Submitted to: Texas Journal of Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2001
Publication Date: N/A
Interpretive Summary: Large feedyards are becoming more highly regulated by State and Federal governments regarding their suspected contribution to contamination of the air, soil, and water than in the past. Yet there is practically nothing published on feedyard microbial contamination, concentration, and duration of viability in playa lakes. Studies were conducted to determine how long common bovine pathogens (10 bacteria, 4 virus and 1 parasite) might surviv and how rapidly they decrease in a High Plains feedyard playa. All pathogens tested, decreased viability (85 to 99%) very rapidly (1 to 56 days) when they came in contact with the playa water through a membrane dialysis tube. Pathogens in screw-cap plastic tubes having no contact with external playa water, also decreased in viability (55 to 99%) but more slowly (1 to 295 days) than those in dialysis tubes. The microorganisms decreased in viability more rapidly in the hot summer than in the winter. The Pasteurella isolates died out within 7 to 35 days. Fungi were more resistant to dying than the bacteria or viruses. The parasite (Cryptosporidium parvum) survived the winter but died during the hot weather of the summer. Many pathogens could enter a feedyard playa but most died rapidly and only low concentration of pathogens existed in the water for a year. Never the less, feedyard owners should be cautious in how they use their playa water resource. Pathogens in feedyard playas appear to present little danger to the environment.
Technical Abstract: Sixteen microbes and one enteric parasite were secured in screw-cap vials (CV) and dialysis tubes (DT) and placed in a feedyard shallow lake (playa). They were removed weekly or monthly depending on their susceptibility to the water. There were two overlapping studies; one started in September 1996 and was terminated 390 days later. The second study started in May 1997 and was terminated 188 days later. These studies were used to determine the decrease in titers of 10 bacteria (Pasteurella haemolytica A1, Pasteurella multocida A:3, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Actinomyces pyogenes, Salmonella enterica serovar dublin, Bacillus thuringiensis, Klebsiella pneumoniae, and Pseudomonas aureoginosa); 2 fungi (Aspergillus fumigatus, and Aspergillus niger); 4 viruses (Infectious Bovine Rhinotracheaitis (IBR), Bovine Virus Diarrhea Virus (BVD), Bovine Respiratory Syncytial Virus (BRSV), Bovine Parvovirus (BPV), and one protozoal parasite (Cryptosporidium parvum), over time. The Pasteurella isolates died within 7 to 35 days. Actinomyces pyogenes died within 84 days in the 1996 study and survived for 188 days in the 1997 study. The remaining bacterial isolates in 1996 survived for 390 days with low titers, except for P. aureoginosa (titer of 2.35x10**6). Both fungal isolates died by 390 days in the 1996 study. All bacteria and fungi survived the 188 day study in 1997, except for the Pasteurella isolates. The four viral titers decreased rapidly over 42 days, except for the BPV in the 1996 study, and all viruses were inactivated by day 42 in the 1997 study. Cryptosporidium parvum survived the 1996 winter but lost its ability to infect infant mice during the month of May 1997. Microbial survival decreased more rapidly in DT samples compared to CV samples.