How can dairy producers protect their animals, businesses, and the surrounding community? By following best management practices (BMPs) for manure management! Animal waste can contain both pathogens and chemical contaminants that can cause sickness and even death. Not all pathogens are created equal. Survival is dependent on temperature, manure processing, and environmental conditions. How you handle and process the manure on your farm matters! Every day the average dairy cow produces approximately 120 lbs. of wet manure making manure management a critical aspect of dairy farming.
Producers must decide how to use everything their animals generate in a way that improves the farm, protects the environment, and keeps the public safe. The application of manure to crops or pasture and the composting of manure to sell requires an understanding of the risks involved. Manure from livestock can be loaded with disease-causing pathogens, harboring the potential for illness in animals and humans. It is important to understand what pathogens may be found in manure and how BMPs can be used to reduce risk.
Pathogen transmission can occur through direct and indirect contact. Direct transmission occurs with animal-to-animal or animal-tohuman contact. Indirect transmission may occur through contaminated food or water.
Manure processing can drastically alter the pathogen load. Typically, farms store manure in lagoons or stacked piles. During dry stacking and composting it is critical to turn manure, ensuring all areas of the pile reach at least 145F° for several days, then leave undisturbed for at least a month to reduce or kill pathogens. Lagoon or slurry storage will reduce pathogen numbers from initial loading amounts, but still requires a storage for a period of one month before spreading on land. The FDA recommends a 120-day interval between application of raw manure for crops in contact with the soil and 90 days for crops not in contact with the soil. When applying manure to land, the type of equipment used and environmental conditions can play huge roles in transportation and movement of pathogens.
There are six common pathogens found in dairy manure that can cause sickness to both farm animals and humans. E. coli and Salmonella are frequently in the news due to foodborne illness in humans. Cattle are the primary reservoir for E. coli, with the greatest prevalence found in heifers and calves under 24 months of age. Calves recently weaned from milk have the highest incidence and shedding of infection. Up to 75% of dairies will test positive for Salmonella and over 50% of the cattle on the farm are shedding the pathogen. Listeria is another common dairy manure pathogen with great health implications to humans. Listeria is naturally found living on plants and soil, and can be found on poorly fermented silage. E. coli has a higher incidence of infection compared to Listeria in manure but lower incidence of death. While some pathogens have the ability to live in warm temperatures Listeria can live in colder temperatures and cattle actually shed more in their feces during colder winter months. Cryptosporidium parvum and Giardia lamblia are two more pathogens found in calves as young as 7-21 days old. Water contaminated by manure is usually the main contact route for “Crypto” and Giardia, however humans become infected primarily during the handling of young calves. Campylobacter jejuni is a gram-negative pathogen that can cause infertility and abortions in cattle and enteritis or septicemia in humans. Another concerning pathogen for dairy producers—one that only takes two thimbles full of manure to cause drastic problems—is Mycobacterium paratuberculosis which causes Johne’s disease.
Managing manure by utilizing BMPs protects both the environment and the public by reducing contamination risk. Some BMPs to help reduce incidence of contamination are: 1) installing vegetative filter strips to help control runoff and erosion; 2) controlling runoff and leaching from stockpiled manure open lots and even silage piles; 3) installing clean-water diversions like berms and ditches to divert runoff to proper collection areas; and 4) eliminating or reducing livestock access to waterways and ponds. Programs exist to assist financially with many of the BMP practices related to reducing the risk and potential point source contamination. For more information, contact your local extension office.
Virginia Cooperative Extension materials are available for public use, reprint, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.
February 28, 2017