Deep Bedding – An Alternative to Sand
We always hear our bedding options in freestalls are either mattresses or sand. Common thinking is that mattresses will allow us to utilize a conventional manure system but will sacrifice cow comfort, whereas sand will give ultimate cow comfort but will create a challenge with manure handling. It would be nice to find a system that would give us the animal comfort benefits of sand and allow us to handle our manure in a conventional manner.
Some Minnesota producers are using various versions of deep bedding in freestalls to attempt to maximize cow comfort while minimizing manure-handling issues. We could describe deep bedding as five inches or more of bedding material in freestalls. Deep bedding freestall designs are essentially identical to sand freestalls; they have a cement curb next to the alley and have a five-inch or more sunken floor under the cow to hold the bedding. The type of bedding material used in deep-bedded freestalls may include chopped straw, corn stalks, grass, sawdust, composted manure, separated manure solids, or digested separated manure solids.
What type of bedding material is used most frequently in deep-bedded freestalls? It is my observation that separated digested solids from a methane digester or separated undigested solids seem to have the highest utilization rate. In order to utilize bedding from one of these sources, a farm must either possess the technology to produce the separated solids or needs to purchase it from a farm that does. Digested or undigested separated solids usually work well through a liquid manure system. Another option is utilizing the compost out of a compost-bedded pack barn as a base and then frequently adding fine bedding like sawdust to this base. This provides a bedding pack with a consistency similar to separated solids.
Separated solids or compost bedding moisture can have moisture percent into the sixties; therefore, somatic cell count (SCC) control is always a question. SCC has been a challenge on some farms, but continued vigilance on the part of farm managers has usually found a workable management solution. Many of these farms using separated solids or compost bedding are able to maintain a SCC close to or less than 200,000. One advantage of higher moisture bedding is that the bedding will tend to stay in the stall better than dry bedding. Most producers with the high moisture bedding systems cultivate the back two feet of the stall during each milking while others have found a system of just grooming the stalls that works for them. All freestall systems require cleaning of manure patties and thorough grooming during each milking.
Other bedding options are dry sawdust, chopped straw, chopped corn stalks, or chopped grass. Part of the challenge of using the chopped bedding is getting it fine enough for manure systems with combinations of gravity flow and manure pumps. The typical three- to six-inch length chopped bedding can be a problem if used in higher volumes required by deep bedding; the bedding usually needs to be cut to a one-quarter inch length to work properly. Chopping the bedding this fine usually requires a field chopper or tub grinder, and a storage building similar to that used for storing sawdust will be needed. Since this bedding is dry and fluffy, cows kick it onto the cross-alley easier than the wetter bedding described previously, thus the potential of a higher bedding usage rate.
So how do these systems compare to sand? We can only compare different systems on different farms and some before and after situations since I am unaware of any one barn utilizing all these options to enable side-by-side comparisons. The systems utilizing sawdust or chopped dry bedding have a higher bedding cost than sand. While the bedding cost of systems utilizing one's own separated solids would be minimal, there needs to be a cost recovery of the separator investment. One farm that converted from mattresses to deep bedding observed an almost immediate six-pound milk increase per cow per day. The farmers with deep bedding report fewer hock lesions and swollen hocks as compared to their present or previous stalls utilizing mattresses. Farmers utilizing deep-bedding freestalls feel that cow comfort is equal to sand. The walkways are not gritty like those with sand-bedded freestalls as the sand almost eliminates cow slipping. Many of the walkways in the barns utilizing deep bedding seem to be somewhat drier than other barns. Some farms needed to add a system of injecting flush water or recirculated pit liquid in the barn to enable better manure flow to the pit.
In conclusion, deep-bedded freestalls seem to be a feasible option for producers who are unable to or do not wish to use sand. Whatever the bedding choice, providing optimum cow comfort is king on the dairy farm.