The Dam Quality Revolution: Part 4 — The Mating Patterns Behind Superior Results
Across Parts 1–3 of this series, we established three core principles:
• Dam quality is a major determinant of foal performance
• G2 and G3 mares deliver the best long-term value
• Colts and fillies respond differently to mare class
In this final chapter, we examine how stallion selection interacts with mare quality, and we test seven long-standing breeding theories using a global dataset of more than one million runners.
The findings provide a practical, evidence-based framework for designing more effective matings ahead of the 2026 Northern Hemisphere and 2025 Southern Hemisphere breeding seasons.
How Stallion Quality Interacts With Dam Class
Stallion influence is significant, but it does not operate symmetrically across all mares. The data shows that:
• High-class mares paired with aligned stallion types produce the strongest outcomes
• G2 and G3 mares generate the most efficient value return when matched appropriately
• Listed mares show the largest proportional uplift when upgraded to stronger stallions, but remain behind G2/G3 mares in absolute terms
• Non-stakes mares provide limited uplift regardless of stallion tier
This creates a clear hierarchy of mare-class “peaks”:
Performance peak: G1 mares
Value peak: G2 and G3 mares
Uplift peak: Listed mares
Baseline: Non-stakes mares
This framework underpins all seven theory tests below.
THEORY 1: “A great stallion can lift a weak mare.”
Non–stakes-winning mares only, by sire tier
| Sire Tier | SW% from Non-SW Mares |
|---|---|
| G1 Sire | 4.01% |
| G2 Sire | 2.69% |
| G3 Sire | 2.21% |
| Listed Sire | 1.49% |
| Non-SW Sire | 1.35% |
Verdict: MOSTLY FALSE
Elite stallions do improve outcomes from non-stakes mares — from ~2–3% up to ~4% — but the ceiling remains low. Even the best stallions cannot elevate weak mares into a high-class production profile.
THEORY 2: “A strong mare can fix a stallion.”
Stakes-winner rates for mares bred to low-producing sires (<3% SW%)
| Mare Tier | SW% |
|---|---|
| G1 Mare | 3.40% |
| G2 Mare | 2.90% |
| G3 Mare | 2.94% |
| Listed Mare | 2.69% |
| Non-SW Mare | 1.27% |
Verdict: FALSE
Even the best mares cannot overcome stallion limitations. A G1 mare bred to a weak sire produces just 3.40% SW — barely above baseline. Stallion ceilings cannot be overridden.
THEORY 3: “Mid-tier stakes mares get the most out of better stallions.”
Uplift when mares are bred to G1 sires versus Listed/Non-SW sires
| Mare Tier | SW% (G1 Sire) | SW% (Listed/Non-SW Sire) | PP Improvement | % Improvement |
|---|---|---|---|---|
| G1 Mare | 11.73% | — | — | — |
| G2 Mare | 9.25% | 4.48% | +4.77 | +106% |
| G3 Mare | 9.19% | 3.23% | +5.96 | +185% |
| Listed Mare | 7.88% | 3.43% | +4.45 | +130% |
Verdict: TRUE (with nuance)
G3 mares show the strongest uplift when upgraded (+185%), followed by Listed mares (+130%). G2 mares also benefit (+106%). G1 mares show minimal uplift as they already run near the ceiling.
Proportional uplift does not replace absolute performance: G2/G3 mares remain the most efficient value tier.
THEORY 4: “Stallions throw better colts than fillies.”
Improvement from Non-SW mares → G1 mares, by sex
| Sex | SW% from Non-SW Mares | SW% from G1 Mares | % Improvement |
|---|---|---|---|
| Colts | 3.49% | 10.79% | +209% |
| Fillies | 3.17% | 11.35% | +258% |
Verdict: PARTIALLY TRUE
Colts outperform fillies in absolute terms, but fillies gain more proportionally from higher-class mares.
THEORY 5: “You should never send a G1 mare to a young stallion.”
G1 mares by stallion age at covering
| Stallion Age | SW% |
|---|---|
| Young (≤5yo) | 9.25% |
| Prime (6–10yo) | 9.98% |
| Mature (11–15yo) | 12.62% |
| Veteran (16+yo) | 11.71% |
Verdict: FALSE
Young stallions perform competitively with prime-aged sires when covering elite mares. Age alone is not a barrier.
THEORY 6: “Successful crosses repeat themselves.”
Nick consistency (≥10 runners per nick, YOB ≥ 2011)
| Metric | Value |
|---|---|
| Total nicks analysed | 2,923 |
| High-performing (>1 SD above mean) | 470 (16.1%) |
| Low-performing (<1 SD below mean) | 392 (13.4%) |
| Average StdDev in SW% | 6.33 PP |
Top repeatable nicks (≥25 runners)
| Sire | Damsire | SW% |
|---|---|---|
| Galileo | Anabaa | 38.46% |
| Galileo | Pivotal | 37.50% |
| Galileo | Storm Cat | 34.04% |
| Frankel | Dansili | 28.00% |
| Galileo | Danehill Dancer | 27.62% |
| War Front | Sadler’s Wells | 27.59% |
| Galileo | Fastnet Rock | 27.03% |
Verdict: TRUE
High-performing nicks repeat reliably. Their structural compatibility produces materially higher SW rates.
THEORY 7: “A mating is only as strong as its weakest parent.”
Mare × Stallion matrix (selected rows)
| Mare Tier | G1 Sire | Non-SW Sire |
|---|---|---|
| G1 Mare | 11.73% | Small sample: 0% from 7 runners |
| G2 Mare | 9.25% | Small sample: 0% from 9 runners |
| G3 Mare | 9.19% | 3.70% |
| Listed Mare | 7.88% | 3.24% |
| Non-SW Mare | 4.04% | 1.60% |
Verdict: MOSTLY TRUE
Elite × elite produces elite outcomes. Weak mares cap elite sires at ~4%. Weak sires cap elite mares. Quality on both sides matters.
The Four Peaks Framework (Final Summary)
Performance Peak: G1 mares
Value Peak: G2/G3 mares
Uplift Peak: Listed mares
Baseline: Non-stakes mares
Conclusion: Designed Matings Outperform Discovered Ones
Alignment between mare class and stallion capability produces the strongest outcomes. Evidence-based mating design outperforms intuition or tradition.
Use the G1 Goldmine Broodmare Report to assess mare patterns, and Stallion Match to analyse compatible stallions and sales trends.