While many conversations surrounding judicious antibiotic use on the dairy start with mastitis treatments, a key time frame to consider evaluating your antibiotic usage is during weaning. During the weaning period,  calves are at a high risk of developing respiratory disease, which often requires antibiotics to be treated successfully.   

“Antibiotics should only be used as a supplement to well-planned and -executed management protocols leading up to and during the weaning period,” said Mark van der List, DVM, Boehringer Ingelheim.

A good preventive health program can reduce the number of calves that succumb to bovine respiratory disease (BRD), lessen the severity of clinical signs, and decrease the number of animals that develop complications.

Dr. van der List encourages producers to take a close look at their current weaning protocols, and identify any areas that could be changed to further mitigate the antibiotic use on their dairy.  

Consider talking through the following questions with your herd veterinarian. Are there any small changes you could make?

1. What environmental stressors are present on your operation, and how are you working to offset them? In the cattle industry, there are a number of built-in stressors such as weaning, shipping, commingling and dehorning. But even seemingly minor environmental events, like changes in temperature, dust, poor ventilation and moisture, can be factors. “Judicious use of antibiotics starts with identifying ways in which stressors that cause disease can be minimized in your herd,” stated Dr. van der List. 
    
2. Do your dry cow protocols contribute to quality colostrum production? A nationwide evaluation of colostrum on dairy farms in the United States showed that 60% of maternal colostrum fed to newborn dairy calves is inadequate, causing many calves to be at risk of failure of passive transfer.¹
   
   When calves don’t receive enough high-quality colostral antibodies, they do not acquire necessary protection against the most common viral and bacterial infections found within their environment. They’re also more likely to develop scours or pneumonia, and are at greater risk of death.
   
   Colostrum quality starts with healthy cows. The management of cows during the last 60 days of pregnancy; proper nutrition, ensuring cow comfort and reducing stress; will optimize cow health and good colostrum development.
   
   Vaccines, safely administered at appropriate times within the dry cow period also help to keep the dam healthy and enhance antibody levels in colostrum.² Cows vaccinated during the dry period are more likely to enter the next lactation with a robust immune system to fight off infectious-disease threats.
    
3. Do you have a calf vaccination program in place to extend immunity? For calves, respiratory vaccines are important to stimulate the acquired immune system, which develops immunological memory. When the animal encounters these respiratory pathogens in the future, this memory response results in a rapid and specific immune response. Vaccines help protect the individual calf, prevent the spread of infection to other calves and lessen the severity of disease.
   
   Dr. van der List suggests producers consult with their veterinarian about the use of vaccines prior to weaning to increase immunity against common respiratory pathogens. “The time frame for vaccinating calves will vary from farm to farm, but ideally, the calf will have had time to develop a robust immune response from the vaccine by the time it starts facing the challenges associated with weaning.”
   
   Both modified live and killed vaccines can be used successfully, but it is important to use vaccines that contain the appropriate antigens and have good research backing against viral pathogens such as bovine viral syncytial virus, infectious bovine rhinotracheitis, bovine viral diarrhea virus (BVDV) Type 1 and Type 2 and bacterial pathogens such as Mannheimia and Pasteurella.
   
   Dr. van der List notes that antibodies absorbed from colostrum can interfere with the development of immunity from vaccines for several months after birth, so it’s also important to administer a vaccine proven to develop immunity in calves even in the presence of colostral antibodies.³
    
4. Are there ways in which calf nutrition could be improved? The immune response in the calf is strongly influenced by nutrition. When calves switch from a milk-based diet to solid food, we have to make sure they are eating enough so that they don’t go into an energy-deficit period. Working with a local nutritionist can help you determine the appropriate amount and type of feed required to transition diets smoothly.  
    
5. How are calves grouped? How quickly are they required to adjust to a larger group? “We don’t want calves to go into very large groups right after weaning,” asserted Dr. van der List. “They should be introduced into a group of no more than 10 animals in the first week post weaning, and the size of the group should be increased very gradually to minimize stress.”
    
6. How fast are sick calves receiving the necessary treatment? Rapid identification of animals showing signs of BRD with bacterial involvement and administering a fast-acting, effective antibiotic are very important. This not only helps them recover quickly, but it also reduces the likelihood of future complications. Choosing an antibiotic that provides 10 days of therapy from a single injection can reduce the time and labor associated with extra treatments. It also eliminates any stress placed on the calf due to extra handling. 
   
   Dr. van der List also encourages producers to evaluate the animal’s chance of recovery before administering treatment. “If you have a calf  that has been treated multiple times, the calf likely has a very poor chance of recovery,” he said. “When our goal is to reduce antibiotic usage in the dairy herd, we want to be targeting those antibiotic treatments to animals that have a high chance of recovery.”
    
7. Are you practicing metaphylaxis? Why or why not? In the dairy business, metaphylaxis is not typically recommended as a standard procedure, but there are certain times that it can be used very effectively and contributes to judicious use.
   
   “If you know animals are undergoing more stress than usual or are at a higher risk of developing bacterial respiratory disease, this may be a time to consult your veterinarian and determine if metaphylaxis is warranted,” concluded Dr. van der List.
   
   Even a minor change in your weaning protocols in an effort to reduce antibiotic usage is a step in the right direction. Local experts such as your herd veterinarian and nutritionist can assist in troubleshooting any problems, provide additional resources and help you design more effective weaning protocols.  

References:

¹ Morrill KM, Conrad E, Lago A, et al. Nationwide evaluation of quality and composition of colostrum on dairy farms in the United States. J Dairy Sci 2012;95(7):3997–4005.

² Smith BI, Rieger RH, Dickens CM, et al. Anti-bovine herpesvirus and anti-bovine viral diarrhea virus antibody responses in pregnant Holstein dairy cattle following administration of a multivalent killed virus vaccine. Am J Vet Res 2015;76(10):913–920.  

³ Zimmerman AD, Boots RE, Valli JL, Chase CL. Evaluation of protection against virulent bovine viral diarrhea virus Type 2 in calves that had maternal antibodies and were vaccinated with a modified-live vaccine. J Am Vet Med Assoc 2006;228(11):1757–1761.

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