Phenotypic and Genetic Analysis of Lori-Bakhtiari Lamb's Longevity Up to Yearling Age for Autosomal and Sex-Linked Chromosomes

محورهای موضوعی : Camel

آ. سالمی ¹ , م. وطن خواه ² , ب. اسدی ³

1 - Department of Animal Science, Behbahan Branch, Islamic Azad University, Behbahan, Iran
2 - Department of Animal Science Research, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Center, AREEO, Shahrekord, Iran
3 - Department of Animal Science, Behbahan Branch, Islamic Azad University, Behbahan, Iran

تاریخ دریافت : 1395/05/17 تاریخ پذیرش : 1395/08/25 تاریخ انتشار : 1395/12/11

کلید واژه: Longevity, autosomal and sex-linked, Lori-Bakhtiari lambs,

چکیده مقاله :

The data set used in this study contained 8793 records of lamb's longevity (days) from 320 sires and 2349 dams collected during 1989 to 2014, from the Lori-Bakhtiari flock at Shooli station in Shahrekord, Iran. Genetic parameters (partitioned into autosomal, sex-linked and maternal) and breeding values of cumulative lamb's longevity from birth up to yearling age (at 1, 2, 3, 6, 9 and 12 months) were estimated using restricted maximum likelihood procedure. The results showed that the overall mean of the cumulative longevity of lamb up to yearling (12 months of age) was 295.87 days. The effect of fixed factors; year and month of birth, sex of lamb, age of dam, lamb birth weight as quadratic covariate and dam body weight as linear covariate were significant (P<0.05) on lamb's longevity. The heritability estimates of lamb's longevity were low and ranged from 0.01 to 0.08 for autosomal, 0.01 for sex-linked and 0.02 to 0.03 for maternal additive genetic effects. The estimates of autosomal, sex-linked and maternal genetic correlations of lamb's longevity in different ages were high. The pearson and spearman correlation coefficients between autosomal breeding values and sex-linked breeding values in lamb's longevity at different ages were 0.15 to 0.46 and 0.11 to 0.43 respectively. Thus, lamb's longevity up to yearling can be improved by farm management practices and improving environmental factors at first. Genetic analysis using linear models which able to estimate breeding values in direct (autosomal and sex-linked chromosomes separately) and maternal effects, could be more effective to improve longevity in lambs.

چکیده انگلیسی:

در این پژوهش از رکوردهای طول عمر تعداد 8793 رأس بره، حاصل از 320 رأس قوچ و 2349 رأس میش، مربوط به گله ایستگاه پرورش و اصلاح نژاد گوسفند لری بختیاری (ایستگاه شولی) واقع در شهرکرد، جمع‌آوری شده طی سال‌های 1368 تا 1393 استفاده گردید. پارامترهای ژنتیکی (به تفکیک اتوزومی، وابسته به جنس و مادری) و ارزش‌های اصلاحی صفات با استفاده از روش حداکثر درست نمایی محدود شده برآورد گردیدند. نتایج نشان داد که میانگین کل تجمعی طول عمر بره‌ها از تولد تا سن یک سالگی 87/295 روز بود. اثر عوامل ثابت سال و ماه تولد، جنس بره، سن مادر و متغیرهای کمکی وزن تولد بره‌ها به صورت درجه دو و وزن بدن مادر بر طول عمر بره‌ها معنی‌دار (05/0P<) ولی نوع تولد غیر ‌معنی‌دار (05/0P>) بودند. برآورد وراثت‌پذیری اتوزومی (01/0 تا 08/0)، وابسته به جنس (01/0) و مادری (02/0 تا 03/0) طول عمر بره‌ها در حد پایین بودند. همبستگی‌های ژنتیکی اتوزومی، وابسته به جنس و مادری برای طول عمر بره‌ها در سنین مختلف در حد بالا بودند. ضرایب همبستگی پیرسون و رتبه‌ای، بین ارزش های اصلاحی اتوزومی و وابسته به جنس در سنین مختلف برای طول عمر بره‌ها به ترتیب (08/0 تا 46/0) و (11/0 تا 43/0) برآورد شدند. بنابراین، به منظور بهبود زنده مانی و طول عمر بره‌ها ابتدا بایستی شرایط محیطی را بهبود بخشید. تجزیه ژنتیکی طول عمر بره‌ها با استفاده از مدل‌های خطی که قادر به برآورد ارزش‌های اصلاحی کروموزوم‌های اتوزومی و جنسی باشند، می‌تواند انتخاب ژنتیکی مؤثر‌تری برای بهبود طول عمر بره‌ها ایجاد نماید.

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