Estimation of some population parameters and inbreeding rate in Lori-Bakhtiari farmer flock's sheep

In this study, to estimate some population parameters and inbreeding rate in Lori Bakhtiari sheep flocks, the data set of 81 flocks of sheep were recorded from farmer flocks under current systems during 2015 to 2016. Questionnaire survey was used to collect data from last year information, recorded information, direct recording during visit the farm and interview with the smallholder farmer. The results showed that in 68% of the studied flocks, the male replacements were selected from the within flock, the selection criterion for all of the flocks was visual apparent characteristics and the type of mating was random. The average generation interval, the number of breeding ewes, the number of breeding rams, the proportion of ram to ewe, the duration of the ram stay in the flock were 3.30 years, 98.6, heads, 4.5 heads, 4.6%, 3.4 years, respectively, and 34.57% the flocks had at least one lamb with a visual genetic abnormality. Accordingly, the effective size and the rate of inbreeding, regardless of family size variance were 17.2 and 4.9%, respectively, and with family size variance estimated as 9.8 heads and 7.5%, respectively. The effect of city and type of breeding system were significant on most of the studied population parameters and inbreeding rate (P< 0.05). Therefore, the mean of effective size in farmer flocks was lower than minimum recommended for maintaining genetic diversity and implementation of the improvement breeding program, and this fact has caused an inbreeding rate of more than 5 to 7 times the permissible limit.