Genetic Evaluation of some Carcass Characteristics Assessed by in vivo Real Time Ultrasonography in Baluchi Sheep
محورهای موضوعی : Camel
ع. محمدی
1
(Department of Animal and Poultry Breeding and Genetics, Gorgan University of Agricultural Science and Natural Resources, Gorgan, Iran)
س. حسنی
2
(دانشگاه علوم کشاورزی و منابع طبیعی گرگان)
س. زره داران
3
(Department of Animal Science, Ferdowsi University of Mashhad, Mashhad, Iran)
م. باقری
4
(Veterinary Clinic, Near Laleh Residential Complex, Asian Highway, Mashhad, Iran)
ع. میرشاهی
5
(Department of Clinical Science, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran)
کلید واژه: genetic parameters, backfat thickness, Baluchi sheep, longissimus muscle area, ultrasound measurements,
چکیده مقاله :
In order to evaluate carcass characteristics of a nucleus flock of Baluchi sheep, in vivo ultrasound technique was used to measure backfat thickness (UBFT) and longissimus dorsi muscle area (ULMA) and also to estimate genetic parameters for these ultrasonic traits and live weights in different ages. The data were collected from 576 animals during 2011. (Co)variance components were estimated by univariate and bivariate animal models using restricted maximum likelihood and Asreml software. Females had higher UBFT and ULMA than males. Estimates of direct heritabilities were 0.32, 0.23, 0.27, 0.02, 0.12, 0.22 and 0.18 for UBFT, ULMA, birth weight (BW0), weaning weight (BW3), 6 month weight (BW6), 9 month weight (BW9) and yearling weight (BW12), respectively. There were positive and high genetic (0.68±0.15) and phenotypic (0.62±0.03) correlations between UBFT and ULMA. The genetic correlations among ultrasonic and pre 6 month weights were positive and low except for BW0 and ULMA (0.39±0.28). Contrarily, moderate to high positive genetic correlations between ultrasonic traits and weaning and post-weaning weights were found (0.33 to 0.61). Phenotypic correlations between ultrasonic and growth traits were positive and ranged from 0.09 to 0.37. High positive genetic correlation between UBFT and ULMA suggests that selection for larger muscle mass result in higher fat carcasses.
در تحقیق حاضر، به منظور ارزیابی خصوصیات لاشه یک گله هسته اصلاح نژادی گوسفند بلوچی از روش اولتراسوند در موجود زنده برای اندازهگیری ضخامت چربی پشت و مساحت ماهیچه کمر و نیز تخمین پارامترهای ژنتیکی برای این صفات اولتراسونیک و اوزان زنده در سنین مختلف استفاده شد. داده‌ها از 576 حیوان در سال 1390 جمع‌آوری شد. اجزاء (کو) واریانس با استفاده از مدلهای حیوانی یک متغیره و دو متغیره با روش حداکثر درستنمایی محدود شده و نرمافزارASREML تخمین زده شدند. حیوانات ماده ضخامت چربی پشت و مساحت ماهیچه کمر بیشتری نسبت به حیوانات نر داشتند. تخمینهای وراثت‌پذیری مستقیم برای ضخامت چربی پشت، مساحت ماهیچه کمر، وزن تولد، وزن شیرگیری، وزن شش ماهگی، وزن نه ماهگی و وزن یکسالگی به ترتیب برابر با 32/0، 23/0، 27/0، 02/0، 12/0، 22/0 و 18/0 بود. همبستگی ژنتیکی (15/0±68/0) و فنوتیپی (03/0±62/0) مثبت و بالایی بین ضخامت چربی پشت و مساحت ماهیچه کمر وجود داشت. همبستگیهای ژنتیکی بین صفات اولتراسونیک و اوزان قبل از شش ماهگی به استثناء وزن تولد و مساحت ناحیه کمر (28/0±39/0) مثبت و پایین بود. برعکس، همبستگیهای ژنتیکی مثبت متوسط تا بالایی بین صفات اولتراسونیک و اوزان شیرگیری و پس از شیرگیری وجود داشت (33/0 تا 61/0). همبستگیهای فنوتیپی بین صفات اولتراسونیک و رشد مثبت و در دامنه 09/0 تا 37/0 متغیر بود. همبستگی ژنتیکی مثبت و بالای بین ضخامت چربی پشت و مساحت ماهیچه کمر نشان می‌دهد که انتخاب برای توده ماهیچه بزرگتر باعث تولید لاشههایی با چربی بیشتر می‌شود.
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