You can cut dairy odor emissions by using sand or pine shavings rather than other bedding products, according to a new report in the Journal of Dairy Science.
Alvaro Garcia, SDSU extension dairy specialist, explains the findings:
When equal volumes of urine were applied to equal depths of dry bedding, ammonia emissions were less from sand and pine shavings than from chopped newspaper, chopped corn stalks, and recycled manure solids. Emissions from chopped wheat straw only differed from those of sand.
The physical characteristics of the bedding materials were more important than their chemical composition in decreasing emissions. Ammonia emissions increased with the absorptive capacity of the bedding, and decreased as the density of the packed bedding increased.
For a given depth of bedding, the loose, open structure of chopped straw, chopped corn stalks, and chopped newspaper resulted in less urine being absorbed. As a result, there is a greater surface area coated with urine from which ammonia emissions can occur.
Sand had the highest bulk density, followed by pine shavings and recycled manure solids. Sand has the advantage that the urine penetrates readily to the bottom layer. Consequently, ammonia emissions are reduced because of the increased resistance of the gas to move from the bottom layer to the bedding surface.
Recycled manure solids had the greatest absorbance capacity compared with other bedding materials. As a result, most of the urine was retained in the upper layer potentially resulting in greater emission.
Which bedding material to use will depend on factors, such as availability, handling capability, cow comfort, hygiene and manure management system , Garcia says.
Recent research suggests that cow preference for different bedding types depends on the animalâ€™s previous experience. Cows previously bedded with straw will prefer it when given a choice of straw or sand, and those previously on sand would prefer sand.
In terms of hygiene, no significant effects on cleanliness or health of stock were noted among sawdust, newspaper, straw or shavings, although it has been reported that bacterial counts increased in organic materials when compared with inorganic bedding materials (sand or limestone).
"Choosing the right bedding type will depend on what we wish to accomplish," Garcia says. "If the concern is keeping the cattle drier, then a more absorbent material might be the right alternative. On the other hand, if lowering ammonia emission is the goal, it is important to avoid saturating bedding with urine, as emissions will be high."