Heterosis Effects on Stayability
by Troy Smith, Angus Journal® field editor
BILOXI, Miss. (June 11, 2015) — Cattle breeders are wise to apply selection pressure for cow herd stayability, according to Scott Speidel, Colorado State University research geneticist.
“It’s an efficiency trait,” he told attendees of the 2015 Beef Improvement Federation Annual Convention June 9-12 in Biloxi, Miss. Speaking during a committee breakout session, Speidel talked about heterosis effects on stayability.
Citing data from multi-breed studies, Scott Speidel said an increase in heterosis, or hybrid vigor, corresponds with an increase in stayability. Looking at the heterosis effect on females even younger than the typical 6-years-of-age threshold, researchers also determined that the heterosis effect increases with age end point.
Speidel explained that stayability is not the same as cow longevity. Rather, stayability is one of many factors that contribute to a beef cow’s ability to remain as a productive member of a breeding herd. More specifically, noted Speidel, stayability is a measure of reproductive efficiency.
As tools for genetic selection, expected progeny difference (EPD) values for stayability predict the probability that a sire’s daughters will remain in the breeding herd and deliver a calf each year until 6 years of age. Age 6 is considered to be the threshold at which a beef female has produced enough calves to recover her cost. Explaining that it accounts for 53%-77% of the value of most maternal indexes, Speidel called stayability a significant contributor to economic efficiency.
Citing data from multi-breed studies, Speidel said an increase in heterosis, or hybrid vigor, corresponds with an increase in stayability. Looking at the heterosis effect on females even younger than the typical 6-years-of-age threshold, researchers also determined that the heterosis effect increases with age end point. Heterosis increased stayability in 3-year-olds by 5.4% and in 4-year-olds by 9.2%. In cows 5 and 6 years old, heterosis increased stayability by 10.9% and 12%, respectively.
“The literature suggests that heterosis can account for as much as a 38% increase is stayability, depending on the breed crosses involved,” added Speidel.
Speidel spoke Thursday, June 11, at a joint session of the Cow Herd Efficiency and Adaptability Committee and the Live Animal, Carcass and End Product Committee.
The 2015 BIF Annual Convention was hosted by Mississippi State University and the Mississippi Extension Service June 9-12 at the Beau Rivage Casino and Hotel in Biloxi. The Angus Journal and LiveAuctions.tv provide comprehensive online coverage of the event at www.BIFconference.com. Visit the Newsroom for summaries, proceedings, PowerPoints and audio of the sessions; the Awards page for announcements of award winners; and the Photos page for photo galleries of the tour stops.
Editor’s Note: This summary was written under contract or by staff of the Angus Journal®. Through an agreement with the Beef Improvement Federation, we are encouraging reprinting of the articles to those who will adhere to the reprint guidelines available on this site. Please review those guidelines or contact Shauna Rose Hermel, editor, at 816-383-5270. PowerPoints are posted with permission of the presenter and may not be reproduced in whole or in part without the express permission of the presenter.
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