Heifers are one of the biggest economic investments that producers make each year, and producers want those heifers to be fertile early – but not too early – in the breeding season.
In addition, they want to develop the heifers to maximize their lifetime productivity.
The key to a heifer’s fertility that can lead to maximizing the heifer’s lifetime productivity is nutrition, according to Shelby Rosasco, Extension beef specialist at the University of Wyoming.
“When we pick out those heifers, we have them for a long time before we get that first calf,” Rosasco said. “So how can we pick out and develop the best heifer that will not only be reproductive in that first year, but produce those good calves and stay in the herd for a long time?”
There are some central topics producers can consider when thinking about how to raise, develop, and select heifers:
• Are we going to develop heifers from our own herd?
“Keeping heifers from the herd allows us to have good control over the genetics. We know how she’s been raised – there are a lot of good things with that,” she said.
• Producers may decide to purchase heifers, which eliminates the time that they would have to spend managing those heifers before that first breeding season.
“We could even skip heifers and decide to buy down cows,” Rosasco said.
• The main thing producers are looking for from a heifer/cow is good fertility.
“They want their heifers/cows to consistently get bred every year, hopefully early in that first breeding season and be able to have a marketable calf each year,” she said.
• When selecting the right heifers, it is a good idea to consider what the ideal cow is.
In a 1988 paper, a researcher listed the different traits that would make up an ideal cow, including structure, fertility, health, resistance to disease, among other things. These “ideal” traits would differ between operations. The researcher also focused on getting the cow to maintain a 365-day calf interval that tied directly back to her fertility – her ability to wean a marketable calf each year and have adequate longevity.
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Drought conditions, particularly in the western states, have impacted the efforts to keep cows in the herd long enough that they can bring a profit to the operation.
“Sometimes we need to think about our heifer development systems as a stocker operation where we think about our inputs and figure out how long it takes us to recruit those development costs,” she said.
The biggest hurdle producers will face with reproduction is having heifers that will attain puberty prior to the breeding season. Fewer heifers attain puberty when they are at a low body condition going into that first breeding season.
“The goal is to get her pregnant and to calve by 2 years of age. I always like to add that my goal for heifers is that they get bred in the first 21 days of the breeding season on that first cycle,” Rosasco said.
In addition, the heifer should be able to calve without assistance and producers should be able to market a marketable calf.
Nutritional management of heifers during that first year of life can have a “big impact” on their fertility, and pre-weaning nutrition can help heifers attain puberty.
In addition, after heifers get pregnant in the first year, they should be managed for staying long-term in the herd.
In a New Mexico study, heifers were either developed on native range, with a 36 percent crude protein supplement utilizing 50 percent rumen-undegradable protein, or they were developed in a dry lot.
“Heifers who were developed grazing native range had an increased retention through breed year four compared to the dry lot group,” she said.
During the early part of the development period, stair-step diets for heifers can be used in the dry lot.
In the stair-step diet, low rates of gain can be targeted during the early part of the development period and nutrition can be increased to target higher rates of gain in the later part of the development period. Stair-step heifers had increased fertility and attained puberty earlier compared to control heifers fed diets targeting a consistent rate of gain.
Research from the USDA Animal Research Center in Nebraska analyzed 16,000 heifers divided into three groups: green, black, and red. The green line groups calved in the first 21 days, while black line heifers calved between day 22 and 42, and red line groups calved after 43 days.
“Those animals that calved in the first 21 days were set up to be more successful,” she said. “I don’t know that there’s anything super magical about that other than if they can calve early, they have a longer time to recover before that next breeding season. It’s also that those were the ones that attained puberty earlier, and maybe, they were a little bit higher fertility heifers.”
When researchers checked the weaning weights on the green group’s calves, they had increased average weaning weights over their first six months.
“To me, that’s a big bonus. Not only is she staying longer in the herd, but she’s being more productive over her lifetime,” Rosasco concluded.