Evaluation of inbreeding effects on pre-weaning growth traits and lamb survival in Iran-black sheep

The inbreeding effects on pre-weaning growth traits and lamb survival from birth to weaning for Iran-black sheep were estimated from 5716 data for birth weight (BW), and lamb survival (LS) and 4801 data for weaning weight (WW), per-weaning average daily gain (PADG) and kleiber ratio (KR), respectively. Data were collected by Sheep Breeding Station of Abbasabad, located in Khorasan Razavi province, north-eastern of Iran, over the period from 1984 to 2011. Genetic parameters were estimated with univariate animal models using restricted maximum likelihood (REML) procedures. The 55 percent of population was inbred. The mean of inbreeding coefficients in population and inbreed animals were 4.19 and 7.59, respectively. Minimum and maximum level of inbreeding coefficient for inbred animals was 0.02 and 34.7%, respectively. Inbreeding trend per year and per generation was 0.34 and 1.33 percent (p<0.05). The estimates of inbreeding depression per 1 percent of increase of inbreeding coefficient were 9, 29, 0.34 g for BW, WW PADGand -0.03 percent for LS respectively, (p<0.05). The estimation of inbreeding depression per increasing of inbreeding coefficient for KR was not significant (p>0.05).