Relationship of plasma urea nitrogen and urea-cycle amino acid concentrations in swine to dietary electrolyte balance and water intake.
1995
Cai Y. | Zimmerman D.R.
Castrated male pigs were used to evaluate effects of dietary electrolyte balance (dEB) and water intake on concentrations of plasma urea nitrogen (PUN) and urea-cycle amino acids. In Trial 1, pigs were allowed free access to either a corn-soybean diet as a control or the diet containing 1% Na2CO3 substituted for corn to increase the cation to anion ratio. Added cation (Na) elevated (P < 0.05) the concentration of plasma citrulline and shifted the forms of nitrogen excreted in the urine by increasing urea (P < 0.05) and decreasing ammonia (P < 0.01). The constant total nitrogen of urea, ammonia and allantoin illustrates a role of dEB in synchronizing ammoniagenesis and ureagenesis in nitrogen excretion via the kidney. In Trial 2, pigs were fed twice per day and offered water intakes of 1.5 or 3 times feed intakes per day. The low water intake increased (P < 0.01) PUN, but did not affect (P > 0.10) concentrations of plasma urea-cycle amino acids in the pigs. The studies demonstrate that cation to anion ratio and water intake are factors that should be controlled in design of experiments and interpretation of results when PUN is used to be indicative for the dietary amino acid adequacy.
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