Composting Bedded Pack Barns - Q & A
Published in Dairy Star August 27, 2005
For the past couple of years the composting bedded pack barn has been the talk of the dairy industry in the Upper Midwest . Cow comfort has always been a major issue on most dairy farms and this new kind of barn seems to address this major concern. In fact, it almost seems too good to be true. Dairy producers who have constructed these barns report that cows have responded almost immediately with higher milk production and lower somatic cell counts. They are telling us again and again that these barns really work.
Just a quick review of the compost bedded pack barn concept. It is basically a loose housing type of facility bedded with fine, dry sawdust. The cows rest on the bedded pack between milkings when not at the feed manger. While the cows are being milked, the bedded pack is stirred to incorporate the urine and manure that has accumulated between milkings. Stirring is accomplished by using a skid steer loader equipped with some sort of incorporating tool like a section from an old field cultivator. Manure handling on a daily basis takes very little time, only about ten minutes to stir the pack and just another few minutes to scrape the feed alley where the cows stand when they eat, for a total of less than half an hour per day.
So, is there a downside to this type of facility? It seems too good to be true. The following are some answers to common questions about this new concept in dairy housing.
- What about sawdust supply? This is the biggest concern right now. If hundreds of barns around the Upper Midwest are constructed, will there be enough sawdust to go around? The answer, I think, is yes. If there is demand for a product, someone will fill that niche. I hosted a group of dairy producers from the northwestern part of the state last summer. After touring some of the area barns, I asked them that very question. Their response was very positive. They mentioned that until now tons and tons of sawdust ended up in landfills. They felt there was a huge supply available with more that could be tapped if there was enough demand. There is some competition from greenhouses and other facilities. But there seems to be more than enough to fill any future dairy demand. Just to note, the University of Minnesota is conducting research to determine alternative bedding materials that would work in these barns.
At present, dairy producers with this type of housing system are spending 35 to 50 cents per head per day. If milking 100 cows, this would amount to $35 to $50 per day just for sawdust. However, this cost will be more than offset with increased milk production and with more longevity for some cows. If the herd average goes up 10 pounds per cow and the milk price is $14 per hundredweight, this 100-cow herd would be adding another $140 per day which would more than offset the cost of the sawdust. In free-stall barn systems, many producers are already spending close to that amount for bedding. So, take into consideration all factors when making a decision on whether or not a composted bedded pack barn is for you.
- How will the manure from these barns affect soil fertility? The dairy producers who have used manure from composted bedded pack barns report no crop effects from the manure. However, Kevin Blanchet , Regional Extension Educator for Crops at Farmington, and I conducted some research tests of the manure coming out of these barns to determine what was happening to the nitrogen. The most significant piece of information was the carbon/nitrogen ratio. Straight sawdust has a C/N ratio of around 400 to 1. This means that breakdown of sawdust will tie up nitrogen in the soil. Our research showed that the manure from these barns had a C/N ratio of 12-20 to 1. This is the same as well rotted manure. The conclusion from the study is that the nutrients from the manure are ready to be utilized by the growing crop without any tie up in the soil.
- How do the cows avoid stepping on each other? Cows are smarter than we give them credit for. Very few injuries have occurred based on reports I have received.
- What about odor and ventilation needs? Excellent ventilation is a must as it is in all dairy facilities. Another remarkable side benefit of these barns is very little odor is noticed and very few flies. The sawdust serves as a powerful sink for the nitrogen, a large source of odor. The twice a day stirring seems to disturb the flies enough to deter a good egg hatch.
Adding up all the benefits contained in the answers to these questions along with increased milk production, lower somatic cell counts, and a good environment in which to work, it is easy to understand the enthusiasm for the composting bedded pack barn type of dairy housing that is taking place across the state.