Herd health is top priority when raising livestock, but its impact could go unnoticed to the untrained eye. Herd health displays not only in the number of sick or injured animals, but also in your animals’ welfare and productivity on the whole. Many producers don’t realize that their animals are fighting off an underlying disease that is costing them money. Ailments can be hard to spot without monitoring feed intake and production numbers. In short, some might assume that if they don’t see any visible signs of sickness, their animals are healthy.
When your farm has a disease outbreak, there are two groups affected: a small number of the sick ones, and the rest that are fighting off the disease but may not be showing any signs. Those seemingly healthy animals are paying a price just like those more obviously afflicted. It’s like an iceberg, and the majority of your production losses are invisible under the water, because it is a decrease in milk, eggs, fiber growth, or weight gain.
Dairy producers who monitor milk production on a daily basis are well aware of the impact of subclinical diseases. They can tune into a disease outbreak before any visible signs of sickness appear because they’re aware of any drop in milk production. This production loss is due to the fact that the immune system requires large amounts of energy to fight off illness, and animals tend to eat less when they don’t feel well. Boosting your herd’s immunity is the most important part of maximizing your herd’s production and welfare.
Components of health
Your animal’s health is a result of the interplay of three things: its immunity, the pathogen, and the environment. These are interacting daily, even when disease isn’t visible on your farm. The environment is constantly impacting an animal’s immunity and the number of pathogens an animal is exposed to. How you manage your animals impacts all three of these factors by determining how many stresses your animals have in their environment, indirectly affecting their immunity, directly boosting their immunity with vaccinations, and determining which pathogens are present and how numerous and widespread. Whether you see disease in a herd is determined by two things: the ability of the low-immunity animals to fight off disease and the number of pathogens those animals are exposed to.
It is important to note that the environment only decreases an animal’s immunity; it cannot increase it regardless of any marketing claims of nutritional supplements. A clean, comfortable environment along with proper nutrition allows the immune system to perform at its best, but does not better prepare the immune system to fight off particular diseases. The best we can do is help keep an animal’s immunity functioning to its fullest and minimize their exposure to pathogens through proper herd management.
Think of the immune system as an army; improving the environment can be equated with keeping the army well-fed, well-rested, clean, and in good fighting condition, which while important for winning a battle, does little to turn the outcome if they have to manufacture their weapons after the enemy arrives. The only way to truly increase your animal’s immunity is through vaccinations or natural disease exposure. However, vaccines require proper herd health management to work to their fullest. The goal of herd management is to minimize the number of pathogens and improve the environment. Then, depending on the farmer’s preference, vaccinating can maximize your animal’s immunity (knowing that the environment is constantly trying to lower it).
Not all stressors are painful or would seem that detrimental, but they can add on to each other, with each stress successively reducing an animal’s immunity. Eventually, the animal’s immunity can decrease to a level that can be overwhelmed by the particular number of pathogens it is exposed to, and result in subclinical production losses and eventually illness.
Another thing to consider is that there are no truly closed herds, where there are no new pathogens being brought onto your farm — only varying levels of disease risk. Any new animals, including sires, semen, and embryos, can bring disease onto your farm. Often you hear of “closed herd” farmers or ranchers purchasing a new breeding sire or taking on an orphan from the auction barn. Even animals getting out and mixing, fence-line contact, or you visiting a neighbor’s farm or auction can be a potential source of infection. Wildlife and the usual roaming farm dog are common sources of disease transfer. It is important for producers to consider any possible ways that disease could enter their herd or flock, and have a management plan that can help prevent the introduction of any preventable diseases.
Many people confuse vaccines and antibiotics, thinking they are the same thing. In reality they are completely different, and vaccines actually help reduce the number of antibiotics producers might need to use. Proper use of vaccines helps minimize the amount of antibiotic and parasitic treatments.
A vaccine mimics a natural infection without actually causing infection. This boosts an animal’s immunity to that bacteria or virus, protecting them from future disease. A suitable analogy is that we’re showing the immune system the uniform of an enemy so it can be recognized when the real enemy comes. Though the immune system will generally respond to infection, the response is delayed, often by several days, while the immune system prepares itself. Conversely, an animal with an immune system that has been “primed” by past exposure — such as a vaccine — is ready to fight off the pathogen as soon as it arrives, as opposed to several days later after production loss or disease has set in.
By boosting your animal’s immunity, you may reduce the number of times they have to fight off an infection and require antibiotics, which also helps reduce antibiotic resistance. In fact, proper management to reduce stressors, along with vaccinations, play a major role in reducing antibiotic use in livestock. While vaccines help, they are not a crutch for poor management. The benefit of vaccination is its ability to boost the animal’s immunity, which provides a buffer against stressors.
Herd immunity is another important part of preventing the spread of disease within a group of animals by reducing the amount of pathogens shed by the whole herd. Animals that have been vaccinated to have a strong immunity fight off infections faster and therefore are a source of exposure to the rest of the herd for a shorter amount of time. This protects the animals that didn’t respond to the vaccine, or have a weakened immune system, by keeping the pathogen load to manageable numbers.
On the flip side, some livestock producers avoid immunization because they feel they are unnecessary and might even inhibit the natural ability of the herd to adapt to their environment and develop immunity to specific common pathogens.
Maintain a relationship with your veterinarian, too, so you and your vet can develop a herd health plan that is best tailored to your farm, as diseases can be specific to your area and farm. Veterinarians know best what diseases and nutritional deficiencies are common in your area and can help you develop a herd management plan to combat them. It’s important to remember that your livestock are pretty good at taking care of themselves, but there may be a few additional measures you can take to provide them with the best possible environment and ensure they’re living the good life.
Common stressors for livestock
• Temperature extremes
• Poor nutrition or a change in feed
• Handling and sorting — even for non-painful procedures such as shearing
• Castration and other painful procedures such as branding, dehorning, teeth cutting
• Breeding — of particular concern for breeding males in a herd, who generally fail to eat and rest as much as they should during breeding season
• Introducing new livestock
• Remember that disease can also be caused by vitamin and mineral imbalances, toxicities, and parasites, and that vaccination cannot protect against any of these problems
What’s the difference between bacteria & viruses?
Bacteria are single-celled microorganisms that can reproduce on their own. Bacteria can be killed by antibiotics, which are medications that directly affect bacterial cells but do not affect animal cells. Many common bacterial diseases can be prevented with vaccines; vaccines that protect against bacterial infections are called bacterins.
Unlike bacteria, viruses cannot reproduce on their own. Viruses consist of genetic material (DNA) in a protective capsule, and reproduce by finding a host cell in another organism, such as an animal, and tricking that cell into making copies of them. Viruses cannot be killed by antibiotics. While there are some antiviral medications, they are very non-specific, quite expensive, and not available for use in animal production. The most effective means of preventing viral infection is through vaccination.
Many viral infections lead to secondary bacterial infections. For example, a viral pneumonia infection damages the cells in the airways, which breaks down the animal’s natural defenses and allows secondary bacterial invaders to set up their own infection.
Tips to maintain your herd’s health
• Avoid auction marts and stockyards for purchasing animals when possible — purchase directly from producers that don’t buy a lot of animals from off farm, but keep a healthy herd of their own. Enquire about their health management program prior to purchasing animals.
• Ensure your animals have proper nutrition and consistent access to clean water.
• Avoid temperature stressors by providing shade and cool areas in the summer, and windbreaks and bedding in the winter.
• Quarantine new animals for two to three weeks before introducing them to the herd — this means not just a separate pen, but no fence-line contact or shared water source.
• Always practice proper workflow — youngest to oldest, healthy to sick, and always disinfect equipment and footwear after being used on or around sick animals.
• Watch your run-off. Many diseases occur because of manure run-off that accumulates.
• Use pain control and anti-inflammatory medication to minimize the impact of disease and painful procedures.
• Avoid stacking stressors. For example, don’t work animals on extremely hot or cold days, if it can be helped. Spread out painful procedures such as castration and ear tagging. Hold off on non-essential procedures on new animals until they settle into their new environment. This includes not vaccinating new animals the day they arrive. Stressed animals will not respond as well to vaccination as happy, healthy animals.
• Develop a relationship with your veterinarian. Create a herd management program to minimize the effect of disease in your herd and perform herd health audits.
• Keep records of your animals’ performance. The bare minimum would be feed intake and their output (eggs, milk,weight gain, fleece growth). If you notice a drop, you need to talk to your veterinarian, as this is an indicator that something might be wrong in the herd.
• Remember that most of your profit losses will not be the visibly sick animals.
Ryan Ridgway owns a rural veterinary practice. He enjoys blacksmithing in his spare time, and is the author of the book Home Blacksmith.