Planning for calving is a lot like formulating a battle plan. It can fall apart when the first shot is fired, but preparation and planning for contingencies often makes for the most optimum results.
“Successful calving seasons are planned in advance, with consideration for minimizing the risks of the known hazards of this phase of cattle production,” says Dave Smith, University of Nebraska-Lincoln (UNL) Extension veterinarian. These include minimizing the risks of birthing, environment and disease.
Minimize birthing risks
“Successful calving occurs when a live calf is born without complications to the calf or the dam,” Smith says.
The calf factors in dystocia are generally related to size, posture and presentation of the birthing calf. The consequences can be metabolic or physical injury, which can result in death during or after birth.
Meanwhile, the dystocia factors related to the dam are her age, pelvic size and metabolic health. Heifers tend to have more problems with dystocia owing to their more immature stage of development.
There are long- and near-term strategies for preventing birthing problems, Smith says. The long-term strategies include selecting for calving ease and pelvic size, and implementing sound heifer breeding and development programs.
Near-term strategies include:
Providing exercise and balanced nutrition to heifers and cows prior to and after calving;
frequent monitoring of calving progress;
early and appropriate calving assistance;
ready access to the appropriate tools for calving assistance;
copious use of lubricants; and
attention to sanitation (e.g., use of soap and water) during birthing.
Among the environmental factors presenting dangers to new calves are weather extremes, crowding, predators and physical sources of injury, Smith says.
At birth, calves have limited ability to regulate their body temperature. Thus, extremes of heat or cold present a risk for hyperthermia, or hypothermia, respectively. That's especially true when accompanied by wet and muddy or dry and dusty conditions.
“In addition, crowded conditions increase chances for injury from trampling or butting by other cattle, as well as increased opportunities for pathogen exposure,” he says.
Physical hazards in the calving environment are another source of calf injury. These include protruding nails, broken posts, loose wire, holes, steep embankments, standing water, various sources of electricity, and toxins (such as from lead batteries or chemical containers discarded in or near calving facilities or on pastures), Smith says.
While cows are less susceptible to weather stresses than their calves, dystocia or metabolic disease increase their risk of hypothermia or hyperthermia. At the time surrounding calving, cows also may be more likely to slip and fall, a likelihood exacerbated by floor surfaces with steep slopes or slippery traction due to snow, ice or mud.
“In addition, cows calving near ditches and streams or other low spots are at risk to fall or not be able to rise after lying down,” Smith says. “As with calves, cows may be injured by a variety of physical hazards that may be present in the calving environment.”
The risk of injury to cow or calf can be minimized, however, by paying attention to environmental conditions. Long-term strategies include breeding so that calving occurs during favorable weather conditions, and planning for calving facilities with minimal physical hazards. Near-term strategies include a pre-calving survey of the facilities for potential sources of injury, as well as routine surveillance of the herd during the calving season.
Minimize disease risks
Diarrhea, commonly called scours, is one of the most likely causes of sickness and death in young calves. It's a complex disease — an interrelationship between agent, host and environmental factors (see “Up & Running,” page 30).
Even calves that are immunologically well-protected can be overcome by a sufficient level of exposure to a pathogen. That's why keeping the environment clean has long been recognized as important for controlling calf diarrhea, Smith says.
While adult cows are likely the source of scours pathogens from year to year, the average dose-load of pathogen exposure to calves tends to increase over a calving season. That's because calves infected earlier serve as pathogen-multipliers and become the primary source of exposure to younger, susceptible calves.
“This multiplier effect can result in high calf infectivity and widespread environmental contamination with pathogens,” Smith says. That's why “biocontainment” is important in controlling calf diarrhea.
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 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.”
SCS consists of a series of large contiguous pastures. Learn more about the SCS system at: http://vetext.unl.edu/publications.shtml?to=Beef. Here's how it works:
Cows are turned into the first calving pasture (Figure 1) 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 result, Smith says, is multiple pastures, each with calves within one week of age of each other. Cattle from different pastures can be commingled after the youngest calf is four weeks of age.
This age segregation prevents transfer of pathogens from older to younger calves. Meanwhile, moving pregnant cows to new calving pastures minimizes the pathogen load in the environment, as well as a newborn calf's contact time with those pathogens.
“Ranchers using the system have observed meaningful and sustained reductions in sickness and death due to calf scours, and greatly reduced use of medications,” Smith says. He adds that although SCS was tested and initially adopted in ranches typical of the Nebraska Sandhills, the principles on which it's based are widely applicable.
Smith says the SCS principles of limiting calf exposure to pathogens also apply to calving barns. “A good strategy is to be judicious in their use. Try not to use them when the weather is favorable for outside calving,” he says.
Dave Smith is a University of Nebraska-Lincoln (UNL) Extension veterinarian.