Stocking Density Influences Predominantly Blue Grama Pasture Mass and Animal Performance

Abstract

The optimum grazing management practices to sustain or increase grassland resilience must be determined. The effects of the current and previous year’s stocking densities (light, medium, and heavy stocking densities of 0.53, 0.89, and 1.24 AU ha−1, respectively) at the same stocking rate (35 AUD ha−1 yr−1) of yearling heifers (Bos taurus) grazing predominately blue grama [Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths] pastures on animal gains and pasture mass during the growing season were evaluated at New Mexico State University’s Rex E. Kirksey Agricultural Science Center at Tucumcari, NM USA, over three years. Previous grazing management had no influence on animal performance (p > 0.14) but seasonal average daily gains and total gains ha−1 were decreased from low- to high-density grazing (p < 0.002). Nevertheless, for grassland resilience, when low followed either high or medium, blue grama mass increased compared to low following low. Alternatively, when medium followed high, blue grama mass was reduced, but when high followed either low or medium, forage mass numerically increased (p < 0.0117 for the previous × current year’s stocking density interaction). Consequently, short-duration, high stocking density may be best using multiple pastures, each with the same grazing period each year to allow for a long-duration rest. Otherwise, during persistent drought, a longer-duration, medium stocking density could be used to allow for recovery.