Dr. Rick Funston has been an integral figure over the years in the study and advancement of cattle reproductive physiology. Rick grew up on a farming and ranching operationin central North Dakota before obtaining his bachelor’s and master’s degrees in animal science from North Dakota State University and Montana State University, and a doctorate in reproductive biology from the University of Wyoming.
Since 2002, Rick has been a faculty member in the University of Nebraska-Lincoln’s (UNL) Department of Animal Science, where he serves as a professor and reproductive physiologist at the UNL West Central Research and Extension Center. Previously, Rick also worked with the Montana State University Extension, was an assistant animal science professor and rodeo coach at Chadron State College and worked as a nutritionist for a feed company.
Over his decades-spanning career, he has been involved in numerous research projects and has co-authored hundreds of publications, holding a special interest in heifer development and rebreeding of the first-calf heifer. In addition to his academic contributions, Rick has actively participated in various industry committees, many related to cattle reproduction. Notably, he has been involved with the Beef Reproduction Task Force since its inception.
New research highlights
In some newer research, published in the 2024 Nebraska Beef Cattle Report, Rick and his co-authors researched AI’ing beef heifers with multi-sire semen. The practice has been used in the beef industry for a number of years, routinely so in Australia, but less prevalently in the U.S.
The project originated with a producer in southwest Nebraska wanting more females out of his cattle using his own genetics. Sexed semen has been used more frequently over the years, but still has challenges associated with its use. The sex-sorting process can reduce semen quality, decreasing heifer pregnancy rates especially when not in estrus.
Previous research has indicated that pregnancy rates increase when heifers are inseminated with multi-sire semen. A mixture of bull’s semen was hypothesized to provide a longer period of viability compared to a single bull. Thus began the study of AI’ing beef heifers with multi-sire sexed semen at one ranch and single-sire and multi-sire conventional semen at another ranch.
“We had really good results,”Rick said, referring to the use of multi-sire semen. “We only bred cattle that were in heat with sexed semen though, and that’s one thing I recommend with sexed semen: don’t breed anything that’s not in standing heat.”
The study ultimately concluded that further research may indicate AI’ing with multi-sire semen can increase pregnancy rates and improve pregnancy rates in heifers that do not show estrus during a timed AI protocol with conventional semen.
Managing for success
For producers wanting to best optimize their AI success, Rick points to nutrition as one of the key factors.
“I think sometimes we overdo it thinking that we need heifers in a real high rate of gain and then breed them and then, sadly, they don’t perform as well when they go to pasture,” Rick said. “Try to keep cattle in reasonable condition but not gaining too much, maybe a pound and a half a day—something that they will at least equal or exceed post breeding on grass.”
Going onto pasture on a lower plane of nutrition than prior to breeding can lead to more embryonic loss, he said.
The next factor is considering synchronization protocols. Rick recommended the Beef Reproduction Task Force as a resource for determining protocols, beefrepro.org. The recommended protocols can also be found in the latest edition of WLJ‘s Genetic & Reproductive Technologies publication.
While there is no one protocol that works best for every operation, Rick prefers setting heifers up with longer-term progestin protocols, using either 14-day CIDRs or the MGA plus prostaglandin protocol. During a Zoetis-funded study, researchers looked at the difference between the two protocols and found a minimal difference between the two.
“If you can get MGA into heifers, the cost is significantly less,” Rick said, noting that MGA is only authorized for use in heifers.
Rick was part of a study that evaluated the impact of extended MGA feeding, which fed for 18 days instead of the recommended 14 days.
“We didn’t see any difference,” he said. “I don’t know if that was a revolutionary breakthrough by any means, but oftentimes we can be in the middle of a protocol and something comes up or we have to change our breeding dates, and we might already be in the middle of feeding MGA. So,I think this just tells us that we have some latitude with how long we feed.”
He noted that in this instance it was only four extra days that didn’t make a difference, but it was unknown what the outer limit might be.
On the cow side, while there are some newer protocols gaining more traction, Rick said a 7-day CIDR protocol is tried and true for females who have calved before.
“The 7-day CIDR has really been a staple for anything that’s not a heifer,” he said. “Some people use it in heifers because they don’t want a longer-term protocol,” he said, but added that studies have indicated longer-term progestin protocols tend to work better for heifers.
While AI offers benefits for producers utilizing the tool, Rick noted that some of the benefits are not directly related.
“Over half of the benefit of an AI program is the fact that cattle are synchronized,” he said. “The percent of calves born in the first cycle is a huge economic driver of any operation. I think we greatly underutilize synchronization with natural service, and I think those benefits exist.”
He continued that while there could be less genetic benefits compared to using an AI bull, using any of the synch protocols can help an operation’s bottom line. A relatively simple protocol, not on the protocol sheets, is to turn bulls in with heifers or cows, then inject prostaglandin five days later. A calf born in the first 21 days of the calving cycle could add an extra 40 pounds per calf to a producer’s pocket.
It’s also important not to forget the bull’s role in the success of an AI program. Just like with females, nutrition can play a large role in the quality of a bull’s semen. Rick recommended a balanced mineral program, along with not overfeeding bulls.
“Every year there are cases of bulls that don’t provide adequate post-thaw semen quality and it appears in many cases to be associated with over-conditioned bulls,” he said. This could be due to several reasons, such as the ability to regulate temperature in the scrotum.
Whether you implement natural or AI service on your ranch, one thing is clear: nutrition comes first. — Anna Miller, WLJ managing editor
