John Kirk
UC Davis
School of Vet Medicine
Statement of Problem: To determine the usefulness of fly ash to controlling bacterial growth in dairy cattle bedding. In California, cogeneration plants burn various combustible materials such as wood, trees, rice hulls, coal and sawdust to produce steam for the production of electricity. The materials are burned at 1800 F leaving only a powdery, gray ash which is commonly called fly ash. The oxide and carbon content and the pH of the fly ash varies from plant to plant depending on which materials are burned. Currently many dairymen are experimenting with fly ash in cattle bedding materials hoping to control the growth of mastitis causing bacteria.
Approach: Studies have been conducted at the Veterinary Medicine Teaching and Research Center (VMTRC) in Tulare and on nearby dairies. The primary focus has been on the use of fly ash mixed with various types of manure bedding. The aim was to determine if fly ash could significantly reduce the bacterial populations in the manure bedding. If such an effect could be documented, the use of fly ash might prove to be an aid in controlling environmental mastitis. We found that fly ash from different sources has varying pH. To be effective in reducing bacterial populations in bedding, the fly ash had to have sufficiently high pH to create an fly ash/bedding mixture with pH of >10. When the mixture of ash and bedding exceeded pH 10, bacterial growth in the bedding materials was reduced compared to bedding material alone. The effect lasted about 3-5 days under farm conditions. It should be noted that the use of fly ash is under investigation by the Toxic Substances Control Program of the State of California Department of Health Services due to the high pH of some ash.
Project Support: The project was privately funded by several co-generation companies and a trucking firm. Laboratory support was provided by the Milk Technology Laboratory (VMTRC) and Dr. Bill Sischo’s Laboratory.
Commodity Impact: Fly ash is being widely used on dairies in bedding and other housing areas. Our research suggests that fly ash may be beneficial in controlling the potential mastitis pathogens in dairy cattle bedding materials. The effect is not marked or long lasting. Users should determine the pH of the ash in order to use it properly. The use of fly ash will in no way reduce the need for good management practices such as daily grooming of bedding and routine replacement of bedding materials. The impact on the dairy industry of the Toxic Substance Control Program investigation is pending.
Kirk, Brazil, Sischo, Finger, Holmberg and Higginbotham