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Given the current economic environment in the dairy industry, interest in strategies that will lower expenses is high.
In areas where freestalls are typically bedded with organic bedding, there is increased interest in using manure solids in one form or another to replace more expensive shavings, straw and other types of organic bedding.
Even in areas where cost has not historically been as big a consideration, there is a trend to less availability of shavings due to a combination of reduced production as well as increased recycling of woods-based byproducts for energy generation.
The use of manure solids for bedding has been common in climates where solids can be dried at least during the drier seasons and then stockpiled for use during the rest of the year. In areas where the climate tends to be wetter and solids cannot be consistently dried, concern that solids contribute to poorer udder health has limited their use.
Recently, several studies were done to determine which management strategies lead to success. Some studies used effluent from methane digester units that was subsequently separated; others used separated fresh manure. Researchers examined various combinations of use, from fresh off the separator to postseparation composting strategies.
While it's always important to be cautious when translating research-based observations into conclusions across broader use, there are some things that I think stand out as being consistent across these studies and probably point to "takeaways” that are applicable more widely.
that was fairly consistent is that manure solids seem to improve cow comfort. This was particularly true where mattresses are used.
The reason could be that there is a tendency to put more bedding on top of mattresses when using manure solids as compared to more expensive materials such as shavings. When solids are used as deep bedding in stalls, there was also a trend toward higher cow comfort.
Experience says cow comfort can be highly dependent on management strategy. Fresh manure solids will pack if they are not actively worked in the stalls. This tendency seems to be less a problem with digested solids.
In either case, frequent active harrowing or tilling to a depth of 4" to 6" not only keeps the bedding surface from getting hard, it also promotes drying of material after it's put in the stalls. In addition, frequent tilling promotes bedding turnover, which is important in controlling bacteria numbers in the stalls.
The frequency with which stalls are refilled is also key. Experience indicates that filling more often, while promoting active turnover of stall bedding, is the preferred method. Swings in milk production and dry matter intake are common when rebedding occurs infrequently.
The perception that manure solids contribute to higher bacteria, mastitis and SCC levels does not appear to be merited, according to the studies. Composting or digesting manure solids tends to lower the existing levels of microorganisms when compared to using fresh uncomposted solids. However, bacteria counts increased significantly by 24 to 48 hours after addition to freestalls.
This is also true for other organic-type beddings, as well as sand. By 48 hours, all bedding types tend to support relatively higher bacteria levels. This just highlights that parlor practices, particularly premilking preparation, is critical in controlling the link between bacteria levels in the cows' environment and incidence of mastitis.
There are an increasing number of dairies that are using separated manure solids in one form or another and seem to be able to maintain consistently low SCC and clinical mastitis levels. In addition, many report that cow comfort has improved with their use. It may be time to give this serious consideration in your operation.
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