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Herd Health — Summer 2009 | Out Here Magazine

Guiding your herd from preventable problems


By Heather Smith Thomas
Photography by Greg Latza


The health of each animal on your farm is important, but livestock health is often discussed in terms of the whole herd. That's because whether you have two cattle or 200, what distresses one easily can affect the others.


Transmissible diseases, environmental conditions, and weather may affect every animal.


Your cattle management is the key to your herd's health — how you move them, whether you quarantine sick animals, grazing methods, parasite control, and much more.


Well-planned herd management, which includes minimizing stress and crowding, careful care of calves, and implementing a good vaccination program, can help prevent most illnesses.




One of the most effective ways to keep contagious diseases off your farm is to keep a closed herd. Avoid bringing in new cattle unless you are sure they are disease-free.


It's often safer to raise your own heifers than to purchase new cows. If you buy cows, heifers, or a new bull, buy from a reputable breeder, where you know the animals' genetics and health history.

A healthy animal may pick up a disease at an auction yard, if penned around 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 tiny calf may not have received colostrums — the mother's first milk that contains important antibodies against diseases — and might be vulnerable to illnesses 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 healthy 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, because vaccinations are never 100 percent effective.

There is a BVD 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.


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 and balance of food and minerals to meet its particular needs.

Protect your cattle from deadly internal parasites by spreading out your herd on large pastures, preventing close grazing, and moving them to a new pasture after deworming.

Mineral Requirements For Cattle
Calcium, percent 0.31 0.18 0.27  
Chromium, ppm       1000.00
Cobalt, ppm 0.10 0.10 0.10  
Copper, ppm 10.00 10.00 10.00 100.00
Iodine, ppm 0.50 0.50 0.50 50.00
Iron, ppm 0.50 0.50 0.50 1000.00
Magnesium, ppm 0.10 0.12 0.20 0.40
Manganese, percent 20.00 40.00 40.00 1000.00
Molybdenum, ppm       5.00
Nickel, ppm       50.00
Phosphorus, percent 0.27 0.18 0.27  
Potassium, percent 0.60 0.60 0.70 3.00
Selenium, ppm 0.10 0.10 0.10 2.00
Sodium, percent 0.07 0.07 0.10  
Sulfur, percent 0.15 0.15 0.15 0.40
Zinc, ppm 30.00 30.00 30.00 500.00
Source: University of Missouri Extension


Even if you diligently vaccinate cattle, they may still get sick if they are malnourished or have a mineral deficiency. 

Poor nutrition is the underlying cause of diseases such as scours, respiratory illnesses, and foot rot, along with infertility in adults and slow growth in young animals. Pregnant cows with inadequate protein levels don't produce enough colostrum for their newborn calves, making those babies more vulnerable to disease during their first weeks of life. 

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 orally or by injection. Consult your vet, extension agent, or a cattle nutritionist to examine your feeds and help you make necessary adjustments. 

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.

Vaccination is the only way to prevent environmental diseases and should always be a part of your total herd health plan.

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 if they don't drink enough during cold weather, causing their urine to become too concentrated.




Develop an appropriate vaccination schedule for your herd to prevent the most prevalent or devastating diseases in your region.


Many stockmen who want to avoid use of antibiotics and other drugs to produce natural or organic meat and milk 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.


Some diseases come to your cattle 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, parasites, both internal and external, may be robbing them of nutrients. The results? Lower weaning weights in calves, less milk production, less efficient immune system, and lower reproduction rates.


External parasites such as flies, mosquitoes, and ticks carry disease and steal an animal's nutrients by sucking blood.

Solutions include insecticide applicators such as back rubbers or dusters, or insecticide ear tags.

Internal parasites such as stomach and intestinal worms rob nutrients and may lower resistance to disease. The aptly-named liver fluke, for example, damages the liver, causing organ failure.

If cattle are spread out on large pastures, internal parasites are not as much of a problem. In small areas, however, cattle continually graze where they defecate, picking up worm larvae that hatch from eggs passed in manure.

Because most of the larvae are on the lowest part of the plant, overgrazed pastures — where plants are eaten off close to the ground — are most risky for re-infecting the cattle.

Break the worm's life cycle and keep parasitism to a minimum by seasonal worming at proper times to prevent contamination of pastures, avoiding close grazing, and moving cattle to a new pasture when they are dewormed.

If an animal does show signs of illness, immediately isolate it to prevent spread of disease to the others.

Protect your cattle from deadly internal parasites by spreading out your herd on large pastures, preventing close grazing, and moving them to a new pasture after deworming.

Deworming Schedule For Beef Cattle
Mature cows Near freshening Benzimidazole (Oct 30-Apr 15)
Avermectin/Milbemycin (Apr 15-Oct 30)
Bulls Spring and fall Benzimidazole (Oct 30-Apr 15)
Avermectin/Milbemycin (Apr 15-Oct 30)
Calves 3-4 months of age Avermectin/Milbemycin
Replacements and Stockers Weaning/purchase and at spring/fall (minimum)
Weaning/purchase and every 3-4 months until yearlings
Weaning/purchase and placed on safe pasture

Yearlings Spring and fall until mature Avermectin/Milbemycin or Benzimidazole
Source: The Cooperative Extension System



Prevent disease outbreaks by frequently removing manure and old bedding in pens or barns and disinfecting contaminated barns, stalls, calf hutches, or other buildings where sick animals have been.

Starting with clean surfaces, however, is essential to your cattle's health because disinfectant isn't effective on dirty walls or a barn floor. Organic matter such as straw and manure inactivates many disinfectant products and also gives pathogens a place to hide. Clean surfaces allow the chemical disinfectant to 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.

Pasture Management

Keep your cattle out of pastures that contain forage risky to livestock. Sorghum and johnsongrass, for example, may contain high levels of hydrocyanic acid under certain conditions and may be very toxic to livestock. Either eradicate those plants, or use the pasture when those plants are less toxic.

In early spring, fast-growing cereal grains or certain grasses may cause a metabolic disorder called grass tetany, a magnesium deficiency that particularly affects lactating cows. Avoid the problem by using these pastures for weanlings or dry cows during risky times of year, or make sure every animal gets an adequate magnesium supplement.

Some legumes, especially young, lush alfalfa, can cause bloat. If those pastures must be grazed, mow that area a few hours ahead of turning your cows in, so the plants are starting to wilt and dry before being eaten.

Further reduce bloat risk by keeping cattle off a pasture 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.

When cattle are handled gently and patiently, stressful situations, such as getting an ear tag, don’t take as much of a toll on them.

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, they generally become rapidly and severely sick.

Inadequate nutrition, as mentioned, can physically stress animals, as can bad weather. Provide shelters to minimize heat or cold stress. In a hot climate, use 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 structures.

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.

But over a longer period of time, the extra cortisol hinders the immune system. Lungs are especially vulnerable, since some pathogens are always present 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. Avoid doubling up on stresses.

Don't dehorn, castrate, and brand calves at the same time you wean them. It's best to perform some of these procedures when they are small, when it's a lot easier on them.

Develop a quiet and conscientious way of handling cattle. When they are handled gently and with patience, rather than enduring chasing dogs, cattle prods, and manhandling, they learn that coming into the corral is not frightening.

Next time, they will come in more willingly — with less stress.

Heather Smith Thomas, of Salmon, Idaho, is the author of several books on raising cattle.


Signs of Illness

By paying close attention to your cattle, you'll better be able to tell when behavior changes may be signaling illness. Noticing illness early will allow you to start treatment immediately.

  • Slowed mobility — stands up and moves slowly
  • Posture — Stance may indicate lameness or pain
  • Anxiety and restlessness
  • Coughing
  • Runny nose
  • Body condition — too thin or too fat
  • Coat — Thinning, dull, rough
  • Separated from the herd
  • Not chewing its cud — signals pain, digestive problem, fever
  • Lack of interest in its surroundings
  • Manure — amount, consistency, frequency
  • Urination — amount, frequency