Animal Industry News Update - March 2015

Theresia Lavergne, Page, Timothy G., Garcia, Matthew, Walker, Neely, Pruitt, J. Ross, Johnson, Rodney  |  3/31/2015 7:29:13 PM

Equine Infectious Anemia in Louisiana


Dr. Neely Walker

Equine Infectious Anemia (EIA) commonly referred to as swamp fever due to its prevalence in Gulf Coast states, is an infectious viral disease that only affects livestock of the Equidae family (horses, mules, donkeys and zebras). EIA can present itself in three different degrees of infectiousness: acute, chronic, or inapparent. The acute form is the most damaging and the most difficult to diagnose. This form is often associated with the first exposure to the virus and may cause fever and small areas of hemorrhaging on the mucus membranes within seven to thirty days after exposure. If the horse survives the acute stage of EIA, it may progress and develop chronic symptoms of the disease including fever, small patches of hemorrhages on the mucus membranes, depression, weight loss, swelling of legs and abdomen, and anemia. Most horses are inapparent carriers of EIA and appear normal, displaying no clinical abnormalities associated with infection; however these horses are lifelong carriers of the virus.

Transmission of the EIA virus from one horse to another is typically caused by the transfer of blood by blood sucking insects or by using blood-contaminated materials on different horses. Many epidemics of EIA have been linked to the reuse of hypodermic needles or non-sterile surgical equipment. The most significant transmitters of EIA are horseflies and deer flies, but other blood sucking insects like mosquitoes and gnats can spread the virus as well. It is thought that horses in the acute stage of infection are the major sources of transmission. Research done at Louisiana State University has shown that a single horse fly can transmit the infection from a horse in the acute stage of EIA to another horse.

Diagnosis of EIA was not possible until the 1970s when Dr. Leroy Coggins developed a serologic agar-gel immunodiffusion test, now commonly known as the Coggins test. More recently, enzyme-linked immunosorbent assays (ELISA tests) have reduced the time for a lab result from 24 hours to less than one hour. Accurate testing allows timely identification of infected animals and removal of those animals from herds, potentially preventing the spread of the disease.

EIA regulations vary from state to state. In Louisiana, all horses are required to have a Coggins test performed annually. Foals are required to be tested no later than one year after the foal is born. Animals testing positive for EIA in Louisiana must be euthanized or sold for slaughter only. All animals located within 200 yards of an animal testing positive for EIA are subject to quarantine and require a minimum 30 day negative test before a quarantine release can be issued. Additionally, horses sold in Louisiana must have a negative test within six months of the transfer date.

Currently there is no effective treatment, cure, or vaccine for EIA. While the survival rate of horses infected with EIA is high, those animals become lifelong carriers and threaten the health of their offspring and other horses. To diminish the effect this contagious disease has on the general horse population, it is important for owners to follow their state’s regulatory laws and implement proper biosecurity practices.

Goat Predator Control

goat guard dog

Rodney Johnson

One of the major issues faced by all sheep and goat producers is predation. While the major predators for small ruminants, like sheep and goats, are dogs and coyotes; other predators such as birds of prey, bobcats or foxes can be a problem in some areas. Coyotes thrive in all environments and can cause problems regardless of the location. However, producers in more urban areas may have greater losses due to domestic dogs.

The three basic methods of predator control, or a combination of these methods, that have proven effective are guard animals, special fencing and lethal methods of control. Each has its advantages and drawbacks, but they work best in combination. Most goat producers will find that using a guard animal along with good fences will be enough to keep losses under control. Other producers find that good fencing with night pens works best for them.

Guard Animals for Goats
There are special considerations when selecting the type of guard animal for goats. The first is how much care you want to provide that animal. Dogs are the most commonly used guard animals but they need special feeding. Donkeys and llamas can consume what the goats eat but will require other care to remain healthy, including foot trimming and shearing of the llamas.

You should select your guard animal from a producer who is willing to work with you and make sure you are satisfied with the animal. Many guard animals need an adjustment period to accept the new location and owners. This is more of a problem with dogs than other animals. Young dogs tend to adjust quicker than older ones. It is also a good idea to utilize neutered males of all types and have female guard dogs spayed. This reduces the aggressiveness towards humans. Intact male dogs are more likely to roam off of the farm, and intact female guard dogs have been known to ignore the herd when in heat, producing many unwanted puppies

Guard animals should have a natural dislike for all other canines. The best guard animals have been raised with the same type of animal you want them to guard. Also, young donkeys and llamas may wish to play with the goats, potentially causing injury to them. This can especially be a problem during the kidding season.

A variety of dog breeds can work for predator control. The Great Pyrenees is the most widely used; but the Komondor, Akbash, Anatolian and Maremma also are used as guard dogs. It is important to remember that guard dogs are not stock or herding dogs. Guard dogs act largely independent of man; doing what instinct and conditioning tell them to do. You should work to select a guard dog that allows you to catch it, but the dog should not be so friendly that it wants to always follow you and leave your animals.

Female donkeys are often used as guard animals. Intact male donkeys often do not make suitable guardians because they can become aggressive with does and bucks during breeding season. Good guard donkeys will chase and trample a predator, bed down with the goats and sound a fearsome alarm at any strange noise or smell. It can be more difficult to find a good guard donkey than a guard dog. Donkeys may be better for some locations, such as near subdivisions and small open pastures. An obvious advantage is the donkey eats what the goat eats; no special daily feeding is required.

Llamas are becoming more popular as guard animals. However, research on their effectiveness is limited. Again, intact males do not make good guard animals because they may become protective of does during the breeding season and they may become very aggressive with people. Llamas also have an advantage of consuming forage with goats. Those that are good are very good, but the bad ones can be very dangerous to both livestock and people. The number of llamas is critical. People have found that if they have one in a pen without visual or vocal contact with others, the llama has a greater tendency to stay with the goats or sheep.

Goat Fencing for Predator Control
There is a lot of truth in the statement “good fences make good neighbors.” This concept applies to predator control as well. The first thing you need to realize is that you cannot fence out all predators. They will always find a way into your fields. Good fences make it more difficult for them, increasing the chances that they will look for food elsewhere. The most common fences for predator control involve good woven wire and electric trip and stand-off wires on the outside of the pasture. The normal use of this type of fencing is in the construction of a night penning area. This is a special area, generally around a shelter, where animals are penned each night. Because most predation occurs at night, this provides protection without the very high price of changing your total farm fencing.

Lethal Methods of Predator Control
Lethal methods of predator control have been around for a long time, with varied results. These include shooting and trapping of problem animals. In the past, poisoning has been used, but that method is almost universally banned today. As mentioned earlier, be sure to check the legal regulations before starting a lethal predator control program. Laws can change so make sure to stay up-to-date. Also, in some locations and situations, hunting and trapping licenses may be required

Utilization of traditional performance tested bulls versus forage tested bulls


Dr. Matthew Garcia

The benefit of utilizing a performance tested bull during breeding season has many advantages. Primarily, it allows a producer a method to evaluate the bull’s growth potential, but it also allows the producer to make an educated decision as to whether that bull is compatible with their current cow base and will produce the types of calves the producer requires. In the traditional performance test system, bulls are tested in a feedlot type setting for 112 days. This means the bulls are not only getting hay, but they are also receiving some type of high energy feed like corn. The bulls are weighed every 28 days in order to evaluate growth potential and efficiency. They are given a breeding soundness exam at the end of the test period to ensure functional breeding status. While this method of testing has been utilized for decades and allows the producer a method to evaluate a new herd bull, this system has some limitations. The first is that although a bull may be very efficient and fast growing in a feedlot setting, this performance is not indicative of how he will perform in a pasture based mating system. The bulls finish the test very heavy and in good body condition, but once integrated into a pasture mating system they tend to lose a lot of body condition. This is not only due to trying to cover cows, but is mainly attributed to the bull’s rumen not being able to fully utilize forage after being on a feedlot performance test for an extended period of time.

To evaluate an alternative method to developing bulls, the LSU AgCenter, at the Central Research Station in Baton Rouge, has conducted a forage based performance bull test since 2009. Bulls are tested for the same 112 day period; with all of the same requirements of a traditional performance bull test. However, they receive no grain and are developed solely on ryegrass. A common myth associated with forage bull tests is that the animals do not gain weight quickly and that they are not large enough to breed upon completion. However, since 2009, bulls on the LSU AgCenter Forage bull test have gained ~3lbs per day and have completed the test at an average of 1050 lbs. Furthermore, of the 112 bulls that have completed the test since 2009, 97% have passed breeding soundness exams at the completion of the test. Moreover, the bulls that have been developed on the forage test and retained as herd sires do not exhibit the extreme weight loss associated with breeding season because they are very much acclimated to the environment in which they are expected to perform. This leads to a much more functional bull during the breeding season and a very low maintenance bull after the breeding season.

While forage tested bulls provide a valuable resource to producers, it is understandable that this method of development is not readily available or feasible for all producers. As such, producers electing to utilize traditional performance tested bulls should ideally allow for an acclimation period back to forage after performance testing is completed so that a rapid drop in body condition is not observed during breeding season.

Porcine Epidemic Diarrhea Virus Disinfectant

pigs in trailer

Dr. Tim Page

There is a new disinfectant for pork producers to use to control Porcine Epidemic Diarrhea Virus (PEDV). It is an accelerated hydrogen peroxide (AHP) being sold under the brand name Accel. Researchers at Iowa State University (funded by Pork Checkoff) reported that the disinfectant inactivates PEDV even in the presence of feces found in swine trailers. According to a leading swine veterinarian, the real key to the study was the fact that the study mimicked harsh, real-life conditions.

One particular area of the study was to investigate how the disinfectant worked in cold weather, a condition in which PEDV thrives and spreads easily. For the study, Iowa State researchers prepared PEDV-positive feces and PEDV-negative feces which they spread onto aluminum trays designed to replicate the floor of a commercial livestock trailer. The trays were placed in a refrigerator at 39 degrees F for 30 minutes to replicate the inside of trailers during winter.

The AHP disinfectant was mixed with a 10 percent solution to keep it from freezing under winter like temperatures (14 degrees F). The chilled trays were subjected to one of 10 treatments that involved the AHP disinfectant at concentration rates of 1:16 and 1:32. The contact times of 40 and 60 minutes and heavy or light loads of PEDV-infected feces were used. Following the treatments, each tray’s contents were collected and administered to groups of four-week-old pigs to determine whether the PED virus remained infectious.

These results indicate that when mixed with propylene glycol, AHP effectively inactivates PEDV in the presence of light or heavy feces loads at temperatures below freezing. This was true for both the 40 minute and 60 minute disinfectant contact time periods. The results also held true for both AHP disinfectant concentration rates. This is not absolute control of PEDV but it is another important tool in fighting it and other swine infectious diseases.

Avian Influenza

AI map

Dr. Theresia Lavergne

Since the end of 2014, several cases of avian influenza have been detected in the U.S. The cases have been in wildlife, backyard poultry flocks, and commercial turkey flocks in several states (Oregon, Washington, Idaho, California, Minnesota, Missouri, Arkansas, and Kansas). It is thought that some of these cases were spread via migratory birds. However, many of the wild birds that have been tested have been negative for the virus, and the virus has spread in an opposite direction of the normal migratory path. Officials and experts are continuing to work to determine the exact source of the avian influenza.

Thus, poultry producers and hobbyists need to be aware of what avian influenza is and they need to take precautions to prevent its spread.

What is avian influenza?
Avian influenza is a contagious disease caused by the type A influenza virus. There is a low pathogenic and a high pathogenic form of the virus.

What are the signs of avian influenza in birds?
The signs can vary but may include decreased feed intake, reduced egg production, ruffled feathers, swollen heads, coughing, sneezing, diarrhea, depression, and death.

How is avian influenza transmitted from bird to bird?
Avian influenza is transmitted from bird to bird by direct contact with nasal and respiratory secretions, saliva, and feces from infected birds.

How can I prevent avian influenza from infecting my flock?
Prevention must be done through biosecurity protocols. These include: preventing contact between poultry and wild birds (as well as with their feces and respiratory secretions), avoiding the introduction of birds of unknown disease status into a flock, proper cleaning and disinfection of facilities, and controlling and limiting human visitors.

Can humans get avian influenza through eating poultry and eggs?
Humans cannot get avian influenza through eating properly cooked poultry and eggs. The process of cooking poultry and eggs destroys the avian influenza virus. Cook poultry and eggs, as well as foods containing poultry and eggs, to a temperature above 165 degrees F.

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