Using Leftover Forage Resources

Depending on where you live in Wyoming, rangeland grass production this year has been anywhere from slightly below normal to almost non-existent due to the dry spring and early summer we experienced. However, there may still be some forage for livestock on rangelands of the state due to the high amount of spring precipitation received in 2011.
    Rangeland grass production was greater than the norm in many locations last year, and as a result, more grass was left following grazing than usual, especially in pastures where good grazing management has been practiced. In addition, because of the mild winter with little snowfall, most standing dead grass was not knocked down, so it is available as a forage source for livestock, especially in pastures that have received little to no grazing at this point.
    Taking advantage of this forage resource may allow ranchers to avoid selling as many animals and/or purchasing more hay than usual. However, this carryover grass is basically winter grass, and although energy content won’t be too bad, its crude protein content will be low.
    If you graze your livestock on the range over the winter and early spring you know that the animals need a protein supplement to maintain body condition. The amount of protein that needs to be supplemented will depend upon the quality of the range forage, the needs of the livestock and how much protein the supplement contains.   
    Dormant winter range grass generally contains four percent or less crude protein and around 50 percent Total Digestible Nutrients (TDN). A 1,200 to 1,400 pound beef cow in late lactation requires at least seven to eight percent crude protein and 52 percent TDN. However, if she is dry but in mid-gestation her crude protein and TDN needs drop to as low as six percent and 45 percent, respectively.
    A 150 to 160 pound sheep ewe in late lactation needs nine to 10 percent crude protein and just over 53 percent TDN. If she is not lactating her crude protein needs decline to 7.2 percent, but her TDN needs remain about the same.
    Based on these amounts it is apparent that weaning the offspring when forage quality is low would be advisable, as fewer supplements would need to be provided. In addition, a dry beef cow requires up to 20 percent less forage then when she is nursing and a sheep ewe 30 to 50 percent less, depending on whether the ewe is nursing a single lamb or twins.
    Aside from providing the livestock a protein supplement for making up the shortfall in the range forage it also helps meet their energy needs. Remember the adage, “Feed the rumen bugs to feed the animal.” If the degradable portion of crude protein in the forage is low in relation to the amount of energy the forage contains, not all of the energy will become available to the animal. This can result in the cow or ewe not being able to consume enough forage to maintain proper rumen function. The provision of a protein supplement, especially one that is highly degradable, will furnish the rumen bugs enough protein to meet their needs resulting in them being able to more completely degrade the fiber in the forage, releasing its energy to the animal. Digestion of low quality forage will also be faster, resulting in it passing through the rumen more quickly maintaining rumen function.
    If your rangeland pastures have a significant amount of carryover grass from last year and water for the livestock is not an issue, then this is a resource that could help get you through the remainder of this year’s grazing season. One caveat though is that in some areas the old grass is so dry it readily breaks off, reducing the amount available for grazing. You do need to view this as the same as winter grazing. For ranchers that graze their livestock on range year round they know what to do, whereas those of you that generally don’t, visit with your neighbor that does or your local UW Extension Educator.
    Blaine Horn is the UW Northeast Area Range and Forage Management Educator and can be reached at bhorn@uwyo.edu.