Date of this Version
Shropshire A.J., 2018 Grazing Strategy Effects on Utilization, Animal Performance, Aboveground Production, Species Composition, and Soil Properties on Nebraska Sandhills Meadow. MS Thesis, University of Nebraska-Lincoln.
Ultrahigh stocking density (a.k.a., mob grazing) is proposed as a management tool that results in greater harvest efficiency, animal performance, aboveground plant production, species richness, and soil carbon content. The study objective was to determine grazing treatment, haying, or non-defoliated control effects on forage utilization, aboveground production, animal performance, and soil properties. In 2010, 25 ha of Sandhills meadow were divided into 2 replications of 3 grazing, a hay, and control treatment. Grazing treatments were a 120-pasture rotation with one grazing cycle (mob), a 4-pasture rotation with one cycle (4PR1), and a 4-pasture rotation with two cycles (4PR2) at stocking densities of 225,000, 7,000, and 5,000 kg ha-1, respectively. Pastures were stocked by yearling steers (365 kg) at 7.4 AUM ha-1 from May to August in 2010 to 2017. Hay was harvested annually in July. Control plots were not defoliated. In grazed treatments, aboveground biomass was clipped at ground level to estimate utilization after grazing periods (24 hours, 10 and 15 days,). Aboveground biomass was clipped at ground level annually within experimental units in mid-August. Species composition was determined annually in June. Soil cores were taken in 2010 and 2018 at 0-10 cm and 10-20 cm depths. Utilization in grazed treatments differed by treatment. Mob utilization and trampled vegetation was highest followed by 4PR1 and 4PR2. Harvest efficiency did not differ by treatment. Residual standing live herbage had a treatment by year interaction where mob was usually lowest and 4PR2 was usually highest. Aboveground production did not differ among grazing and hay treatments but was greater for grazed treatments than control. Animal performance differed by treatment and year with steers gaining more in 4PR2 than the other treatments. Cool-season grasses decreased in control but increased in grazed treatments. Warm-season grasses decreased in control and were unchanged in grazed treatments. Prairie cordgrass and white clover were affected by treatment. Soil carbon, nitrogen, and bulk density did not differ among treatments. We concluded that management strategy was a driver of utilization, animal performance, and species composition. After 8 years, mob grazing was not a driver of aboveground production or soil property changes.
Advisors: Walter H. Schacht and Jerry D. Volesky