پديد آورنده :
فروتن، مهرنوش
عنوان :
آناليز ژنتيكي مرگ و مير گوساله هاي شيري و تليسه هاي جايگزين در گله هاي گاو شيري
مقطع تحصيلي :
كارشناسي ارشد
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي
صفحه شمار :
ده، 61ص.: مصور، جدول
يادداشت :
ص.ع. به فارسي و انگليسي
استاد راهنما :
سعيد انصاري مهياري، محمدعلي ادريس
توصيفگر ها :
مدل خطي , مدل آستانه اي , پارامترهاي ژنتيكي , همبستگي اسپيرمن
تاريخ نمايه سازي :
19/10/91
استاد داور :
غلامرضا قرباني، آقافخرميرلوحي
تاريخ ورود اطلاعات :
1396/09/22
چكيده فارسي :
به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي
چكيده انگليسي :
Genetic Analysis of Mortality in Dairy Calves and Replacement Heifers in Dairy Herds Mehrnush Forutan mehrnush forutan@gmail com Date of Submission September17 2012 Department of Animal Science Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Saeid Ansari Mahyari s ansari@cc iut ac ir Mohammad Ali Edriss edriss@cc iut ac ir Abstract Mortality of calves is not only costly for dairy cattle farmers but it is also a problem related to animal health and welfare This study was carried out to estimate genetic parameters of mortality in female calves in different age groups until an age of 760 d nearly first calving Records of 123256 female calves born in the years 1998 to 2011from 60 Holstein dairy herds in Isfahan province were used Six age periods of mortality 1 to 30 d 31 to 180 d 181 to 365 d 366 to 760 d d 1 to 450 and the full period 1 to 760 d were considered Records of animals slaughtered or exported within a defined period were set to missing values whereas their records were kept for preceding periods After data editing records of 52311 female calves born in the years 1998 to 2009 from 50 Holstein dairy herds were used The pedigree consisted of 519 sires and 993 animals and for the estimation of genetic parameters linear sire model and threshold sire model were applied Effects accounted for were fixed effects of herd year season number of dam s parity calving ease and twin as well as the random effect sire Mortality rates were 2 17 3 42 1 98 4 17 8 2 and 12 4 for the six mentioned periods respectively Observed heritabilities were low and ranging from 0 3 to 2 Heritability estimates by threshold models were 2 to 3 times greater than linear model and ranging from 0 6 to 2 3 Heritabilities by threshold and linear models were distinctly higher for 180 to 365 d The genetic correlations between six different periods ranged from 0 22 to 0 82 Genetic correlations between 1 to 30 d and other periods were lowest and indicating that different genes control mortality in the early and late postnatal stages The Spearman rank correlations for breeding values of these bulls estimated by linear and threshold models were high and indicating that only small changes in ranking of bulls occurred depending on the evaluation method Because of lower frequency and higher heritability and genetic coefficient of variation for mortality in 180 to 365 d and also the high genetic correlations between this period and 31 to 180 d and 366 to 760 d the period of 180 to 365 d could be taken into account for future developments aimed at routine evaluations Key words calf mortality linear model threshold model genetic parameters spearman rank correlation
استاد راهنما :
سعيد انصاري مهياري، محمدعلي ادريس
استاد داور :
غلامرضا قرباني، آقافخرميرلوحي
