STEER PERFORMANCE ON NATIVE AND MODIFIED NORTHERN GREAT-PLAINS RANGELAND

Research was conducted to quantify the effects of various range improv ement treatments on diet quality and summer weight gain of steers graz ing semiarid rangeland from 1983 through 1988. Treatments were: no tre atment (i.e., control), contour furrowing, intertilling with a prototy pe range improvement machine and combinations of the range improvement machine, nitrogen fertilization, legume interseeding, or brush contro l. Diet quality was measured in 1987 and 1988. Data were analyzed usin g various repeated measures analysis of variance models. Various relat ionships between the animal performance data and previously published herbage standing crop data were examined using standard correlation pr ocedures. There were no significant treatment (P>0.17) or year by trea tment (P>0.82) interaction effects relative to average daily gains, to tal gain steer(-l), and gain ha(-1) . However, all year effects were s ignificant (P<0.05) for these variables with years accounting for abou t 67% of the observed variation in weight pains. Percentage crude prot ein 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 gazing season (P<0.05). However, in vitro dry matter digestibility of diets was greater in 1988 than 1987 primarily because digestibility o f diets increased in 1988 from the beginning to the end of the trial. Significant correlations between gain steer(-1) and gain ha(-1) and ea rly season total and perennial cool-season grass standing crop estimat es indicated same rudimentary information is available at the beginnin g of each grazing season for predicting season-long weight gains. Beca use average daily pains during late spring and early summer were sever al fold greater than late season gains in all years except one, it is hypothesized that intensive early stocking strategies may be appropria te for stocker cattle grazing in the Northern Great Plains.