INFLUENCE OF GRAZING MANAGEMENT ON INTAKE AND COMPOSITION OF CATTLE DIETS

A study was conducted to evaluate the influences of seasonlong and sho rt duration grazing management on the botanical composition, chemical composition, and organic matter intake of cattle diets in the Northern Great Plains, Pour sampling periods; spring, early summer, late summe r, and early fall, were conducted during the grazing seasons of 1990 a nd 1991. Six ruminally cannulated crossbred steers were used to collec t diets while 10 ruminally cannulated crossbred heifers were used to e stablish intake values, In each sampling period, diet collections were obtained from the steers, allowed to graze for 60 to 90 min in each o f the treatments after total rumen evacuation, Intake was estimated us ing an indigestible marker and twice-daily fecal collections from 5 he ifers under each of the 2 treatments, The primary constituent of cattl e diets in both seasonlong and short duration treatments was graminoid which was consumed in slightly greater quantity under short duration management, Nutritional content of the diet was improved under short d uration management, This is most notable with regard to nitrogen and d igestibility, which were higher (P<0.05) in the short duration treatme nt in 5 of the sampling periods, Organic matter intake trended higher for cattle under short duration management with 3 of the analyzed samp ling periods showing differences (P<0.10). These results suggest that livestock grazing under a properly implemented rotational grazing syst em may be presented with an opportunity to consume more of higher qual ity forage.