Intensified Grazing Management in the Northern Plains – Improving the Harvest Efficiency of Our Rangelands.

Selecting the appropriate stocking rate is considered by many the most important grazing management decision a producer can make.  Relationships between stocking rate and productivity of vegetation and livestock were initially determined for northern mixed grass prairie in the mid-1910s.  Today, ranchers need to harvest “less with more” – achieve a stocking rate that maximizes the amount of forage consumed while providing ample standing crop to protect the soil, maintain a health plant community, and provide wildlife and invertebrate habitat.  The basic principles are to improve grazing efficiency (the proportion of forage consumed by livestock compared to the total that disappears due to all other activities) and increase harvest efficiency (the proportion of forage consumed by livestock compared to the forage produced). There is little doubt that grazing systems do not improve livestock performance, at least not in the first 5 to 10 years.  Grazing systems do not grow more forage, at least not in the first 3 to 5 years.  What grazing systems achieve is improve the harvest efficiency of the grazing animal by reducing waste, improving evenness of grazing, and reducing intake by individual animals.  Most ranchers’ GOAL from a grazing system is to increase the stocking rate on the same acres while not overgrazing.  This goal will increase the pounds of beef produced per acre, increasing the economic return from the land while maintaining or improving range health.  The standard harvest efficiency in season long grazed pastures is 25%.  Of the herbage produced annually, half of the total production is left to maintain healthy, vigorous plants that will sustain the rangeland. Twenty-percent percent is not harvested by the animal due to trampling, fouling, natural death of the plant tissue, weathering, and consumption by wildlife.  This leaves 25% for livestock consumption or a harvest efficiency of 25%.  A rancher’s or land manager’s goal is to improve the harvest efficiency of the grazing animal while maintaining 50% of the total production on the land.  If you improve the efficiency to 35%, your stocking rate will be increased by 40%.  So, for every percent increase in efficiency creates a 4% increase in stocking rate without increasing degree of disappearance.  So, how do you improve harvest efficiency?  Harvest efficiency can only be increased through increasing the stock density (more animals per acre for a given period of time).  As stocking density increases, harvest efficiency also increases. Two changes in grazing behavior occur with increased stock density: 1) increased number of plants grazed in a cell or pasture (improved uniformity) and 2) reduced forage intake by the animal. Cattle tend to consume based on taste and graze near water.  If the stock density is low, they will select the best plants and over-consume. It is not uncommon for a cow to consume 18 to 23 kg of dry forage a day if it is extremely palatable.  Remember, a cow only needs 12 to 16 kg of dry forage per day to maintain condition, provide milk for her calf, and rebreed.  Increasing the stock density forces livestock to be less selective, cover more area to find better palatable plants, and compete with other individuals for grazing space.  When cattle are forced to consume less desirable plants, consumption declines and waste is reduced.  This is also the primary reason why livestock performance is not improved with grazing systems, and in some cases reduced (at least in the short-term).  Secondly, increased stock density forces livestock to cover more area within a cell or pasture, dramatically increasing the number of plants grazed.  When a plant is grazed while actively growing, a prolonged immature stage of plant development occurs (versus maturation and stem development), reducing the loss of plant tissue through senescence and weathering.  Thus, more plant tissue is harvested through the animal, increasing the consumption of plant tissue.  You’re not increasing forage production, but increasing the amount of forage consumed by the animal; thus, improved harvest efficiency.