Objective—To determine the impact of feedyards on
endotoxin concentration, fecal coliform count, and
other water quality measurements during winter and
summer in feedyard playas (shallow lakes).
Sample Population—Water samples obtained from
7 feedyard playas and 3 nonfeedyard control playas.
Procedure—Surface water samples were collected
from each playa and at various depths from 3 feedyard
playas. Endotoxin concentrations, 22 water quality
variables, and fecal coliform counts were determined
in samples collected in summer and winter
from various combinations of playas.
Results—Cattle numbers per feedyard ranged from
40,000 to 175,000 head/y. Mean endotoxin concentrations
were significantly lower in control playas than
in feedyard playas in winter and summer. Endotoxin
concentration appeared to be homogenous at various
water depths. Values for 20 of 22 water quality variables
were higher in the feedyard playas than in control
playas in winter and summer. In winter only, mean
total fecal coliform concentration in feedyard playas
was significantly greater than in control playas.
Conclusions and Clinical Relevance—Results indicated
that feedyards have the potential to impact
water quality in playas, and cattle should not be
allowed access to them. Feedyard playa water should
not be used under high pressure to settle dust in pens
with cattle or to cool cattle, because aerosols containing
pathogens and high concentrations of endotoxin
are a health hazard for humans and cattle. (Am J
Vet Res 2001;62:1402–1407)