Dairymen are increasingly becoming aware of the cow comfort, health and production benefits associated with compost-bedded pack barns. However, these potential benefits will not arise unless the pack is properly managed.
Elizabeth Eckelkamp, a University of Kentucky dairy science researcher, and dairyman Bill Crist of Lexington, Kentucky, who installed a bedded pack barn five years ago, share their top tips for managing this type of cow facility.
1. Stocking rate
Both Eckelkamp and Crist agree, the first limiting factor to a successful bedded pack barn is stocking rate.
“Dairymen must realize that just like pasture or the feedbunk, you can’t overstock the barn and expect it to perform,” Eckelkamp says. Each cow should have a minimum of 100 square feet of lying space. Higher stocking rates create excess moisture and make the pack more difficult and expensive to manage.
“Our stocking rate increased to just 75 square foot this year, and it’s definitely not ideal. We have to bed down much more often,” Crist says, whose cow numbers have increased since moving cows from a freestall to the bedded pack. “We have hardly any cull cows from hock or feet issues now, so our cow numbers are increasing every year.”
2. Bedding material
Sawdust and wood shavings are the most commonly used bedding materials in pack barns. Eckelkamp says these materials, though similar, can act differently, noting, “Sawdust offers good bulk density and is usually very dry. Shavings have larger particles, so they allow more air into the pack for composting.”
Most farmers use a mixture of both materials. “We use the driest, finest kiln-dried sawdust we can find,” Crist says. “The drier sawdust is best for keeping the pack dry in winter weather.”
Eckelkamp claims straw is unsuitable, as its waxy coating limits moisture absorption and composting.
3. Tilling
Tilling the pack twice daily is crucial for incorporating air into the bedding. Air promotes aerobic composting, which in turn promotes increased temperature. High pack temperature keeps the bedding surface at the correct moisture level through evaporative water loss.
“Tilling methods depend on what equipment is on the farm,” Eckelkamp says. “Most dairymen will use a rotavator to till the top 8 inches.” She also says it’s important to till down 12 inches at least weekly. Deep tilling mixes highly composted material into the top layers, which accelerates the rate of composting.
During the tilling process, steam and evaporation can often be seen rising from the pack. Eckelkamp claims there is little ammonia loss or smell in this evaporation.
“Because the process is aerobic, the ammonia is bound to the material. The ammonia smells associated with lagoons are caused by anaerobic fermentation, which does not bind ammonia,” she explains.
4. Measure
Measuring the temperature and moisture of bedding is necessary to make informed management decisions. At 4 inches deep, the compost process performs best at approximately 55 percent moisture and 80°F.
Electronic temperature and moisture meters are useful for farmers managing a bedded pack for the first time. After some experience, Eckelkamp says many farmers make decisions by eye and touch.
“At 55 percent moisture, the bedding should form a ball when squeezed in your hand. It should then fall apart when you bounce it on your hand,” Eckelkamp says. “Fifty-five percent moisture is sufficient for the bacteria to compost the material, while still being dry enough not to stick to the cow.”
However, at 60 percent moisture, bedding does not break apart when bounced. This indicates the bedding is too wet and needs fresh sawdust. If the bedding does not form a ball, it is below 55 percent moisture. This moisture level is slightly too dry for the bacteria to work efficiently but has no negative effect on cows.
Additional points
- Weather conditions will affect the management of the bedded pack. Humid, damp and cool weather will lower the internal temperature of the pack. This results in less evaporation, and more bedding is needed to maintain 55 percent moisture.
- Good ventilation helps to keep the bedded pack dry. Fans and curtain sides will increase the airflow through the barn.
- Feed and water should be available on a concrete alleyway. “High-traffic feed areas become too muddy and difficult to manage if they are compost-bedded. A 16-foot concrete feed alleyway is recommended,” Eckelkamp says.
- When cleaning out the barn, leave a 6-inch base layer of compost to speed up the composting cycle during the next housing period.
- Bedding supply can fluctuate throughout the year. It may be necessary to forward-purchase sawdust or shavings during the more plentiful summer months. PD
