Sheep farming is an important activity in the livestock sector, as it provides food products that contribute to food security and improve farmers’ livelihoods. Awassi sheep occupy a prominent position in Iraq and the Middle East due to their ability to adapt to different environmental conditions, as well as their importance in meat and milk production. Despite these advantages, improving reproductive efficiency and increasing the number of lambs produced per ewe remain major objectives of modern genetic improvement programs. Reproductive performance in sheep is influenced by several genetic and environmental factors, including age, body condition, nutrition, general health, and breeding season. Genes also play an important role in regulating ovarian follicular development, ovulation, and embryonic development. Advances in molecular genetics have helped identify genetic variations that may be associated with reproductive traits, providing opportunities to develop more effective selection strategies and improve livestock productivity. The hormone-sensitive lipase gene (HSL), also known as LIPE, is associated with lipid metabolism and energy regulation in the body. This gene encodes an enzyme that contributes to the breakdown of stored fats and the release of fatty acids, which serve as an energy source. This function is particularly important during different physiological stages, including mating, pregnancy, and lactation, when the animal requires an appropriate balance between available energy and physiological demands. The relationship between metabolic status and reproductive performance is an important topic in animal production research. Energy deficiency and inadequate nutrition may affect ovarian activity, ovulation efficiency, and the likelihood of successful pregnancy. Therefore, investigating genes involved in lipid metabolism, including HSL, may help determine whether genetic variations are associated with differences in fertility and litter size in sheep. A study published in 2024 investigated the 216G>A genetic variation in the HSL gene in Awassi sheep to evaluate its association with reproductive traits. The study included 100 ewes and identified two genotypes, GG and GA. The results showed a difference in mean litter size between the two genotypes, with an average of approximately 1.66 lambs per ewe in the GA group, compared with 1.34 lambs per ewe in the GG group. The findings also indicated an association between the GA genotype and a higher twinning rate in the studied population. These findings are scientifically relevant because they highlight a possible relationship between genetic variation in the HSL gene and certain reproductive traits in Awassi sheep. However, this association does not necessarily demonstrate that the mutation itself directly causes an increase in the number of lambs, as other genetic factors, environmental conditions, and nutritional management may also influence reproductive performance. One potential application of these findings is the use of genetic markers in breeding improvement programs through Marker-Assisted Selection (MAS). This strategy involves incorporating genetic information into the selection of breeding animals to promote desirable traits and improve productivity over time. Further validation of the 216G>A mutation may help determine whether it can serve as a useful supplementary marker for selecting ewes and rams with superior reproductive performance. Improving fertility does not depend on genetic selection alone. It also requires balanced nutrition, appropriate body condition, adequate health management, and effective breeding practices. Integrating these factors can improve the likelihood of successful pregnancy and increase lamb survival rates, ultimately enhancing overall flock productivity. In conclusion, genetic variation in the HSL gene, particularly the 216G>A mutation, represents a promising research area for investigating the relationship between lipid metabolism and reproductive traits in Awassi sheep. Preliminary findings suggest that this variation is associated with certain litter-size and twinning indicators, highlighting the need for further studies involving larger sheep populations and different production environments. Such research may help establish the actual predictive value of this genetic marker and evaluate its potential application in sustainable genetic improvement programs, with the aim of increasing productivity while preserving the breed’s adaptive characteristics. Al-Mustaqbal University Ranks First Among Private Universities in Iraq
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