Preparing for Weaning and Beyond

– Dr. Michelle Arnold, UK Veterinary Diagnostic Laboratory

Preconditioning programs for feeder cattle have long been recognized by the beef industry as a way for cow-calf operators to add credibility and, therefore, value to their annual calf crops. These programs prepare the calf for the known stressors ahead associated with weaning, transportation, and commingling that make calves more likely to get sick with bronchopneumonia, also known as Bovine Respiratory Disease (BRD). Most preconditioning programs recommend starting vaccinations 2-3 weeks prior to weaning because it allows sufficient time to develop protection before natural exposure to the BRD “bugs”. At minimum, preconditioning programs require two rounds of viral vaccine (at least one must be modified-live vaccine or “MLV”) and Clostridial (blackleg) vaccinations, a Mannheimia haemolytica toxoid (“Pasteurella” shot), deworming, castration of bull calves and healed, heifers guaranteed not pregnant, and a minimum of 45-60 days weaned. Some programs require producers to use products manufactured by only one pharmaceutical company. In addition, weaned calves are expected to know how to eat from a feed bunk and drink from a fountain or tank but should not be over-conditioned or “fleshy”. Buyers prefer weaned calves that have been properly fed and with documented vaccinations and parasite control compared to similar quality non-vaccinated and non-weaned calves, which can translate to price premiums that vary in size depending on the market that day. Additional information on weaning strategies can be found in the Extension fact sheet ID-258 Weaning Beef Calves http://www2.ca.uky.edu/agcomm/pubs/ID/ID258/ID258.pdf .

The importance of preparing calves properly before weaning cannot be emphasized enough when it comes to health. Prevention of disease, especially BRD, is far more effective and less expensive than treatment but it requires the protective antibodies to be in place before leaving the farm and before the inevitable exposure to the respiratory viruses and bacterial pathogens that cause disease. “Stress” is a known factor that negatively affects a calf’s immune system and plays just as important a role in disease development as the infectious pathogens (“bad bugs”). However, research has shown that there are 2 distinct types of stress; acute (short-term) lasting less than 24 hours and chronic (long-term) lasting 24 hours or more. Acute stress is actually believed to be a “good thing” because it revs up the immune system and increases resistance to infection and response to vaccines. Conversely, chronic stress causes immune dysfunction due to the excess production of cortisol which reduces the ability of white blood cells to do their job fighting disease-causing organisms. Calves properly vaccinated and retained on the farm at least 60 days after weaning are known to have less sickness and health costs at the feedlot, provided their nutritional needs, including critical trace minerals, were fully met.

It is important to understand that the cow-calf sector of the beef industry single-handedly holds the keys to successful reduction of BRD and antibiotic use throughout the feeding period and all the way to slaughter. First and foremost, proper nutrition and vaccination of the mature cow herd is the foundation for a healthy calf crop. “Fetal programming” is an emerging topic of importance as researchers are starting to understand the critical steps involved in fetal immune system development that only occurs during pregnancy. Secondly, vaccinations against the viral and bacterial agents involved in BRD, when given to nursing calves while still on the home farm, are strong weapons against future disease challenge. Vaccinations given to healthy calves while still “on the cow” induce acute or short term stress that enhances the antibody response in healthy animals. There are 3 distinct times a cow-calf producer should give vaccines to completely precondition their calves; at “branding” (1-4 months of age), pre-weaning (2-3 weeks prior to separation from dams) and after weaning (once the stress is over, typically 10 days to 2 weeks post-weaning, but prior to leaving the farm). The Animal and Plant Health Inspection Service (APHIS) veterinary website echoes the need to vaccinate healthy animals; it specifically states that licensed cattle vaccines “… are typically shown to be effective in healthy animals. A protective immune response may not be elicited if animals are incubating an infectious disease, are malnourished or parasitized, are stressed due to shipment or environmental conditions, are otherwise immunocompromised, or the vaccine is not administered in accordance with label directions.” https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/veterinary-biologics/CT_Vb_licensed_products

Although we live in an age with state-of-the-art cattle respiratory vaccines and potent antibiotics specifically formulated for bronchopneumonia, BRD sickness and death rates continue to climb year after year. Indeed, there is little incentive for a producer with a small herd to implement a pre-conditioning program and a majority of cow-calf operations are small and typically run a bull year-round. But these calves will eventually leave the farm and enter stocker or backgrounder operations as “high risk calves”, meaning they are lightweight, unweaned (or weaned on the trailer on the way to the yards), never or poorly vaccinated and most are trace mineral deficient. At the auction barn they are mixed or “commingled” with similar calves from multiple farms then sold, allowing virus transmission to begin prior to delivery to the stocker/backgrounder facility or feedlot. After arrival and a brief rest period, these calves are usually processed through the chute and receive multiple vaccines, deworming and the bulls are castrated. These calves experience chronic stress causing immune dysfunction and will typically break with respiratory disease within the first 2 weeks after arrival. It is estimated that 60-70% of calves marketed through sale barns are considered high risk.

If considering implementing a preconditioning protocol, talk to your veterinarian first to develop a comprehensive vaccination plan and find a marketing program to promote this extra effort. For additional help with vaccine selection and marketing, most pharmaceutical companies offer “cookbook” preconditioning programs using their products:

The following is a protocol including the minimum requirements for most calf preconditioning programs but be aware that certain marketing programs may have additional requirements. Some preconditioning programs are now requiring vaccines to be given to the dams as well as the calves. Linked here (in PDF) is an up-to-date listing of available vaccines and dewormers and their manufacturers to help with product selection. The products listed are in no particular order and are not to be considered as endorsements by the University of Kentucky. In addition, the list is not “all- inclusive” as there are too many products on the market to list them all.

“Two Rounds Viral Vaccines”

a. First round contains the respiratory viruses (IBR, BVD, PI3, BRSV) in either a killed or modified live viral (MLV) vaccine preparation.
• Best Time to Administer First Round: 2-3 weeks prior to weaning
• Best Type of Vaccine: Modified Live (MLV)- (List D1)
Warning: Only use modified live vaccines in calves nursing pregnant cows if the dams were vaccinated with MLV within the last 12 months. The virus vaccines replicate in the newly vaccinated calf and can be spread to the pregnant dam, increasing the risk of abortion if the dam is not adequately vaccinated (always check vaccine label for specific requirements).
• If this requirement is not met, a killed vaccine (List D2) should be used or wait until the calf is weaned to begin the program.
• 2nd Best Option to Administer First Round: “At” weaning (after stress is over). Use MLV (List D1)
• What you actually see on the label of a respiratory virus vaccine:
Bovine Rhinotracheitis-Virus Diarrhea-Parainfluenza 3-Respiratory Syncytial Virus Vaccine (See Figure 1 for label examples)

b. Second Round-Booster according to label directions. Use MLV (List D1)

c. A combination product containing both MLV viral vaccine and Mannheimia haemolytica (“Pasteurella”) vaccine may be used instead as the 1st or 2nd round. See “Live Product with Pasteurella” option below for further explanation.

d. Virus vaccines may also contain Histophilus somni bacterin or “Somnus”. Killed virus vaccine + Somnus (List D2B) and MLV vaccine + Somnus (List D1B) are both available.

“Two Rounds of Blackleg”

• There are many 7 or 8-way Clostridial vaccine products available (List D5). Most require a two shot series, administered 2-3 weeks apart for protection. A few vaccines also contain tetanus toxoid (important if banding bull calves).
• Blackleg vaccines may be found in combinations with Pinkeye Vaccine (List D5B), with Histophilus somni bacterin “Blackleg + Somnus” (List D5C), or with Mannheimia haemolytica toxoid “Blackleg + Pasteurella” (List D5D)
• What you typically see on the label for a 7-way blackleg vaccine:
Clostridium chauvoei-septicum-novyi-sordelli-Perfringens Types C & D Bacterin-Toxoid

“A ‘Pasteurella’ shot-calves must get at least one round”

• This is actually a Mannheimia haemolytica toxoid (List C3). Some of these products also contain a Pasteurella multocida bacterial extract.
• Best Time to Administer: 2-3 weeks prior to weaning. Safe in all nursing calves.
• Read the label! Available in many combinations so be careful when selecting products.
• What you see on the label: Mannheimia haemolytica toxoid (may also say “Pasteurella multocida” “bacterial extract” or “bacterin”). See Figure 2 for a label example.

“Live Product with Pasteurella” option

• A Mannheimia haemolytica toxoid and MLV Respiratory Virus Vaccine Combination product (List C4) can be given to meet the “Pasteurella” vaccine requirement and the MLV viral vaccine requirement with just one injection. Merck and Zoetis also offer this combination by administration of an intranasal vaccine and an injectable vaccine manufactured to be given at the same time.
• Best Time to Administer: 2-3 weeks prior to weaning
• Warning: Only use modified live vaccines in calves nursing pregnant cows if the dams were vaccinated with MLV within the last 12 months because of the risk of abortion (always check vaccine label for specific requirements).
• If this requirement is not met, wait until the calf is weaned to use this product.
• What you actually see on the label:
Bovine Rhinotracheitis-Virus Diarrhea-Parainfluenza 3-Respiratory Syncytial Virus-
Mannheimia haemolytica (± Pasteurella multocida) Vaccine. (see Figure 2 Example)

“Deworming-must include product and date”

• Deworming with an endectocide (List D6A) will control internal and external parasites, usually 30 days or slightly longer (LongRange is an extended duration product of 120+ days).
• A drench anthelmintic or ‘white dewormer’ (List D6B) is given by mouth and has a short duration but very effective clean-out of internal parasites. An insecticide is often required for external parasite (lice/flies/ticks) control as well.
• Giving newly weaned calves both types of dewormers at the same time, a white dewormer by mouth (List D6B) and an endectocide by either injection or pour-on (List D6A), is a tremendously effective combination to remove internal parasites, control external parasites, and prevent reinfection for a 30 to 40-day period.