New World Screwworm Confirmation: The Bad and the Good News

Derrell S. Peel, Oklahoma State University Extension Livestock Marketing Specialist
The shoe has finally dropped.  For many months producers and markets have operated under the threat of New World Screwworm (NWS) coming into the U.S.  Now that it’s here, we can get on with the reality of dealing with it.  The bad news is that NWS will be costly and a management headache for affected producers and those nearby, along with industry and agency folks tasked with controlling and eradicating the pest.  Time spent planning and anticipating an outbreak now shifts to actions.

The psychological impact has been mostly one of relief, especially in futures markets.  The arrival of NWS has been one of many sources of uncertainty hanging over cattle markets for months.  Confirmation of NWS in the country removes one source of uncertainty and allows the market to focus on the reality, which has largely been priced into the market.

The “good” news in all this is that it is not a broader market issue.  NWS will affect relatively few animals and is not something that will affect the cattle supply or beef production.  It also is not a food safety issue and there are no impacts on meat.  Beef market supply and demand fundamentals are not affected and no significant market impacts are anticipated.
Additionally, no major trade impacts are warranted or expected relative to NWS.  However, the reaction of trade partners is unpredictable.  Canada has announced a temporary ban on livestock from Texas.  This is seen as a largely symbolic political move as it will affect a very small volume of trade. Although there is significant bilateral cattle trade between Canada and the U.S., very few Texas cattle are typically involved. Canada is well north of the climate boundary for NWS and the threat is minimal.

Another part of the uncertainty about NWS is the continued closure of the Mexican border.  It is uncertain if the fact of NWS in the U.S. will change political decisions regarding the status of border.  The market will continue to wait for news about when the border might open.  Once again, the impacts are more related to the uncertainty than the reality.  When it happens, opening the border will likely be a deliberate and relatively slow process.  Over time, Mexican cattle flows into the U.S. may rebuild with marginal impacts on feeder cattle supplies in the country but no immediate disruptive shocks to cattle markets are anticipated.

Like most disasters, the impacts of NWS will be primarily local.  It will take significant efforts and dollars to ensure a perimeter around the outbreak and effective animal movement controls to contain the pest along with diligent monitoring and treatment of any affected animals.  It is uncertain at this point how large of a region might be involved in this outbreak, but no major cattle or beef market impacts are anticipated.

Foot Rot in Cattle

Mark Z. Johnson, Oklahoma State University Extension Beef Cattle Breeding Specialist Recent moisture and wet ground has led to some producer questions about the cause, prevention and treatment of foot rot. Foot rot is a sub-acute or acute necrotic (decaying) infectious disease of cattle, causing swelling and lameness in at least one foot. This disease can cause severe lameness and decreased weight gain or milk production. Lame bulls and females will be reluctant to breed. If treatment is delayed, deeper structures of the foot may become affected, leading to chronic disease and a poor recovery prognosis. Severely affected animals may need to be culled from the herd. The incidence of foot rot varies according to the weather, season of the year, grazing periods and housing system. Foot rot occurs in all ages of cattle, it is usually random in occurrence but does increase during wet, humid conditions.

Cause

Fusobacterium necrophorum is the bacterium most often isolated from infected feet. This organism is present on healthy skin, but it needs injury or wet skin to enter the deeper tissue. Normal healthy skin will not allow the bacteria to enter the deeper tissues. Moisture, nutrient deficiency, injury or disease can result in compromised skin or hoof wall integrity, increasing the likelihood of the bacteria invading the skin. Deficiencies of zinc, selenium and copper can lead to higher frequency of foot rot infections due to the important role these trace minerals play in skin and hoof integrity as well as immune function. Injury is often caused by walking on abrasive or rough surfaces such as stony ground, sharp gravel and grazing stubble on recently mowed pasture, which may irritate the interdigital skin. Standing in pens or lots heavily contaminated with feces and urine softens the skin and provides high exposure to the causative bacteria. High temperatures and humidity will also cause the skin to chap and crack, leaving it susceptible to bacterial invasion.

Clinical Signs

When case incidence increases in hot and dry conditions, attention must be directed to loafing areas, which are often crowded and extremely wet from urine and feces deposited in small shaded areas. The first signs of foot rot include:

• Extreme pain leading to sudden onset of lameness, which increases in severity as the disease progresses.
• Acute swelling and redness of interdigital tissues and adjacent coronary band.
• Lesions in the interdigital space are often necrotic along its edges and have a characteristic foul odor.
• Evenly distributed swelling around both digits and the hairline of the hoof, leading to separation of the claws.
• Loss of appetite.

Diagnosis

Diagnosis of foot rot can be made by a thorough examination of the foot, looking at the characteristic signs of sudden onset of lameness (usually in one limb), elevated body temperature, interdigital swelling and separation of the interdigital skin. There are several other foot conditions causing lameness that may be confused with foot rot. That being said, early treatment of lameness is key to quick recovery.

Treatment

Treatment of foot rot is usually successful, especially when instituted early in the disease course. When possible, treatment should always begin with cleaning and examining the foot to establish that lameness is actually due to foot rot. A veterinarian may recommend antibiotics and dosages for each situation. Use of a non-steroidal anti-inflammatory product may be indicted for pain relief. There are multiple antimicrobial products labeled for the treatment of foot rot. When possible, treated cattle should be kept in dry areas until healed. If improvement is not evident within three to four days, it may be an indication that the infection has invaded the deeper tissues. Infections not responding to initial treatments need to be re-evaluated by a veterinarian in a timely manner. A veterinarian will determine if re-cleaning, removing all infected tissue, application of a topical antimicrobial and bandaging are appropriate, along with a change in the antimicrobial regimen. In severe cases, options may be limited to harvesting the animal (following drug withdrawal times), claw amputation or claw-salvaging surgical procedures. A veterinarian will be able to provide information needed in making this decision.

Summary

Foot rot is a major cause of lameness in cattle and can have a severe economic impact on animal health, animal performance and enterprise profitability. Skin and hoof lesions allow bacteria to invade live tissue. Therefore, the most important preventive measures are centered on the protection of interdigital skin health. Important preventative measures include a well-balanced mineral nutrition program and minimizing exposure to conditions that may cause skin or hoof injury. Treatment is frequently successful if the disease is diagnosed and treated soon after symptoms develop.

Reference: Foot Rot in Cattle, id: AFS-3355

Virtual Fencing: A New Tool for Grazing Management

Paul Beck, Oklahoma State Extension Beef Cattle Nutrition Specialist
Virtual fencing is rapidly moving from a new technology to a practical grazing management tool for livestock producers. The concept is simple: livestock wear a collar or device that uses GPS-based boundaries to create a “fence” without permanent wire. When cattle approach the virtual boundary, they receive an audio cue. If they continue forward, a mild electrical stimulus may be delivered to encourage them to turn back.

The real fence is not just in the technology. It is in the training of the animal to create a psychological barrier. Proper training is essential for success. Cattle must learn that the sound cue means they should turn away from the boundary. Most systems use a stepwise training process, often beginning near a physical fence before moving to more flexible virtual boundaries.

Several commercial systems are now available, and while they have similar basic functions, each has strengths and limitations that must be considered before choosing a system. Some systems rely on cellular service, while others use satellite or base-station communication. This matters because terrain, tree cover, canyons, and lack of service can affect performance. Some systems offer more animal behavior monitoring, such as grazing activity, calving alerts, estrus detection, or location history. Others may be simpler but still effective for containment or exclusion areas. Battery life, collar fit, livestock species, technical support, data access, and ease of use are all important considerations.

The potential benefits are significant. Virtual fencing can be used to keep cattle out of riparian areas, wetlands, newly seeded pastures, or hay storage areas. It can help concentrate grazing on areas with weed problems or create grazed strips that may reduce fine fuel loads for wildfire mitigation. On large pastures or public lands, knowing where cattle are located can save labor, improve gathering efficiency, and allow quicker response when cattle are sick, injured, or threatened by wildfire.

Virtual fencing may also expand grazing options where building permanent fence is difficult, expensive, or undesirable. This can be especially useful on leased land, public land, or multi-use areas where recreation and wildlife movement must also be considered.

Even with these advantages, virtual fencing is not a complete replacement for conventional fence. No fence is completely impervious; this is true for virtual fence too. Physical fence is still needed in high-risk areas such as highways, heavily traveled roads, or places where failure would create unacceptable risk. Cattle may cross a virtual boundary if the attraction on the other side is strong enough, such as to get with calves, water, or highly desirable forage. Some cattle will not adapt to this system and may need to be moved to locations with good physical fence or culled.

Virtual fencing should be viewed as a tool for adaptive grazing management, not a shortcut around good management. Producers still need to understand grazing behavior, forage growth, timing, intensity, duration, frequency, and plant recovery. When matched to the right operation and used with realistic expectations, virtual fencing can provide flexibility, labor savings, better livestock monitoring, and new opportunities to manage grazing distribution across the landscape.