It may be a nasty equation for cow-calf producers and their herds: hard winter + tight and low-quality feed supplies = added stress. With that added stress, say two Michigan State University Extension specialists, comes additional ailments, especially calf scours.
However, they say, a well-rounded management plan for calving season could keep calf scours away, or at least controlled.
Scours is a term for diarrhea; another term that may be applied to this disease is enteritis, which means inflammation of the intestinal tract, says Kevin Gould of MSU Extension and Dan Grooms, DVM, MSU College of Veterinary Medicine. Most cases occur within the first month of life.
There are a variety of causes of scours in baby calves, including:
• Viruses: Examples include rotavirus and coronavirus, bovine virus diarrhea virus
• Parasites: such as Cryptosporidium and coccidian
• Bacteria: Certain strains of Escherichia coli, Salmonella, and Clostridium perfringens
• 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, Gould and Grooms say. These agents are mostly shed in fecal matter, and 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. Shedding increases as the pregnant cows approached their calving date, and is heaviest in heifers.
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. Shedding tended to increase after cold weather, Gould and Grooms say.
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, Gould and Grooms say. 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. Also, 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 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, Gould and Grooms add. Planning ahead with a prevention strategy followed by close observation and immediate treatment can improve calf health and lower mortality rates.
Watch for part two on this topic later this week regarding prevention, symptoms and treatment.
Source: MSU Extension
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