Effect of prolonged intravenous glucose and essential amino acid infusion on nitrogen balance, muscle protein degradation and ubiquitin-conjugating enzyme gene expression in calves

Table 3 Mean plasma concentration and urinary excretion of urea nitrogen and 3-methylhistidine (3-MH) in calves on the final day of a five day intravenous infusion of saline (control); glucose; essential amino acids (EAA) and glucose + EAA.

	Control	Glucose	EAA	EAA+Glucose
Plasma Urea N mmol/L	8.8^a ± 0.91	5.8^b ± 0.37	11.0^c ± 0.79	6.7^ab ± 0.51
Plasma 3-MH μmol/L	3.3^a ± 0.36	1.6^b ± 0.24	1.9^b ± 0.61	1.9^b ± 0.13
Urinary Urea N g/d	16.8^a ± 1.06	12.4^b ± 1.19	25.3^c ± 3.70	15.8^ab ± 1.71
Urinary 3-MH:Creatinine mg/g	13.3^a ± 0.51	12.2^b ± 0.33	12.5^a ± 0.24	12.2^a ± 0.22
Net Nitrogen Balance g/kg/d	0.52	0.80	1.06	1.66

Values are averages of 6 blood samples taken at hourly intervals during the last 6 hours of the infusion or pooled urine collected over the last 4 days of infusion. Net nitrogen balance is the difference between digested nitrogen intake (assuming a nitrogen digestibility of 0.85) and urinary nitrogen excretion. Values are means ± standard error of the mean (SEM). ^a,b,c Values within the same row with different superscripts are significantly different (P < 0.05).

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