The ovine melatonin receptor 1A (MTNR1A) and aromatase (CYP19) genes were structurally characterized and the association between their variants and reproductive and growth traits was studied in Kurdi sheep at Kurdi sheep breeding station located in Shirvan, Iran. The genomic DNA was extracted by guanidine thiocyanate-silica gel method. Polymerase chain reaction was carried out to amplify 824 bp fragment of exon 2 of MTNR1A and 140 bp fragment of the exon 3 of the ovine CYP19 genes. The PCR products were digested with restriction endonucleases RsaI for MTNR1A and BstMBI for CYP19 genes and checked by polyacrylamide gel electrophoresis for the presence of restriction sites. Two alleles were found for all the loci investigated, which were named as A and B for CYP19, and R and r for MTRN1A. Allelic frequencies for MTRN1A were 0.49 and 0.51 for R and r alleles, while in the case of CYP19 gene, frequencies were 0.475 and 0.525for A and B alleles, respectively. Association analysis did not show any significant relations between MTNR1A gene polymorphisms and litter size (LS), age at first lambing (AFL) and lambing interval (LI). Moreover, CYP19 gene polymorphism did not affect birth weight (BW), weaning weight (WW), 6, 9 and 12 months (YW) body weights, age at first lambing (AFL) and lambing interval (LI). تفاصيل المقالة

In order to evaluate carcass characteristics of a nucleus flock of Baluchi sheep, in vivo ultrasound technique was used to measure backfat thickness (UBFT) and longissimus dorsi muscle area (ULMA) and also to estimate genetic parameters for these ultrasonic traits and live weights in different ages. The data were collected from 576 animals during 2011. (Co)variance components were estimated by univariate and bivariate animal models using restricted maximum likelihood and Asreml software. Females had higher UBFT and ULMA than males. Estimates of direct heritabilities were 0.32, 0.23, 0.27, 0.02, 0.12, 0.22 and 0.18 for UBFT, ULMA, birth weight (BW0), weaning weight (BW3), 6 month weight (BW6), 9 month weight (BW9) and yearling weight (BW12), respectively. There were positive and high genetic (0.68±0.15) and phenotypic (0.62±0.03) correlations between UBFT and ULMA. The genetic correlations among ultrasonic and pre 6 month weights were positive and low except for BW0 and ULMA (0.39±0.28). Contrarily, moderate to high positive genetic correlations between ultrasonic traits and weaning and post-weaning weights were found (0.33 to 0.61). Phenotypic correlations between ultrasonic and growth traits were positive and ranged from 0.09 to 0.37. High positive genetic correlation between UBFT and ULMA suggests that selection for larger muscle mass result in higher fat carcasses. تفاصيل المقالة

The aim of this study was to describe inbreeding and population structure in Sangsari sheep breeding station. For this reason, data from 7028 Sangsari sheep which were collected during 1987-2014 in Sangsari sheep breeding station located near to Damghan city, Semnan province were used. Lambs born during 2010-2014 were considered as reference population. The genetic structure analysis of the population was realized by the ENDOG (v.4.8) software. Mean inbreeding of total population and reference population was 0.28% and 0.70%, respectively. Average relatedness, realized effective population size based on individual increase in inbreeding, effective numbers of founders (fe),and founder genome equivalents (fg) were estimated 0.59%, 148.75, 140 and 49.97, respectively. Mean generation interval in present population was 4.24 years and average number of equivalent to discrete generations was estimated as 1.64. Average coancestry, effective number of ancestors (fa) and average equivalent complete generation were calculated 1.0005%, 76 and 3.02, respectively. Ratio of fe/fa which expresses the effect of population bottlenecks was 1.84. 50% of total genetic variation was explained by the 32 most influential ancestors. By monitoring parameters associated with genetic diversity and breeding management, the reduction of genetic diversity and probable harmful effects resulting from excessive increase of inbreeding can be prevented. تفاصيل المقالة