پديد آورندگان :
اسلمي نژاد ، علي اصغر نويسنده , , ساقي، داود علي نويسنده , , داشاب، غلامرضا نويسنده , , ضابطيان، مهسا نويسنده ,
چكيده فارسي :
ماندگاري بره ها تا زمان عرضه به بازار يكي از فاكتورهاي مهم و تاثير گذار بر اقتصاد دامپروري مي باشد عوامل محيطي از قبيل آب و هوا، مديريت و ساير عوامل غير ژنتيكي مثل سن مادر، تيپ تولد، چند قلو زايي و وزن تولد اثر بسيار مهمي بر زنده ماني بره ها دارند. به منظور ارزيابي عوامل موثر بر زنده ماني در بره هاي بلوچي از9989 ركورد جمع آوري شده توسط مركز اصلاح نژاد شمالشرق كشور (عباس آباد) در طي 20 سال گذشته (از سال 1362 الي 1388) استفاده شد. صفات مورد مطالعه عبارت بودند از بقا از تولد تا 10 روزگي، تولد تا 30 روزگي، تولد تا 60 و تولد تا 90 روزگي كه هريك از اين صفات به صورت جداگانه با در نظر گرفتن عوامل ثابت شامل گله، سال، جنس، نوع تولد، سن مادر و عامل كواريت وزن تولد (خطي و درجه دوم) توسط نرم افزار SAS مورد تجزيه و تحليل آماري قرار گرفتند. از 9989 بره بدنيا آمده 5174 (5/51 درصد) بره نر و 4847 (5/48 درصد) بره ماده بودند كه 56 درصد كل بره ها تك قلو، 42 درصد دو قلو و 2 درصد سه قلو بدنيا آمده بودند. در بره هاي تك قلو 5/1 درصد قبل از ده روز اول، 1/4 درصد و68/6 درصد، 8/7 درصد به ترتيب قبل از 30، 60 و 90 روز بعد از تولد تلف شده بودند. نتايج نشان داد كه بره هاي نر نسبت به بره هاي ماده از تولد تا شيرگيري كمتر تلف مي شوند و بره هاي تك و دو قلو نسبت به سه قلو ها بيشتر زنده مي مانند همچنين بره هاي بدنيا آمده از ميش هاي دو ساله نسبت به بره هاي بدنيا آمده از ساير ميش ها بيشتر زنده ماندند. متوسط وزن بره هاي بدنيا آمده 28/4 كيلو گرم بود كه بره هاي نر نسبت به ماده ها (4/4 در مقابل 1/4 كيلوگرم) همچنين بره هاي تك قلو نسبت به بره هاي دو يا چند قلو (6/4 در مقابل 8/3 و 3/3 كيلوگرم) سنگين تر بودند. رابطه خطي و درجه دوم وزن تولد با زنده ماني تا 10 ، 30 ، 60 و 90 روز بعد از تولد معني دار بود. حداكثر زنده ماني از تولد تا شيرگيري در بره هايي با وزن تولد 5 كيلوگرم بود در حالي كه ميانگين وزن تولد گله 3/4 كيلوگرم بود. وزن تولد مطلوب براي تك، دو سه قلو به ترتيب 7، 5 و 3/4 كيلوگرم با زنده ماني 93 ، 93 و 92 درصد بود. بره هاي ماده زنده ماني بيشتري نسبت به بره هاي نردر وزن مشابه داشتند.
چكيده لاتين :
Lamb survival is one of the major factors affecting overall sheep productivity. Lamb survival affected by environmental effect such as management, birth-type, year, season of birth, dam-age, maternal behavior, genotype of parents, and birth-weight. The data comprised 9989 records were collected from 1989 to 2009 in Iranian Baluchi sheep at Abbasabad sheep breeding station. Four binary traits created, value 0 was assigned for lambs dead and 1 for lambs alive at certain ages. Cumulative survival to day 10, 30, 60 and 90 (weaning) was calculated. Birth-weight, litter-size, birth-type, dam-age and birth-year considered in analysis. Statistical analyses of cumulative lamb survival at 10, 30, 60 and 90 days after birth analyzed by application of logistic model with binary response variable. Analysis of variance for cumulative survival each trait separately were analyzed using SAS with a linear model. The fixed effects of the model included dam-age, birth-year, birth-type, herd and sex. From 9989 lambs born at Abbasabad station over the period 1989-2009, There were 5147 (51.5%) lambs born as male and 4847 (48.5%) female which that 5583 (56%) lambs as singles 4239 (42%) as twins and 167 (2%) as triplet. Among the singles, 79 (1.5%) were dead at 10days after birth, 229 (4.1%), 373 (6.68%), 435 (7.8%) died at 30, 60 and 90 days after birth respectively. The results indicated survival of male lambs less than female at from birth to weaning, single and twin born lambs were more survival than triplet at each age. Lamb born from ewes 2 years old or in first parity had lowest survival compared with other parities. The least survival occurred in first parity as result of lack of maternal experiences of ewes at that stage. Average birth weight all lambs was 4.28 ± 0.7 Kg. male lambs had heavier birth weight than female lambs (4.4 ± 0.7 vs. 4.1 ± 0.6) also single born lambs (4.6 ± 0.6) heavier than twin or triplet born lambs 3.8 ± 0.6 , 3.3± 0.6 respectively . Linear and quadratic of birth-weight had significant effect on survival at 10, 30, 60 and 90days after birth. There was a curvilinear relationship between birth-weight and survival from birth to weaning. Survival for during birth to weaning maximized at 5 Kg although average birth-weight in this study was 4.3 Kg. Optimum birth-weight for survival of single, twin and triplet born lambs were 7, 5 and 4.3 Kg with (0.93, 0.93 and 0.92 %) survival compared average birth-weight at single, twin and triplet (4.6, 3.8 and 3.3 Kg) with (0.92, 0.92 and 0.91 %) survival. Female lambs had greater survival rate than male lambs at the same weight (1 to 2 %) Survival was maximized at 7 Kg birth weight for female (94 vs. 91.5% at average birth-weight) and male at 5 Kg which was only slightly heavier than average birth weight of 4.4 Kg.
