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Age-Related Shifts in the Density and Distribution of Genetic Marker Water Quality Indicators in Cow and Calf Feces
Citation:
SHANKS, O. C., C. A. KELTY, L. PEED, M. SIVAGANESAN, T. Mooney, M. Jenkins, AND E. VILLEGAS. Age-Related Shifts in the Density and Distribution of Genetic Marker Water Quality Indicators in Cow and Calf Feces. Presented at American Society of Microbiology 111th General Meeting, New Orleans, LA, May 21 - 24, 2011.
Impact/Purpose:
To inform the public.
Description:
Recent studies have shown that different adult bovine animal feeding practices dramatically influence fecal indicator bacteria shedding, however very little is known about juvenile milk-fed calves. Calves (≤ 6 months of age) make up about 16% of the current bovine population in the United States and can excrete high levels of human pathogens. For example, more than 50% of cattle Cyrpotosporidium parvum shedders are neonatal calves. We describe the density and distribution of genetic markers from seven water quality PCR- and real-time quantitative PCR-based assays. Each assay was tested against a collection of 154 individual bovine fecal samples representing 22 mother and calf pairings collected over an eight month time period. Genetic markers reported to be associated with ruminant and/or bovine fecal pollution were completely absent in calves for up to approximately 120 days from birth suggesting that physiological changes in calf rumen function impact fecal source identifying genetic marker shedding. In addition, general fecal indicator markers for Bacteroidetes, E. coli, and enterococci exhibited three separate density and distribution trends across time indicating that these bacteria respond differently to age-related physiological changes in calf development. Results of this study suggest that currently available PCR-based water quality indicator technologies can under- or overestimate fecal pollution originating from juvenile milk-fed calves and identify a need for calf-associated source identification methods.