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Bull Breeding Soundness Exam

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As November approaches, the fall calving season should be coming to an end which means that it is time to get the bulls ready to turn out for breeding. All bulls should have a breeding soundness exam (BSE). A BSE is a procedure performed by a veterinarian that ensures a bull has met a minimal set of standards that reflect his reproductive potential. The exam is not a guarantee that the bull will breed cows because some bulls are not aggressive breeders. However, the test does ensure that the bull has the potential to breed cows. The exam does have limits. The exam is only true at the time of the test and cannot ensure results for the future. The exam has three components. A physical exam is performed to ensure that the bull is in good health. A reproductive exam evaluates the health of the reproductive organs. The final component is an evaluation of the semen for motility and normality. This small investment in a BSE to ensure a fertile bull may reduce the number of cows found open when they are pregnancy checked.

The BSE begins with a general physical exam. The breeding bull should have a body condition score of 6.  Since a good aggressive breeding bull will most likely lose weight, a bull in poor body condition may not service cows as the breeding season progresses for lack of stamina. A bull will be on the move during the breeding season, so good mobility is essential. Any feet, joint, or leg problems would be considered not satisfactory. A bull should have good eyes for finding those cows in heat. Any abnormality in the physical exam is a cause for concern.

Next, the veterinarian will evaluate the internal and external reproductive organs. A rectal exam is performed to assess the internal organs for any abnormality. Organs that are abnormal will likely affect semen quality. The scrotum is examined and measured. The testicles should be of similar size and move freely in the scrotum. The testicles should not be soft or have any palpable abnormalities. A scrotum that only has one testicle is a disqualification. The skin is examined for abnormalities such frost bite.  Problems in the skin could result in problems regulating the temperature of the testicles. Variations in temperature could result in abnormalities in the sperm. The size of the scrotum is measured in centimeters. A scrotal measurement of 30 cm is required for bulls of 15 months of age and the minimal size increases with age up to 2 years which is 34 cm. Scrotal size gives an estimate of the daily sperm production. During the collection process, the penis will be examined for any growths, hair rings, warts, or damaged which may affect the bull’s ability to breed.

The final part of the BSE is the evaluation of the semen. Once a sample is obtained, the veterinarian will place a drop of semen diluted with saline on a slide and examine it under the microscope for motility. A motility score will be based on individual progressive motility. Progressive motility means that the sperm are moving in one direction and not just spinning in a circle. The minimal acceptable score is 30% of the sperm have progressive motility. The veterinarian will next examine the morphology of semen. Morphology is looking for normal and abnormal sperm. A minimal score requires that 70% of the sperm must be normal. Producers should refrain from assuming that if a bull has a high motility and morphology score that this makes the bull a superior breeder. The breeding ability of the bull is not improved based on a higher score.

Once the exam is completed, the bull with be classified as a “satisfactory potential breeder”, “unsatisfactory potential breeder”, or “deferred”. The “satisfactory potential breeder” has met the minimal levels for scrotal circumference, sperm motility, and sperm morphology. As well as the bull’s physical and reproductive exams were acceptable. An “unsatisfactory potential breeder” has not met the minimal standards and/or has a physical or reproductive problem that is highly unlikely to improve over time. A “deferred” classification means that the bull did not meet the minimal standards and/or has a physical or reproductive problem that with time may improve. “Deferred” bulls should be retested at a later date. The “deferred” classification is not uncommon for immature bulls.

A BSE does not detect infectious diseases that might be present in the bull. These diseases may cause infertility or other reproductive problems. Testing for diseases such as Trichomoniasis or Persistently Infected Bovine Virus Diarrhea might prevent unwanted infections in the cow herd. This is a convenient time to obtain the samples necessary to complete these tests.

Studies have been done that compare untested bulls to those that have passed a BSE. Bulls turned in with cows that passed a BSE get more cows settled than untested bulls. Also, BSE tested bulls get cows settle earlier in the breeding season. Earlier pregnancy equals calves being born early in the calving season. Producers should consider the cost of a BSE as an insurance. For more information about BSE, please contact the local veterinarian or the local Oklahoma State University County Extension Agriculture Educator.

Read more in the November 2020 issue of Oklahoma Farm & Ranch magazine.

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Farm & Ranch

Inventions of Agriculture: The Reaper

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Agriculture has been a staple of human society since around 9000 BCE during the Neolithic Era, when humans began developing and cultivating their own food.

For centuries, food production was a slow, tedious process until the invention of agricultural machinery. One such invention was the reaper. Until its time, small grains were harvested by hand, cut with sickles or scythes, hand-raked and tied into sheaves.

While a few had unsuccessfully attempted to create a similar machine, it was Cyrus McCormick who would ultimately be credited with the invention of the first commercially successful reaper in 1831.

McCormick’s invention was a horse-drawn machine used to harvest wheat, a combination between a chariot and a wheelbarrow. He had joined together the earlier harvesting machines into a single, timesaving one. His reaper allowed producers to double their crop size, capable of cutting six acres of oats in just one afternoon. In contrast, it would have taken 12 workers with scythes to do the equivalent in the same amount of time.

McCormick had simply followed in his father’s footsteps. Growing up in Rockbridge County, Virginia, his father had also created several farming implements and even worked to invent a mechanical reaper of his own.

McCormick would patent his invention in July 1834, a year after Obed Hussey had announced the making of a reaper of his own. In 1837, McCormick began manufacturing his machine on his family’s estate.  

In 1847, McCormick recognized Chicago as the future of the agricultural machinery industry. The railroad to Galena was nearing completion, the Illinois and Michigan Canal would soon be open, and a telegraph link to the east was coming. So, in 1847, McCormick, together with his partner and future Chicago mayor Charles M. Gray, purchased three lots on the Chicago River and built a factory where they would produce the reaper. It was the first of many industrial companies that would make their way to the area, making Chicago an industrial leader.

McCormick wasn’t done yet. He purchased an additional 130 acres in Chicago in 1871, but the Great Fire of 1871 threatened to destroy his company when the factory burned. It was his young wife, Nettie Fowler McCormick, who pushed the company forward when she went to the site just days after the fire and ordered the rebuilding of the factory. By 1880, McCormick was the largest machinery producer in Chicago and employment reached 7,000, a whopping fifth of the nation’s total.

McCormick joined the companies of Deering and Plano to form the International Harvester Company in 1902. At its height, the company controlled more than 80 percent of grain harvesting equipment in the world. While the Great Depression would hit Chicago’s agricultural industry hard, McCormick’s invention of the reaper forever changed the face of agriculture.

Resources

Carstensen, Fred. (2005) Agricultural Machinery Industry. Encyclopedia of Chicago. Retrieved from http://www.encyclopedia.chicagohistory.org/pages/29.html

Cycrus McCormick, Mechanical Reaper. (2022) The National Inventors Hall of Fame. Retrieved from https://www.invent.org/inductees/cyrus-mccormick

Although the author has made every effort to ensure the informa­tion in this article is accurate, this story is meant for informational purposes only and is not a substi­tute for historical documents.

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Farm & Ranch

Scrapie

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Barry Whitworth, DVM
Senior Extension Specialist Department of Animal & Food Science Ferguson College of Agriculture

Scrapie is a chronic, progressive disease of the central nervous system that affects sheep and goats. Scrapie is the oldest of the group of neurodegenerative diseases known as transmissible spongiform encephalopathies (TSE). Some of the other TSE are Bovine Spongiform Encephalopathy known as mad cow disease, Chronic Wasting Disease which is found in deer, and Creutzfeldt Jacob Disease which is found in humans. TSE are protein-misfolding diseases that lead to brain damage and are always fatal.

The cause of Scrapie is not completely understood, but evidence indicates that an infectious protein referred to as a prion is responsible for the disease. These infectious prions cause damage to the normal prion proteins found in the brain. The mis-folding of the proteins lead to brain damage and the presentation of clinical signs of the disease. Prions are very resistant to destruction, so once in the environment, they are difficult to remove.

Scrapie is believed to primarily be transmitted by the oral route. Typically, lambs and kids might ingest the prion when they come in contact with the infectious agent through placentas and birthing fluids from infected ewes and does. Older animals may be exposed to the prions this way as well. Colostrum and milk are also sources of prions. Other secretions such as urine, feces, saliva, and nasal secretions may contain infectious prions as well. Once ingested, the prions cross into the lymphoid system. The prions will incubate for a long time usually two to five years before entering the nervous system.

Genetics plays a part in Scrapie infections. Certain breeds are more susceptible to the disease due to genetic composition. Genetic testing is available for producers to help them select breeding stock with resistant genes.

Clinical signs most commonly associated with Scrapie are intense pruritis, ataxia, and wasting. Early in the disease, small ruminant producers may notice slight changes in behavior with sheep and goats infected with Scrapie. Initially, animals may have a staring or fixed gaze, may not respond to herding, and may be aggressive towards objects. As the disease progresses, other clinical signs noticed are progressive weight loss with normal appetite, incoordination, head tremors, and intense pruritis. In the terminal stages, sheep are recumbent and may have blindness, seizures, and an inability to swallow. Once initial clinical signs are notice, death usually occurs in one to six months.

The gold standard for postmortem (dead animals) diagnosing of Scrapie is the use of immunohistochemistry test on brain tissues as well as microscopic examination of brain tissue for characteristic TGE lesions. Live animal diagnosis is possible by testing lymphoid tissues from the third eyelid and rectal mucosa scrapings.

There is no treatment available for Scrapie, so prevention is key to controlling the disease. Following biosecurity protocols is a good starting point for preventing Scrapie. Part of the biosecurity plan is to maintain a closed flock and only buy replacement animals from certified Scrapie free flocks. Producers should limit visitors’ contact with their animals. Sanitation is important in lambing and kidding areas. Manure and bedding contaminated with birthing fluids and placentas should be disposed of properly. Genetically resistant animals should be used for breeding to produce genetically resistant offspring.

It should be noted that there is a novel or atypical form of Scrapie. This disease may also be referred to as Nor98 variant. This atypical version of Scrapie was initially found in Norway. It has been diagnosed in the United States as well. The disease is usually only found in a single old animal in the flock or herd. The brain lesions in atypical Scrapie are different from classical Scrapie. Currently, experts believe that natural transmission of atypical Scrapie is not likely.

The United States Department of Agriculture (USDA) has been battling Scrapie for decades. According to recent information from the USDA, the United States (US) is close to accomplishing eradication of the disease. In order for the United States to achieve Scrapie free status, no sheep or goats can test positive for classical scrapie for seven years and a certain level of testing needs to be done each year that represents the sheep and goat populations within the country. Small ruminant producers can assist the USDA eradication efforts by contacting the USDA when they have an adult sheep or goat exhibiting clinical signs of Scrapie or an adult animal dies or is euthanized. Producers should contact the Oklahoma State Veterinarian, Dr. Rod Hall at 405-522-6141 or the USDA Veterinary Services at 405-254-1797. This will aid the USDA in reaching sampling testing goals. There is no charge for the collection or testing of the samples for scrapie. 

Scrapie is a disease that needs to be eliminated from the US. Once eliminated, the US will have additional export markets for sheep and goat products. Oklahoma State University Cooperative Extension Service has an informative fact sheet on Scrapie. Please visit the Local County Extension Office and asked for fact sheet VTMD-9135 or producers may view the fact sheet online at  https://extension.okstate.edu/fact-sheets/scrapie.html. Also, the USDA National Scrapie Eradication Program website has valuable information as well at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/sheep-and-goat-health/national-scrapie-eradication-program

References Cassmann, E. D., & Greenlee, J. J. (2020). Pathogenesis, detection, and control of scrapie in sheep. American journal of veterinary research81(7), 600–614. https://doi.org/10.2460/ajvr.81.7.600

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Farm & Ranch

Avian Influenza Update

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Barry Whitworth, DVM

Area Food/Animal Quality and Health

Specialist for Eastern Oklahoma

High Path Avian Influenza (HPAI) continues to be a problem in commercial and backyard poultry in the Unites States (US) with over 60 million birds affected. Since the start of the outbreak in 2022, 879 flocks (347 commercial and 532 backyard flocks) have been confirmed with HPAI in the US. Many wild birds and mammals have been affected as well. Five backyard flocks and one commercial flock have been confirmed with HPAI during this outbreak in Oklahoma. The latest was detected in a backyard flock in Carter County on October 16, 2023. For a complete listing of domestic birds, wild birds, and mammals affected by HPAI visit 2022-2023 Detection of High Path Avian Influenza website at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/2022-hpai.

Avian influenza (AI) is a highly contagious viral disease. The virus is classified as either Low Path Avian Influenza (LPAI) or HPAI depending on the virulence. This virus infects many food producing birds such as chickens and turkeys while it commonly resides in migratory waterfowl and many other wild birds. Most often ducks, geese, and wild birds harbor the virus in the intestinal tract without having any clinical signs of the disease. The virus is shed in the feces and respiratory secretions from infected birds. Poultry can be infected with the virus when they come in direct contact with infected birds or consume feed that is contaminated with the virus. The virus can be spread indirectly through objects like shoes, clothes, or equipment contaminated with the virus.

Clinical signs of the disease vary depending on the severity of the virus and the organ system affected. LPAI usually results in no clinical signs or only mild problems. However, HPAI has many different clinical signs. Death with no symptoms is a common finding. Respiratory problems such as coughing, sneezing, watery eyes, and nasal discharges may be seen. Depression resulting in loss of appetite and decrease consumption of water may occur. Egg production may be impacted with a decrease in production and/or softshell or misshapen eggs. A bird’s comb, wattle, head, eyelids, and hocks may swell. Combs and wattles may turn purple. Nervous system disorders including tremors, incoordination, and unusual positions of the head may be seen. Diarrhea has been reported in some cases. For more information about clinical signs visit Defend the Flock-Signs of Illness at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/defend-the-flock-program/outbreak-illness/outbreak-illness.

For commercial and backyard poultry flocks, the best defense against HPAI is a sound biosecurity program. Biosecurity is the development and implementation of management procedures intended to reduce or prevent unwanted threats from entering a flock. The protocol is designed to reduce or prevent the spread of unwanted threats through the flock and eliminate any unwanted pathogens that may enter the flock. Lastly, a biosecurity plan is designed to prevent threats from infecting neighboring poultry operations. Biosecurity can be broken down into four basic areas which include traffic, isolation, sanitation, and husbandry.

The first line of defense should be limiting the traffic that enters the area. Poultry operations should have a perimeter buffer area (PBA). For backyard poultry operations, this could be a fence. In commercial operations this may be a fence or road that surrounds the facility. All entry points need to be clearly marked with “Do Not Enter” signs. In a study by United States Department of Agriculture (USDA) evaluating factors associated with introduction of HPAI in layer farms in the US, the presence of a gate was found to be protective against the introduction of the virus. Gates with signage may encourage people to follow biosecurity protocols.

Inside the PBA, a line of separation (LOS) needs to be established. The LOS isolates the birds from possible sources of infections. The LOS is usually the walls of the poultry building plus the entry point.  No person should cross this line without following proper biosecurity protocols. Producers should provide visitors with clean coveralls and disposable shoe covers. Visitors should wash their hands before and after visiting the facility. All visitors should dip their shoes in a disinfectant solution when entering and exiting the facility. Also, no other animals, wild or domestic should cross the LOS.

Sanitation is one of the most important parts of a biosecurity plan. All equipment, feeders, waterers, and buildings need to be cleaned and disinfected regularly. First, all fecal material and dirt should be physically removed. Next, disinfectants must be applied and allowed sufficient contact time to work properly. Foot baths need to be properly maintained. The property outside the poultry house should be kept mowed and cleaned. Failure to keep the grass cut and/or to promptly clean up feed spills is associated with HPAI.

Poultry producers must also practice good animal husbandry. Flocks need to be observed several times per day. Producers need to collect and dispose of dead birds frequently. Producer should know the clinical signs of a sick bird. Any unusual increases in sick or dead birds should be reported to proper authorities. Backyard producers have several options. They can contact their veterinarian or Oklahoma State University County Extension office. They can also contact the Oklahoma State Veterinarian at 405-522-6141.

The National Poultry Improvement Plan (NPIP) has guidelines for a biosecurity protocol. Commercial and backyard poultry producers should examine the NPIP 14 standards of the biosecurity protocol. Any areas that do not meet the standards need to be addressed. The NPIP biosecurity audit form can be found at http://www.poultryimprovement.org/documents/AuditForm-2018BiosecurityPrinciples.pdf. Additional sources for backyard poultry producers can be found at the USDA Defend the Flock website at healthybirds.aphis.usda.gov, Protect Your Poultry From Avian Influenza at  https://www.aphis.usda.gov/publications/animal_health/bro-protect-poultry-from-ai.pdf or Oklahoma State University fact sheet Small Flock Biosecurity for Prevention of Avian Influenza ANSI-8301.

Avian Influenza is a major threat to the US and Oklahoma poultry industry. It is the responsibility of all commercial and backyard poultry producers to do everything in their power to protect this industry.

Reference 

Swayne, D.E. and Halvorson, D.A. 2003 Influenza. In Y. M. Saif (ed.). Diseases of Poultry, 11th ed. Iowa State Press: Ames, Iowa, 135-160.

Green, A. L., Branan, M., Fields, V. L., Patyk, K., Kolar, S. K., Beam, A., Marshall, K., McGuigan, R., Vuolo, M., Freifeld, A., Torchetti, M. K., Lantz, K., & Delgado, A. H. (2023). Investigation of risk factors for introduction of highly pathogenic avian influenza H5N1 virus onto table egg farms in the United States,

2022: a case-control study. Frontiers in veterinary science10, 1229008.

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