Abstract :
Genetic and environmental (co)variance components for productivity traits in Moghani
sheep were estimated using data from 1344 ewes. The data were collected in the Jafarabad
breeding station, north-east of Iran, during a 13-year period (1995–2008). The studied traits
were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born
(LMWLB), littermeanweight per lambweaned(LMWLW),total litter weight at birth (TLWB)
and total litter weight at weaning (TLWW). A model including direct additive genetic effects
as well as permanent environmental effects related to repeated records of ewe was the most
appropriate model for all the studied traits. Genetic parameters were estimated applying
restricted maximum likelihood (REML) procedure. Direct heritability estimate for LSB, LSW,
LMWLB, LMWLW, TLWB and TLWW were 0.11, 0.02, 0.15, 0.07, 0.07 and 0.06, respectively.
Corresponding values for repeatability estimates were 0.16, 0.19, 0.18, 0.11, 0.13 and 0.09.
Genetic correlations between the studied traits ranged from −0.99 for LSB–LMWLB and
LSW–LMWLB to 0.99 for LSB–TLWB. Phenotypic and environmental correlation estimates
were generally lower than those of genetic ones. Estimates of permanent environmental
correlation among traits were positive and medium to high. Although low direct heritabilities
were estimated for the reproductive traits, as these traits are of interest then they
should be included in a breeding program.
