News Update
July 9, 2009

Stress + Bacterial Agents + Viral Agents = BRD

Bovine respiratory disease (BRD) continues to be the most significant health problem in the beef industry.1 It is commonly caused by three factors — stress, bacterial agents and viral agents2 — which means producers are leaving money on the table if they are not helping protect calves from all elements of the BRD equation.

“Bovine respiratory disease is still the most costly disease in the beef industry, and it only makes sense that we do everything we can to help minimize it,” says Chris Chase, professor, College of Veterinary Medicine, South Dakota State University. “Cow-calf producers regularly use four-way viral vaccines; however, there is no doubt that bacterial pneumonia also is an important cause of bovine respiratory disease and shipping fever.”

Mannheimia haemolytica and Pasteurella multocida are the major bacterial pathogens associated with bacterial pneumonia, which has been documented in 75% of BRD cases.3 Chase says this is consistent with the findings he has seen in the university’s diagnostic lab, which is why he recommends that producers help calves fight these two important bacteria by vaccinating for them prior to weaning.

“If we vaccinate calves during preconditioning or while they are still on the cow, we can help minimize the spread of bacteria already present in the herd and help calves prepare to face the stress of weaning by raising their immunity to the disease,” Dr. Chase says.

M. haemolytica and P. multocida bacteria are normally found in the upper respiratory tract of healthy cattle and don’t cause a problem.3 However, when the animal’s defenses are compromised, such as during weaning or from a viral infection, the bacteria can get into the lower respiratory tract, reproduce rapidly and spread throughout the lungs — causing pneumonia.3

Dr. Bruce Nosky, manager, Merial Veterinary Services, says producers can help calves fight off the effects of bacterial pneumonia this fall with a preconditioning program that includes a Pasteurella vaccine.

Dr. Nosky adds that when choosing a Pasteurella vaccine, it is important that producers use one that is effective against both major causes of bacterial pneumonia.

“Not all Pasteurella vaccines protect calves against both Mannheimia haemolytica and Pasteurella multocida,” he says.

1Duff GC, Galyean ML. Board-invited review: Recent advances in management of highly stressed, newly received feedlot cattle J Anim Sci 2007:85:823-840.
2Batley CV, Matthews NJ, Snyder DL. Vaccinating to prevent pneumonia. Utah State University Extension Animal Health Fact Sheet. July 1997.
3Richey EJ. Pasteurella disease in beef cattle. University of Florida Extension.

— Adapted from a release provided by Merial.

Good management can reduce incidence of heat stress in cattle

Understanding and avoiding heat stress in cattle can be a valuable management tool in Oklahoma, where most areas of the state experience 70 or more days each year with temperatures that exceed 90° F.

“Cattle have an upper critical temperature that is approximately 20 degrees Fahrenheit cooler than humans,” said Glenn Selk, Oklahoma State University (OSU) Cooperative Extension livestock specialist. “When we’re uncomfortable at 80 degrees and feel hot at 90 degrees, cattle may well be in the danger zone for extreme heat stress.”

The potentially bad news does not end there. Humidity is an additional stress that intensifies ambient temperature problems by making body heat dissipation more difficult. In other words, it can be tough to cool off in Oklahoma during the summer, for people and cattle.

High humidity contributes to the likelihood of heat stroke or prostration because water evaporation from the oral and nasal cavities is decreased, in spite of rapid panting, a heat regulatory device in cattle.

“Panting often occurs at rectal temperatures at or above 104 degrees Fahrenheit, but may begin at even lower body temperatures,” Selk said.

Signs of overheating in cattle may develop suddenly and depend on the environmental conditions and health of the animal. Some overheated cattle manifest restlessness, excitement and muscle spasms. Others may be dull and depressed. A protruding tongue may be covered with saliva, and frothy mucus may be discharged at the nostrils.

Fortunately, overheating in cattle can be prevented under most management conditions. Allowing cattle access to cool water and mineral supplements is a must during hot summertime weather. Access to shade and air circulation should be provided if at all possible.

Nathan Anderson, Payne County Extension director and agricultural educator, reminds producers that it is a good idea to work cattle before 8 a.m. during hot weather, and all cattle work should be completed by 10 a.m.

“While it may seem to make sense to work cattle after sundown, they may need at least six hours of night cooling before enough heat is dissipated to enable them to cool down from an extremely hot day,” he said.

Cattle that must be handled during hot weather should spend less than 30 minutes in the working facility, according to OSU recommendations. Drylot pens and corrals loaded with cattle will have little if any air circulation.

“Cattle will gain heat constantly when in these areas,” Anderson said. “By limiting the cattle’s time in a working facility, the producer can help limit the animal’s heat gain and, therefore, the heat stress.”

The most basic rule is to make every effort to provide cattle access to cool, fresh water, especially for animals that are in close, confined areas for any length of time.

“During hot weather, cattle will drink more than 1 percent of their body weight per hour,” Anderson said. “Producers need to be certain that water supply lines are capable of keeping up with demand when working cattle during hot weather.”

Excitable cattle will be even more prone to heat stress if handled at high environmental temperatures.

“If animals are going to have limited access to water under stressful conditions such as shipping by truck or trailer, they should be allowed water prior to further stressful situations,” Anderson said.

Anderson and Selk point out that it is fortunate most cattle handling for health and production purposes in Oklahoma occurs in the relatively cooler weather of spring and fall, resulting in only an occasional need for cattle handling in the heat of summer.

— Release provided by OSU.

Producers Advised to Test-Bale Crop Stover

Numerous corn and sorghum samples have tested positive for high levels of nitrate and prussic acid, according to a Texas AgriLife Extension release.

Forages containing high levels of either compound are potentially lethal when grazed or fed as hay to livestock, according to a Texas AgriLife Extension Service expert.

“Agricultural producers can follow several steps to minimize nitrates in the baled forages, including raising the cutter height to leave the high-nitrate lower stalk in the field,” said Tony Provin, AgriLife Extension soil chemist and director of the Soil, Water and Forage Testing Laboratory, available at http://soiltesting.tamu.edu. Since nitrate accumulation and prussic acid occur in different parts of the plant, Provin said, it’s difficult for one sample to detect both potential threats.

“Producers should sample multiple plants and segregate the lower portion of the stalks for nitrate analysis,” he said.

Samples between 8 inches (in.) and 16 in. will help reveal concentrations at different heights, allowing the producer to adjust cutting equipment accordingly and minimize nitrates baled in the hay.

“While nitrate levels are highest in these lower stalks, a producer may elect to measure nitrate concentrations in the remaining plant to provide added assurance that it is safe for grazing, in the event the lower 16 inches of the stalk (often considered the highest a cutter bar can be raised) is highly elevated with regard to nitrates,” Provin said.

Meanwhile, prussic acid only occurs in a select number of crops and weeds, he said. Producers should pay special attention to Sudan grass, sorghum, and Johnsongrass.

“For these species, prussic acid can form in the newest leaves or recently damaged leaves,” he said. “Samples collected for prussic acid analysis should be comprised of the newest leaves and damaged leaves.”

The Texas A&M System Texas Veterinary Medical Diagnostic Laboratory, available at http://tvmdl.tamu.edu, can provide further information on the sampling and testing of these samples.

Tight bales may require more than nine months for prussic acid levels to decline below levels of concern, he said. Good field curing of hay, specifically aided by the utilizing crimper/conditioners, usually reduces the threat to more negligible levels.

“Nitrate levels will remain constant unless significant water leaches through the bale, a factor often reducing the feeding value of the hay to near zero,” Provin said.

A publication is available for download at the AgriLife Extension bookstore that provides complete background and sampling instructions at http://agrilifebookstore.org/publications_details.cfm?whichpublication=1671.

— Release provided by Texas AgriLife Extension.

Funding Available for Communities to Assess Future Water and Wastewater Infrastructure Projects

Agriculture Secretary Tom Vilsack today announced that the U.S. Department of Agriculture (USDA) is providing $14.2 million to help rural communities identify water and wastewater infrastructure needs that can be financed through the American Recovery and Reinvestment Act.

The funding will be provided under USDA Rural Development’s Rural Water and Wastewater Circuit Rider Program to enable the National Rural Water Association to add 15 water and 71 wastewater technical assistance staff in 2009 and 2010 to help rural communities operate and maintain water and wastewater infrastructure, and provide training and other technical assistance to local staff throughout the country.

Known as Circuit Riders, these technical assistance staff will help rural communities prepare proposals for water and wastewater systems, manage construction, offer on-site expertise and ensure that health and environmental protection requirements are met.

The first $4.1 million in funding will be for technical assistance services performed between June 1, 2009, and October 31, 2009. The remainder will be used beginning November 1, 2009. In addition to the $14.2 million, USDA Rural Development anticipates making Recovery Act funds available later in the year through a competitive grant process for further technical assistance services. All states and the Territory of Puerto Rico are eligible to apply.

Visit www.usda.gov for further information.

— Adapted from a release provided by USDA.

— Compiled by Crystal Albers, associate editor, Angus Productions Inc.