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Of the 774,367 pounds of forage only 25 percent can be eaten by
livestock if the pasture is properly stocked. Hence, 193,592 pounds are
available for grazing. The pasture is currently stocked at 25 acres per
stock unit. How long will this forage supply last without additional
forage growth?
To determine the number of days of grazing available, calculate the number of stock units in the pasture (1,014 acres/25 = 41). Determine the amount of forage required by the herd for each day (41 stock units x 19.6 pounds per stock unit per day = 803.6 lb./day). Divide the pounds available for grazing by the pounds required per day to determine how many days this forage supply should last (193,592/803.6 = 241 days). Therefore, regrowth must occur within this period of time or the present herd will have to be removed from the pasture to prevent over-utilization. If the rancher expected good regrowth by November 1, (111 days from July 12th), the stocking rate could be increased. However, surplus forage may be desirable for winter grazing. The increased number of stock units would be based on excess forage available [193,592 -(803.6 x 111 days)] = 140,392 lb. Divide the excess by the total amount required for 1 stock unit (111 days x 19.6) to determine the number of stock units that could be added (104,392/2175.6 = 48).
ConclusionUsing this forage survey procedure should help improve grazing management decisions and reduce range resource damage due to over-utilization. More timely restocking during drought will help keep plants healthy for future growth and provide cover for increased rainfall effectiveness with less soil erosion. Rather than waiting until the forage supply is gone, a forage supply survey will help forecast whether a change in stocking rate is appropriate. This allows better planning to meet crisis situations.
ReferenceTroxel, T.R. and L.D. White. 1988. Balancing forage demand with forage supply. Texas Agricultural Extension Service, B-1606, 7pp. College Station, Texas.
AcknowledgmentThe authors wish to acknowledge John K. Finegan, Val Verde County rancher; Jim Willingham, Uvalde County rancher; Preston Faris, Sutton County Extension Agent; Tom Payton, Soil Conservation Service; Total Ranch Management Workshop participants; Dr. Charles Taylor, Nick Garza and Dr. Keith Owens, Texas Agricultural Experiment Station for valuable suggestions, field testing, editorial comments and support for this effort. Authors: Larry D. White, Calvin Richardson |