A study of inbreeding trend and its effect on wool weight of Baluchi sheep in Abbas Abad breeding center of Mashhad

In this research a total of 46466 wool weight records belonging to 12821 Baluchi lambs 6334 males and 6487 females) (progeny of 413 rams and 4879 ewes) born from 1983 to 2006 in two herds of Abbas Abad breeding centre, Mashhad, Iran were utilized to study inbreeding effect on wool weight of Baluchi sheep. Inbreeding coefficient was calculated for individual lambs using pedigree software. Data were analyzed by a linear model using SAS software. Year and month of shearing, age at shearing, inbreeding coefficient, sex and birth type had statistical significant effect on wool weight (P<0.0001). In total pedigree animals, 2441 was inbred (19.4%). Average andstandard deviation of inbreeding coefficient for total and inbred population were found to be 0.669±2.60% and 3.90±5.17%, respectively. Minimum and maximum of inbreeding coefficient were 0 and 31.25%, respectively. Average inbreeding coefficients for male and female lambs were 0.708±2.69 and 0.733±2.68%, and for single and twin lambs were 0.684±2.59 and 0.785±2.84, respectively. No statistical significant difference was found between two means of inbreeding coefficients of male and female lambs while statistical significant difference was revealed between two means of twin single and twin lambs (P<0.05). Inbreeding had negative effect on performance of wool in twin male and female lams (P<0.05). Increasing 1% of inbreeding coefficient of twin male and female lambs was accompanied with decreasing 2.86 and 6.62 g in their wool weight, respectively. Annual change trend in inbreeding coefficient for total and inbred population were0.075% and -0.26%, respectively that was statistically significant (P<0.0001).