A study on inbreeding coefficient trend of lamb and parents and its effect on wool weight of Iran Black sheep in Animal Breeding Station of Abbas Abad

Effects of lamb and parents coefficient of inbreeding (CI) on wool weight were studied using 10،868 wool records belonging to 3،244 Iran Black lambs (1،633 males and 1،611 females) representing 96 rams and 995 ewes collected during 1983-2006 from Animal Breeding Station of Abbas Abad. Year and month of shearing، CI of lamb and dam، sex and birth type had significant affect on wool weight Among 3،244 pedigree animals، 3،005 heads (92. 6 percent) were found to be inbred. Mean and standard deviation of CI of lamb، sire and dam in whole population were 8. 1±6. 1، 6. 5±6. 1 and 5. 3±5. 8 percent، respectively. The corresponding figures in inbred population were 9. 0±5. 7، 7. 0±6. 1 and 5. 7±5. 8 percent، respectively. Minimum and maximum CI of lamb was 0 and 36. 4 percent، respectively. Increase of CI by one percent was accompanied with a decrease of 26. 9 g (quadruplet male)، 4. 8 g (twin female)، 4. 3 g (triple female) and 13. 1 g (quadruplet female) in wool weight. A decrease of 1. 4 g in wool weight of lamb was observed as the CI of dam was increased by one percent. Statistically significant annual change trend were estimated to be 0. 2±0. 02 percent and 0. 1±0. 02 percent for whole and inbred populations، respectively. A controlled mating is needed to reduce deleterious effects of inbreeding.