Influence of grazing management on intake and composition of cattle diets

Abstract

A study was conducted to evaluate the influences of seasonlong and short duration grazing management on the botanical composition, chemical composition, and organic matter intake of cattle diets in the Northern Great Plains. Four sampling periods; spring, early summer, late summer, and early fall, were conducted during the grazing seasons of 1990 and 1991. Six ruminally cannulated crossbred steers were used to collect diets while 10 ruminally cannulated crossbred heifers were used to establish intake values. In each sampling period, diet collections were obtained from the steers, allowed to graze for 60 to 90 min in each of the treatments after total rumen evacuation. Intake was estimated using an indigestible marker and twice-daily fecal collections from 5 heifers under each of the 2 treatments. The primary constituent of cattle 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 duration management. This is most notable with regard to nitrogen and digestibility, which were higher (P < 0.05) in the short duration treatment in 5 of the sampling periods. Organic matter intake trended higher for cattle under short duration management with 3 of the analyzed sampling periods showing differences (P < 0.10). These results suggest that livestock grazing under a properly implemented rotational grazing system may be presented with an opportunity to consume more of higher quality forage.