Breed Health
Miniature Silky Fainting Goats Association
Genetic-health indicators for the recorded MSFGA population, computed from pedigree records. These describe the breed's genetic diversity and how it is changing over time.
Effective population size over time
Effective size (Nₑ) by birth-year cohort, 3-year smoothed. The bars show the median pedigree depth behind each year — a rising line that merely tracks rising depth reflects better record-keeping rather than real diversity gains.
Birth-year cohorts
| Birth year | Nₑ | Animals | Pedigree depth | Mean inbreeding | Status |
|---|---|---|---|---|---|
| 2026 | 61 | 402 | 8.4 | 5.7% | reliable |
| 2025 | 59 | 863 | 8.0 | 5.6% | reliable |
| 2024 | 60 | 993 | 7.7 | 5.4% | reliable |
| 2023 | 55 | 1167 | 7.5 | 5.6% | reliable |
| 2022 | 59 | 1175 | 7.1 | 4.9% | reliable |
| 2021 | 52 | 1283 | 6.8 | 5.3% | reliable |
| 2020 | 51 | 1053 | 6.5 | 5.2% | reliable |
| 2019 | 40 | 996 | 6.2 | 5.5% | reliable |
| 2018 | 35 | 819 | 5.9 | 5.7% | reliable |
| 2017 | 44 | 785 | 5.5 | 4.9% | reliable |
How these are computed. Effective population size (Nₑ) is estimated from the rate of inbreeding across generations (Gutiérrez & Cervantes), normalized by each animal's pedigree depth so it is comparable across uneven records. Generation interval is the average age of parents at offspring birth. All figures are pedigree-based; genomic estimates from DNA are more precise where available.
Reading Nₑ. As a conservation rule of thumb, an effective size below 50 indicates short-term inbreeding risk, and below 500 indicates long-term diversity that needs active management.
Nₑ is concentration, not headcount. It measures how fast the gene pool is narrowing, not how many animals exist — a large breed can have a small Nₑ when a few sires dominate (the popular-sire effect), and a smaller breed can have a larger one when contributions are spread evenly. Because deeper pedigrees reveal more inbreeding, Nₑ is most meaningful read within this breed over time (the trend above); the headline figure is not directly comparable between breeds with different pedigree depth.
When a figure is withheld, and how firm it is. Nₑ is shown for a cohort only when at least 20 animals carry a usable pedigree and the median depth is at least 3 complete generations. Below either cutoff the estimate is unreliable — too few animals make it noisy, and shallow pedigrees underdetect inbreeding, which makes Nₑ read misleadingly high — so such cohorts are marked "not enough data" rather than shown as an over-optimistic number. That 3-generation cutoff is deliberately permissive so younger registries see a figure sooner; estimates below about 5 generations are flagged provisional and firm up as pedigrees deepen.
Last updated Jun 8, 2026.