Should Beef Producers Implement Genotyping Technologies/DNA testing into their Selection Strategies?

Dr. Matthew Garcia

What are genotyping technologies?
The genotyping technologies that are currently being marketed to beef producers are based off of genetic markers that have been identified to be associated with economically important traits. A producer can have DNA extracted from an animal’s sample of hair, tissue or blood for future genomic testing. Specifically, these genomic tests evaluate genetic markers that are inherited by animals that are either high producers for a trait or low producers for a trait. Typically, these markers are located on a single gene or in a specific place in the bovine genome. The goal in using these technologies is to increase the accuracy of selection from traits ranging from growth, efficiency, carcass quality, fertility and disease resistance. The genotyping technologies are used to try to identify the underlying genetic predisposition for important traits so that producers can select for their superior animals early in the production process. This is prior to having to maintain an animal to a specific production point to visualize if that animal is indeed superior. These technologies, if developed further, could provide a method for producers to more rapidly improve lowly heritable traits such as fertility or disease resistance.

How can genotyping technologies have limitations if we are looking at the genetic makeup of an animal?
The idea that producers could make selection decisions much earlier in the production process led to the commercialization of many genotyping tests. Initially, this type of testing seemed like a good method to try to improve traits that were highly desirable or might be hard to measure in a live animal. However, producers must really understand that the concept of selecting animals based on their genetic makeup is still in the early development stages for a couple of reasons. First, there are an estimated 30,000 genes and three billion individual nucleotides in the bovine genome. Researchers are still attempting to understand where exactly these genes are and what tissues of the body those genes influence. Second, many of the traits that producers are interested in, such as disease resistance and fertility, are lowly heritable and most likely influenced by multiple genes. As such, relationships among genes and mutations on these genes need to be evaluated prior to marker assisted selection (MAS) becoming an accurate method of selection. Selecting for single markers affecting a single trait may not be the most accurate method of selection as that particular marker may not account for a large amount of variation for that trait. Thus, if producers begin selecting for single markers for single traits, it may in fact result in little if any significant improvement for that trait.

Should a producer use genotyping technologies?
There are questions producers should ask themselves prior to implementing this technology into their selection. They are:
1. What traits am I trying to improve?
2. Are these traits highly or lowly heritable?
3. How much improvement in one generation or multiple generations can I expect to see by implementing this tool as part of my selection strategy?
4. Will I be able to cover the cost of testing (tissue collection, shipment, DNA extraction and cost of the DNA test) with the increased performance of my animals?

As previously stated, this technology has been around for many years but is still in the early development stages. While this technology may prove to be beneficial for some producers, it may not be cost effective for others. It is always important to know as much as you can about these technologies prior to implementation so that a decision can be made as to whether it is going to bring an added benefit to your operation. While genomic tests are still relatively new, they are getting more accurate and will continue to improve. As such, this technology, if developed correctly, will provide producers a new selection tool in the future to make them more profitable and sustainable.

Anhidrosis in Horses

Dr. Neely Walker

Increased heat and humidity across the Southeast have caused a rise in an equine condition known as anhidrosis. This condition impairs the horse’s ability to regulate its body temperature through sweating. A normal horse loses approximately 65-70% of its body heat due to the evaporation of sweat, while only 15-25% of heat is lost through respiration. Therefore, the inability to sweat in hot, humid climates can become a serious health threat.

The prevalence of anhidrosis is higher in the Gulf South; however, there have been reports of horses suffering with this condition located in the desert states of the Southwest as well. Research suggests that inadequate temperature acclimation may be a factor that predisposes horses to the condition. However, both horses imported and those raised in hot, humid conditions are both at risk for developing anhidrosis. One study suggests that horses moved from Midwest and western states into the South are two times more likely to develop the condition. Horses of all breeds, sex, age and colors are equally at risk for developing this condition.

The most common indication that a horse is developing anhidrosis is its inability to cool down after exercise. When horses with anhidrosis are exposed to conditions that would cause a normal horse to sweat, they will have small, patchy areas of sweat under the mane and saddle and in the flank, as well as increased respiration rate and body temperature. As the condition progresses, horses may develop dry, flaky skin, hair loss, loss of appetite, fatigue and decreased water intake. If horses with anhidrosis are forced to exercise in hot environments, respiration, temperature, heart rate and blood pressure can rise to dangerous levels, and in extreme situations may cause death.

While most veterinarians will diagnose anhidrosis as a result of clinical symptoms, a quantitative test is available.

Currently there is no research-supported treatment that will reverse this condition. The only known successful therapy is moving affected horses to a cooler climate. Horses affected with this condition must be managed carefully to prevent overheating.

· Provide climate controlled areas during the day (fans, misters, A/C)
· Provide access to cool drinking water
· Reduce concentrate (grain) feed
· Reduce exercise during extreme conditions
· Provide electrolytes

Many supplements have been used in an attempt to control the symptoms of anhidrosis but have varied results. Additional methods of treatment and prevention are currently under investigation. Until a more reliable treatment option becomes available, make sure to carefully manage horses with this condition.

References:
1. Johnson, E.B., Mackay, R.J. & J.A. Hernandez. 2010. An epidemiologic study of anhidrosis in horses in Florida. J. Am. Vet. Med. Assoc. 236:1091-1097.
2. MacKay, R.J., Mallicote, M., Hernandez, J.A., Craft, W.F., & J.A. Conway. 2015. A review of anhidrosis in horses. Equine vet. Educ. 27(4):192-199.
3. Hubert, J.D., Beadle, R.E., & G. Norwood. 2002. Equine anhidrosis. Veterinary Clinics of North America: Equine Practice. 18:355-369.

Winter Feeding Beef Cattle

Dr. Tim Page

During the winter, even on the Gulf Coast, beef cattle must have supplemental forage and/or feed. Most cattle producers in the South spend approximately 40% of their operating costs on producing or purchasing hay and purchasing supplemental feeds. Feed costs represent the second highest production cost annually with cattle production. This cost is second only to the original purchase price of the cattle. The overall feeding program represents a major input to cattle operations where the possibility of trimming some costs is possible. However, it is extremely important to remember that the nutritional status and body condition of the cow is closely related to efficient reproductive performance, and reductions that negatively affect the cow’s nutritional status will ultimately cost the producer more in the long run.

Most beef cattle producers can reduce their winter feed costs substantially by improving their forage management practices. One of the primary ways to reduce the need for supplemental feed during the winter is to produce high-quality hay. Forage quality relates to such things as crude protein and digestibility. There are forage production aspects that are under direct control of the producer in quality hay production. One of those is proper fertilization of hay fields, and the other is the stage of maturity of the forage when it is cut and baled. Granted, fertilizer is a high-dollar input, but if you want to produce high-quality hay, you must fertilize properly. Nitrogen is second only to moisture in importance regarding dry matter production. There is a high correlation between fertilizer nitrogen and crude protein. As nitrogen rate increases, so does forage crude protein. For nitrogen fertilizer to be most effective, other soil nutrients, such as phosphorus and potassium, must be adequate, and the soil pH must be appropriate for the forage being produced. Soil fertility tests are a must for proper fertilization of forage.

The other critical part of quality hay production is to harvest the forage at the appropriate stage of maturity. With increasing maturity, there is a decrease in digestibility of the forage. The forage nutritive value will decline with time, so it is imperative that the forage be harvested while nutritive value is high. The critical aspect of forage production management is to have enough dry matter in the field to justify the cost of cutting and baling and in the end, have a good balance of dry matter production and quality hay. The method of storing hay can be critical to minimizing dry matter loss and maintaining nutrient value. Some research shows that as much as 50% loss of dry matter occurs when large bales are stored outside. If you store your round bales outside, they just cost you twice as much. Many producers believe that a good hay storage barn is the only building on the farm that will actually pay for itself.

As mentioned earlier, winter feed bills are one of the largest expenses of a cattle operation, but winter feed costs can be reduced with some action now. September is still a good time to act in Louisiana. Producers can stockpile warm-season grasses. Think of stockpiling warm-season grasses as making hay without cutting and baling it. The grass will cure naturally in the field, and the cattle can eat it where it grows. Labor costs are reduced because it does not have to be cut, baled or hauled to and from the barn. Instead, the cattle harvest it for you. To stockpile, clip pastures to about 3-4 inches, and fertilize with 50 pounds of nitrogen per acre. Allow the grass to grow until late October. When cattle have eaten all the available summer forages, strip graze the stockpiled forage. It is even better if you can use temporary electric fences across the stockpiled forage and allow the cattle to eat. As cattle eat down the forage, move the fence to allow them access to more forage. Allowing the cattle access to only a portion of the stockpiled forage at a time reduces waste from trampling and manure. Also, cattle do not have to be backfenced out of the area they have already grazed. The grasses are dormant and will not be harmed by additional grazing or hoof traffic.

Many beef cattle producers in the Gulf Coast use cool-season forage pasture for winter supplementation. Cattle performance is usually good to excellent, and the cost of fresh forage can be less than hay and supplements or supplements alone. Most winter feeding programs in the Gulf Coast area involve some sort of hay plus supplemental feeding. The supplement can be molasses-based liquid feed, protein tubs, mixed feed, range cubes, soybean hulls or cottonseed meal with salt. All these supplements can be utilized to provide proper winter nutrition for cattle. However, these methods can be more expensive than cool-season forage production. One of the least expensive forms of winter supplementation is ryegrass that is limit-grazed. In a limit grazing system, the cattle are allowed to graze ryegrass on limited basis of two to three hours per day and spend the rest of the day on dormant grass pasture where they may receive supplemental hay. Producers that have bermuda grass can overseed ryegrass successfully. Depending on the weather and the amount of rainfall, grazing on ryegrass can usually begin in early to mid-December. Remember, no matter what winter supplementation method you use, do not neglect mineral supplementation as well.

Reducing winter feed costs, while maintaining performance, is critical for producer profit. By evaluating cattle nutritional requirements, quality forage nutrient contribution and evaluating alternative supplemental sources, an optimal winter feeding program can be designed. The lowest cost will not always be the best program for you. You also have to consider convenience, available labor and your feeding system. First, determine your costs, and then compare differences with other factors that affect your operation.

Preventing Avian Influenza and other Poultry Diseases

Dr. Theresia Lavergne

While there have not been any new findings of avian influenza (AI) in the U.S. since June, both commercial producers and small flock producers are concerned about the possibility of AI returning to the U.S. Therefore, all poultry producers need to practice strict biosecurity procedures to prevent AI or any other disease.

According to the United States Department of Agriculture “Biosecurity Guide for Poultry and Bird Owners,” there are six guidelines to utilize to prevent poultry diseases.

These guidelines are:

• “Keep your distance” – Keep people away from your birds; restrict access to your birds; outside birds should be kept in a screened area to restrict contact with migratory waterfowl and game birds.
• “Keep it Clean” – Designate clothes and shoes to only be worn around your birds; clean and disinfect your shoes; clean cages, change food and water daily.
• “Don’t Haul Disease Home” – Cages, equipment, and vehicle tires need to be cleaned and disinfected before returning to your poultry; if your birds go to an exhibition, they need to be isolated from the rest of your flock for at least two weeks after returning home; new birds should be kept isolated from your existing flock for at least 30 days.
• “Don’t Borrow Disease from Your Neighbor” – Do not share birds, equipment, or supplies as all of these can carry disease to your birds.
• “Know the Warning Signs of Infectious Bird Diseases” – Look for signs that may indicate something is wrong with your birds, such as, deaths, sneezing, coughing, diarrhea, lack of appetite, decrease in egg production, swelling around the head, purple discoloration (comb, wattles, legs), tremors, twisting of the head or neck, or lack of movement.
• “Report Sick Birds” – If you suspect unusual disease signs or there are unexpected deaths, contact your county agent, veterinarian, State veterinarian, or USDA Veterinary Services office; The USDA can be contacted at 1-866-536-7593.

Additionally, pet bird owners need to take precautions to prevent AI or other diseases in their birds. The same six guidelines above can be used and/or modified for preventing diseases in pet birds.

Hunters also need to use precautions when handling wild birds. They should not handle or eat game that are sick or found dead. While cleaning wild game, hunters should not eat or drink, and they need to wear rubber gloves. Hands need to be washed immediately after handling game. Also, the tools and surfaces used to clean game need to be washed and disinfected. Uncooked game needs to be kept in separate containers and away from cooked and ready-to-eat foods.

Consumers need to cook all poultry and game thoroughly. Disease organisms are killed by heat, and properly cooking poultry and game to an internal temperature of 165 degrees F will ensure that wild game and poultry are safe to eat.

More information on poultry disease prevention is available at: https://www.aphis.usda.gov/wps/portal/aphis/ourfocus/animalhealth/sa_animal_disease_information/sa_avian_health?1dmy&urile=wcm%3apath%3a%2FAPHIS_Content_Library%2FSA_Our_Focus%2FSA_Animal_Health%2FSA_Animal_Disease_Information%2FSA_Avian_Health%2FSA_Biosecurity_for_Birds

(Source: Biosecurity Guide for Poultry and Bird Owners, United States Department of Agriculture, Animal and Plant Health Inspection Service, Program Aid No. 1885, Revised April 2014)