Maternal Lineage of Warmblood Mares Contributes to Variation of Gestation Length and Bias of Foal Sex Ratio.
Authors: Kuhl J, Stock K F, Wulf M, Aurich C
Journal: PloS one
Summary
# Maternal Lineage and Reproductive Outcomes in Warmblood Mares Maternal mitochondrial DNA is known to influence performance traits in horses, but whether it affects reproductive parameters remains unclear. Researchers at Brandenburg State Stud examined 786 foalings from 142 Warmblood mares across multiple maternal lineages, analysing gestation length and offspring sex ratios using variance analysis to account for confounding variables including mare age, breeding year and foal sex. Gestation length varied significantly by maternal lineage (p<0.001), ranging from 313 to 370 days around a mean of 338.5 days, with individual mare genetics, age, breeding season and foal sex all contributing significantly to this variation. The sex ratio deviated from the expected 1:1 ratio depending on maternal lineage and mare age—younger and aged mares produced proportionally more female foals (52% overall female)—suggesting maternal factors actively influence fetal sex survival or development. These findings have practical implications for stud management and breeding predictions, as maternal lineage appears to programme reproductive characteristics that could inform mare selection, gestational monitoring protocols and expectation-setting around foaling dates and offspring demographics.
Read the full abstract on PubMed
Practical Takeaways
- •Maternal lineage is a heritable factor affecting gestation timing and foal sex outcomes—consider dam pedigree when predicting foaling dates and managing breeding expectations
- •Young first-time mares and older mares tend to produce more fillies; factor this into breeding plans if colts are preferred
- •Gestation length varies widely (57-day range observed); use individual mare history and lineage as guides rather than relying solely on the 340-day average
Key Findings
- •Maternal lineage significantly influences gestation length (p<0.001), with mean gestation of 338.5±8.9 days ranging from 313-370 days across 142 Warmblood mares
- •Foal sex ratio is biased toward females (52% female vs 48% male) and is significantly influenced by maternal lineage and mare age (p<0.05)
- •Young primiparous and aged mares produced a higher percentage of female offspring than the expected 1:1 sex ratio
- •Individual mare, mare age, year and month of breeding, and foal sex also significantly influenced gestation length (p<0.05)