Student Case Presentation
Who’s your daddy? A rare case of heteropaternal twin angus calves.
| Date/Time: |
9/11/2025 4:00 pm
|
| Presenter: |
Erica Vincent |
| Veterinary School: |
TT |
Abstract:
Heteropaternal superfecundation, the fertilization of multiple ova by different sires within the same estrous cycle, is a rare but underreported phenomenon in cattle. While commonly associated with assisted reproductive technologies, the occurrence rate in natural service breeding programs is unknown. A multiparous Angus cow gave birth to what was presumed to be twin heifer calves. Routine parentage verification through the American Angus Association unexpectedly revealed that the twins had different sires.
The cow, born on May 23, 2018, had a history of successful calvings, but no twins prior to this incident. The ranch operates a multi-sire breeding system, running four bulls (two 2-year-olds and two 1-year-olds) per 74 head across approximately 2,176 acres during the breeding season from May 16 to September 26, 2023. The herd does not utilize synchronization protocols.
One twin, calf 4542, was abandoned at birth, and the owner initially did not recognize her as a twin. She was bottle-fed for a few days before being grafted onto another female which lost her calf. Only through routine DNA parentage testing was it discovered that calf 4542 and her twin, calf 4616, had different sires. One sire was a 2-year-old bull, while the other was one of the yearling bulls. Birth weights for the twins were 58 lbs (4542) and 60 lbs (4616).
This case confirms the occurrence of heteropaternal superfecundation in a natural service beef cattle breeding program and underscores its potential implications for multi-sire breeding systems, genetic selection, and reproductive management. While such cases may be rare, they could be overlooked without routine parentage testing. Increased awareness and genetic screening can help producers optimize breeding strategies and gain deeper insights into reproductive dynamics in herd management.
