Estimation of inbreeding depression on growth traits in Markhoz kids

The Markhoz goat is one of the most important breeds In Iran. These animals had an important cultural role in Kurdistan because the mohair obtained from these animals is used for making national clothes. The mating of related individuals produces an inbred offspring and leads to an increased homozygosity in the progeny, genetic variance decrease within families and increase between families. The ratio of homozygosity for individuals was calculated by inbreeding coefficient. The trend of inbreeding is an indicator for determination of inbreeding level in the herd. Result of researches showed increasing of inbreeding resulted to decrease of phenotypic value in some of production and reproduction traits. So the aims of this study were estimation of inbreeding coefficients and its effects on birth weight (BW), weaning weight (WW), average daily gain to weaning (ADG), 6 month weight (6MW), 9 month weight (9MW) and yearling weight (YW) of Markhoz goats.
In this study, pedigree data of 4186 Markhoz goats which were collected from 1992-2012 by Markhoz Goat breeding center located in Sanandaj, were used. Inbreeding coefficient was estimated by the CFC software program. Inbreeding depressions in growth traits were estimated by restricted maximum likelihood (REML) method under 12 animal models that animal and dam’s inbreeding coefficients added to models as a covariate. The most appropriate model for each trait was determined by Akaike’s information criterion (AIC).
The 58.07% of animal were inbred. The mean inbreeding coefficient for the herd and inbred population was 3.03 and 5.21% respectively. Maximum inbreeding coefficient was 31.25%. The 47.04% of animal was inbreeding coefficient between 0 to 10 percent. 553 head of dams were inbred and inbreeding coefficient for the whole and inbred dams was 2.05 and 4.91% respectively. Inbreeding coefficient was increased 0.24±0.04 percent in each year (P Estimated inbreeding coefficients for this breed showed high degree of close mating in this flock and due to significant effect of inbreeding on some growth traits it is suggested that this breeding station should use a breeding plan to avoid mating of close relative animals.