A Study on the Effect of Inbreeding Depression on Growth Traits in Baluchi Sheep

In this research, a total of 11,837 weight records of Baluchi lamb (6,030 males and 5,807 females) representing 300 rams and 3,694 ewes of Baluchi collected during 1978- 2008 from Abbas Abad breeding centre, Mashhad were utilized for investigating inbreeding trend and its effect on pre-weaning weight traits. The traits under consideration were birth weight (BW), weaning weight (WW) and pre-weaning daily gain (PWDG). Inbreeding coefficient of all animals was computed using CFC software. A linear model was applied for analyzing the data using SAS software. Among the animals, 8,903 (75.21%) were inbred. Average (standard deviation) of inbreeding coefficient were found to be 3.17 (3.94) and 4.22 (4.02) % for whole and inbred populations, respectively. Minimum and maximum inbreeding coefficients were 0 and 33.23 %, respectively. In whole population, average (standard deviation) of inbreeding coefficients were 3.20 (3.92) and 3.14 (3.95) % for male and female lambs,respectively. The corresponding figures were 3.07 (3.89) and 3.32 (4.00) % for single and twin lambs, respectively. Inbreeding depression was detected for BW, WW, W3 and PWDG in single male and single twin lambs and for BW in twin male lams (P<0.05). Annual trends of inbreeding coefficient were 0.117 and 0.022 % for whole and inbred animals which were found to be statistically significant (P<0.0001).