TY - JOUR ID - 53784 TI - Estimation of genetic, environmental and phenotypic trends for economic lifetime of the Lori-Bakhtiari ewes JO - Iranian Journal of animal Science JA - IJAS LA - en SN - 2008-4773 AU - Beygi, Moslem AU - Vatankhah, Mahmood AU - Faghani, Mostafa AD - M. Sc. Student, Islamic Azad University, Shahrekord Branch AD - Associate Prof. Agriculture and Natural Resources Research Center, Shahrekord AD - Assistant Prof. Islamic Azad University, Shahrekord Branch Y1 - 2014 PY - 2014 VL - 45 IS - 3 SP - 273 EP - 278 KW - Genetic and phenotypic trends KW - economic lifetime KW - Lori- Bakhtiari ewe DO - 10.22059/ijas.2014.53784 N2 - In this study, the number of 1802 longevity records of ewes collected during 1989 to 2010 in Breeding Station of Lori-Bakhtiari sheep flocks were used to estimate of genetic, environmental and phenotypic trends for economic lifetime. The breeding values of a ewe’s lifetime were estimated by restricted maximum likelihood procedure under an animal model of univariate analysis. The best linear unbiased prediction of breeding values estimated and genetic trends were estimated as a regression coefficient of average breeding values on the birth year of ewes. The environmental and phenotypic trends estimated as a regression coefficient of average environmental deviation and phenotypic deviation (deviations of phenotypic values from overall mean) on the birth year of ewes. The results showed that, genetic trend of longevity was positive (0.033 days) but insignificant from zero. While the environmental and phenotypic trends were equal to -27.81 and -27.78 days, respectively, and significantly different from zero (P<0.05).  Thus, selection for growth traits did not affect longevity traits as genetically and to exhibit negative phenotypic trend for longevity the environmental factors should improve firstly UR - https://ijas.ut.ac.ir/article_53784.html L1 - https://ijas.ut.ac.ir/article_53784_92c4f9444bb7d3473c39a9e01e38a888.pdf ER -