In this study, two novel indels within the sheep SIRT7 gene, 5′ promoter region-insertion-7 bp and 3′ UTR-insertion-17 bp, were identified in 709 individuals from five different Chinese and Mongolian sheep breeds. Genetic diversity within the SIRT7 gene and its effect on body size traits were explored. The findings from this research will potentially provide useful DNA markers for the improvement of economic traits in sheep genetic breeding.

Analysis of the genomic variation within a breed is an essential requirement for keeping the breed’s integrity and for defining proper breeding objectives. This research aimed to analyze the genomic structure of Iranian Zandi sheep and showed that a more dense marker is required to achieve genetic gain in Zandi sheep using genomic selection. Attention should be given to adopting an optimal mating system in order to avoid the further loss of genetic diversity in this breed.

This study was carried out to detect polymorphisms in the melatonin receptor 1A and arylalkylamine N-acetyltransferase genes and their association with reproductive traits. Blood samples of 126 animals from three Egyptian sheep breeds were collected. DNA was extracted and subjected to PCR-restriction fragment length polymorphism analysis using the RsaI and SmaI enzymes. Two alleles (C and T) and three genotypes (CC, CT and TT) for MTNR1A and for AA-NAT (A and G; GG, GA and AA) were detected.

Sexual dimorphism for growth-related traits in Afshari lambs was studied. Greater estimates of residual and maternal variances in male lambs together with interactions between sex of lamb with effects of birth year and birth type suggested greater environmental sensitivity of male lambs compared to female lambs. However, cross-sex genetic correlations were positively high, suggesting no need or opportunity for sex-specific selection to create or modify sexual-size dimorphism in sheep.