Steer performance on native and modified Northern Great Plains rangeland.

Abstract

Research was conducted to quantify the effects of various range improvement treatments on diet quality and summer weight gain of steers grazing semiarid rangeland from 1983 through 1988. Treatments were: no treatment (i.e., control), contour furrowing, intertilling with a prototype range improvement machine and combinations of the range improvement machine, nitrogen fertilization, legume interseeding, or brush control. Diet quality was measured in 1987 and 1988. Data were analyzed using vitrious repeated measures analysis of variance models. Various relationships between the animal performance data and previously published herbage standing crop data were examined using standard correlation procedures. There were no significant treatment (P > 0.17) or year by treatment (P > 0.82) interaction effects relative to average daily gains, total gain steer-1, and gain ha-1. However, all year effects were significant (P < 0.05) for these variables with years accounting for about 67% of the observed variation in weight gains. Percentage crude protein in diet samples was greater in 1987 compared to the severe drought year of 1988 and was greater at the beginning than at the end of each grazing season (P < 0.05). However, in vitro dry matter digestibility of diets was greater in 1988 than 1987 primarily because digestibility of diets increased in 1988 from the beginning to the end of the trial. Significant correlations between gain steer-1 and gain ha-1 and early season total and perennial cool-season grass standing crop estimates indicated some rudimentary information is available at the beginning of each grazing season for predicting season-long weight gains. Because average daily gains during late spring and early summer were several fold greater than late season gains in all years except one, it is hypothesized that intensive early stocking strategies may be appropriate for stocker cattle grazing in the Northern Great Plains.