Earth surface feedlots and springtime in Iowa typically don’t go well together. When temperatures start to warm above freezing and ground begins to thaw, any additional moisture can create mud issues. Of course spring is not the only time mud can be an issue. Any time we have excess moisture from rain and snow, mud can become a problem.
Mud can affect cattle performance and well-being in three ways, all negative as far as performance is concerned. It can affect the insulation provided by the hair coat if the hair becomes matted. The loss of insulation will result in cattle being affected by cold stress and increased maintenance requirements at temperatures that are higher than if their hair coat was clean and dry. A matted hair coat is only about 20% as effective in providing insulation as a dry clean winter hair coat so matted might need increased energy at temperatures around 30 - 40 degrees instead of 10 - 20 degrees. Mud that affects the hair coat when temperatures are around freezing or below can increase maintenance requirement and decrease gain significantly.
Mud in a feedlot also can decrease feed intake. It would depend on the situation on how far cattle need to travel to access feed but the National Resource Council Nutrient Requirements of Beef Cattle publication estimates feed intakes could decrease by 5 - 15 % with 4 - 8 in of mud and up to 30% if mud was 15 in deep.
Finally, if mud is deep enough that cattle have to increase their effort to move or they can’t lay down to rest, that increased effort also would increase maintenance requirements. This could occur even at higher temperatures than the effect on hair coat insulation.
All of these effects are likely combined when reports of the impact of mud are reported. Several reports show impact of 10 -15% decreased gain and 10 -12% decreased feed efficiency with mud depths of 4 -10 inches.
With an earth lot and no way to control precipitation amounts, how do producers manage mud? More space in an earth feedlot can decrease mud. Allowing 250 versus 150 sq. ft. per head in an earth lot decreased mud depth about an inch in a University of Nebraska simulation. However, increasing to 350 sq. ft. per head did not change mud depth.
Making sure lots are clean and have good drainage is important. Preventing additional water from moving on to the lot can help, as can removing snow from the lot. In the same University of Nebraska simulation, mud depth was worse at 16 degrees versus 26 or 36 degrees because more of the moisture was snow and stayed in the lot. Bedding can decrease the effect of mud but it takes a quite a bit in wet muddy conditions.
Lots need to be cleaned when the surface manure has melted but the soil is still frozen. This is a critical time that often occurs after morning feeding and before noon. This scraping can be left to thaw in a part of the lot, and later spread or stockpiled in a good location outside of the lot. This needs to be a high priority because if spring rains melt more than an inch or so of the soil, equipment will tear up the feedlot.
Properly shaped mounds that are maintained and drain well can help cattle deal with mud also. Without enough slope and drainage, concrete and/or shelter are options to help prevent severe mud effects. But even cattle on concrete or with shelter can be impacted somewhat by mud or manure.