BIOGENIC-AMINES IN SILAGE, APPARENT POST-RUMINAL PASSAGE, AND THE RELATIONSHIP BETWEEN BIOGENIC-AMINES AND DIGESTIVE FUNCTION AND INTAKE BYSTEERS

A 4 x 4 Latin square experiment was conducted to examine abomasal pass age of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of th e dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substit uted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to fou r ruminally and abomasally cannulated steers. The roughage component o f the diet constituted 50% of the DM and consisted of 60% alfalfa sila ge or hay and 40% tropical corn silage. The concentrate was composed m ainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentratio n in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines wa s 5 to 20% of intake. Abomasal recovery of cadaverine was correlated w ith depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of retic ular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in st eers fed diets that contained more alfalfa silage. Ruminal fluid pH an d NH3 concentration increased in steers fed more alfalfa silage; howev er, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabol ism of biogenic amines is extensive based on the relatively low quanti ties recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated phys iological effects.