Supplementation of Yearling Steers Grazing Fertilized and Unfertilized Northern Plains Rangeland

Abstract

Supplementation studies were conducted with yearling steers on a silty range site in central North Dakota, where yearly precipitation averaged 380 to 410 mm. The studies were conducted for 3 summers on both fertilized (45 kg N/ha) and unfertilized native pastures. Animal performance was compared to seasonal changes in the chemical composition of pasture samples collected with esophageal-fistulated steers. Chemical composition differences between diet samples from the fertilized and unfertilized pastures were inconsistent, but generally protein was higher and acid detergent fiber lower on the fertilized pasture. Supplementation with barley in the early summer resulted in little benefit, but supplementation with barley in the late summer, especially when pasture digestibility (in vitro) dropped to 50 to 52%, was beneficial on both the fertilized and unfertilized pastures. However, the response was not consistent between years. Barley supplementation appeared to be economically viable, but the feasibility of this practice will vary from year to year, depending on the price of barley relative to the price of steers. The results of protein supplementation were more erratic, possibly because of differences in precipitation patterns and hence plant growth between years.