Calving Systems

By Grant Dewell, DVM, MS, PhD, Iowa State University

Calf diarrhea, also known as scours, is the second leading cause of death in cow-calf herds after reproductive losses (late abortions, still births, and dystocia). Scours prevention focuses on two key areas: the health of the calf and cleanliness of the environment. Optimal calf health is achieved through proper care of the cow prior to calving and ensuring adequate intake of colostrum at birth. The pathogens that cause neonatal diarrhea are transmitted by fecal oral contamination. One of the easiest routes of transmission is from contaminated mud/manure on the cow’s udder that is ingested by the calf when it nurses.

The calf scour pathogens are normally present at very low levels in the mature cows. However, as the calving season progresses, the number of pathogens increases exponentially as young calves become exposed, infected, and begin to shed large numbers of pathogens. This cycle is particularly evident when cows are calved in a single calving area. Generally, there are no problems with diarrhea early on, but pathogen numbers slowly rise and then explode to a major disease issue. Calves that are 7 to 14 days older than newborn calves can be a major source of pathogens. Although many operations may get by with calving in the same area all the time, eventually most will suffer a severe outbreak with up to 10% calf mortality. Rotational calving areas, such as the Sandhills Calving System, control calf diarrhea by limiting the buildup of pathogens in the environment where the most susceptible calves are.

Sandhills Calving System

Managing the flow of cows and calves through the calving season can play a major role in controlling diarrhea. Typically, calves born early in the calving season do not have calf scour problems. After several waves of calves have been born, pathogen levels reach an infective threshold and calf scours can become a major problem. Separating groups of calves by age will not only decrease pathogen loads in general but protect the most susceptible newborn calves from being exposed to pathogens shed by older calves.

A method to manage pathogen/disease exposure is to implement the Sandhills Calving System, which incorporates use of multiple calving areas on pasture. Cows are calved in a calving area, and after 7-10 days, the pregnant cows are moved to a new area to calve and the pairs are left behind in the area in which they calved. The next group of cows calves in a fresh, clean environment for 7-10 days and then moves on (Figure 1). This management system prevents older calves that may be shedding higher levels of pathogens than cows (even though they may not have clinical diarrhea) from exposing young, at-risk calves. The 7-10 day movement is foundational to the system as the most common pathogens for calves (rotavirus, coronavirus, and Cryptosporidium) typically affect calves that are 7-14 days of age, so the movement effectively breaks transmission to new calves.

Figure 1: Schematic of the Sandhills Calving System in the fifth week of the calving season. During Week 5 cows are calving in the 4th pasture and calves born in the previous pastures remain behind in age-related groups. From Smith et al. 2003.

Besides breaking the transmission of pathogens, the Sandhills system also has other advantages for the cow herd. Generally, it is less stressful on both cows and people to move pregnant cows to a new pasture than it is to sort off pairs. Leaving pairs in the same area where they were born will let calves develop social interactions with calves of similar age and feel safe in their surroundings. Exposing young calves to new environments and diverse herd interactions may add stress and exposure to other diseases. Additionally, it is easier for caregivers to observe and interact with these neo-natal calves in smaller groups.

Although the Sandhills system has been shown to be very effective at controlling calf scours, it may not be easy to implement in operations that do not have large land base to utilize. This system requires 6-8 calving areas to move to and may not be practical to implement in smaller farms or operations that lease ground and cannot justify expenditures for water supply, shelter, and other costs.

Modified Sandhills System

A modified Sandhills system can be implemented that can help prevent calf scours outbreaks. A modified system should have three calving areas available. Calving areas can include calving barns, drylots, and pastures. Movement of pregnant cows to the next calving area can either be timed or in response to disease. A set timed move should happen every 20-30 days. Although this does not protect every calf from exposure to disease, it often breaks the cycle enough that a scours problem can be managed instead of getting out of control. The other option is to use your primary calving area until calf diarrhea starts and then move your pregnant cows to a new calving area. With this management system, you may be able to calve some years in the same place all season without problems. If problems with scours arise, you have planned options for where you will move your cows to protect the calves that are yet to be born.

Dr. Grant Dewell received his DVM from Colorado State University in 1993 and was in a primarily beef cattle practice in central South Dakota for two years. Besides obtaining a Master’s degree in Agriculture Economics and a Ph.D. in Epidemiology from CSU, he was a clinical instructor at University of Nebraska’s Great Plains Veterinary Education Center in Clay Center, Nebraska. Since 2008, he has been the Beef Cattle Extension Veterinarian at Iowa State University. Dr. Dewell’s research interests are health management of cattle, animal welfare and economic considerations for beef production operations.

References

Dewell GA, Cooper VL. Control of Calf Diarrhea in Midwest Beef Cattle Farms. Iowa State University Extension and Outreach. PMR 1019, February 2016. https://store.extension.iastate.edu/product/Control-ofCalf-Diarrhea-Scours-in-Midwest-Beef-Cattle-Farms

Smith DR, Grotelueschen D, Knott T, Ensley S. Managing to Alleviate Calf Scours: The Sandhills Calving System. The Range Beef Cow Symposium XVIII. Mitchell, NE. December 9-11, 2003. https://digitalcommons.unl.edu/cgi/ viewcontent.cgi?referer=&httpsredir=1&article=1069&con text=rangebeefcowsymp