Increasing longevity and fertility: How to utilize nutrition to develop more productive, fertile heifers
The Beef Reproduction Task Force welcomed University of Wyoming Department of Animal Science Assistant Professor and Extension Beef Specialist Dr. Shelby Rosasco to discuss nutritional management of replacement heifers on Feb. 15.
Rosasco shares producers can increase longevity and fertility rates in heifers with a development program specific to their herd.
Heifer development considerations
“One of the biggest economic decisions producers make each year is deciding whether or not to retain and develop replacement heifers,” says Rosasco.
Although developing replacement heifers can be challenging, Rosasco insists the benefits outweigh the extra time and financial commitment.
“How we manage these heifers during the first few years of life has a big influence on heifer performance and reproduction, as well as plays a key role in establishing heifer fertility,” she says.
Rosasco mentions each cattle operation is unique, so there isn’t a specific right or wrong way to develop heifers for all operations.
“Producers need to come up with nutritional management strategies to fit within their system,” she adds.
Rosasco recommends producers first decide whether to retain and develop their own heifers or purchase heifers.
“There are pros and cons to both retaining and purchasing heifers. If producers are buying, it’s still going to give an opportunity to positively impact fertility and help them pick out the right heifers,” says Rosasco.
She recommends selecting heifers that look the best, are expected to have high levels of fertility, get bred early and wean marketable calves.
Rosasco also mentions financial impacts are important for producers to consider.
“I always think it’s important to consider the economic side of our heifer development systems. We need to make sure these heifers have the ability to breakeven and repeat their development costs and start providing us a profit,” she explains.
Rosasco encourages producers to create expectations for the first couple years of the heifers’ lives.
“We are putting a lot of pressure on these heifers, especially from a reproductive standpoint,” she adds.
Rosasco says producers should expect heifers to attain puberty prior to breeding season, become pregnant to calve by two years of age, calve without assistance, wean a marketable calf, rebreed as a first-calf heifer and maintain a 365-day calving interval.
“All of these expectations are going to lead towards maximizing heifer lifetime productivity. This includes maximizing her fertility and reproductive performance,” says Rosasco.
Rosasco recommends producers evaluate the current status of their herd before selecting and developing a productive heifer.
She adds, it’s important for producers to note if there have been issues with “heifers attaining puberty prior to the start of the breeding season.”
Evaluating pregnancy rates is another important selection step, says Rosasco.
“If pregnancy rates are low, this could be an indicator we are having issues with puberty attainment and we may need to bump nutrition up,” she says. “If pregnancy rates are acceptable, this is telling us puberty attainment is probably at an OK level in the herd.”
Rosasco also mentions selecting heifers typically becoming pregnant early in the first breeding season influences cow longevity.
She notes a study from the U.S. Meat Animal Research Center in Clay Center, Neb. finds producers with heifers calving within the first 21 days of their first calving season “have an increased percentage of heifers remaining in the herd over nine calving seasons.”
“This can be really important from a longevity standpoint and the heifers’ ability to be productive,” says Rosasco. “It’s also important from a fertility standpoint. When heifers are bred early and attain puberty earlier on, they are fertile at the beginning of the breeding season – helping pass this trait on.”
Rosasco mentions the study also shows calving periods impact productivity.
“Those heifers calving in the first 21 days of their first calving season had an increased average calf weaning weight over their first six calves,” she says.
Rosasco mentions producers have the ability to nutritionally program heifers during the first year of their life.
“We can use nutrition to impact puberty attainment and potentially program timing and on-set of puberty attainment,” she adds.
Rosasco notes the importance of developmental windows early in a heifer’s life.
“The pre-pubertal period is a time point we can target from a nutritional standpoint to ensure our heifers have the best opportunity to attain puberty and decrease the age of puberty attainment,” she adds.
Rosasco shares, research from the 1960s to 1990s created guidelines saying replacement heifers should reach 60 to 65 percent of mature body weight by the beginning of the breeding season. She says in western, arid parts of the country, this target weight can be economically challenging for producers.
“With the amount of feed we have to put in these heifers, with corn and feed prices the way they are this year, pushing these heifers to this 65 percent mature body weight can be a challenge,” Rosasco shares.
She notes more recent research finds, “Producers can actually develop heifers closer to 50 or 55 percent mature body weight, and producers can develop heifers out grazing and utilizing winter range as a way to reduce development cost while still maintaining reproductive performance in these heifers.”
Rosasco explains this new research gives producers more options when considering a development plan.
“It gives producers opportunities to consider what best fits in their production system to get heifers to meet their specific goals,” she says.
Post-breeding nutritional management
Rosasco mentions nutritional management during the post-breeding period is a crucial step in the development program.
“Alterations in plane of nutrition during post-breeding can actually alter conception rates and embryo quality,” she says.
Rosasco shares, studies have found heifers on a diet designed for gain “had an increase in conception rates” compared to heifers on a diet designed to maintain or lose.
“This suggests we need to keep these heifers on a positive plane of nutrition in order to ensure the work we put into these heifers is not going to waste,” Rosasco concludes.
Kaitlyn Root is an editor for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.