیری از افت ناشی از آن در نه ماهگی و یکسالگی اهمیت فراوانی دارد و باید مد نظر قرار گیردhttps://animalscience.tabrizu.ac.ir/article_21418_f9ff5922b3b8820b1be082f5a92c689a.pdfدانشگاه تبریزپژوهش های علوم دامی (دانش کشاورزی)2008-512536120260522Measuring Structural Changes in Iranian Livestock Product Consumer Preferences: A Seasonal Time Series Analysis with Emphasis on Economic Shocksسنجش تغییرات ساختاری در ترجیحات مصرفکنندگان محصولات دامی ایران: تحلیل سری زمانی فصلی با تأکید بر تکانههای اقتصادی771012185510.22034/as.2026.70623.1798FAالهاموفائیاستادیار، مرکز پژوهشهای توسعه و آیندهنگری، تهران. ایران.مهدیپندارگروه اقتصاد کشاورزی، دانشکده اقتصاد و توسعه کشاورزی، دانشگاه تهران، کرج، ایرانمحمدرضوانیگروه اقتصاد کشاورزی، دانشکده اقتصاد و توسعه کشاورزی، دانشگاه تهران، کرج، ایرانJournal Article20251208Introduction: The livestock sector is of strategic importance as one of the key pillars for supplying protein and ensuring food security in the country. Animal products play a crucial role in community food security and account for a significant share of Iranian households' food expenditure basket. Therefore, price volatility in these products has always been a major concern for policymakers, and understanding consumer preferences is essential for grasping the nature of consumption changes and adopting appropriate policy measures. From the perspective of economic theory, consumer behavior is based on the assumption of rationality and stable preferences; meaning that any change in the consumption pattern of a good is merely a reaction to changes in price and income, and not a change in the structure of preferences. However, the exposure of the Iranian economy to severe macroeconomic shocks in recent years (including the US withdrawal from the JCPOA in 2018 and the COVID-19 pandemic) has challenged this fundamental assumption, subjecting livestock product consumption patterns to observable and structural changes. The core research question is thus raised: Are the observed changes in consumption patterns merely a rational response by consumers to budgetary constraints and external shocks, or do they indicate a structural break and a change in their underlying food preferences? The main objective of this research is to measure the rationality and stability of preferences for the livestock product basket (Red Meat, Chicken, Eggs, and Milk) and to identify the precise timing of structural breaks in consumption patterns, in response to major shocks such as the US withdrawal from the JCPOA and the COVID-19 pandemic. The key innovation of this study lies in seasonal disaggregation and conducting the structural break test using the Kruskal-Wallis (K-W) Statistic separately for warm and cold seasons. <br />Materials and Methods: This study utilizes quarterly data for the livestock products basket (Red Meat, Chicken, Eggs, and Milk) spanning the period from Spring 2015 to Winter 2022. Price and per capita consumption data for the four aforementioned products were calculated and extracted from official sources, including the Joint Stock Company for the Support of Livestock Affairs. To test the stability of consumer preferences, the non-parametric approach of the Weak (WARP) and Strong (SARP) Axioms of Revealed Preference was employed. This approach is independent of any specific functional form assumption and solely tests the consistency of the data with the condition of rationality. Initially, preference consistency was assessed across the entire period by calculating the Dual Matrix. Subsequently, the non-parametric Kruskal-Wallis (K-W) Statistic was used to determine the precise timing of instability and structural breaks. The structural break analysis using the K-W statistic is performed separately for warm seasons (Spring and Summer) and cold seasons (Autumn and Winter). This methodological disaggregation is essential to ensure that climatic effects on consumer behavior are not mistakenly interpreted as violations of the axioms or structural breaks, and that the observed results reflect only the impact of macroeconomic shocks on demand.<br />Results and Discussion: The results of the preference consistency tests indicate that consumer behavior exhibited 6 pairs of violations of the Weak Axiom of Revealed Preference (WARP) and 188 pairs of violations (equivalent to 38%) of the Strong Axiom of Revealed Preference (SARP). This high volume of contradictions in SARP confirms that consumer behavior throughout this period was not rational in terms of transitivity. The Structural break Analysis using the Kruskal-Wallis (K-W) Statistic based on WARP showed the first evidence of a structural break in Autumn 2020, with the rising trend of the statistic from Spring 2021 confirming a structural change in preferences following the COVID-19 pandemic. Analysis of the K-W statistic based on SARP confirms the existence of a structural break starting from Winter 2018, despite a temporary return to stability in Autumn 2018. Furthermore, the results of the seasonal disaggregation indicate that in the Warm Seasons (Spring and Summer), no WARP violations were observed, but a structural break based on SARP occurred starting from Spring 2020. In the Cold Seasons (Autumn and Winter), only one WARP violation was recorded. However, the SARP analysis showed the first break in Autumn 2018, which subsequently led to intermittent instability in preferences rather than a permanent break. <br />Conclusion: <br />The current research delivers a clear policy message: Structural break in consumer preferences for animal products is not a mere statistical anomaly but reflects a decline in real purchasing power and a sharp rise in market uncertainty. The Kruskal-Wallis statistic confirms this Structural break and severe SARP violations are linked to economic shocks and reduced household buying power. Therefore, the primary policy recommendation is indirect intervention via stable monetary and foreign exchange policies, as short-term support measures are ineffective until exchange rate fluctuations and general inflation are controlled. Furthermore, due to the substitution effect observed during cold seasons and economic shocks (like the shift from red meat to cheaper chicken and eggs, destabilizing preferences), it's crucial to re-evaluate income support programs for lower-income deciles (such as electronic coupon) and to stabilize the supply chain of substitute goods to prevent further Structural break and a drop in overall animal protein consumption. Finally, policymakers should avoid interpreting Structural break as a change in consumer taste and, instead of relying on temporary measures (like the Preferential Exchange Rate in 2018), must accept preference instability as a new structural reality when formulating policies. These findings emphasize that price shocks immediately resulted in non-transitive changes and substitution in the consumption basket. Therefore, policymakers are advised to, in addition to strengthening macroeconomic stability, utilize tools such as electronic coupon to compensate for the substitution effects and prevent a further decline in animal protein consumption.زمینه مطالعاتی: پژوهش حاضر در بستر تئوری ترجیحات آشکار شده و با تأکید بر تکانههای مختلف بر رفتار مصرفکنندگان قرار میگیرد. بررسی با پایداری ترجیحات مصرفکنندگان سبد محصولات دامی ایران (شامل گوشت قرمز، مرغ، تخممرغ و شیر) در دوره زمانی بهار ۱۳۹۴ تا زمستان ۱۴۰۱ و در مواجهه با تکانههای کلان اقتصادی، اهمیت بالایی دارد. هدف: هدف این پژوهش سنجش عقلایی بودن و پایداری ترجیحات مصرفکنندگان سبد محصولات دامی و شناسایی زمان وقوع شکست ساختاری در الگوهای مصرف، در پاسخ به تکانههای مهمی از جمله خروج آمریکا از برجام و همهگیری کووید-19 است. روش کار: این پژوهش از رویکرد ناپارامتریک اصول ضعیف و قوی ترجیحات آشکار شده (WARP و SARP) برای تحلیل دادههای فصلی استفاده کرده است. به منظور سنجش پایداری ترجیحات، ابتدا سنجش سازگاری ترجیحات در کل دوره زمانی صورت گرفت. سپس، برای شناسایی زمان و مکان نقضها، تحلیل شکست ساختاری با استفاده از آماره کراسکال-والیس ((K−W)) بر اساس هر دو اصل و با تفکیک فصول گرم و سرد انجام شد. نتایج: نتایج نشان داد که رفتار مصرفکنندگان دارای ۶ جفت نقض در WARP و ۱۸۸ جفت نقض در SARP بوده است که مؤید عدم تعدیپذیری است. آماره K−W بر اساس WARP، اولین شواهد از شکست ساختاری را در پاییز ۱۳۹۹ نشان داد که روند صعودی آماره از بهار ۱۴۰۰، مؤید تغییر ساختاری ترجیحات پس از همهگیری کووید-۱۹ است. تحلیل آماره K−W بر اساس SARP، وجود شکست ساختاری را از زمستان ۱۳۹۷ تأیید میکند. همچنین، در فصول گرم، شکست ساختاری بر اساس SARP از بهار ۱۳۹۹ رخ داده است. در مقابل، در فصول سرد، اولین شکست در پاییز ۱۳۹۷ رخ داده است. نتیجهگیری نهایی: این یافتهها تأکید میکند که تکانههای قیمتی بلافاصله منجر به تغییرات غیرمتعدی و جایگزینی در سبد مصرفی شده است. بنابراین به سیاستگذاران توصیه میشود علاوه بر تقویت ثبات کلان اقتصادی، از ابزارهایی چون کالابرگ برای جبران اثرات جایگزینی و جلوگیری از کاهش بیشتر مصرف پروتئین دامی استفاده کنند.https://animalscience.tabrizu.ac.ir/article_21855_1a87fa513564a3aa7d524f0a3ddf292c.pdf