Filter Area or Barnyard Roof?
A dairy operator has a paved, curbed barnyard. He needs to reduce barnyard runoff. He has
narrowed his choices down to three. He can:
--Install a Filter Area system to collect and treat the runoff, or
--Build a conventional roof over the barnyard to keep it dry, or
--Build a fabric roof over the barnyard to keep it dry.
The following write-up compares the costs and returns of each choice. The analysis does not
include any government cost-sharing.
Barnyard Roof The roof system would cost some $51,000 and last thirty years. Its residual
value is assumed to equal its cost of removal. O&M is estimated at $200 annually. The dairy
operator believes that a roof would provide a more pleasant environment that would pay off in the
form of higher milk production and better herd health. He does not feel comfortable trying to
quantify these benefits at this time.
Barnyard Fabric Roof This alternative uses a fabric roof rather than a conventional roof. Initial
costs are lower ($37,800) but the fabric roof must be replaced within the period of analysis. The
roof's residual value is assumed to equal its cost of removal. O&M is estimated at $200 annually.
This roof is translucent and quieter than a conventional roof. The owner thinks this roof would
probably provide a better environment for his herd, but he questions the durability of the structure.
Filter Area Installation of the vegetated filter area and related tanks and plumbing will cost
some $5000. Its residual value is assumed to equal its cost of removal. Annual O&M is expected
to run about $300. The pump used in the system will need to be replaced five times during the
period of analysis (every five years) at a cost of $800 each.
Barnyard Barnyard Filter Area
Roof Fabric Roof
Total Annualized Cost Of Installation $4,500 $3,400 $400
Annualized Cost of Replacements -0- 1,200 100
Annual O&M 200 200 300
Total Annual Costs $4,700 $4,800 $800
Decision The dairy operator recognizes the need to clean up the runoff from his barnyard. He
sees that the Filter Area is the low-cost approach to getting that job done.
Installing either roof would cost him about $4,000 annually ($4,700 or $4,800 less $800).
Ultimately the dairy operator must decide whether the roof would pay for itself. To do that, the
roof would have to improve his bottom line by the extra money ($4,000 annually) the roof would
cost. That improvement in the bottom line could come about through any combination of
increased milk production, higher quality milk, or reduced veterinary/medical expenses.
Possible Increases in Milk Production As shown in the attached Partial Budget "A," the dairy
operator currently nets $18,198 (Return to Equity, Management & Operator Labor). Partial
Budget "B" shows the operator's net would increase to $23,542 if milk production could be
stepped up 2% and only those costs associated with milk output increased.
The increase in the operator's net (Return to Equity, Management & Operator Labor) is $5,344
($23,542-$18,198). That $5,344 is greater than the extra annual expense associated with either
roof and the costs associated with increased milk production. So if milk production could be
stepped up 2% by installing the roof, with increases only in those costs associated with milk
output and the roof, the roof would pay off.
Milk Quality & Herd Health There is a possibility that a drier barnyard would reduce somatic
cell count and subclinical/clinical mastitis. That would increase milk quality and reduce
veterinary/medical expenses as well as increasing milk production. Those potential benefits have
not been included in the analysis.
Conventional Roof or Fabric Roof? The annualized costs of these two alternatives is so close
that the decision between the two would largely boil down to a question of taste--whatever the
dairy operator preferred. If there was a reasonable likelihood that the roof might one day be
moved, then the relative portability of the fabric roof might tip the decision in its direction. If the
dairy operator felt the durability claims of the fabric roof were overstated he might decide to go
with the conventional roof. In cases like this it can be helpful to use a variation of Ben Franklin's
Balance Sheet Decision Technique. Set down in writing only the advantages each roof has.
Conventional Roof Fabric Roof
Risk Less Risk/Risks Understood
Lighting Better Natural Lighting
Noise Reduced Noise
In this case, a dairy operator who selects a conventional roof would do so because they felt
improved lighting and reduced noise were not sufficient to overcome the uncertainty they felt in
trying out the relatively-new fabric roof technology.
Other Possibilities: Smaller Roof Roof costs could be reduced if the dairy operator could
make do with a smaller roof and a smaller barnyard. This might be the case if the herd could be
managed in a barnyard that did not accommodate the entire herd at the same time. Failing to
cover the entire barnyard would not address the water runoff problem however.
Why Use a Virginia Co-op Extension Budget? Virginia Co-op Extension/Virginia Tech has
their budgets available online (http://www.ext.vt.edu/index.html) in a Microsoft Excel spreadsheet
format that can be easily downloaded and modified. We're free to take their spreadsheet and
input figures that fit our own situation better.
What Are the Patronage Dividends Shown in the Budget? Reimbursements from a co-op.
Try not to get too tangled up in the budgets themselves. Normally we're more interested in the
difference between two alternatives rather than determining the dollar amounts absolutely. The
dairy operator has to pick between three alternatives in this case. The difference between the
three is what is important.
The Somatic Cell Count and Milk Quality
This NebGuide describes what somatic cells are, and their significance related to mastitis
and milk quality.
Duane N. Rice, Extension Veterinarian
Gerald R. Bodman, Extension Agricultural Engineer--Livestock Systems
"SCC levels usually are lowest in a clean, dry, comfortable environment. Weather and
management factors play an important part relative to the control of mastitis. Mastitis control
principles must be maintained at all times. The increased incidence of clinical mastitis
(udder infection that shows visible signs) in the summer months is generally due to a warm
moist environment that increases pathogen exposure and numbers. The animal stress of high
temperatures and excess humidity also may increase susceptibility to new infection and thus,