|Straus, David - TEXAS TECH UNIV|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2009
Publication Date: April 1, 2010
Citation: Purdy, C.W., Clark, R.N., Straus, D.C. 2010. Determination of water quality variables, endotoxin concentration, and enterobacteriaceae concentration and identification in Southern High Plains dairy lagoons. Journal of Dairy Science. 93:1511-1522. Interpretive Summary: Concentrated animal feeding operations (CAFOs) have retention ponds which may contain many different pollutants such as pathogens, hormones, and toxins which may contaminate the surrounding environmental water and air. Federal and State regulations concerning CAFOs are being promulgated under pressure from the public and public health officials; however, there are few peer-reviewed articles published on the types of pollutants and their concentrations contained in CAFOs. We identified and determined the concentrations of pathogens (bacteria, yeast, and fungi), concentrations of endotoxin (a biological reactive substance), and determined the concentration of 20 chemical variables in 4 large dairies lagoons located on the Southern High Plains (SHP). We determined that endotoxin levels were significantly (P < 0.05) higher (9,679 ng/ml) in the winter than in the summer (3,220 ng/ml). We isolated 201 Salmonella spp pathogens, but Escherichia coli O157:H7 pathogens were not recovered. Over 10,000 opportunistic pathogens/ml were isolated from the lagoon water. Eighteen genera of soil fungi (cultured at 28º C) were identified, and several genera of these produce mycotoxins. Seven genera of thermophilic (cultured at 50° C) fungi and 7 genera of yeast were identified. We have minimal concern for ground water contamination. Following irrigation of forage crops with lagoon water, the curing process should not be rushed in order to ensure pathogen desiccation. Sufficient pathogens and endotoxin exists in dairy lagoon wastewater that care should be taken in water usage to avoid zoonotic infections in animals and humans and to avoid endotoxin and pathogen contamination of the air.
Technical Abstract: The objectives of this study were to determine the concentration of endotoxin, determine 20 water quality variables, and identify and enumerate fungal and bacterial pathogens from United States southern High Plains dairy lagoons and control lakes during summer and winter. Water samples were collected in triplicate from the north, south, east, and west quadrants of each body of water. The mean (+/- SEM) winter dairy lagoon endotoxin concentration was significantly higher (9,678 +/- 1,834 ng/mL) than the summer concentration (3,220 +/- 810 ng/mL). The mean endotoxin concentration of the 2 control lakes (summer: 58.1 +/- 8.8 ng/mL; winter: 38.6 +/- 4.2 ng/mL) was significantly less than that of the dairy lagoons. Two hundred-one Salmonella entericaspp. isolates were identified, 7 serovars were recovered from the dairy lagoons, and 259 Salmonella ssp. were identified from 5 other dairy locations (milk barn, ditch effluent, settling basin, feed alley pad flush, and center pivots). Twenty-eight Salmonella spp. were identified from center pivot water. Escherichia coli O157:H7 pathogens were isolated from other dairy locations but not from lagoons. Neither Salmonella spp. nor E. coliO157:H7 were identified from control lakes. Enterobacteriaceae opportunistic pathogens were isolated from both dairies and control lakes. Important mesophilic and thermophilic catabolic (to manure biosolids) fungal isolates were identified from dairy effluent locations, but no thermophilic fungal isolates were cultured from the control lakes. Adequate curing of green forage following center pivot irrigation is important to kill lagoon water enteric pathogens, even though the lagoon water is mixed with fresh water. Recirculating lagoon water to flush the feed alley pad where cows stand while eating, to remove manure and using lagoon water to abate dairy dust in loafing pens and unimproved dairy roads is inconsistent with good environmental practice management.