RED DEER, Alta. – Every time there is a boil-water order in the Lethbridge, Alta., region, the intensive livestock industry is blamed for water pollution.
“No scientific studies have been done to prove or disprove this hypothesis,” said an Agriculture Canada scientist.
Jim Miller is part of a team investigating the effects on water runoff from feedlots. The study received grant money from a beef industry development fund.
According to an Alberta government study circulated last year, agriculture practices contribute to the degradation of water quality.
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Miller’s study is looking for the presence of giardia, often called beaver fever, and cryptosporidium. These are one-celled protozoa that can lead to serious illness in humans. They are also looking for pathogenic bacteria like E. coli strains, salmonella and campylobacter in feedlot water.
Their study site is at the Lethbridge Research Station feedlot, which usually has about 500 head.
They sample fresh and aged manure in the feedyard and, once it is applied to the land, they check for seasonal fluctuations in bacteria content. In addition they are monitoring soil and surface runoff for minerals including phosphorus.
Bedding material is under the study’s microscope.
Many feedlots use wood chips because these keep the cattle cleaner so the tag ratio is lower. Tag is the dirt and manure caught on the hide. It is connected to E. coli shedding, which could contaminate the meat in the packing plant.
Scientists are wondering about wood chips because wood contains some natural antibacterial inhibitors. However, they found the ratio is so low it has no effect.
They also measured bacteria count on wet and dry days.
“The bacteria content is directly related to the moisture content,” Miller said.
“On wet days, you can have extremely high concentrations of E. coli in the manure pack. It’s a good practice to try and keep the pen as clean and dry as possible,” he said.
They have divided the feedlot into several zones for sample taking.
At the centre is usually a mound made of dirt, manure and straw built up for the cattle to lay on and keep dry. Farther away is a thick layer of manure all the way to the pen floor, which is bare dirt.
The bacteria count is higher on the bedding pack compared to the pen floor. The packs develop a firm crust but beneath the surface the bacteria remain alive.
So far, study samples show coliforms and E. coli bacteria levels are generally above the guidelines for human drinking water.
Nitrate measures are low but ammonia is up and phosphorus levels are above acceptable guidelines.
Runoff water from the entire feedlot, as well as drainage alleys has been sampled.
Leaching of contaminants into the soil in the pens is almost zero because the area is so compacted that nothing seeps through. Drainage water in the alleys is higher in bacteria and should be kept compacted to prevent pathogens from flushing into nearby soil.
Within the yard, hoofprint depressions are collection holes for bacteria, so pens should be kept smooth.
Runoff travels into catch basins, and the water in catch basins has a high concentration of bacteria that is above drinking water guidelines.
Although no one would drink from the lagoon, there could be trouble if the water leached into the surrounding soil or overflowed during a flood.
Irrigating crops with this water should not be done just before harvest. More time is needed so sunlight can kill any bacteria present.
One way to get rid of bacteria is to compost manure if it is economical.
Miller’s team looked at composting to see if that process killed pathogens. A compost reaches 60-70 degrees and will kill bacteria and giardia but cryptosporidium may survive. It also kills off the weed seeds.
