Effect of Inbreeding on Birth, Weaning and Yearling Weights in Sohagi Sheep

Abstract

The current study was carried out to evaluate the impact of inbreeding on lamb weight at birth (BW), weaning (W90) and yearling (W360).This study used the pedigree records of 1290 Sohagi lamb progenies of 44 sires and 491 dams reared at experimental farm, Faculty of Agriculture, Sohag University from 2001 to 2021. Non-genetic factors effect on studied traits was investigated. Average of BW, W90 and W360 were 2.98±0.01, 15.05±0.07, and 32.61±0.17 kg, respectively. The results showed that 34.34% of the current dataset were inbred animals. Inbreeding coefficients of inbred animals ranged from 0.02 to 37.5%, averaging 6.57%. Inbreeding regression coefficient on birth year for overall inbreeding coefficient was -0.0003 and that for inbred animals (-0.01) was significantly negative (P<0.01). BW and W90 decreased by 0.004 and 0.002 kg for each 1% increase in the inbreeding coefficient together with an increase of 0.009 kg in W360. The results of rank correlation of Spearman between estimate breeding values (BV's) of animals obtained from adding or not adding inbreeding coefficient of lambs as a covariate term showed no changes of animals ranking. It was concluded that inbreeding showed negligible effect on studied body weight traits. Also, to reduce the level of inbreeding, increasing number and replacement of rams for mating can be a successful strategy.