Dust can become an issue in feedlots under hot, dry conditions which encouraged Nebraska extension educator Larry Howard to round up some advice on ways to minimize the aggravation dust creates for the cattle, and the people looking after them.
Most often, he says, the worst time for dust is during the late afternoon and at dusk when temperatures drop and wind speeds decrease. This is when cattle that have been resting during the heat of the day start moving around, creating more dust that hangs in the cooler evening air.
This can be more than an annoyance since excessive dust can cause health and performance issues for the cattle and, at a minimum, inconvenience for your workers. In some cases, depending on the location of the feedlot, it can even create a traffic hazard.
So, what can be done? Here are Howard’s five suggestions to minimize the amount of dust in the air:
1. First, focus efforts on the feedlot pens and then service roads or alleys. In the pens, common strategies would be removal of excess manure, increasing the pen stock density, or application of water.
2. The most critical strategy is to avoid a buildup of organic matter. Regularly scrape the pens to remove manure and excess feed. That not only limits the amount of dust, but also helps reduce moisture building up on the surface in times of wet weather. The research recommendation is to shoot for one to two inches of well-compacted manure and soil on the surface of the pens.
3. Adjust your stock density. Howard says concentrating animals in the pen during hot weather has been demonstrated to successfully limit the amount of dust in the air because the added cattle distribute more moisture in the pen in the form of manure and urine. Of course, this assumes you have adequate bunk space for the additional animals. Higher numbers also raise the potential for greater disease transmission and lower gains. And, if the weather changes, mud could become an issue. So, while crowding is a strategy that minimizes dust, it does requires careful management.
4. Add water. Adding water by sprinkler or truck is the most common and effective method of dust control. It should begin well in advance of dust becoming a problem. When water is applied to the pens, Howard says you always have to strike that balance between dust control and mud. That point varies each time with the weather, the size of the animals and the depth of the manure. Based on research he says the goal is to maintain the surface manure at 25-35 per cent moisture to minimize the dust and the odours. The smell grows if the moisture rises much over that level. The water is usually added in the evening when the cattle are more active and the surface is at its driest point after the heat of the day.
Adding water may also increase the relative humidity in the pen and that could impair the animals’ ability to shed body heat they have gained throughout the day. Also, avoid overwatering vacant pens, fence lines and feeding areas as you are just improving the breeding ground for flies, and odours.
There are a few chemicals that show potential for dust control, but many been have shown to have little effectiveness in feedlots. Also, they are relatively expensive, require additional applications once the pens are cleaned, and may lessen the value of the manure.
5. Vegetative barriers such as windbreaks and shelterbelts are another effective means of mitigating dust. They also help capture some of the airborne particles and gases coming off the lot, as as well as serving as an aesthetic visual screen for the operation.
Controlling dust on service roads and alleys is best done by sprinkling water and using coarse rock or gravel for repairs instead of sand or smaller gravel.