اثر سطوح مختلف روغن كتان بر عملكرد، تجزيه پذيري، برخي از فراسنجه هاي خوني و صفات كمي و كيفي گوشت در بره هاي پرواري

Effect of different levels of linseed oil on performance, degradability, digestibility, some blood parameters, quantitative and qualitative traits of meat in fattening lambs

اين تحقيق به منظور بررسي تأثير مصرف سطوح مختلف روغن دانه كتان بر تجزيه پذيري، عملكرد، خصوصيات لاشه و فراسنجه ­هاي خوني در بره هاي پرواري انجام شد. در آزمايش اول، تجزيه پذيري شكمبه‌اي ماده خشك، پروتئين خام و NDF جيره­ هاي آزمايشي با استفاده از روش كيسه نايلوني و با 3 رأس گوسفند داراي فيستولاي شكمبه­ اي نژاد زل تغذيه شده در حد نگهداري اندازه ­گيري شد. زمان­هاي شكمبه گذاري در اين آزمايش شامل زمان هاي صفر، 4، 8، 16، 24، 36، 48، 72 و 96 ساعت بود. نتايج نشان داد كه تفاوت معني­ داري در تجزيه پذيري ماده خشك و پروتئين خام بين تيمارها در اين آزمايش مشاهده نشد. در آزمايش دوم، 16 رأس بره نر (وزن 2±27 كيلوگرم و سن حدود پنج ماهگي) براي بررسي اثرات سطوح مختلف روغن كتان بر عملكرد، خصوصيات لاشه و فراسنجه­ هاي خوني، در قالب طرح كاملاً تصادفي با 4 جيره آزمايشي (حاوي صفر، 1/5، 3 و 4/5 درصد روغن كتان) به مدت 90 روز پروار شدند. جيره ­ها از نظر انرژي و پروتئين قابل متابوليسم مشابه بودند. جيره‌هاي آزمايشي اثر معني‌داري بر خوراك مصرفي داشت، علاوه بر اين بره ­هاي تغذيه شده با جيره حاوي 4/5 درصد روغن كتان بيشترين تأثير منفي را بر قابليت هضم مواد مغذي جيره كاملاً مخلوط نشان دادند. همچنين جيره حاوي روغن كتان باعث ايجاد اختلاف معني‌دار در برخي از خصوصيات لاشه بره‌ها نسبت به تيمار شاهد شد. روغن كتان سبب افزايش سهم اسيد لينولئيك، اسيد لينولنيك و نسبت اسيدهاي چرب غيراشباع با چند پيوند دوگانه به اسيدهاي چرب اشباع چربي داخل ماهيچه­ اي در لاشه بره هاي پرواري شد. همچنين روغن كتان تأثير معني­ داري بر فراسنجه ­هاي خوني دام هاي پرواري داشت. نتيجه كلي حاصل از اين تحقيق نشان داد كه با افزايش سطح روغن كتان ، ميانگين تجزيه پذيري الياف نامحلول در شوينده خنثي، مصرف خوراك، و قابليت هضم ظاهري مواد مغذي روند كاهشي داشت ولي در صفات كيفي لاشه بهبود حاصل شد.

Introduction1 The extracted oil from linen contains about 50% linolenic acid from the family of omega-3 fatty acids. Among edible sources, fish oil and linseed oil are a rich source of omega-3 fatty acids. Linoleic acid and linolenic acid are a key factor in the normal growth and reproduction of animal, were not considered an important issue for animal nutrition. Essential fatty acids, including linoleic acid, linolenic acid and arachidonic acid, and in recent years the demand for foods with omega-3 long-chain fatty acid conjugated linoleic acid is high because of important biological role of these fatty acids in the body. Alpha-linolenic acid is an essential fatty acid that cannot be manufactured by the human body, but are essential for the body's metabolism. Although mammals cannot make omega-3 fatty acids, but have limited functionality in the form of fatty acid. Linseed has a high linolenic acid as a substrate for the synthesis of long-chain omega-3 fatty acid that for the (EPA), which is the precursor for eicosanoids. Eicosanoid are similar compounds of hormones that play an essential role in the immune response. In addition, EPA can become (DHA), which is an essential fatty acid in cell tissue layers of the eye and brain. The objective of this study was to evaluate the effects of linseed oil on degradability, performance, carcass characteristics and some blood parameters in fattening lambs Material and methods In first experiment, ruminal degradability of dry matter, crude protein, NDF and ADF were measured by nylon bag technique using three fistulated Zell sheep that fed at maintenance level. Incubation time consisted of 0, 4, 8, 16, 24, 36, 48, 72 and 96. The experimental animal were kept in individual cage and fed at 8 am and 20 pm with experimental diet to ratio of 70 to 30 forage to concentrate. In the second experiment, the effects of various levels of linseed oil on performance, carcass characteristics and blood parameters were studied. The performed experiment was completely randomized design (CRD) with four diets containing zero, 1.5, 3 and 4.5 percent linseed oil on 16 male lambs with initial average weight 27± 2 kg and 5-6 months old for 90 days. Energy and chemical composition of rations were similar. The experimental diet was balanced using the Small Ruminants Nutrition System (SRNS). Monthly weighing was carried out at the end of the experiment by applying 12 hours of starvation before weighing, and daily feed intake was used to calculate the feed conversion ratio. Data obtained were analyzed by statistical software SAS (version 1.9). Results and discussion Dry matter degradability significantly affected by experimental treatments (P<0.05). However, the crude protein, NDF and ADF not observed significant difference between treatments. In first experiment, ruminal degradability of dry matter, crude protein, NDF and ADF were measured by nylon bag technique using three fistulated Zell sheep that fed at maintenance level. Incubation time consisted of 0, 4, 8, 16, 24, 36, 48, 72 and 96 h. Dry matter degradability and crude protein not observed significant difference between treatments. In the second experiment, experimental diets had significant effect on feed intake also results of the current experiment showed that linseed oil in 4.5% of dry matter had most negative effects on nutrient digestibility of total mixed ration (P< 0/05). Diet contained linseed oil and thyme oil affected some carcass characteristics significantly compared to other treatments (P<0/05). Linseed oil increased C18:3, C18:2 and P/S ratio (P<0.05). Linseed oil had a significant effect on the blood parameters of treatments. Conclusion In general, degradation of dry matter results showed that adding linseed oil, had little effect on the degradation of dry matter and protein and numerically, was reduced compared to control. With increasing the level of linseed oil in the diet, the mean of NDF degradability, feed intake, and apparent digestibility of nutrients was a downward trend and did not improve these indices. In this study, adding linseed oil improved daily gain and feed conversion ratio compared to the control. The carcass fatty acids, omega-3 fatty acids increased, which is an indicator of health. The overall result of this study showed that increasing the level of linseed oil decreased the average degradation of NDF, feed intake and digestibility of nutrients but improved the carcass quality traits.