In their article "Control, Management, and Prevention of Bovine Respiratory Disease in Dairy Calves and Cows," in the March 2010 issue of The Veterinary Clinics of North America Food Animal Practice, authors Dr. Patrick Gorden and Dr. Paul Plummer review vaccine and management programs for young calves.

With respect to housing, these authors cite several factors that increase the risk of pneumonia in young calves: (a) sharing airspace with older calves, (b) relative humidity above 75%, (c) increased stocking density, (d) certain types and density of bedding and (e) power washing in the vicinity of calves.

These authors state "The individual calf hutch placed in an outdoor environment often provides the best environment for the prevention of respiratory and other diseases of calves." However, in an effort to improve worker comfort and reduce cold stress on animals, there has been an increase in the use of barns for calf housing. Dr. Gorden and Dr. Plummer cite several significant issues with these barns that contribute to high levels of respiratory disease: (a) less than 24 square feet of space per calf, (b) "Ventilation systems are often designed with minimal regard for or understanding of the microenvironments created by individual housing of calves" and (c) high ambient levels of bacteria (of any type) in the air.

Although deep bedding of straw is associated with higher levels of bacteria in the air, deep bedding is also associated with a reduced risk of pneumonia. Additional factors that reduce the incidence of pneumonia include solid dividers between calves and decreasing age of the calves in the barn.

Research at the University of Wisconsin has shown that there should be 15 cubic feet per minute of fresh air supplied for each calf in the barn. In barns with multiple rows of calves, the "positive pressure ventilation system" has been shown to be very effective in controlling pneumonia. (More information about these systems is available from the U. of W. and secondary sources.)

Following the housing guidelines established in DCHA's Gold Standards I, for calves from birth to 6 months of age, is a good first step to begin your efforts to reduce cases of pneumonia in your young calves. The Gold Standards recommend that housing be clean, dry, draft-free and have good air quality. There are also minimum resting space recommendations as well as feeding space size, based on age of the calf.

Another important long-term consideration for farms considering new calf housing is the availability of computerized feeding systems and the use of group housing. While these systems are not yet popular in the U.S., they are finding wide acceptance in other areas to reduce labor costs, address animal welfare concerns and, in some cases, reduce the frequency of pneumonia. The optimal group size is a topic of considerable debate and has been the topic of several published studies, but to date there is no consensus with regard to group size. Given that farrowing crates and hen cages are now being legislated out of existence here in the U.S., and the future acceptability of small individual calf pens is certainly in doubt, producers planning new calf housing should seriously consider alternatives that will pass legal and public opinion muster in the future.

Source: Roy Williams, Dairy Calf & Heifer Association Leadership Class member.