Genetic Influences on Reproductive Seasonality in Ovine Species

Reproductive seasonality in sheep is governed by a complex interplay between environmental cues and genetic architecture. As short-day breeders, ewes respond to decreasing daylength by increased melatonin secretion, which binds to hypothalamic and pituitary melatonin receptors to trigger gonadotrophin release. Central to this process is the MTNR1A gene, encoding melatonin receptor 1A, whose allelic variation modulates sensitivity to photoperiod and hence the onset and duration of the breeding season. Beyond MTNR1A, polymorphisms in genes such as LEPR, CD226 and neuropeptide Y have been implicated in variation of anoestrous intervals, ovarian cyclicity and fertility traits. Epigenetic mechanisms—including DNA methylation of the MTNR1A promoter—further fine-tune gene expression in response to changing daylength. Unravelling these genetic and epigenetic factors has enabled marker-assisted selection approaches aimed at advancing out-of-season breeding, improving lambing rates and enhancing flock productivity under diverse management regimes.

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Genetic Influences on Reproductive Seasonality in Ovine Species publication trend

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Technical terms

Photoperiod: The duration of daylight exposure, which regulates endocrine signals underlying seasonal breeding.

Melatonin receptor 1A (MTNR1A): A G-protein-coupled receptor mediating the effects of pineal-derived melatonin on reproductive neuroendocrine pathways.

Single nucleotide polymorphism (SNP): A DNA sequence variation at a single base pair, which can influence gene function or regulation.

Genome-wide association study (GWAS): A high-throughput approach to scan the genome for SNPs associated with phenotypic traits.

DNA methylation: An epigenetic modification involving addition of methyl groups to cytosine residues, affecting gene expression without altering the DNA sequence.

References

1. A novel p.127Val>Ile SNP in the MTNR1A gene and its relation to litter size in Thin-tailed Indonesian ewes. Animal Bioscience (2024).
2. Photoperiod Induces DNA Methylation Changes in the Melatonin Receptor 1A Gene in Ewes. Animals (2023).
3. Reproductive Resumption in Winter and Spring Related to MTNR1A Gene Polymorphisms in Sarda Sheep. Animals (2022).
4. The LEPR Gene Is Associated with Reproductive Seasonality Traits in Rasa Aragonesa Sheep. Animals (2020).
5. Genome-Wide Association Study Demonstrates the Role Played by the CD226 Gene in Rasa Aragonesa Sheep Reproductive Seasonality. Animals (2021).