Effect of Sampling Location, Time, and Method of Concentration of Ammonia Nitrogen in Rumen Fluid

Abstract

In experiment 1, rumen fluid samples were obtained from dorsal, midpoint, and ventral regions of the rumen of rumen-fistulated dairy cows at hourly intervals for 24h. Dorsal, midpoint, and ventral rumen fluid samples contained 16.1, 14.2, and 12.1 mg/100ml of ammonia nitrogen. Time after feeding resulted in differences in the concentration of ammonia in rumen fluid with the greatest concentration 30 to 90min postfeeding. The concentration of ammonia nitrogen was greater for cows fed a high-concentrate diet (14.7% crude protein, 86% concentrate) than for cows receiving a normal diet (15.1% crude protein, 42% concentrate), 15.2 versus 13.1 mg/100ml. In a second experiment, rumen fluid samples were obtained immediately before feeding and at 1 and 6h postfeeding by stomach tube and from dorsal, midpoint, ventral, and mixed rumen contents via a rumen cannula. Concentrations of ammonia nitrogen (mg/100ml) in the respective rumen fluid samples were 14.3, 23.0, 18.3, 17.2, and 19.6. Location of sampling, method of sampling, time of sampling, type of diet, and rumen fluid volume are factors that affect the concentration of ammonia nitrogen in rumen fluid.