Figure 3.

Blood [¹⁵N]urea enrichment in control calves and the effects of arginine (Arg) and/or sodium benzoate (Benz) therapy (Rx). (A) Absolute [¹⁵N]urea enrichment (mol% excess) shown as time course of each 2-day stable-isotope study. Measurements were taken at 6-h intervals before feedings with milk and ¹⁵NH₄Cl. Studies without medications (♦), with arginine and sodium benzoate (■), and with only arginine (▴) show that steady-state levels are achieved after three to five doses of ¹⁵NH₄Cl. (B) Average [¹⁵N]urea enrichments over each 2-day isotope study from S6 and S7 on various therapeutic regimens. Determinations were made from blood samples obtained after the third dose of ¹⁵NH₄Cl at steady state. Error bars represent SD.