Can We Shape Calves Before Birth?

Thu, 20 Nov 2025 15:35:49 GMT

What if the most powerful determinant of a calf’s lifetime performance isn’t the genetics you select or the ration you feed, but the environment that calf experienced as a one-cell embryo? As research accelerates, developmental programming is becoming one of the most promising frontiers in cattle reproduction.

For two decades, the beef and dairy industries have focused relentlessly on improving fertility — and it worked. Conception rates rose, days open stabilized and the long slide in reproductive performance reversed. With conventional reproductive efficiency nearing a functional ceiling, scientists are shifting attention upstream, where the environment itself may program the future trajectory of the calf.

It’s well known that a resulting phenotype represents the consequence of genotype and environmental interactions. The performance of an animal depends on the genes they inherited, how much feed they get, whether they get sick, whether it’s hot or cold, and a plethora of other environmental factors.

“We’ve made tremendous progress in optimizing the environment that those animals are raised in by providing the best nutrition, the best housing, the optimal photo period and treating disease with pharmaceuticals to optimize phenotype,” says Peter Hansen of the University of Florida. “But we usually do that after the animals are born. We don’t really think too much about what is happening to those animals when they’re embryos or when they’re fetuses or even when the germ cells are being produced.”

Evidence of Developmental Programming

Recent work has shown us the environment of the mother and the early embryo can affect the postnatal phenotype of that embryo. The environment of the fetus can affect what kind of calf it becomes.

When embryos are produced in vitro, they are put in an artificial medium. Under normal protocols, this culture medium is choline-free. Choline is a methyl donor that may factor into the one-carbon metabolism of bovine embryos. In the uterus, choline is present at millimolar concentrations.

Work led by Eliam Estrada-Cortes in Dr. Hansen’s lab investigated the effect of culturing bovine embryos with or without choline. They found choline cultured embryos resulted in calves that were heavier at weaning with altered muscle DNA methylation.

“We’ve done this experiment three times, and each time the choline calves weigh more than the calves without choline. And that goes all the way through to slaughter,” Hansen says. A nutrient present (or absent) in the culture dish during critical development time can make a big difference.

The condition of the fertilizing bull can also affect embryonic development and quality. Arslan Tariq from the University of Florida investigated the effect of bull overnutrition on fertility, finding heavier bulls produced semen that delayed embryonic development and decreased embryo quality, without changes to sperm motility or fertilization rate.

Historically, seminal plasma is removed from sperm for artificial insemination as it contains elements that can be detrimental during storage. That being said, seminal plasma modulates the maternal environment in a significant way, impacting the establishment and maintenance of pregnancy. As a part of her PhD thesis, Gabriela Macay at the University of Florida evaluated the reproductive, health and production performance of female offspring conceived in the presence of seminal plasma. These animals had increased birth weights, increased milk yield and had greater persistence in the herd compared to controls.

“What we now know is the environment of the mother that the early embryo is in can affect the postnatal phenotype of that embryo. The environment of the fetus can affect what kind of calf it becomes,” Hansen says. “And the environment of the bull.”

How Does This Affect Reproductive Management?

Developmental programming shifts reproductive management from a focus on achieving conception to a broader view of how early-life conditions shape an animal’s long-term health, productivity and resilience. This expands the veterinary role from problem solver to long term system designer who helps producers make choices that shape herd-level outcomes years down the line.

The next revolution in cattle reproduction may come from understanding the earliest biological environment that determines how a calf learns to grow, metabolize and perform.

How One Farm Nearly Doubled Their Pregnancy Rate

Tue, 07 Feb 2023 15:02:00 GMT

Getting cows pregnant is vital to literally keeping the pipeline full on a dairy. According to Jeremey Natzke of Wayside Dairy LLC near Green Bay, Wis., a 35% or better pregnancy rate equates to an outstanding repro program and a number his dairy worked hard to achieve.

Wayside shares that in order to reduce days on feed for heifers, a producer must have a maximum number of times that they breed an animal.

“At some point, you just need to pull the pin if they are not getting pregnant,” he says. “If those DNB (do not breed) cows are milking well, leave them alone and let them milk.”

Alongside Natzke, Wayside Dairy LLC is managed and owned by his father, Dan, his sister Jenna Nonemacher, new partner, Jesse Dvorchek, and himself. Milking around 2,000 cows with 1,850 replacements, the herd has a rolling herd average of 32,171 lbs. of milk and has a 4.3% butterfat with a 3.3% protein.

Natzke serves as the farm’s herd manager, overseeing the farm’s team that works with the cows from reproduction to maternity to milking, and does a lot of the scheduling for the team. About five years ago, they implemented a double lutalyse shot program which improved their conception rates.

Other changes that Wayside Dairy made that boosted their herd’s reproduction include:

Implementing a 4 mL dose of GnRH 10 days before the first breeding
Purchasing and utilizing Cow Manager monitoring system, installing tags in all their cows.

“Our heat detection rate has gone up,” Natzke shares. “The percent of cows being pregnant on herd check day has gone up. The repeat breeders show up on the system earlier so we can breed them before finding them open on herd check day. The Cow Manager tags have also helped improve our cow health. We find sick cows quicker now that we can visibly see them being sick. They get back on their feet so much faster.”

A 35% preg rate seemed nearly impossible 17 years ago for Wayside Dairy. Their preg rate hovered around 18%.

“We kept asking consultants how we can improve,” Natzke states.

Wayside brought in another set of eyes with a new veterinarian and changed nutritionists, which improved the whole team around them.

“They both challenged us and got us out of our comfort zone at times,” Natzke shares. “Double ovsynch has really improved our reproduction. There is a lot of management that takes place to get these programs in place and keep them running smoothly.”

Cattle Reproduction

Can We Shape Calves Before Birth?

Evidence of Developmental Programming

How Does This Affect Reproductive Management?

How One Farm Nearly Doubled Their Pregnancy Rate