پديد آورندگان :
حبشي زاده اصل، مونا دانشگاه تبريز - دانشكده كشاورزي - گروه علوم دامي , رافت، عباس دانشگاه تبريز - دانشكده كشاورزي - گروه علوم دامي , مقدم، غلامعلي دانشگاه تبريز - دانشكده كشاورزي - گروه علوم دامي , نعمت الهي، احمد دانشگاه تبريز - دانشكده دامپزشكي , شجاع، جليل دانشگاه تبريز - دانشكده كشاورزي - گروه علوم دامي
كليدواژه :
فماچا تست , دو رگ گيري , مقاومت , بيماري , نماتود ها , انگل , گوسفند
چكيده فارسي :
زمينه مطالعاتي: امروزه در كنار صفات توليدي، ويژگي هاي مقاومت ژنتيكي دام نيز مورد توجه اصلاح گران قرار گرفته است و علاقمندي به استفاده از قابليت هاي ژنتيكي حيوان براي مقابله با بيماري ها و انگل ها فزوني يافته است.
هدف: هدف از اجراي اين طرح، بررسي مقاومت نسبي گوسفندان نژاد قزل و دو رگه هاي قزل- بلوچي در استان آذربايجان شرقي نسبت به انگل هاي داخلي بود.
روش كار: اطلاعات تحقيق از 24 راس گوسفند يكساله حاصل از دو تركيب ژنتيكي بدست آمد. گروه هاي ژنتيكي شامل 12 راس گوسفند نژاد قزل و 12 راس گوسفند آميخته ي قزل-بلوچي بود. نمونه گيري در دو نوبت و در تاريخ هاي 30/11/1390 و 14/12/1390 در ايستگاه تحقيقاتي خلعت پوشان انجام گرفت. تمامي گوسفندان متولد زمستان 1389 بودند و همه ي آنها در شرايط محيطي يكسان قرار داشتند. صفات مورد بررسي شامل وزن بدن، تعداد تخم نماتودها در هر گرم مدفوع، هماتوكريت و تست فماچا بودند. داده هاي وزن تولد و هماتوكريت توسط رويه ي GLM و بقيه صفات توسط رويه ي MIXED نرم افزارSAS آناليز شد.
نتايج: نتايج بدست آمده نشان داد كه اثر گروه ژنتيكي در مورد كل تخم نماتودهاي موجود در هر گرم مدفوع، تست فماچا و هماتوكريت ، تخم نماتوديروس و مارشالاژيا معني دار است(P<0.05). دورگ گيري قزل با بلوچي موجب افزايش مقاومت نسبي به نماتودهاي دستگاه گوارش از لحاظ صفات اندازه گيري شده در اين تحقيق است ولي دليل ژنتيكي برتري دورگ ها نسبت به نژاد خالص و آگاهي از ماهيت پلي ژني يا اثرات غير افزايشي نياز به تحقيقات بيشتر دارد.
چكيده لاتين :
Introduction: Nowadays, beside of production traits, the characteristics of genetic resistance to diseases is considered as animal breeding aims in animal breeding. There is a growing interest by producers and consumers in the production of meat animals with minimal chemical input to reduce chemical residues in the meat and to increase the sustainability of livestock production. Selection of superior sires with identified resistance should be possible because parasite resistance that usually measured by fecal egg counts (FEC) or blood packed cell volume (PCV), is moderately heritable. One option to control helminth infections is to breed sheep that are resistant to these parasites. Genetic variation in response to parasite infection has been documented in the previous studies in some sheep breeds, mostly involving tropical and subtropical breeds, such as the Red Maasai, St. Croix, Florida Native, and Barbados Blackbelly. These breeds have consistently been more resistant to trichostrongyle infections than temperate breeds, such as Dorset and Rambouillet. The objective of this study was to evaluate differences between blood packed cell volume (PCV), parasitic nematode eggs per gram of feces (FEC) and FAMACHA scores of Ghezel breed and Ghezel-Baluchi crossbreds and determine that which group is more probable resistant to nematode parasites.
Material and methods: Data were obtained from 24 one year-old lambs belonging to two genetic groups. Genetic groups including Ghezel (n= 12) and Ghezel-Baluchi (n=12) crossbreds. Ghezel × Baluchi group was containing 50% of Ghezel breed and 50% of Baluchi breed. Samples were collected at two different times on the 2012/2/19 and 2012/3/4 in the Khalat pooshan research station, Tabriz, East Azerbaijan. All lambs were born in the winter of 2011 and they were not given anthelmintic before and they were at the same environmental conditions. Fecal samples were collected directly from the rectum of animals and samples were tested by the method of Clayton Lane. The FEC were obtained for nematodes of Nematodirus (spp.), Marshallagia(spp.), Trichuris(spp.) and unknown nematode eggs. The other measured traits included body weight, PCV and Famacha test. All data except PCV were analyzed by the MIXED procedure of SAS software.Birth weight and blood packed cell volume were analyzed by the procedure of the GLM.
Results and discussion: Results showed that the effect of the genetic group on nematodes eggs per gram of feces and Famacha test was significant (P<0.01). The results of least square means showed that FEC for Nematodirus and Marshallagia and all nematode egg counts in Ghezel-Baluchi crossbred were 5.13, 7.28 and 20.3, respectively. In Ghezel breed these values were 9.41, 9.98 and 25.64, respectively. Unknown nematode eggs in Ghezel-Baluchi and Ghezel breed were 3.24 and 3.15, respectively. Effect of date was significant on all tests except the Famacha test. The results showed that the effect of the genetic groups in nematode eggs per gram of feces, Nematodirus, Marshallagia's EPG, Famacha test and PCV (P< 0.05). The results of the Famacha test for Ghezel-Baluchi with a value of 2. 59/2 were lower than the Ghezel sheep with a value of 3.1. In FAMACHA test, with an increase in the score, the amount of anemia increases. The results of the analysis of PCV indicate that in Ghezel-Baluchi sheep it was 28.92% that is higher than Ghezel sheep with a value of 23.58 (P<0.01). Some researchers reported that crossbreds are more resistant to parasitic infections than pure breeds. Furthermore, resistance to gastrointestinal nematode infection has been documented in St. Croix and Katahdin sheep breeds. The genetic mechanisms of resistance to parasites is not known clearly but they are some hypothesis that hybrid vigor's effect of crossbreds should be a probabl reason. Correlation between Famacha test and unknown nematode egg counts was low (0.08) (P<0.05).
Conclusion: The Ghezel-Baluchi crossbred ewes appeared to be more resistant to infection than the Ghezel breed in natural grazing condition. Crossbreeding of Ghezel and Baluchi sheep breeds increased resistance to internal parasites of the traits measured in this study. As a general conclusion, this research attempted to find resistance traits in relation to domestic parasites in the domestic environment. These characteristics have been investigated by veterinary parasitologists for many years, but animal breeders also need to consider the issue of improving the genetic resistance of sheep to nematodes, and more precisely how they measure the relevant traits and expressions to use in selection of breeder rams and ewes. It seems that crossbreeding of the Ghezel sheep breed with Baluchi breed increases the relative resistance to internal parasites in terms of Famacha, EPG and PCV as measured in this research. In the future there are two needed subjects in this area of animal science: a) to do more investigations to find exactly genetic explication for the relative superiority of crossbreds to pure breeds; and b) the discovery of the nature of the polygonal or non-additive nature of genetic resistance to nematodes in small ruminants.
