Ruminant Utilization of Silage in Relation to Hay, Pellets, and Hay Plus Grain. II. Rumen Content, Dry Matter Passage, and Water Intake

Open Access
Publisher Website
Google Scholar
Abstract
Two 4 x 4 Latin square experiments were conducted using fistulated Holstein heifers. Experiment 1 compared silage, hay, pelleted hay, and hay plus grain. Experiment 2 compared direct-cut silage and hay harvested from the same source. The wet rumen contents and dry matter percentages were determined by completely emptying the reticulorumen of each animal on each ration at 4 times between 12 hour feeding intervals. From these data dry rumen contents were calculated. The dry rumen content was divided by the daily dry matter consumption to obtain an average retention time. The wet and dry rumen content of heifers when fed silage ad libitum were less than when fed hay. This suggests that silage intake was not restricted by rumen capacity. The retention time of silage was comparable to that of hay. The calculated daily fecal dry matter (DM) excretion relative to body weight was less for silage fed animals than for hay fed animals in a simultaneous growth trial. This suggests that the silage intake . was not limited by feed residues in the lower tract. The undigested residue in the rumen calculated from the passage of stained particles using first order equations showed no consistent relation to the actual amount present. The difference must be caused by the variable portion that is undergoing digestion. The animals drank less water when eating silage as compared to hay but the total water intake per kg feed DM was greater on silage than on hay rations.