What do producers get when they have a full herd of cows in one calving
pasture with calves ranging from one day old to forty-one days old?
University of Nebraska-Lincoln (UNL) animal scientists say for many
producers, they get calf scours.
As calving season progresses, calving pastures become more populated and
some calves start getting scours. However, some Nebraska researchers
have been studying ways to prevent calf scours. After five years of
testing their method, UNL researchers are promoting a system they
believe will help producers lessen or eliminate scours, if they have
previously had scour problems in their herd.
Dr. David Smith, UNL extension veterinarian, said the key to the scour
system is to have the environment the same as it was the first day of
calving. He explained that it takes two things to do that. One is to
make sure the ground hasn’t already been contaminated. The second is to
make sure a producer does not have calves that are already shedding the
organisms that cause scours in high numbers.
The way to accomplish these two simple goals is to subdivide calving
pastures and properly move cows through them because, in a typical
calving pasture, the concentration of bacteria and viruses that cause
scours increase dramatically as calving season progresses.
Smith elaborated on the calving system, saying that the cows all start
out in one pasture for the first week of calving, and, at the end of
that week, all the cows that have not calved yet are moved to a fresh
pasture for seven days. At the end of the second week, cows that have
not calved are moved to a third pasture, and so on. Therefore, the age
range of calves in any one pasture is not more than seven days, meaning
older calves are not exposing younger, more susceptible calves to
massive amounts of pathogens.
“They are all at the same level. They are kind of in-phase together,”
said Smith. “This doesn’t eliminate the organisms, it just minimizes the
dose load that they are exposed to.”
Smith explained that scours is very age-specific. The peak period, as
producers and veterinarians have noted, is between seven and 14 days of
age, just about the time potential exposure to pathogens becomes high.
Smith said veterinarians believe this is because the antibodies the calf
received from the cow’s first colostrum have diminished at that point
and they are exposed to more pathogens than they can handle, which makes
Although called the Sandhills Calving System by researchers, the system
will work anywhere. The system breaks up the scour cycle, and Smith and
his colleagues believe this is because calves of different age groups
are not commingled. Within a pasture, calves are still exposed to a low
dose of pathogens from the cows, but they develop immunity to those
pathogens and are not bombarded with pathogens shed by older calves
shedding viruses, which overloads the younger calves’ immune systems.
When the youngest calf is four weeks old, Smith said researchers feel it
is safe to turn all the cows and calves out on grass together.
Originally, Smith said researchers were going to test the theory of
isolating calves that got scours to see if it would prevent others from
scouring. However, in the past five years on the ranches that have been
testing the calving system, there were not enough incidences of scours
to try it.
Smith noted that one of the trial ranches was historically experiencing
a consistent 10 percent calf crop loss to scours, which is why the
producer contacted UNL for assistance. Since implementing the Sandhills
calving system, this ranch has seen the death loss due to scours drop to
zero for five years.
“I don’t think this is a system that is for everybody, because it is a
little harder and requires more management,” said Smith. “If you’re not
having problems with scours, then you probably don’t need to do this
anyway. But, for ranches that are having problems with scours, this is
something to consider.”
Smith did point out that under this system, a producer only has one
place to watch for calving and one pasture to watch for scour
problems—the pasture with calves in the seven to 14 day of age range.
Another advantage of the Sandhills Calving System is that it allows more
bonding between the cow and the calf. Producers who don’t use the system
typically move cows and calves when they are a day or so old. With this
system, the cow is able to “nest” in one area, give birth to the calf in
that area and remain there for at least four weeks without disruption.
UNL forage specialist Bruce Anderson said, “Obviously, with this system,
selecting the right pastures for calving that can be subdivided with
water available in each subdivision is critical. After all, after eight
weeks you could have cattle in eight different subdivisions.”
Anderson also noted that the system could be beneficial to the pastures
as well to help prevent overgrazing of any single area. “Subdividing
pastures usually improves pasture health, but with the Sandhills Calving
System, it can improve calf health as well,” said Anderson. “This might
sound like a lot of work, but it likely will be less work than treating
sick calves as well as reduce calf losses.”
Anderson and Smith both advise producers to select a certain day to move
cows, so that it is not overlooked.
Smith further commented that the system does take considerable
pre-planning. He encouraged any producer considering trying the
Sandhills Calving System to consult a veterinarian and possibly even a
forage specialist to map out the pastures and ensure appropriate
management of pastures. Producers will need to think about how many
calves are expected week by week.
On a final note, Smith said this system does work better for producers
who have a tighter calving schedule, such as those whose calving season
is only eight weeks. He warned producers not to try to stretch out the
age of calves in one pasture and get by with fewer pastures since that
will break the system.
“Somewhere between seven and 10 days is about right,” said Smith. “The
further you get away from that, the more likely you are to start having
scouring calves.” — Sarah L. Swenson,
WLJ Associate Editor