Research Update: Controlling pre-weaning respiratory disease in beef calves

Study suggests vaccination at fall pregnancy checking may increase immunity against pneumonia during the first 30 days of life.

Respiratory disease in pre-weaning beef calves is a growing problem among Midwestern cow-calf herds. In recent studies, prevalence of pre-weaning calf pneumonia has been observed affecting as many as 20%-30% of calves in some operations.

The main factors in determining disease or health in young beef or dairy calves are the transfer of maternal immunity and the duration of maternal immunity.

Dr. Manuel Chamorro, clinical assistant professor with Kansas State University’s College of Veterinary Medicine Livestock Services, recently completed research as part of a team investigating the effectiveness of vaccinating pregnant heifers at 6-8 months gestation to prevent pre-weaning respiratory disease.

The study
Dr. Chamorro, together with Dr. Emily Reppert and Dr. Lacey Robinson, Livestock Services; Joyce Wick, fourth-year veterinary student; and Dr. Natalia Cernicchiaro, Department of Diagnostic Medicine and Pathobiology; are in the process of publishing the study results.

First-calf heifers vaccinated prior to breeding with a modified live virus (MLV) multivalent vaccine containing BVDV 1, BVDV 2 and BHV-1 were split into two groups. One group received two doses of a killed virus multivalent vaccine 21 days apart between 6.5 and 8 months gestation. The second group received a shot of saline solution. The group then measured the total serum IgG and neutralizing antibodies to BVDV 1, BVDV 2 and BHV-1 in newborn calves.

“The question is, ‘Is the just the total IgG level from colostrum enough,’” Chamorro asked, “or are there other factors? We believe it doesn’t matter the amount of antibodies but their specificity. You can have a high level of antibodies, broad spectrum, but if you are lacking specific antibodies against respiratory disease, your calves may still have it.”

The findings
Serum samples collected from dams revealed higher antibody titers to BVDV 1, BVDV 2 and BHV-1 in heifers vaccinated with the killed virus vaccine during gestation than the control group. Similarly, the mean serum antibody titers to BVDV 1, BVDV 2 and BHV-1 of calves at 24 hours old born to heifers vaccinated during late gestation were also higher.

Ultimately, the group’s study found that vaccinating beef cows during 6-8 months of gestation would reflect an increase in specific antibodies in maternal colostrum and would result in better antibody uptake in young calves. Higher serum antibody titers to the specific disease might result in prolonged duration of maternally derived immunity and better protection against respiratory disease during the pre-weaning period.

“It’s a good idea,” Dr. Chamorro said of vaccinating pregnant cows and heifers against common cattle respiratory pathogens during fall pregnancy checking. “It’s affordable and we’ve seen results.”

Abstract: BVDV and BHV-1 antibody levels in colostrum of beef heifers vaccinated or unvaccinated during gestation with a multivalent killed viral respiratory vaccine

Abstract: Maternally-derived BVDV and BHV-1 antibodies in calves born to dams vaccinated or not during gestation

Dr. Manuel Chamorro is a clinical assistant professor for Livestock Services with the Kansas State University College of Veterinary Medicine. Dr. Chamorro’s research interests are concentrated on respiratory viruses of cattle with specific emphasis in BVDV and in the effect of colostrum-derived immunity on clinical protection and immune response to vaccination in calves. Another area of interest for Dr. Chamorro is the use of bovine colostrum or colostrum replacers as an alternative to reduce disease and the use of antibiotics in calves. 

Research Update: Duration of postpartum anestrus in cows and heifers

The length of time it takes for a cow to resume fertile cycles after calving directly affects the reproductive performance and efficiency of a cow-calf herd. Dr. Robert Larson, professor of production medicine, collaborated with Dr. Doug Shane, Dr. Mike Sanderson, Dr. Matt Miesner and Dr. Brad White to develop a model investigating the effects on herds with differing lengths of time to resume fertility after calving over the course of 10 years.

Ideally, the average cow in a herd takes 50-60 days to resume cycling following calving when the cows are in good body condition. However, herds with a high percentage of thin cows, cows that experienced calving difficulty, or cows that are slower to resume fertile cycles after calving due to presumed genetic reasons may average slightly to much longer length of post-calving infertility.

“Relatively small increases in the length of post-calving infertility have detrimental effects on the herd’s productivity and those effects can persist for several years,” Dr. Larson explained. “Conversely, relatively small improvements also have important benefits.”

While the differences between a herd with optimal reproductive efficiency and less efficient herds can be difficult, if not impossible to see outwardly, the model provides quantitative evidence of change.

Calving heifers ahead of cows
In a separate study, the group developed a 10-year model determining the effects of breeding heifers before mature cows. One of the challenges when managing the length of post-calving infertility is to ensure that the youngest group of cows that just had their first calf are ready to breed by the start of the breeding season. These young cows tend to take longer to return to fertility than mature cows and good reproductive management of this important age-group starts long before they are bred for their first pregnancy.

“Focusing on development of replacement heifers is critical for good overall herd reproductive efficiency,” Dr. Larson said. “If replacement heifers can be managed so that all those that are selected to enter the herd will calve before the start of the mature cow calving season, all (or nearly all) of this age-group will have time after calving to resume fertile cycles by the start of their second breeding season.”

While breeding replacement heifers earlier than the mature cows provides benefits, it also requires additional management and may be inconvenient. The second model investigated how to select the optimum length of time to breed heifers ahead of mature cows. While the optimum heifer lead time is different for different herds, in general, the greatest bang for your buck occurs when heifers are bred to calve three to four weeks ahead of mature cows. While breeding even earlier provides additional benefits, the amount of improvement in reproductive efficiency decreases with each week earlier that heifer breeding is moved.

Read the published abstracts, papers and key points below.

Journal of Animal Science, Volume 95, Issue 4, April 2017: A deterministic, dynamic systems model of cow-calf production: The effects of the duration of postpartum anestrus on production parameters over a 10-year horizon
Key study findings

Journal of Animal Science, Volume 95, Issue 10, Oct. 2017: A deterministic, dynamic systems model of cow–calf production: The effects of breeding replacement heifers before mature cows over a 10-year horizon
Key study findings

Theriogenology, Volume 105, January 2018: Determining potential pregnancy status differences based on a new method of yearling heifer prebreeding examination
Key study findings

Research Update: Do darts deliver?

Pneumatic dart delivery of tulathromycin in calves results in lower antimicrobial concentrations and increased biomarkers of stress and injection site inflammation compared to subcutaneous injection

Research by Dr. Hans Coetzee, department head and professor of anatomy and physiology, Kansas State University; Michael D. Kleinhenz, graduate student, Kansas State University; Dr. Drew R. Magstadt, Iowa State University; Dr. Vickie L. Cooper, Iowa State University; Dr. Larry W. Wulf, Iowa State University; Nicholas K. Van Engen, Dr. Joseph S. Smith, Dr. Nathan Rand, Dr. Butch KuKanich, Kansas State University; and Dr. Patrick J. Gordon, Iowa State University with the College of Veterinary Medicine at Iowa State University

The use of pneumatic darts to deliver medication to livestock animals has been gaining popularity, said Dr. Hans Coetzee, head of the department of anatomy and physiology at Kansas State University (K-State). Due to an increase in the number of reports of the use of the technology by producers and practitioners from the field, Dr. Coetzee, in collaboration with colleagues at the College of Veterinary Medicine at Iowa State University, recently published a study in the Journal of Animal Science detailing the use of pneumatic darts to administer tulathroymycin (Draxxin®) to cattle.

Historically, darting is a practice more commonly used to deliver drugs to wildlife. However, the use of pneumatic darts to deliver medication to sick cattle has seen an increase in some parts of the U.S. In pasture and range conditions, where handling facilities are not immediately available, producers and practitioners have employed the use of darting to administer medication as soon as an illness is identified.

Not a point-and-shoot technology
The team’s first surprise came with the discovery that the darts did not consistently
deliver the drug, Dr. Coetzee said. “There were four out of 15 animals that were successfully darted where the dart failed to deliver the drug altogether.” Darting1

In other cases, trace amounts of the drug were found in the animals, not at levels effective against the bacteria causing the infection, but at levels that could pose a risk of tissue residues or promote the development of antimicrobial resistance.

It’s a significant finding, because when a dart is delivered, it can remain attached to the animal receiving treatment for up to an hour following delivery. Without retrieving the dart, producers would not know if the drug was delivered.

“In all cases, we would recommend that producers label the darts and retrieve them after they are expelled so they know if the drug was actually delivered through the dart to the target animal,” Dr. Coetzee said. Dart retrieval will also prevent the needles from posing a risk to off-target animals and the environment.

A second finding from the study determined animals that were darted had a lower overall exposure to Draxxin® compared to animals that were held in a squeeze chute and injected under the skin. Total drug exposure is a critical requirement for treatment success with drugs like Draxxin®.

“The question our study raised is that with these delivery technologies, is the drug being delivered under the skin or in the muscle?” Dr. Coetzee pointed out. “Drugs like Draxxin® are only approved for injection under the skin. In our study we found that the drug behaved differently in the animal when it was darted versus when it was injected under the skin suggesting that some of the drug may have been injected into the muscle. What we don’t know at this time is whether the site of injection will impact the effectiveness of the drug or the potential for violative tissue residues.” That will take additional studies, he said.

Dr. Coetzee also pointed out a handful of animal welfare concerns surrounding the technology. According to the study, darting appears to result in increased pain sensitivity and inflammation at the injection site, and appears to be more stressful compared to placing animals in a squeeze chute and administering the injection subcutaneously.

Use with caution
Darting can potentially be a useful tool, Dr. Coetzee maintained, but warned producers and practitioners of the limitations to the technology when treating animals.

“There are significant challenges with making sure the drug is delivered correctly,” he said. “If producers are going to use this technology, they should be aware that our study represented the best-case scenario,” he said. “Animals were restrained with rope halters at a fixed distance from an experienced veterinarian who was delivering the dart from a dead rest.”

In spite of this, in one-third of the study animals, the dart was not administered in the Beef Quality Assurance (BQA)-compliant area of the neck.

While darting can be a convenient way to deliver a drug in range conditions, Dr. Coetzee concluded, there are significant limitations to this technology that producers should consider before they decide to deliver drugs this way.

Read the published Journal of Animal Science study. 

Dr. Hans Coetzee is a professor and head of the Department of Anatomy and Physiology with Kansas State University’s College of Veterinary Medicine, and interim director of the Nanotechnology Innovation Center of Kansas State (NICKS) and Institute of Computational Comparative Medicine (ICCM). His professional interests include the development of pain assessment techniques and practical analgesic drug regimens for use in food animals.

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Research Update: Beating BRD

By Shelby Mettlen, communications and marketing specialist

Bovine respiratory disease (BRD) is one of the most common –– and one of the most costly –– diseases affecting North American feedlots. The USDA-APHIS (Animal and Plant Health Inspection Service) reports that more than 21% of cattle are affected by BRD, and previous estimates of the annual economic losses due to death, reduced feed efficiency and treatment cost related to the disease are between $800-900 million.

A recent study conducted by Dr. Dustin Pendell, associate professor of agricultural economics and faculty member with the Beef Cattle Institute, and Kamina Johnson, USDA-APHIS, focused on discussions surrounding new technologies and management strategies that could result in lower BRD prevalence.

“Kamina and I were interested in understanding how a new technology or management program with widespread adoption would affect the beef industry and allied industries,” Dr. Pendell says. A better understanding of the impacts of BRD on beef and allied industries should lead to better decisions being made.

Reduction of BRD prevalence in feedlots translates to an increase in the supply of beef due to lower morbidity and mortality, Dr. Pendell explains. “With an increase in beef cattle supplies, there is a higher demand for feedstuffs leading to higher feedstuff prices.”

Of course, increased cattle supply and downward pressure on beef prices means a loss in returns to beef cattle producers. The silver lining lies with consumers, who benefit from lower beef prices.

“The positive impact on consumers outweighs the negative impact on producers, resulting in an overall positive net impact to society,” Dr. Pendell says.

Early adoption has benefits
“With new technologies related to animal health issues, there will be some winners and some losers,” Dr. Pendell says. “Although the aggregated U.S. beef cattle industry sees a negative return, it is most likely that the early adopters will experience positive returns.”

Market impacts of reducing BRD in feedlots result in lower prices on beef cattle due to increased supply. More beef cattle means higher demand for feedstuffs (and higher prices for feedstuffs, providing greater profits to those producers). As the supply of beef cattle increases and puts downward pressure on the price of beef, consumers will substitute away from other protein sources (pork, poultry and lamb) to beef.

“This information will hopefully help the industry better understand how new technologies and management strategies that come online for BRD, or any other animal health issue, will impact not only their industry, but the allied industries as well in terms of both the magnitude and scope,” Dr. Pendell says.

See the published research paper.

Dr. Dustin Pendell is an associate professor of agricultural economics with Kansas State University and a faculty member with the Beef Cattle Institute. His areas of specialization include animal identification and traceability, animal health economics, and livestock and meat economics.

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