HERE COMES ANOTHER DAIRY REVOLUTION

Page 1, 2

How many dairy revolutions have we gone through? We thought that the large herd, naturally ventilated barns with side wall curtains would be a long term housing change. Now it appears that a new style dairy barn is poised to revolutionize the industry again.

The new style barns feature a system that includes economical cow cooling in the summer and economical warm barn conditions in the winter. These new style barns cost $500 per cow less to build than current naturally ventilated barns with side wall curtains. It is easy to understand why dairymen are excited about these advantages.

The new barns are called low profile cross ventilated barns (LPCV). They have large evaporating pads for cooling the air on one side of the barn. They have many fans on the other side of the barn. Outside air is pulled through the evaporating pads, all the way across the barn and then exits the barn by fans on the other side wall. The roof line is very low with a roof slope of only 0.5 inches in 12 inches. LPCV barns always include a layer of insulation in the roof. The barn features baffles over each double row of cows. Baffles are thin walled structures suspended from the roof rafters. They come down to 6 feet above stall beds. This forces air movement down to the level of the resting cow. You need to see these baffles in person to understand their function.

Research results in LPCV barns reveal nearly one complete air exchange in the barn every minute. Air velocity at the highest fan rate was 6.67 miles per hour at the level of each baffle. Ammonia levels were approximately 4 times less than in naturally ventilated barns. Researchers state that LPCV bars have the best air quality and cow comfort they have ever seen.

The electrical costs to run the fans have been reported as $26.25 per cow in naturally ventilated barns, $21.26 for 8-row LPCV barns and $10.65 for 16-row LPCV barns. If the outside air is 90 degrees, it drops to 75 degrees after passing through the evaporating pads. This varies with humidity levels. In some cases, dairymen may use soaker water lines located over lock-up stanchions to help cool cow.

The bottom line is LPCV barns keep cows cool in the summer and warm in the winter. Air quality and cow comfort is excellent. Employee working conditions are excellent. Most of these new LPCV barns use sand bedding and sand settling lanes.

Summary of advantages of LPCV barns.

1.	Air can be baffled down to the cow level.
2.	All cows are under one roof and closer to the milking parlor.
3.	The cost of construction is less than naturally ventilated bars.
4.	Lower electrical costs for cooling cows.
5.	Fans are easier to service because they are located at ground level.
6.	Site selection is easier because the building site uses less land.
7.	Control of flies and birds are easier because barn doors are closed except for entrance of feed wagons.
8.	Air quality is better.
9.	They are cool in the summer and warmer in the winter.
10.	Employee comfort is better in the summer and winter.

Summary of disadvantages of LPCV barns.

1.	They are 100 percent mechanically ventilated so dairymen need a backup electrical generator.
2.	Snow load on the roof may be a problem
3.	Engineers must do everything 100 % correct regarding requirement for snow load and mechanical ventilation.

Page 1, 2

News Letter from Dr. Whitmore, October No.1-1 2007

LAVA-net HomePage