Effects of environmental factors on growth traits in Ghezel sheep

The present study was carried out to study the effects of environmental factors on growth traits in Ghezel sheep breed. Growth related data (birth weight, weaning weight, month 6 weight, average dailygain from birth to weaning and weaning to month 6) were collected from lambs that have been born during 1994 - 2006 at Ghezel sheep breeding station in west Azerbaijan and data was analyzed usingSAS software. The birth year and herd had a significant effect on all traits (P < 0.01) while the effect of birth type significantly (P < 0.01) affected all traits except birth weight and daily gain from birth toweaning periods. The lamb's sex had a significant effect on all traits except daily gain from weaning to month 6 weight periods. The effect of dam’s age had a significant effect only on daily gain fromweaning to month 6 weight periods. The interactions between birth year and lamb’s sex, birth year and birth type, birth year and herd, lamb's sex and herd and also dam's age and herd were significantlyaffected on all traits (P < 0.01). The interactions between lamb’s sex and dam's age and birth type and dam's age significantly affected weight of birth, daily gain from birth to weaning period and month 6ages, respectively (P < 0.05). In all ages, the male and single lambs were heavier than female and twin lambs. Results showed that environmental factors have an important role in expressing of geneticpotential in the lambs