by: Heather Smith Thomas

The health of each animal on your farm is important, but livestock health is often discussed in terms of the whole herd. Transmissible diseases often affect more than one animal, and environmental conditions (hot, cold, wet, windy, dusty, muddy) may affect all animals. Your management of cattle also plays a role—whether they are crowded into small areas and subjected to social stresses, close contact with sick individuals, or fecal contamination of feed. Well-planned management, which includes minimizing stress and crowding, and utilizing a good vaccination program, can help prevent most illnesses.

Biosecurity – One of the most effective ways to prevent introduction of contagious diseases to your farm is to keep a closed herd. Avoid bringing in new cattle unless you can be sure they are free of disease. It's often safer to raise your own heifers than to purchase new cows. If you buy cows, heifers, or a new bull, buy them from a reputable breeder, where you know the history of the animals.

A healthy animal may pick up a disease at an auction yard, if penned with or next to a sick animal. Bringing a calf home from an auction—especially a day old dairy calf to raise on a bottle or on a beef cow that lost her calf—is a common way to bring home diseases. The baby calf may not have received colostrum (the dam's first milk, that contains important antibodies against diseases) and might be vulnerable to disease, picked up at the dairy where it was born or at the auction yard. That calf may get sick after you bring it home, putting your own animals at risk.

If you purchase new animals, keep them isolated for two weeks to make sure they are not incubating a disease. If an animal becomes sick while in the isolation pen or stall, you have an opportunity to clean that area, removing all feces and using an appropriate disinfectant—rather than having the sick animal infecting your herd.

Some diseases, such as BVD (bovine virus diarrhea) can be devastating. One infected animal brought to your farm can be disastrous, even if your cattle are vaccinated against this disease, since vaccinations are never 100 percent effective. Regarding BVD, there is a test that will show whether an animal is persistently infected (and a danger to other cattle for the rest of its life). Any animal you purchase, such as a new bull, cows or heifers, should be tested before you buy them.

Nutrition – An adequate and balanced diet is the cornerstone of cattle health. Each class of animal (young calves, lactating cows, dry cows, bulls, yearlings being finished for butchering) needs a sufficient amount of food to meet its particular needs, and proper balance of energy (carbohydrates and fats) and protein, and balance of certain minerals. Even if you diligently vaccinate cattle at proper timing for disease prevention, they may still get sick if they are malnourished or have a mineral deficiency. All animals need proper nutrition, especially adequate levels of certain trace minerals, to have a strong and healthy immune system.

Underlying cause of some diseases like scours, pneumonia or upper respiratory illnesses, foot rot, etc. may be poor nutrition. Pregnant cows with inadequate protein levels will not produce enough colostrum for their newborn calves. Those babies will be more vulnerable to disease during their first weeks of life. Shortage of important trace minerals such as selenium, copper, and zinc make animals more susceptible to disease.

Often the reason for infertility in adults or slower growth in young animals is inadequate levels of certain nutrients such as energy, protein, or important trace minerals. Reproduction, for instance, is a luxury that only occurs after all the body's needs for maintenance (or growth, in a young, maturing animal) are met. Copper deficiency may result in heifers being slower to reach puberty, with lower than normal conception rates. Your county extension agent can help you test soils and feeds to see if they are lacking in important minerals, or check your hay to determine protein levels. Trace mineral deficiencies can be corrected by using supplements (added to salt mixes) or given to each animal via oral bolus or by injection. Consult your vet, extension agent or a cattle nutritionist to examine your feeds and help you make any necessary adjustments.

Vaccination – Develop an appropriate vaccination schedule for your herd, to prevent the most prevalent or devastating diseases in your region. Many stockmen want to avoid use of antibiotics and other drugs, to produce natural or organic meat and milk. Some people think they should not use vaccines, but this is a misconception. Vaccination is one of the tools to keep livestock healthy and eliminate the need for antibiotic treatments. Maximizing immune response with a carefully planned vaccination program raises the threshold for disease invaders, reduces the need for antibiotics, and increases the percentage of animals that meet criteria for a natural production program.

Some diseases come to your herd via wildlife, insects, or bacterial spores that are ever-present in the environment. Vaccination is the only way to prevent these diseases and should always be a part of your total herd health plan. The vaccines you use will depend on your region and your herd's risk for transmission. Discuss a vaccination program with your veterinarian, to figure out which diseases to be concerned about, and how often you should vaccinate.

Parasite Control – Even if cattle look healthy, internal and/or external parasites may rob them of nutrients, resulting in slower growth (lower weaning weights in calves), less milk production, less efficient immune system, or poor reproduction (lower conception rates in cows).

External parasites such as flies, mosquitoes and ticks can carry disease and also rob animals of nutrients by sucking blood. Horn fly control, using insecticide applicators like back rubbers or dusters, or insecticide ear tags, can make a big difference in weaning weights of calves. Internal parasites such as stomach and intestinal worms rob nutrients and may lower resistance to disease. Liver flukes cause damage, making the animal susceptible to liver problems, photosensitization (the liver is unable to filter out photodynamic agents and they end up in the bloodstream and go to the skin, where they cause death of skin cells), and redwater disease.

If cattle are spread out on large pastures, internal parasites are not as much problem. In small areas, however, cattle continually graze where they defecate, picking up worm larvae that hatch from eggs passed in manure. The larvae move onto forage plants, to be eaten. Since most of the larvae are on the lowest part of the plant, overgrazed pastures (plants eaten off close to the ground), are most risky for re-infecting the cattle. Seasonal deworming at proper time to prevent contamination of pastures, avoiding close grazing, and moving cattle to a new pasture when they are dewormed, can help break the worm's life cycle and keep parasitism to a minimum.

Sanitation – A clean environment is important. Frequent removal of manure and old bedding in pens or barns, disinfecting contaminated barns, stalls, calf hutches or other buildings where there have been sick animals, is a way to break a disease cycle and prevent future outbreaks. If a sick animal has been confined for treatment, stall walls, floors or calf hutch should be thoroughly scrubbed after the animal is removed. It won't do much good to use disinfectant on dirty walls or a barn floor, since organic matter such as straw and manure inactivates many disinfectant products and also gives pathogens a place to hide. Once the dirty surfaces have been cleaned, a chemical disinfectant will be much more effective.

Areas where cattle are fed, or where cows give birth, must be clean and uncontaminated with feces. Many diseases harmful to calves are spread via contaminated manure. Some are caused by bacteria such as E. coli or Clostridia (C. perfingens type A, C and D) while others are caused by viruses (rotavirus and corona virus), and others are caused by protozoa (coccidiosis and cryptosporidiosis). There are large numbers of these pathogens in feces of scouring calves. If you isolate sick animals and keep feeding areas and water sources clean, cattle won't ingest transmissible fecal pathogens that cause disease.

Herd Management – Some problems can be prevented by conscientious management. Separate heifers from older cows for winter feeding. They are still growing and need a higher level of protein for optimum health, growth, breeding, or to produce adequate colostrum if they're pregnant with their first calves. They need some alfalfa mixed with grass hay, for instance, or a protein supplement. Feeding them separately also makes sure they get their share of the feed.

Always provide adequate sources of clean water. Dirty water may spread disease. If cattle are short on water they suffer from dehydration or impaction, and steers may develop urinary stones in some instances if they don't drink enough during cold weather, and their urine becomes too concentrated.

Provide protection to minimize environmental stresses. In a hot climate, utilize pastures with shade, or create shade roofs tall enough to allow good air movement above the cattle. Winter pastures need windbreaks—either a grove of trees, or man-made. Minimizing heat stress or cold stress can help keep animals healthy.

Bring in any sick animal to treat in a separate place. If you isolate the animal at first sign of illness, you may prevent spread of disease through the herd—whether scours in baby calves, respiratory illness in a group of weanlings, or foot rot in a herd of cows.

Pasture Management – Avoid using certain pastures at times of year they may be risky. Pastures containing poisonous plants should not be grazed until you can eradicate those plants, or use the pasture when those plants are less toxic. Some types of forages such as sorghum and johnsongrass may contain high levels of hydrocyanic acid under certain conditions and may be very toxic to livestock.

In early spring, fast-growing cereal grains or certain grasses may cause grass tetany (especially in lactating cows) if cows consume too much. When growing rapidly, these lush plants may be low in magnesium or high in protein, nitrogen and potassium (which can interfere with absorption and utilization of magnesium in the body). To avoid this problem, use these pastures with weanlings or dry cows during risky times of year, or make sure every animal gets an adequate magnesium supplement.

Some legumes, especially alfalfa, can cause bloat. Avoid grazing when plants are young and lush. If those pastures must be grazed, use electric fencing to hold the herd in a small portion and mow that area a few hours ahead of turning them in—so the plants are starting to wilt and dry before being eaten. Then mow the next day's portion and let it dry before moving the fence to allow cattle access. Another way to reduce bloat risk is to wait until plants are more mature—with a higher ratio of stems to leaves. In the fall, wait until several hard frosts wilt and dry the alfalfa plants.

Fescue pastures can be harmful, if infected with an endophyte fungus. The toxic effect of the fungus hinders blood circulation. In summer this can lead to heat stress in cattle; in cold weather it may cause loss of ears, tails or feet due to poor circulation. This problem can be minimized by never allowing the grass to go to seed (seedheads contain higher levels of the toxin)—either by keeping it grazed short or mowing the pasture if it gets tall. Adding more protein to the diet can also help.

Avoiding Stress – Stress contributes to higher incidence or severity of disease. Stressed cattle do not eat well, so stress interferes with proper weight gain, reproduction and disease resistance. If susceptible animals are highly stressed at the same time they are exposed to disease challenge, they generally become rapidly and severely sick.

Many things stress cattle physically, including bad weather and inadequate nutrition. Psychological stress occurs when cattle are overcrowded, weaned, disrupted in normal social interactions, or suffer fear and anxiety during improper handling.

Stressed animals produce more cortisol, a hormone that helps them cope with short-term stress by changing body metabolism to help it function better under duress. Blood glucose is temporarily increased, for instance, which can be used as an energy source when the animal is unable to eat. But over a longer period of time the extra production of cortisol has negative effects on the immune system, hindering creation of antibodies and white blood cells. The lungs are especially vulnerable to effects of stress, since some pathogens are always present, residing in the respiratory tract, waiting for an opportunity to invade the tissues.

A common stress is human handling—moving, sorting, vaccinating, branding, dehorning, tagging, castrating, weaning, transporting, etc. Don't double up stresses. Don't dehorn, castrate and brand calves at the same time you wean them. It's best to do some of these procedures when they are small, when it's a lot easier on them.

Your herd will be less stressed if you develop a quiet and conscientious way of handling cattle. If they are handled gently and with patience (rather than running them around, yelling, chasing with dogs, beating on them if they won't go down the chute, etc.), they learn that coming into the corral is not frightening; they will more willingly come in the next time—with less stress.

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