Bovine Respiratory Disease

Hidden Pneumonia in Calves: Why More Dairies Use Ultrasound to Catch Respiratory Disease Early

Fri, 17 Apr 2026 20:06:16 GMT

Bovine respiratory disease (BRD) remains one of the most common and costly health challenges in preweaned dairy calves. The challenge is that many cases develop long before calves show visible symptoms.

“By the time calves show obvious clinical signs of respiratory disease, lung damage may already be present,” says Aerica Bjurstrom, regional dairy educator at the University of Wisconsin-Madison. “That’s why tools that help us detect pneumonia earlier can make a big difference in calf health and long-term performance.”

Traditional diagnosis relies on symptoms such as coughing, nasal discharge, or elevated temperature. But these signs often appear late in the disease process. In many cases, calves may look completely healthy while still carrying lung infections.

This form of illness, known as subclinical pneumonia, can reduce growth, feed efficiency and even future milk production.

“The lungs can really act as an indicator organ,” Bjurstrom explains. “Respiratory disease often reflects larger management challenges, such as poor colostrum intake, nutrition issues, or environmental stress.”

The Hidden Pneumonia Problem

Research has shown that pneumonia often develops days before visible symptoms appear.

“Ultrasound allows us to see what’s happening inside the lung tissue, even when the calf looks normal from the outside,” Bjurstrom says. “In many cases, pneumonia can be present for days before any clinical signs appear.”

Studies suggest that 50% to 80% of pneumonia cases may remain subclinical for 7 to 14 days before producers notice symptoms. That delay can allow lung damage to progress before treatment begins.

“Sometimes calves with severe pneumonia don’t show obvious symptoms,” Bjurstrom says. “But an ultrasound exam can reveal lung lesions that tell us the disease is already present.”

How Lung Ultrasound Works

Lung ultrasonography allows veterinarians to examine calf lungs in real time using portable ultrasound equipment.

A normal lung appears air-filled on the scan and produces horizontal white lines that move with each breath. These lines indicate healthy lung tissue.

Changes in the image can reveal early disease.

“Comet tails are bright vertical lines that extend down from the lung surface,” Bjurstrom says. “A few may be normal, but severe or diffuse comet tailing can suggest interstitial disease caused by fluid or inflammation within the lung.”

More advanced disease appears as lung consolidation, where portions of the lung fill with inflammatory material instead of air. On ultrasound, these areas appear as solid gray regions.

Veterinarians often use a 0 to 5 lung scoring system to evaluate severity.

“This scoring system helps identify disease before calves begin coughing or showing nasal discharge,” Bjurstrom says. “Early detection allows for earlier treatment and better outcomes.”

Dr. Ollivett demonstrates positioning for thoracic ultrasound scanning on a calf’s right lung.

(Denise Garlow, University of Wisconsin)

Why Early Detection Matters

Even when calves show no visible symptoms, lung damage can affect their long-term performance.

In one study of more than 600 Holstein heifers, calves with lung consolidation detected at weaning were less likely to become pregnant and more likely to leave the herd before first calving.

Another study found calves with significant lung lesions in the first eight weeks of life produced 1,155 pounds less milk during their first lactation.

“These findings highlight why early detection matters,” Bjurstrom says. “Subclinical disease can still influence growth, reproduction, and milk production later in life.”

Improving Treatment Outcomes

Early detection can also make treatment more effective.

“When pneumonia is caught earlier, treatment tends to work better,” Bjurstrom explains. “We’re able to intervene before the disease becomes severe and causes permanent lung damage.”

Ultrasound can also help veterinarians monitor recovery.

“That monitoring aspect is important,” she says. “It helps ensure calves are improving and reduces unnecessary retreatment.”

A Management Tool for Farms

Beyond diagnosis, lung ultrasound is increasingly used as a herd management tool.

“Ultrasound gives producers objective information about lung health,” Bjurstrom says. “That can help guide decisions about treatment, culling, or adjusting weaning timing for calves that may need more time to recover.”

Regular scanning can also reveal herd-level trends tied to management practices.

“When used consistently, ultrasound becomes a benchmarking tool,” Bjurstrom says. “It can help farms evaluate colostrum programs, ventilation, sanitation, and other factors that influence calf health.”

A Growing Tool in Calf Health Programs

Portable ultrasound units have become more accessible and easier to use, making them more common in calf health programs. With proper training, scanning a calf’s lungs typically takes less than a minute.

“The equipment requires an initial investment, but the information it provides can be incredibly valuable,” Bjurstrom says. “Earlier detection can lead to better management decisions, improved calf growth, and fewer losses.”

As dairy farms continue adopting more data-driven management practices, lung ultrasound is giving producers a new way to detect disease sooner and protect the long-term potential of their calves.

“Lung ultrasound helps us move beyond waiting for visible symptoms,” Bjurstrom says. “It allows producers and veterinarians to identify problems earlier and take action before long-term damage occurs.”

Respiratory Disease Follows Beef-on-Dairy Calves for Life

Wed, 18 Feb 2026 15:32:38 GMT

When beef‑on‑dairy calves first started moving off of dairy farms and onto the next stage of life, they didn’t get much attention. But today, these crossbred calves represent a significant revenue stream for dairy producers, bringing their early-life care into sharper focus.

“Beef-on-dairy calves have exploded in popularity,” says Melissa Cantor of Penn State University. “Holstein bull calves are worth good money, but the beef-on-dairy [market] has really exploded. We saw $1,500 prices for calves here in the Northeast in the past couple weeks.”

When calves are bringing in that kind of money, what happens early on matters — especially around bovine respiratory disease (BRD) issues. During a recent “The Dairy Nutrition Blackbelt Podcast,” Cantor spoke on how even mild respiratory disease early in life can leave a lasting mark that follows beef-on-dairy calves all the way to the packing plant.

Early Respiratory Disease Starts Small

Despite their rising value, many beef-on-dairy calves still receive minimal nutrition early in life. Cantor notes they are often limit-fed and given lower-quality colostrum. At the same time, respiratory disease often spikes around weaning, when stress, nutrition and environment collide.

“We see a lot of respiratory disease around weaning,” Cantor says. “So, we wanted to know: how does that affect long-term growth, and is there something we should change in how we raise these calves?”

To answer that question, Cantor’s team followed 145 beef-on-dairy calves from early life through slaughter. The team used ultrasound around weaning to spot any early signs of respiratory disease. However, when disease was identified, it often looked minor.

“It was just very early lung consolidation — about one centimeter,” Cantor explains. “It’s basically a tiny spot on the lung. The calves still looked healthy. But as a dairy farmer, you’d probably never notice it. Maybe they’d cough a little, but that’s about it.”

In the study, about 25% of the calves showed this level of lung consolidation, which Cantor says is typical for weaning-age animals. But while it appeared mild, it still had consequences.

Feedlot Performance Can Be Misleading

When the calves moved on to the feedlot level, researchers tracked how they ate and grew to see if early respiratory disease showed up later. They monitored feed intake, weight gain and finishing weights.

“We weighed them when they arrived at the feedlot, and we knew what their dry matter intakes were,” Cantor says. “Dry matter intake, acclimation to the diet, average daily gain in the feedlot, finishing weight — they were all the same despite if the calves had respiratory disease or not. We were shocked.”

In other words, calves that had been sick early in life caught up in growth. By the end of the feeding period, they looked just as productive as calves that had never shown signs of respiratory disease.

However, this changed at slaughter.

“We followed these crossbreds all the way out to slaughter, and we actually had carcass tracing on those animals,” Cantor says. “We were able to look at carcass dressing weight and marbling, which is huge.”

That’s where the impact of that early respiratory disease became clear.

“What was so interesting to me is that the marbling in those animals that had respiratory disease was less,” Cantor says.

Lower marbling leads to a lower carcass grade, reducing the animal’s final value.

“If we have a lower marbling score and a lower carcass grade, you’re going to get paid less for that animal, or even potentially get discounted,” Cantor says. “This is how these beef producers are being paid, and no one’s ever thought about managing respiratory disease to deal with these long-term effects.”

So why does early respiratory disease leave this lasting mark? One explanation Cantor offers relates to how calves use energy during critical stages of development. Even when intake and average daily gain even out, healthier calves can direct more energy toward fat deposition, while calves fighting illness may divert nutrients to support their immune system instead.

In short, when calves fight disease during these windows of fat cell development, nutrients may be redirected away from marbling, leaving them with lower carcass quality even if their growth appears normal later in life.

Spotting and Preventing BRD

While early respiratory disease can be easy to overlook, even mild cases can lower marbling and carcass grade at slaughter, reducing the animal’s value long after it leaves the dairy. And while this may not seem like a major concern for dairies that sell calves early, calf ranchers and buyers may avoid sourcing animals from farms with a history of BRD.

Because early cases can be easy to miss, it helps to watch for these symptoms:

Increased or labored breathing
Coughing
Ear droop
Nasal or eye discharge
Lethargy
Poor appetite
Fever
Diarrhea
Isolation from the group

To help reduce the risk of respiratory disease, focus on these prevention steps:

Provide adequate, high-quality colostrum
Maintain consistent milk feeding
Follow vaccination programs
Provide ample, dry bedding
Ensure proper ventilation
Keep housing draft-free
Maintain clean, sanitary facilities
Detect and treat disease early
Keep low stocking densities
Minimize stressors

For dairy farmers and calf ranches, early‑life management still matters, even if the calf leaves the farm soon after birth. Investing in colostrum, nutrition, housing and respiratory disease prevention protects not only calf health but also long-term value.

Harness the Full Potential of Your BRD Vaccine with the Right Adjuvant

Mon, 29 Sep 2025 16:03:14 GMT

Bovine respiratory disease (BRD) is one of the greatest threats to young calves, and gaining protection through vaccines isn’t always straightforward. Maternal antibodies, passed through colostrum, can block some vaccines from boosting immunity. The key to overcoming that hurdle? Choosing a vaccine with the right adjuvant.

Maternal Antibodies Can Interfere with Vaccines

“Years ago, vaccine response was so variable in young calves,” says Curt Vlietstra, DVM, Boehringer Ingelheim. “At the time, we didn’t know if their immune system simply wasn’t ready, or if there was a problem with the vaccines. With the research we have now, we understand that the majority of interference comes from maternal antibodies that are still present in the calf at the time of vaccination.”

Passed down from the cow via colostrum, maternal antibodies are not only a calf’s first line of defense against disease, but they also have the tendency to neutralize vaccines.

Those maternal antibodies naturally wane when the calf is between 2 and 6 months of age. As this maternal immunity dwindles, vaccination becomes critical in boosting and building calf immunity. The largest challenge in bridging these two forms of immunity is timing. Chris Chase, DVM, Professor, Department of Veterinary and Biomedical Sciences, South Dakota State University, says finding a vaccine with the right adjuvant can eliminate this guessing game.

Adjuvants Are Critical to Capturing Immunity in Young Calves

Adjuvants — although often overlooked — can determine whether a calf successfully develops a robust, lasting immune response, or remains vulnerable to BRD pressure. They work by drawing immune cells to the injection site, and helping the calf’s body recognize and remember the vaccine. Some adjuvants also slow the release of the vaccine, giving the immune system more time to respond.

“With the types of adjuvants we have now, we can get strong, long-lasting immune responses, even in calves with maternal antibodies,” Chase shares. “Although, just because a vaccine label says ‘adjuvanted’ doesn’t mean it offers the protection we need. It’s important that we ask what kind of adjuvant it is and what it’s proven to do.”

Over the last few decades, peer-reviewed studies and fieldwork have shown that Pyramid ^® vaccines can succeed, even in the face of maternal immunity, thanks to its unique adjuvant, Metasim^®. Specifically designed to address the challenges of early calfhood vaccination, the dual-phase technology of the Metasim adjuvant can stimulate a balanced, robust immune response in calves as young as 30 days of age.

(Boehringer Ingelheim)

“Historically, it was accepted as fact that maternal antibodies would block the injectable vaccine,” Vlietstra says. “Now we know Metasim works alongside the preexisting antibodies, not against them.”

Systemic Immunity Builds Long-Lasting Protection

Another key factor in vaccine selection is delivery method. For a time, intranasal vaccines were thought to be the only effective option to protect young calves against BRD. While intranasal vaccines can offer local immunity for calves at risk of BRD exposure soon after birth, some may miss the opportunity to stimulate robust, systemic immunity.

While local immunity helps block infection right where it starts (which is usually in the respiratory tract with BRD), systemic immunity is what builds broad, long-lasting protection, by training the calf’s entire immune system to respond.

When calves encounter BRD pathogens weeks or even months after vaccination, a strong systemic immune response helps them recognize and fight off infection more effectively, reducing severity of disease and its long-term impact on health and performance.

“In some ways, we’ve become very reliant on intranasals,” Vlietstra notes . “I’ve seen protocols that say, ‘This calf may not respond to an injectable, so let’s give another intranasal.’ That choice ends up potentially delaying systemic protection.”

Injectable vaccines with the right adjuvant have been proven to stimulate both local immunity in the respiratory tract, and systemic immunity that circulates in the bloodstream.

Even the Best Vaccine Needs Correct Timing and Care

“There are plenty of producers and veterinarians who have firsthand experience of vaccines not working,” Vlietstra says. “If we’re not seeing results, it’s time to evaluate how we’re using the product and when.”

It’s common to schedule vaccination alongside other times calves are being worked, like weaning or transportation. While this may save labor and time up front, vaccinating calves during other stressful events can limit immune response.

“If cattle have had a long truck ride, ideally, we’d let them unload and rest for 24 to 48 hours before we vaccinate,” Chase explains. “I know not all operations have the resources to do this due to labor constraints, but water and rest time after a stressful event will set cattle up for a better immune response.”

To get the most of any vaccination program, good animal handling, husbandry and biosecurity protocols play a role in preventing and controlling BRD. By staying on top of health management and using products according to label, vaccines are more likely to capture desired results.

“The world’s best vaccine is not going to overcome overwhelming challenges,” Chase stresses.

The needs of every herd are different. Working closely with a veterinarian is key to finding success tailored to your cattle and operation.

Five Easy Maternity Pen Moves for Better Calves

Mon, 08 Jul 2024 21:47:47 GMT

What happens in the maternity pen, does not stay in the maternity pen. Rather, the events and environment there can impact a newborn calf for the rest of its life, particularly when it comes to respiratory disease.

Because lung damage in calfhood can impact lifelong health and performance, researchers at the University of California-Davis conducted a multi-phase, large-scale population study examining various management factors and their influence on calfhood bovine respiratory disease (BRD).

On a recent episode of the “ Have You Herd ?” podcast from the American Association of Bovine Practitioners, Dr. Sherif Aly, veterinarian and epidemiologist at the UC-Davis Veterinary Medical Teaching and Research Center at Tulare, Calif., discussed the results.

Aly said the first portion of the study was a survey with more than 40 questions issued to dairies throughout California that helped narrow down the management factors that affect BRD. The next phase, dubbed the “BRD 100” study, drilled deeper into those issues on 104 cooperating dairies. Finally, the resulting information led to the “ BRD 10K ” study, which gathered health and performance data on more than 11,000 calves from birth to weaning on 5 dairies located in the 3 major milksheds in California.

In that study, management practices were assessed by risk factors that contributed to BRD in varying degrees. A score of 1.0 or higher indicated a risk factor. Of particular interest was the maternity pen, where the following risk factors were identified:

(1) Cows and heifers calving together – Commingling first-calf heifers in the same maternity areas as multiparous cows resulted in a BRD offspring risk factor of 1.4, meaning there would be a 40% greater likelihood of calves contracting BRD.

(2) Bedding changes – Changing the maternity pen bedding 6, 7, or 8 times per month significantly reduced the risk of calves contracting BRD. Interestingly, changing the bedding 9 times per month actually produced an uptick in BRD risk to calves.

(3) Bedding materials – Compared to dried manure solids mixed with gypsum, both dirt and plant-based bedding materials (rice hulls, almond hulls, straw, and wood shavings) showed higher risk factors for BRD. Dirt had a whopping 4X odds ratio compared to a manure solids/gypsum base.

(4) Pasture calving – Calving on pasture produced a higher risk factor for BRD compared to enclosed maternity pens.

(5) Dam separation – Removing calves from their dams within 1 hour of birth produced a significant reduction in BRD risk.

The study also examined the association of BRD incidence related to herd demographics, colostrum delivery, vaccination, nutrition, and housing.

Aly said BRD is a complex, multi-factorial disease, lamenting that the incidence in dairy calves has not improved significantly over several decades. His team’s work revealed that 22-23% of calves contract BRD in the preweaning period, which leaves much room for improvement.

By drilling deep into the management practices and related BRD incidence on California dairies, Aly is hopeful the data and knowledge gleaned from their work can help dairies reduce their struggle with the disease. “BRD in preweaning period sets the stage for the success of these cows later on in life,” he declared.

Keep Replacement Heifers Thriving this Winter: Three Expert Tips You Need to Know

Fri, 03 Jan 2025 17:51:20 GMT

When dairy farmers think about animals impacted by cold stress, calves are often the first that come to mind. Their smaller size and limited fat reserves make them especially vulnerable to harsh winter conditions. However, it’s important to remember that cold stress doesn’t just affect calves—it can also significantly impact heifers.

Younger animals, like post-weaned heifers, are particularly susceptible as they have less developed coats, and higher energy needs to maintain their core body temperature. For dairy farmers, understanding the signs of cold stress and implementing preventative measures across all age groups in the herd is essential for maintaining health, productivity, and growth during the winter months. While calves often receive extra attention, ensuring proper care for heifers and older animals can make a big difference in the overall success of the operation during the colder seasons. For these replacements to grow and thrive, dairy farmers must take proactive steps to prevent cold stress and minimize associated health issues.

Daniela Roland, dairy extension educator at Pennsylvania State University, provides the following tips for providing adequate care to replacement heifers during frigid temps.

Understanding Cold Stress

While lactating cows are relatively tolerant of cold temperatures and can handle conditions below 18°F when equipped with a heavy winter coat, young heifers face challenges at temperatures below 32°F.

“Normally, a heifer’s winter coat, plus their natural metabolic processes, like rumination, can keep them warm,” Roland says. “But during extremely cold temperatures - especially if there is inadequate housing, lack of dry bedding, insufficient nutrition, or a combination of these - heifers may experience cold stress.”

Housing and Bedding

Dry, well-bedded pens are essential to help heifers tolerate winter conditions. Bedding materials like straw, shavings, or corn fodder should be clean, dry, and absorbent to retain body heat.

“One way to test the dryness of heifer pens is the knee test,” Roland says. “To do this, try dropping to your knees in several areas around the pen. If your knees are still clean and dry after 10–15 seconds of kneeling on the bedding, then the bedding is sufficient. But if your pants are dirty or damp, more fresh bedding should be added.”

Wet or muddy coats reduce the insulating properties of a heifer’s hair, also increasing their susceptibility to cold stress. Excess manure or mud buildup should prompt farmers to add fresh bedding or clean pens more frequently.

Additionally, heifer housing should allow for adequate air exchange without creating drafts. Insufficient ventilation can increase the risk of respiratory diseases like bovine respiratory disease (BRD), which costs farmers an average of $252 per case and can delay a heifer’s growth and first calving, according to Roland.

Proper heifer housing is another critical factor to consider during cold weather. Housing should shield heifers from environmental extremes such as harsh winds, heavy snow, and freezing temperatures while maintaining a comfortable and healthy environment.

One key aspect of housing is ventilation. While barns and shelters must prevent drafts, they should also allow for proper air exchange to reduce humidity and prevent the buildup of harmful gases like ammonia. It’s essential to monitor heifers for signs of respiratory distress, such as coughing, labored breathing, or nasal discharge, as these could indicate inadequate airflow or other health issues. If respiratory problems are detected, improving ventilation should be a priority.

Heifers housed outside also need special attention.

“Heifers housed outdoors need to have access to either natural or constructed windbreaks,” Roland adds. “Wind significantly reduces the actual temperature, increasing cold stress on heifers.”

Nutrition for Winter Growth

In colder weather, heifers expend more energy to stay warm, making proper nutrition vital. Farmers should aim for daily growth rates of 1.75 pounds for large breeds and 1.3 pounds for smaller breeds to ensure heifers reach optimal breeding size.

“Data has shown that undersized heifers may calve later than the desired age range of 22 to 24 months. These smaller heifers tend to be more prone to calving problems and less productive,” Roland says. “Farmers should work with their nutritionist to make sure that their heifers have enough energy in their diet to help protect them from the cold weather and to ensure proper growth.”

Water Access

Water availability is another critical factor in winter care. Frozen or excessively cold water can limit intake, reducing feed consumption and energy availability.

“Dairy heifers between the ages of 5 and 24 months will drink about 3.8 to 9.6 gallons of water per day,” Roland adds. “Monitoring for frozen waterers is important during the extreme colder temperatures.”

Why It Matters

Investing in proper heifer care during winter ensures these replacements grow to their genetic potential and transition into productive lactating cows. By focusing on housing, bedding, nutrition, and water, farmers can safeguard their herd’s health, prevent growth setbacks, and optimize future productivity. Taking these steps helps ensure your heifers thrive, even in the coldest months.

USDA Reports First H5N1 Detection in Swine

Wed, 30 Oct 2024 23:27:10 GMT

USDA announced on Oct. 30 the first reported case of H5N1 in a pig in an Oregon backyard farm. It’s important to note there is no concern about the safety of the nation’s pork supply as a result of this finding, USDA said. This farm is a non-commercial operation, and the animals were not intended for the commercial food supply.

“The confirmed case in Oregon poses no threat to consumer health or food safety; properly handled and cooked pork products remain safe for consumption,” Bryan Humphreys, National Pork Producers Council (NPPC) CEO said in a statement. “The entire pork industry remains committed to safeguarding food safety and human and animal health.”

The case was discovered on a backyard farm that includes a mix of poultry and livestock, including swine. The Oregon Department of Agriculture announced on Friday, Oct. 25, that poultry on this farm represented the first H5N1 detection in Crook County, Oregon. On Tuesday, Oct. 29, the USDA National Veterinary Services Laboratories also confirmed one of the farm’s five pigs to be infected with H5N1, marking the first detection of H5N1 in swine in the U.S., USDA reports.  

“The livestock and poultry on this farm shared water sources, housing, and equipment; in other states, this combination has enabled transmission between species. Although the swine did not display signs of illness, the Oregon Department of Health and USDA tested the five swine for H5N1 out of an abundance of caution and because of the presence of H5N1 in other animals on the premises,” USDA wrote.

The swine were euthanized to facilitate additional diagnostic analysis. Although test results were negative for two of the pigs, and test results are still pending for two others.  
The farm has been quarantined to prevent further spread of the virus. Other animals on the farm include sheep and goats that remain under surveillance.  

“USDA’s National Veterinary Services Laboratories (NVSL) has conducted genomic sequencing of virus from the poultry infected on this farm, and that sequencing has not identified any changes to the H5N1 virus that would suggest to USDA and CDC that it is more transmissible to humans, indicating that the current risk to the public remains low,” USDA wrote.

H5N1 detections include viral genome sequencing to provide additional information of interest to medical professionals and the research community to improve understanding of the virus. Genetic sequencing for these samples is underway, but results may be inconclusive due to low viral levels in the samples, USDA said.   

Pork Producers Practice Biosecurity to Protect Pigs
Biosecurity is critical to eradicating H5N1 and other viruses. Not only does biosecurity protect the health of livestock, but it also protects the health of farmworkers and their families. For more information on protecting farmworkers, visit the CDC’s website .
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10 Powerful Take Homes to Enhance Biosecurity on Your Pig Farm
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The pork industry has worked alongside USDA’s Animal and Plant Health Inspection Service (APHIS) since 2009 to carry out the swine influenza surveillance program to identify influenza viruses circulating in swine, proactively detect reassortment viruses that could impact public health, and gain knowledge to contribute to improved animal health diagnostics and vaccines, NPPC pointed out in a statement.

“Pork producers have always been proactive and diligent about implementing biosecurity plans as part of their daily production practices to assure animals wellbeing and food safety,” Lori Stevermer, NPPC president and Minnesota pork producer said. “This detection serves as a reminder for producers of all sizes to understand and address influenza virus risks.”

What’s Next?
USDA recently approved two vaccine field safety trials for vaccine candidates designed to protect dairy cows from H5N1, and continues to explore vaccine options for other species.   As USDA takes additional steps to protect the health of livestock, it will continue to work closely with CDC to protect the health of people and FDA to protect the safety of the food supply.

“These collective, collaborative efforts have helped protect farmworkers and farmers, the health and welfare of livestock animals, and reaffirmed the safety of the nation’s food supply. The U.S. government remains committed to addressing this situation with urgency,” USDA said.

Learn more about USDA’s response to HPAI in dairy cattle.

The situation is being monitored by local public health officials, Oregon Health Authority, Oregon State Veterinarian, Oregon Department of Agriculture, as well as USDA and U.S. Department of Health and Human Services.   

Read More:
Get the Facts Straight on Highly Pathogenic Avian Influenza
Animal Health Experts Open Up About Future Disease Preparedness
How the Swine Industry Responded to H5N1 Outbreak in Dairy Cattle
A Message to the Ag Industry about H5N1

Health Traits Have Genetic Heritability in Calves

Mon, 19 Aug 2024 17:32:06 GMT

In the quest to raise healthy, productive, profitable calves comes an emerging element: genetics.

Along with the myriad factors dairy producers embrace to raise the healthiest potential offspring, there is growing evidence that calves can inherit disease resistance from their parents. Thus, traits for resistance to diseases like pneumonia and scours may become an increasingly important factor in dairy genetic selection, according to Dr. Isaac Haagen, Assistant Professor of Animal Science at the University of Minnesota.

Haagen shared his thoughts on dairy calf genetic health traits on a recent episode of The Dairy Podcast Show. He discussed data that he gathered during his graduate studies at Pennsylvania State University, which encompassed 15 organic dairy herds from across the United States, ranging in size from about 30 cows to several thousand.

Specifically, he merged the calf health data from those herds, which was gathered via a variety of herd software platforms. Then, using traditional pedigree analysis and a limited amount of genomic data, he was able to determine that, based on that data set, health traits in calves are heritable to a degree similar to more widely monitored traits like Daughter Pregnancy Rate (DPR) and Productive Life – generally, about 5-10%.

Haagen said that rate is similar to the heritability reported by Zoetis for the Calf Wellness Index^TM (CW$^TM) in their Clarifide® Plus genomic test. The Clarifide Calf Wellness Index encompasses traits for respiratory disease, scours, and calf livability.

A Canadian study recently published in the Journal of Dairy Science further supports the notion that calf diseases can be controlled in part via genetic selection. In that study, records from more than 62,000 dairy calves from 1,617 Canadian herds spanning 2006-2021 were evaluated.

The Canadian researchers found that heritability for respiratory disease and diarrhea ranged from 2-7%. They also discovered that calves born to the bottom 10% of sires for the traits were 1.8 times more likely to develop respiratory disease, and 1.9 times more likely to develop diarrhea, compared to daughters born to the top 10% of sires.

That group advocated for a national recording system to allow for national genetic evaluation, a concept that Haagen also supports in the United States. He said the evidence is strong enough to make the argument for a calf health specific index among the national traits evaluated by the Council for Dairy Cattle Breeding.

“While 5-10% heritability is a relatively small number, we know from other health traits that even that small number can have an impact over many generations,” Haagen stated.

He added that with any selection index, “we’re really selecting for profitability. With heifer replacement costs generally running as the second or third highest expense on farms, there is value in selecting for healthier animals that are expected to live longer.”

An interesting and related factor in Haagen’s research was an analysis he ran on serum total protein (STP) as a health measure. His findings indicated that, in addition to crucial factors like colostrum delivery, STP also is a heritable trait in calves.

“We found that calves differ in their ability to acquire passive immunity,” he stated. When he and his colleagues separated animals according to breeding value for STP, they found that 4-6% more of the heifer calves in the top quartile would remain in the herd at one year of age compared to the worst calves.

Haagen is continuing his research on calf health genetic traits using 20 years’ worth of data on more than 6,000 calves from commercial Minnesota dairy herds. He hopes the longer range of that data will help him extrapolate lifetime performance evidence related to genetic factors for calves, providing yet more proof of the link between the two.

The Eyes Have It When Detecting Early Calf Respiratory Disease

Tue, 07 Feb 2023 21:06:23 GMT

Detecting the subtle signs of the onset of pneumonia in calves is the best way to assist them with effective treatment, and hopefully avert long-term lung damage, according to Tiago Tomazi, DVM, technical services veterinarian for Merck Animal Health .

On a recent webinar hosted by the Dairy Calf and Heifer Association , Tomazi shared that he always looks at calf’s head and facial features first. “There’s so much about the head that can indicate the onset of respiratory disease,” said Tomazi. “Think of how we feel when we’re starting to get a cold. It’s similar for calves – they have itchy, watery eyes, their ears droop a little, they salivate more, and they may be licking their nostrils more frequently.”

Tomazi said intermediate symptoms will appear as the disease progresses – mild fever, lethargy, sleepiness, slow movement, lack of interest in eating and drinking, and slightly bowed heads. By the time obvious symptoms like high fever, heavy breathing and coughing, head tilt, and thick nasal and eye discharge appear, it’s often too late for treatment to do much good.

“Anyone can detect those sick animals, but by then the probability of those calves having permanent lung lesions is very high,” he stated.

Tomazi shared research data that showed the long-term impact of lung consolidation and lesions on lifetime performance, including:

Calves with at least 3 cm. of lung consolidation produced an average of 1,157 lbs. less milk in their first lactations.
Heifers diagnosed with lung consolidation at 60 days of age were significantly slower in achieving pregnancy.
Calves with lung lesions detected at 3 months of age were significantly less likely to survive to first lactation.

He said if diagnosis of respiratory disease is delayed, it can lead to prolonged use of antibiotics, increased risk of treatment failure, high relapse rate, and advanced disease progression. In addition to chronic lung injury and abscesses, that also might include ear infections and more widespread respiratory disease in the herd.

Employee training to recognize and efficiently treat respiratory disease in calves is critical to keeping it in check. Tomazi said explaining WHY it is so important to detect and treat calves early, rather than just telling workers what to do, should lead to more attentive care early in the disease process, when it can increase the cure rates and potentially reduce losses associated with the disease.

For more on calves, read:

Respiratory Issues in Young Calves Leads to Lower Milk Production

Thu, 12 Nov 2020 05:54:29 GMT

Calves with respiratory issues in the first eight weeks of life are able to survive to adulthood, but those lung issues do lead to a significant loss of milk production in their first lactation, according to a study conducted at the University of Guelph in Ontario.

Researchers used ultrasound weekly on 215 Holstein heifers during the first eight weeks of life to determine the amount of congestion in their lungs. They found over half (57%) had at least one case on congestion during that time.

The heifers were then tracked through their first lactation. There was no difference in the age at first calving between calves with at least one case of lung congestion and those with no cases. But heifers that had at least one case of congestion produced, on average, 1,155 lb less milk in 305 days.

Also of note: Twenty five percent of calves in the study did not reach the end of their first lactation. Seven percent of the animals died as calves, and a further 18% were sold prior to the end of the first lactation. The Guelph researchers, however, did not report any differences in these attrition rates to heifers with or without lung issues.

The study was reported in the June issue of the Journal of Dairy Science. Click here to read an abstract of the study.