title: Effect of ensiling whole plant corn on voluntary intake, rumen fermentation, retention time and rate of digestion in steers.
abstract: The study was designed to determine whether products of fermentation in corn silage could limit its voluntary intake. Six rumen-cannulated Hereford steers were assigned randomly to diets of corn silage (CS) and dried corn forage reconstituted either with water (DC + W) or with extracts from corn silage (DC + CSE) according to a crossover design with three experimental periods. During each period, steers were fed ad libitum for 18 days and then restricted to 65 g DM/kg BW.75 for another 13 days. During the restricted feeding period, measures of rumen fermentation were made, and mean retention time (MRT) of rumen digesta was estimated after a single injection of the liquid and solid phase markers, 51Cr-EDTA and 103Ru-Phenanthroline complex (103Ru-P), respectively. Daily voluntary intake of DM (g/kg BW.75) for diet DC + W (80.2) was not diffferent (P greater than .05) from that for CS (89.7) but was significantly lower than that for DC + CSE (93.5). The corresponding estimates of MRT were 16.1, 14.1 and 17.4 hr (SEM +/- .5) for 51Cr-EDTA and 23.2, 23.9 and 24.3 hr (SEM +/- .7) for 103Ru-P. Measurements of osmolality, pH and VFA concentrations in rumen fluid were not related to daily DM intake. A study of rate of DM digestion, conducted by the rumen bag technique with samples of freeze-dried corn silage residue obtained after liquid extraction, yielded rate constants (hr-1) of .039 +/- .0030, .055 +/- .0028, and .0030 when steers were fed CS, DC + W and DC + CSE, respectively.
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004063:Digestion; D004435:Eating; D005285:Fermentation; D012417:Rumen / Q000378:metabolism / Q000502:physiology*; D012820:Silage