Genetic Analysis of Ewe Productivity Traits in Baluchi Sheep
محورهای موضوعی : Camel
م. جعفراوغلی
1
(
دانشکده کشاورزی، دانشگاه پیام نور
)
ع. صفری
2
(
Department of Animal Science, Faculty of Agricultural Science, University of Guilan, Rasht, Iran
)
ع.ا. شادپرور
3
(
Department of Animal Science, Faculty of Agricultural Science, University of Guilan, Rasht, Iran
)
ن. قوی حسین-زاده
4
(
Department of Animal Science, Faculty of Agricultural Science, University of Guilan, Rasht, Iran
)
کلید واژه: reproduction traits, heritability, genetic parameters, repeatability, Baluchi sheep,
چکیده مقاله :
The present study was carried out to estimate (co)variance components and genetic parameters for some productivity traits of Baluchi ewes. The data were collected during a 31 year period (1984-2014) at the experimental breeding station of Baluchi sheep, which is located in north-east of Mashhad, Iran. The analysis was based on 14030 records of lambs and 4371 records of ewes. Investigated traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB) and litter mean weight per lamb weaned (LMWLW) as basic traits, total litter weight at birth (TLWB) and total litter weight at weaning (TLWW) as composite traits. Genetic analysis of the studied traits was performed applying restricted maximum likelihood (REML) procedure by fitting a linear mixed animal model. Direct heritability estimate for LSB, LSW, LMWLB, LMWLW, TLWB and TLWW were 0.10, 0.08, 0.13, 0.07, 0.12 and 0.05, respectively. Corresponding values for repeatability estimates were 0.18, 0.17, 0.19, 0.15, 0.18 and 0.15, respectively. Direct genetic correlation estimates among the studied traits varied from -0.52 for LSW and LMWLB to 0.99 for TLWB and TLWW. Phenotypic and environmental correlation estimates were generally lower than those of genetic ones. Although low direct heritability’s were estimated for the reproductive traits, as these traits are of interest then they used as the primary selection criterion to bring about genetic improvement in ewe productivity traits.
مطالعه حاضر برای برآورد اجزای (کو)واریانس و پارامترهای ژنتیکی تعدادی از صفات تولیدمثلی میشهای نژاد بلوچی انجام شد. دادههای مورد بررسی در طول 31 سال (2014-1984) در ایستگاه اصلاح نژاد گوسفند بلوچی که در شمال شرقی خراسان قرار دارد، جمع‌آوری شده بود. تعداد 14030 رکورد بره و 4371 رکورد میش مورد بررسی قرار گرفت. صفات مورد بررسی شامل؛ تعداد برههای بدنیا آمده (LSB)، تعداد برههای از شیرگیری شده (LSW)، میانگین وزن برههای بدنیا آمده (LMWLB)، میانگین وزن برههای از شیرگیری شده (LMWLW) به ازای هر رأس میش به عنوان صفات اصلی و صفات مجموع وزن برههای بدنیا آمده (TLWB) و مجموع وزن برههای از شیرگیری شده (TLWW) به ازای هر رأس میش به عنوان صفات ترکیبی بودند. ارزیابی ژنتیکی به روش REML تحت مدل حیوان انجام شد. مقادیر وراثت پذیری LSB، LSW، LMWLB، LMWLW، TLWB و TLWW به ترتیب 10/0، 08/0، 13/0، 07/0، 12/0 و 05/0 و تکرار‌پذیری به ترتیب 18/0، 17/0، 19/0، 15/0، 18/0 و 15/0 برآورد گردید. همبستگی ژنتیکی صفات مورد بررسی از 52/0- بین LSW و LMWLB تا 99/0 بین TLWB و TLWW متغیر بود. همبستگیهای فنوتیپی و محیطی برآورد شده به مراتب کمتر از مقادیر ژنتیکی بودند. اگرچه همبستگی ژنتیکی مستقیم کمتری برای صفات تولیدمثلی برآورد شد اما تمایل بسیاری برای قرار دادن در معیار انتخاب و بهبود ژنتیکی صفات تولیدمثلی وجود دارد.
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