EFFECTS OF STOCKING RATE ON FORAGE NUTRIENT COMPOSITION OF NEBRASKA SANDHILLS UPLAND RANGE WHEN GRAZED IN EARLY SUMMER AND THE EFFECTS OF GRAZING ON NEBRASKA SANDHILLS MEADOW FORAGE NUTRIENT COMPOSTION

The objectives of this research were to 1) evaluate the effects of stocking rate on forage nutrient quality 2) quantify the relative proportions of current vs. previous year growth being consumed in early summer upland range pastures and 3) determine how grazing effects forage nutrient quality in subirrigated meadows in the Nebraska Sandhills. Experiment 1 was a two year study conducted on the experimental upland range paddocks at Gudmundsen Sandhills Laboratory. Twelve 2-hectare paddocks were assigned one of three treatments stocked at 0 (control), 0.57 (light), and 0.85 (heavy) AUM/ha. Ten 0.25 m2 quadrats were clipped per paddock during the study. Diet quality was determined using esophageally fistulated cows. Experiment 2 was conducted at a commercial ranch near Lakeside, NE. Esophageally fistulated cows sampled pastures either grazed or non-grazed throughout the grazing season starting on June 14 and ending late August in a two year study. Samples were analyzed for IVOMD, CP and NDF content. Stocked upland range paddock diet samples had decreased CP, IVOMD, and greater NDF content compared with control paddocks for diet samples. Diet samples were lower in quality compared with current year growth but greater in quality compared with previous year growth indicating cattle consumed previous year growth as part of the diet. Forage accumulation increased linearly in control paddocks but did not change in stocked paddocks. Grazed samples had lower CP content than non-grazed pastures early in the grazing season and unaffected later in the season. Neutral detergent fiber was greater in grazed compared with non-grazed pastures early in the grazing season. Diet IVOMD was most affected by grazing as season progressed. These studies indicate grazing and stocking rate effect diet quality in subirrigated meadows and upland range. Producers need to rotate cattle frequently in early summer to ensure high quality intake. Advisor: L. Aaron Stalker and Terry J. Klopfenstei