The mechanism of lipid metabolism is complex, and the manipulation of fat storage for lean meat production is very important in the sheep-breeding industry. The present study aimed to study the genetic profiles of fat tissues and to discover the diversity in the genetic mechanisms defining fat deposition between two morphologically different sheep breeds. Analysis of the diversity of fat deposition may aid the recognition of genes and pathways responsible for the formation of tail fat.

The objective was to assess the genetic diversity and phylogenetic relationship of nine sheep populations. Overall, these sheep populations in the study exhibited a rich genetic diversity. The nine sheep populations can be divided into two groups. SUF and DST were clustered in one group, and GMM–BAS–BAM, HUS–STH and DOS–DOP were divided into three clusters. This clustering result is consistent with sheep breeding history. TreeMix analysis also hinted at the possible gene flow from GMM to SUF.

The expression patterns of the HPG axis-related genes in rams were analyzed using qPCR. It showed that DIO2 and KISS1 were mainly expressed in pituitary and hypothalamus in both breeds, respectively. EYA3 and GPR54 were widely expressed in both breeds, with significant differences in testis and vas deferens. We speculated that the four genes may regulate the estrous mode in different regions in rams. This is the first study to analyze the expression patterns of HPG axis-related genes in rams.

The state of local breeds is precarious worldwide because of the introduction of breeds with improved traits. Our study analyzes the genetic variation of four Romanian local sheep breeds using nuclear DNA markers. Tsurcana and Tsigai showed an intense gene flow among them and were less differentiated than Ratska and Teleorman Blackhead. The results of this study may be useful for breeding programs and conservation plans since the genetic resources of the local breeds must be preserved.

Sheep milk production and ingredients are influenced by genetic and environmental factors. In this study, we implemented selection signature analysis to identify candidate genes related to ovine milk traits. The results revealed six selection signature regions showing signs of being selected (P < 0.001) located in chromosomes 1, 2, 3, 6, 13 and 18. In addition, 38 QTLs related to sheep milk performance were identified in selection signature regions, which contain 334 candidate genes.

Selective breeding for milk production traits in sheep using molecular marker technology offers a possibility of selecting accurately elite ewes and rams for milk production traits at early age. Our findings suggest that ovine FABP4 has a role in the variation of the milk production traits which may be of economic importance to sheep farmers. Variation in this gene could potentially be used as gene markers for milk production traits if such associations exist.

Increasing genetic resistance to gastrointestinal parasite infections in sheep would limit the use of drugs and the emergence of resistant parasites. However, this is a very complex trait. The identification of genomic areas associated with the trait is hindered by genotype–environment interactions. Therefore, it is necessary to obtain information from non-cosmopolitan sheep populations. Here, the West African Djallonké sheep genomic profile is analyzed to contribute to solve this gap.

Birth of twins is partly controlled by genetic factors. Here, we genotyped ewes with triplet births, twin births, and single births as well as two infertile ewes from Iranian sheep breeds for the BMP15 gene. A new mutation was detected in two sterile ewes and all ewes with triplet-birth lambing. There is a relationship between the mutation and higher litter numbers. However, this mutation is not responsible for sterility or triplet births in Iranian sheep.

The aim of present study was the analysis of differences in expression profiles of ovine genes related to lipid metabolism (LPL, ACACA, SCD) depending on feeding system and tissue type (fat, liver). The genes expression measurement showed that supplementation of diet with an addition of fresh grass or red clover modified the expression of all genes in fat tissue. The nutrigenomic regulation of analyzed genes confirmed that these genes play a critical role in regulation of lipid metabolism.

Sheep farming in Iran can be a great source of income for marginal and landless farmers. Animal genetic diversity is required to facilitate rapid adaptation to changing breeding objectives. Hence, the objective of this research was to measure the genetic polymorphism of five microsatellite markers in 14 sheep types in Iran. The high degree of variability demonstrated within these sheep implies that these populations are rich reservoirs of genetic diversity that must be preserved.

The aim of this study was to investigate the polymorphism in the IGF-I gene and its associations with growth, body size, carcass and meat quality traits in Coloured Polish Merino sheep. The IGF-I genotype was found to have an effect on fore shank weight, kidney fat class and EUROP fat class, external fatness on carcass class, drip loss, and subjective assessment of meat colour. The IGF-I gene could be considered as a candidate gene of selected carcass and meat quality traits in sheep.

The 29 bp indel of sheep LHX3 gene was firstly verified in four Chinese indigenous sheep breeds of various fecundity. Genotypic frequency and allelic frequency distributions were significantly different between the high-fecundity breeds (Hu sheep, HS; small-tail Han sheep, STHS; and Lanzhou fat-tail sheep, LFTS) and the low-fecundity breed (Tong sheep (TS)) based on an χ² test (P < 0.05). Moreover, four significant differences were found in body length and chest width in TS and STHS (P < 0.05).

Stearoyl-CoA desaturase 1 is a critical enzyme that catalyzes the synthesis of monounsaturated fatty acids. The objective of the present study was to evaluate the level of mRNA of SCD1 gene in three different ovine tissues strongly associated with lipid homeostasis. The significant correlation between SCD1 transcript abundance and fattening and slaughtering traits (fatness traits) indicates the ability to improve important production traits in sheep via modification of expression of SCD1 gene.