Understanding calf scours for cow/calf producers

News
Mar 7, 2014
by WLJ

— Managing calf scours in young beef calves, plus the signs and treatment strategies

The winter of 2013-14 is going down as one of the hardest in recent memory for beef cattle operations. Significant winter cold stress combined with tight and lower quality feed supplies may be the perfect storm for spring calving operations.

The Michigan State University (MSU) Extension Beef Teams wants all cow/ calf producers to experience a productive calving season with healthy animals. You should take note of several key management criteria below to help reduce the risk of calf scours and develop your own management plan. What is scours, and what causes it?

Scours is a term for diarrhea; another term that may be applied to this disease is enteritis, which means inflammation of the intestinal tract. Cattle of any age can develop diarrhea, however, most cases of calf scours occur in the first month of life.

There are a variety of causes of scours in baby calves. Most of these are infectious agents:

• Viruses including rotavirus and coronavirus, bovine virus diarrhea virus;

• Parasites such as Cryptosporidium and coccidian;

• Bacteria including certain strains of Escherichia coli, Salmonella, and Clostridium perfringens;

• Scours is often caused by more than one of these infectious agents acting together.

How does infection occur?

Research has shown a substantial proportion of normal, healthy-appearing adult cattle can shed many of the infectious agents that cause calf scours. These agents are mostly shed in fecal matter. This shedding is particularly common for rotavirus, coronavirus, and cryptosporidium.

Studies have demonstrated that many pathogens responsible for scours are shed in the normal-appearing feces of healthy, pregnant beef cows and shedding increases as the pregnant cows approached their calving date. Shedding is heaviest in heifers, and shedding tended to increase after cold weather.

Further, healthy older calves can become infected with these agents, remain otherwise healthy, and shed large numbers of these agents into the environment, thereby contributing to accumulation of these agents in high enough numbers on a farm that a calf scours outbreak occurs. In the end, calves become exposed to scour-causing pathogens from the fecal contaminated environment. More contamination translates into greater risk for disease.

The question often comes up: “If some of these infectious agents are commonly shed by healthy cows, why do scours outbreaks occur on one farm but not another, and vary in occurrence from year to year on the same farm?” This variability in the incidence of scours from farm to farm and year to year likely reflects the fact that the rate of occurrence is influenced by many different factors. With respect to scours these factors may include:

Nutritional status of the cow herd. Protein, energy and micronutrient (mineral and vitamin) malnutrition during the latter half of gestation will likely affect calf health.

Age of the cow. Calves born to heifers are at higher risk of developing scours.

Duration of time in one area. In general, the longer that cattle are kept on any calving area, the more fecal contamination occurs. This translates to more scours risk for calves.

Weather. Cold, wet, windy weather will cause cattle to congregate together in sheltered areas. As the amount of fecal contamination increases in these areas, so will the amount of scours agents. Wet conditions favor survival of these agents in the environment. Remember that when the cows lay down, whatever is on the ground is going to contact their udder—and therefore be taken in by the calf when it nurses. Cold weather also increases the rate of shedding of certain agents by the cows.

Immunization status of the cow herd. This influences the availability of antibodies in the colostrum (first milk) that may help protect the calf against certain scours-causing agents.

Stocking rate. Scours risk increases with higher stocking rates especially in the calving and post-calving area.

The number of calves infected. Once infected, calves can produce millions, even billions, of infectious agents each day. This can cause the number of affected calves to increase rapidly.

Sanitation. Clean calving and post-calving areas reduce the risk of scours.

Genetic makeup of the herd. This is always tough to quantify and verify, but certain breeds and lines appear to have heartier newborns than others.

What to look for

Winter has added significant stress in many cow/calf operations. This is likely a year when scours risk will increase, so planning ahead with a prevention strategy followed by close observation and immediate treatment should help reduce morbidity and subsequent mortality in your calf crop. Knowing what to look for and how to react is essential.

The common signs of calf scours include:

• Watery stools that may be brown, grey, green, yellow in color. Occasionally blood and mucus may be evident in the stools. Rust colored or very bloody stools are often associated with infection with Salmonella, Coccidia, or Clostridium perfringens.

• Calves are often weak and depressed, and may lose their desire to nurse.

• Calves develop a sunkeneyed appearance as a result of dehydration. The bony prominence of their hips, shoulders, and ribs may become more apparent as the calves dehydrate and metabolize their body fat reserves.

• Calves may stagger or sway as they walk; this often reflects weakness, low blood sugar concentrations, and/ or alteration of the acid-base balance of their bodily fluids.

• Calves become too weak to stand. Left untreated, death typically occurs within 24 hours.

Depending on the cause(s) and the severity of the infection, a case of scours in a calf can last one to two days or as long as two weeks.

Treatment strategies

The highest priority in treating scours is to give back to the calf the water and electrolytes it lost in scours—this is called fluid therapy. This corrects dehydration, restores normal acid-base balance, and replaces salts in the calf’s bodily fluids. Methods include:

Oral administration. This option is most appropriate for scouring calves that are still able to stand and who are alert enough to follow their dams and move away when approached. Since most beef calves will not accept being fed by a bottle, water and electrolytes are most often delivered by an esophageal feeder. Electrolyte powders that have been prepared by veterinary pharmaceutical manufacturers are carefully balanced to provide the correct proportions of salts relative to water for optimal benefit to the calf; these are recommended over home-prepared recipes. Depending on the size of the calf and the severity of the scours, 2 to 6 quarts of electrolytes may need to be administered each day. Typically, the total volume of fluid is divided into two or more feedings per day.

Intravenous administration. This route of fluid administration is typically reserved for those calves that are too weak to stand or too lethargic to follow the dam or avoid being caught. The fluids are typically administered through a catheter placed in the jugular vein. Some experienced operators can place a catheter in a scouring calf’s vein; this is most often performed by a veterinarian or veterinary technician. The volume to be given depends on the calf’s size and the severity of the scours.

Nutritional support. A calf with severe scours may not want to nurse much in the first day or two of the illness. Most calves will regain their appetite with appropriate fluid therapy, as described above. However, since scours can last several days, baby calves who fail to nurse or be fed milk are at risk of starvation. Consult with your veterinarian to develop a feeding regimen for scouring calves.

Thermal support. Providing bedding, shelter from wind, rain, and snow so that the calf does not experience excessive cold stress on top of its existing disease.

Practicing proper biosecurity is critical. Ideally, people working with infected calves should not work with healthy calves. Whenever possible, isolate scouring calves and their dams from healthy cattle.

It is important to note that some infectious agents that make calves ill can also make people sick. People working with scouring calves should wash their hands before and after handling calves, their feed or their bedding. Practicing proper biosecurity is critical.

Scours prevention

Ensure that all newborn calves receive colostrum. If the delivery was difficult, the dam may be tired or in pain, and the calf may be weakened as well; this may result in a failure of the calf to nurse colostrum. In such cases, it is prudent to milk the colostrum from the dam and feed it to the calf via an esophageal feeder. How much colostrum should a calf receive? The calf must nurse or be given 2 quarts of colostrum during the first two to four hours after being born and a total of 4 quarts in 12 hours.

It is often a good plan to obtain fresh colostrum from a local dairy and freeze it or purchase a colostrum replacer for occasions when the dam does not have colostrum. If sourcing colostrum from a local dairy farm, beware of potential pathogens that can be transmitted through colostrum such as Johne’s disease and Bovine Leukosis Virus.

Consider a vaccination program for your cow herd. Be sure to consult your local veterinarian about vaccine products and time of administration. Timing is critical as colostral antibodies need to be in adequate concentrations in colostrum to provide ample passive immunity to the calf.

Maintain a clean calving area. Do not calve on pastures where cows have been kept in large numbers for long periods of time or sours has been recently diagnosed.

Calve in dry areas and drain pastures or corrals to minimize accumulation of moisture.

Segregate calves by age to prevent passage of infectious agents from apparently healthy older calves to newborns. See the Nebraska Sandhills calving system as an example.

Maintain adequate protein, energy, and micronutrient nutrition for the dam during gestation.

This all may seem overwhelming to inexperienced producers. The key is to prevent a scours infection and outbreak whenever possible. Good biosecurity, hygiene and proper nutrition for the dam and calf are imperative.

Infectious agents that cause calf scours are shed by healthy cows and calves so it is not considered practical to expect to prevent scours from ever occurring on your farm. A target should be to have no more than 2-3 percent of calves born each year develop scours. Look for additional management related topics at the Michigan State University Beef Team website. — Kevin Gould, Michigan State University Extension and Dan Grooms, DVM, MSU College of Veterinary Medicine

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