متاآنالیز مطالعات مربوط به تخمین پارامترهای ژنتیکی صفات اقتصادی گاو هلشتاین ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه علوم دامی، دانشکده کشاورزی؛ دانشگاه فردوسی مشهد

2 گزوه علوم دامی، دانشکده کشاورزی، دانشگاه فردوسی مشهد

3 گروه آمار، دانشکده علوم ریاضی، دانشگاه فردوسی مشهد

4 گروه علوم دامی، دانشکده کشاورزی، دانشگاه فردوسی مشهد

چکیده

سابقه و هدف: روش متاآنالیز برای تجمیع نتایج مطالعات انجام شده در زمینه برآورد پارامترهای ژنتیکی صفات تولیدی و تولیدمثلی در گاو شیری با استفاده از داده‌های مقالات موجود و رسیدن به نتایجی با صحت بالاتر مورد استفاده قرار گرفت. بدین منظور یک مطالعه متاآنالیزی، از داده‌های مربوط به 96 مقاله منتشر شده در زمینه برآورد پارامترهای ژنتیکی صفات تولیدی و تولیدمثلی گاو ‌هلشتاین، در ایران استفاده شد. صفات مورد بررسی در گاو هلشتاین شامل تولید شیر، تولید چربی شیر، تولید پروتئین شیر، درصد چربی شیر، درصد پروتئین شیر، سن اولین زایش، فاصله گوساله‌زایی، روزهای خشک، روزهای باز، طول دوره آبستنی و طول دوره شیردهی‌ بودند.
مواد و روش‌ها: ابتدا، مقادیر وراثت‌پذیری و همبستگی‌های ژنتیکی و فنوتیپی از مقالات مرتبط استخراج شد. پس از آماده‌سازی داده‌ها، -مدل متاآنالیز با اثرات تصادفی با استفاده از بسته Metacor نرم افزار R نسخه 3،3،1 و نرم افزار CMA نسخه 3 برای برآورد میانگین وزنی وراثت‌پذیری و همبستگی‌های ژنتیکی و فنوتیپی، خطای استاندارد و حدود اطمینان 95 درصدی صفات تولیدی و تولید‌مثلی مورد استفاده قرار گرفت. بررسی مطالعات موجود، نشانگر وجود ناهمگنی زیاد برای اکثر صفات مورد بررسی بود. بنابراین، برای برآورد میانگین وزنی اثرات، امکان استفاده از مدل اثر ثابت وجود نداشت. داده‌ها توسط نرم‌افزار CMA مجددا مورد تجزیه و تحلیل قرار گرفتند و نتایج حاصل از مدل اثرات تصادفی به عنوان نتایج نهایی متا‌آنالیز گزارش شد.
نتایج: میانگین وزنی وراثت‌پذیری برای صفات تولیدی در محدوده 19/0 تا 27/0 بود. بیشترین میزان وراثت‌پذیری مربوط به صفت درصد پروتئین شیر (27/0) و کمترین میزان وراثت‌پذیری مربوط به صفت تولید چربی شیر (19/0) بود. میانگین وزنی وراثت‌پذیری برای صفات تولیدمثلی در محدوده 03/0 تا 14/0 بود. در این بین میزان وراثت‌پذیری طول دوره آبستنی (14/0) از سایر صفات بیشتر و وراثت‌پذیری روزهای باز (03/0) از سایر صفات تولیدمثلی کمتر بود. میانگین وزنی همبستگی ژنتیکی برای صفات تولیدی و تولیدمثلی در محدوده 56/0- تا 88/0 و میانگین وزنی همبستگی فنوتیپی صفات در محدوده 42/0- تا 83/0 ‌بود. بررسی نتایج حاصل از متاآنالیز در این پژوهش و مقایسه آن با نتایج مطالعات انفرادی نشان داد که تجمیع نتایج مطالعات و نجزیه مجدد آنها با روش متاآنالیز از طریق کاهش خطای استاندارد سبب افزایش صحت در نتایج حاصله می‌شود. به طور مثال دامنه تغییرات وراثت‌پذیری در مقالات مورد استفاده در مورد صفت تولید شیر بین 047/0 تا 41/0 ، چربی شیر بین 05/0 تا 56/0 و پروتئین شیر بین 0 تا 7/0 بود، در حالی که پس از تجمیع نتایج توسط روش متاآنالیز، محدوده 95% برای وراثت‌پذیری این صفات به ترتیب به 23/0 تا 25/0، 17/0 تا 21/0 و 19/0 تا 29/0 کاهش یافت. از طرفی مقایسه خطای استاندارد متاآنالیز در مورد هر صفت با خطای استاندارد مطالعات نشان داد که تجمیع نتایج و افزایش حجم نمونه باعث کاهش شدید خطای استاندارد برآورد وراثت‌پذیری در صفات مورد بررسی بخصوص صفات تولیدی شد.
نتیجه‌گیری: بنابراین استفاده از روش‌هایی نظیر متآنالیز با تجمیع کلیه اطلاعات موجود منجر به بهبود برآوردها و افزایش کارائی برنامه‌های اصلاح نژادی و بهبود پیشرفت ژنتیکی صفات اقتصادی بخصوص در جمعیت‌های فاقد رکورد و یا با رکوردهای نامناسب خواهد شد.

کلیدواژه‌ها


عنوان مقاله [English]

Meta-Analysis of studies on genetic parameters of economic traits in Iranian Holstein dairy cows

نویسندگان [English]

  • Saeed Zerehdaran 1
  • Fateme Ghobakhloo 2
  • Mehdi Jabbari Nooghabi 3
  • Mohammad Mahdi Shariati 4
1 Animal Science department, Faculty of Agriculture, Ferdowsi University of Mashhad
2 Animal Science department, faculty of Agriculture, Ferdowsi University of Mashhad
3 Department of Statistics, Faculty of Mathematics Science, Ferdowsi University of Mashhad
4 Animal Science department, Faculty of Agriculture, Ferdowsi University of Mashhad
چکیده [English]

Abstract
Background and objectives: Meta-analysis method was used for gathering studies done on genetic parameters estimation in Holstein cows to increase the accuracy of estimations. For this purpose, data from 96 articles on genetic parameter estimation of productive and reproductive traits on Iranian Holstein dairy cows were used. Productive traits were milk production, amount of milk fat, amount of milk protein, milk fat percentage and milk protein percentage and reproductive traits were age at first calving, calving interval, dry days, open days, pregnancy period and lactation period.
Materials and methods: First, heritability estimates, genetic and phenotypic correlations were obtained from articles. After data preparation, the meta-analytical model with random effects using Metacor package, R 3.3.1 software and CMA ver.3 software were used for estimating weighted average of heritability and genetic and phenotypic correlations, standard errors and 95% confidence interval for productive and reproductive traits. Investigating available studies showed high heteroginty among studies. Therfore, using fixed model meta-analysis was not possible for estimating weighted average of effects. Data were reanalysid using CMA software and results of random model meta-analysis were reported as final results.
Results: The weighted average of heritability for productive traits in dairy cows were between 0.19‌ and 0.27. Milk protien percentage had the highest (0.27) and milk fat had the lowest (0.19) heritability estimates amonge productive traits. The weighted average of heritability for reproductive traits was in the range of 0.03 to 0.14. Pregnancy period (0.14) had the highest and open days had the lowest (0.03) heritability estimates amonge reproductive traits. The weighted average of genetic correlations of productive and reproductive traits was in the range of -0.56 to 0.88 and the mean weight of the phenotypic correlations of traits was in the range of -0.42 to 0.83. Comparing the results of meta-analysis in present study with the results of individual studies showed that aggregating studies and analyzing by meta-analysis improves the accuracy of the results through reducing standard errors. For example, in studied articles the range of heritability estimates for milk production were between 0.047-0.41, for milk fat were between 0.05-0.56 and for milk protein were between 0-0.7. However, after using meta-analysis method, these ranges were reduced to 0.23-0.25 for milk production, 0.17-0.21 for milk fat and 0.19-0.29 for milk protein. In addition, because of aggregating studies and increasing the amount of data, standard error of estimates in meta-analysis were considerably reduced compared to standard error of estimates in individual studies, especially for productive traits.
Conclusion: Using methods like Meta-analysis will increase the performance of breeding programs and will improve genetic progress of economic traits of animals by gathering all available information, especially for populations with no or not accurate data.

کلیدواژه‌ها [English]

  • genetic parameters
  • Genetic and phenotypic correlation
  • Heritability
  • Holstein
  • meta-analysis
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