Understanding Calf Scours for Cow-Calf Producers

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

Scours: often caused by more than one of these infectious agents acting together.Research has shown that a substantial proportion of normal, healthy-appearing adult cattle can shed many of the infectious agents that cause calf scours. 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. 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. 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: 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.

Adapted from Michigan State University Extension.Understanding Calf Scours for Cow– Calf Producers (2014) http://msue.anr.msu.edu/news/understanding_calf_scours_for_cow_calf_producers_part_1

Adapted by Jason Detzel, Livestock Educator, CCE Ulster County

Last updated July 26, 2019