پروار بره های با ابعاد دنبه کوچک و مقایسه آنها با دنبه بزرگتر بر عملكرد رشد صفات لاشه بره‌هاي نژاد گوسفند لري
محورهای موضوعی : فصلنامه زیست شناسی جانوری
بهروز یاراحمدی
1
,
محسن محمدی ساعی
2
,
میرحسن بیرانوند
3
,
امین کاظمی زاده
4
1 - بخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
2 - بخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
3 - بخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
4 - بخش تحقیقات علوم دامی مرکز آموزش و تحقیقات کشاورزی و منابع طبیعی لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
کلید واژه: بره‌هاي نژاد لري, دنبه کوچک, خصوصيات پرواري, ضریب تبدیل خوراک, صفات لاشه,
چکیده مقاله :
این مطالعه باهدف پروار بره‌های با دنبه كوچك در مقایسه با بره‌هاي با دنبه بزرگ بر عملکرد رشد و صفات لاشه بره‌های نژاد گوسفند لری انجام شد. به‌منظور انجام اين پروژه، تعداد 30 رأس برۀ نر بر اساس اندازه دنبه انتخاب شدند. بره‌ها با وزن حدود 30 کیلوگرمی و سن سه ماه از شیرگیری، انتخاب و به دو گروه 15 رأسی تقسیم شدند. بره‌های گروه آزمایشی شامل بره‌هایی كه عرض دنبه آنها بين 5/19-5/15 سانتي‌متر و طول دنبه 22-17 سانتي‌متر بوده و گروه شاهد تمام بره‌هایی که دنبه آنها دارای عرض بیش از 5/19 سانتي‌متر و طول دنبه 22 سانتي‌متر بودند. در پايان ميزان افزايش وزن روزانه، خوراک مصرفي و ضريب تبديل خوراک اندازه‌گيري شد. در انتهاي مرحله پروار 90 روز تعداد 8 رأس از هر گروه دنبه كوچك و دنبه بزرگ توزين و ذبح شدند و صفات لاشه اندازه‌گیری شد. با استفاده از آزمون t مستقل مقایسه دو گروه انجام شد. نتايج نشان داد بالاترين افزايش وزن روزانه در بره‌های با دنبه کوچک با ميزان 210 گرم در روز و كمترين افزايش وزن روزانه مربوط به بره‌های با اندازه دنبه بزرگتر با ميزان 182 گرم در روز بود. ضریب تبدیل خوراک در بره‌های با دنبه کوچک در مقابل بره‌های با اندازه دنبه بزرگتر (21/7 در مقابل 35/8) وضعیت بهتری داشت. بالاترين راندمان لاشه، وزن لاشه سرد و گرم، درصد قطعات لاشه و درصد گوشت لخم مربوط به بره‌های دنبه كوچك بود. ازنظر چربي كل لاشه، بين دو گروه تفاوت معني‌دار وجود داشت و بره‌هاي دنبه كوچك با 29/17درصد كمترين و دنبه بزرگ‌ها با 63/23 درصد بيشترين چربي كل لاشه را داشتند. بین بره‌های دنبه کوچک و بره‌های شاهد از نظر درصد گوشت لخم معني‌دار (05/0p <) و طول لاشه، درصد استخوان و سطح مقطع عضله راسته معني‌دار نشد (05/0p >). نتایج نشان داد قیمت هر كيلوگرم افزايش وزن به‌ازای خوراک مصرفی برای بره‌های با دنبه کوچک 65/13 درصد ارزان‌تر از بره‌های با دنبه بزرگتر بوده و از این نظر، ارزش اقتصادی بالاتری داشتند. بر اساس نتايج به‌دست‌آمده، بره‌هايي با اندازه دنبه كوچك به علت ضريب تبديل خوراک مناسب، افزايش وزن روزانه بالاتر و صفات لاشه مناسب‌تر به همراه هزينه توليد هر كيلوگرم افزايش وزن و لاشه پائين‌تر جهت پروار قابل توصيه است.
This study was conducted with the aim of fattening lambs with small fat-tail compared to lambs with large fat-tail on growth performance and carcass traits of lambs of the Lori breed. In order to carry out this project, 30 male lambs were selected based on the size of the tail. The lambs weighing about 30 kg and three months old of weaning were selected and divided into two groups of 15. The experimental group lambs included lambs whose fat-tail width was between 15.5-19.5 cm and fat-tail length 17-22 cm, and the control group included all lambs with tails with widths greater than 19.5 cm and tail length greater than 22 cm.. Finally, daily weight gain (ADG), feed intake (FI), and feed conversion ratio (FCR) were measured. At the end of the 90-day fattening phase, 8 lambs from each small-tailed and large-tailed group were weighed and slaughtered, and carcass traits were measured. The two groups were compared using an independent t-test.The results showed that the highest ADG in lambs with small fat-tail and 90 days of fattening was 210 grams per day and the lowest ADG was related to lambs with larger fat-tail of 182 g/d.The FCR was better in lambs with small fat-tail compared to lambs with larger fat-tail (7.21 vs. 8.35). The highest carcass yield, cold and hot carcass weight, percentage of carcass parts, and percentage of lean meat were in small-tailed lambs. In terms of total carcass fat, there was a significant difference between the two groups and small tail lambs had the lowest total carcass fat with 17.29% and large tail lambs had the highest total carcass fat with 23.63%. There was a significant difference between small-tailed lambs and control lambs in terms of lean meat percentage (p < 0.05) and carcass length, bone percentage and rectus muscle cross-sectional area were not significant (p > 0.05). he results showed that the cost per kilogram of weight gain per feed consumed for small-tailed lambs was 13.65% cheaper than that of larger-tailed lambs, and in this respect, they had a higher economic value. Based on the results obtained, lambs with small tail size are recommended for fattening due to their appropriate feed conversion ratio, higher daily weight gain and more suitable carcass traits along with lower production cost per kilogram of weight gain and carcass.
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