Sources and References
The primary references behind our published figures. Every number is checked against at least two independent sources before publication; disagreements become published ranges, not silent choices. See also the methodology and editorial policy.
| Source | Primarily used for |
|---|---|
| Merck Veterinary Manual | Gestation ranges and reproductive physiology for livestock, pets, and horses |
| USDA National Agricultural Library | Livestock reproduction references and animal science data |
| USDA APHIS | Animal health and breeding program guidance |
| Cornell University College of Veterinary Medicine | Companion animal reproduction and health |
| Penn State Extension | Dairy and beef cattle, sheep, and goat reproduction |
| University of Minnesota Extension | Livestock gestation and breeding management |
| University of Wisconsin Extension | Cattle gestation and calving management |
| American Kennel Club | Dog breeding, litter, and breed information |
| American Angus Association | Breed-specific cattle gestation data |
| American Hereford Association | Hereford gestation and breeding charts |
| American Boer Goat Association | Boer goat gestation and kidding |
| AmphibiaWeb (UC Berkeley) | Amphibian development and breeding biology |
| IUCN Red List | Wild species biology including reproduction |
| Smithsonian National Zoo | Exotic and zoo species gestation |
| San Diego Zoo Wildlife Alliance | Wildlife reproduction data |
| National Wildlife Federation | North American wildlife biology including deer |
| Alabama Cooperative Extension (ACES) | Poultry incubation and southern livestock |
| Mississippi State University Extension | Poultry incubation and catfish aquaculture |
| Food and Agriculture Organization (FAO) | Global livestock and aquaculture reproduction |
| PubMed / NCBI | Peer-reviewed reproduction research for exotics |
Individual calculators and articles cite their most relevant subset of this list in their own Sources sections. When an article cites a specific study or document, it is linked directly there.
K
Kanika
Researched and reviewed by Kanika, founder of GestationCalc. All gestation data is verified against primary veterinary and agricultural sources before publication.
Last reviewed: October 1, 2026