Neonatal calf scours is a multifactorial disease, says Dave Smith, University of Nebraska-Lincoln (UNL) Extension veterinarian. The ideal scenario for an outbreak is to have susceptible hosts (naïve calves) existing in an environment (infected communal calving area) that's conducive to the proliferation of (and continued exposure of the host to) the disease agent, be it E. coli, Salmonella, rotavirus, cryptosporidia, etc.
Smith says even the healthiest calf can fall prey -- particularly in the wet, muddy conditions common to spring calving periods -- if the pathogen load is high enough, or the exposure long enough, to overcome the passive immunity provided by the calf's mother.
And that's the idea behind the UNL-developed Sandhills Calving System (SCS). Named after the Sandhills area of north-central Nebraska where it was tested, SCS is a system that utilizes a series of calving pastures to minimize newborn calves' contact with disease agents. The idea is to minimize both the disease load and newborns' exposure to the disease agents until their immune systems have sufficiently matured to better withstand them.
"We're trying to recreate the conditions of the first week of calving season during each of the remaining weeks of the calving season. We want a clean calving area without the presence of older calves that may be shedding pathogens," Smith says. "I like to say we're creating eight, one-week seasons rather than one, eight-week season."
Adopted in 2000, SCS consists of a series of large contiguous pastures. Learn more about the SCS system at: vetext.unl.edu/publications.shtml?to=Beef.
Here's how it works:
- Cows are turned into the first calving pasture as soon as the first calves are born, and calving continues for two weeks.
- After two weeks, the cows that haven't calved are moved to Pasture 2, with cow-calf pairs remaining behind in Pasture 1.
- After a week of calving in Pasture 2, the cows that haven't calved are moved to Pasture 3, and cow-calf pairs born in Pasture 2 remain in Pasture 2.
- With each subsequent week, cows that haven't calved are moved to a new pasture, and pairs remain in their pasture of birth.
The segregation of calves by age prevents the transfer of pathogens from older to younger calves. In addition, moving pregnant cows to new calving pastures helps minimize the pathogen load in the environment, as well as a newborn calf's contact time with those pathogens.
Smith says the key component is the age segregation of calves and the movement to new pastures of cows that haven't calved rather than moving pairs.
"Segregating calves by age prevents the transfer of pathogens from older calves to younger calves," Smith says. "Meanwhile, routinely moving heavy cows to new pastures prevents pathogen buildup in the calving environment over the course of the calving season, which would result in the exposure of the latest-born calves to an overwhelming dose load of pathogens."
Smith says the program was designed for beef operations typical of western Nebraska -- larger herds on larger acreages," Smith says. "But the age segregation of calves is the most important factor, not the number of acres and stocking density, so it should work for smaller herds on smaller acreages, as well."
Implementing SCS isn't without its challenges, however, he points out. In some cases, cross-fencing is necessary. Making sure there's water access for the groups is another concern.
"Feed delivery in a spring-calving operation might entail more labor, as well," Smith points out. "And, we like to encourage such producers to vary their feeding locations within any given pasture."
For more on calf scours or other herd health management topics, visit www.beefcowcalf.com, a free electronic resource from BEEF magazine that includes links to more than 2,000 information sources on cow-calf production and management topics.
-- Joe Roybal