Understanding calf scours for cow-calf producers: Part 1

Managing calf scours in young beef calves.

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 maybe the perfect storm for spring calving operations. The Michigan State University 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: Examples include rotavirus and coronavirus, bovine virus diarrhea virus
  • Parasites: such as Cryptosporidium and coccidia
  • Bacteria: Certain strains of Escherichia coli, Salmonella, and Clostridium perfringens
  • Scours: often caused by more than one of these infectious agents acting together

How do baby calves become infected with the infectious agents that cause scours?

Research has shown that 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.

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 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, 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 sours.
  • 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.

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.  For additional cattle management resources, visit the Michigan State University Beef Team website.

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