Two experiments were conducted to clarify the effects of L-arginine supplementation on the growth performance, nitrogen balance, blood urea nitrogen (BUN) and plasma free amino acids profiles in weaning pigs. In experiment 1, eight castrated weaning male pigs (8.2±0.2 kg) were divided into two groups. One was control group, which were fed to a basal diet containing 15% of skim milk, another one was arginine group, which were fed to a basal diet plus 0.5% of arginine. Experimental period was 14 days and nitrogen balance test was conducted during the final three days. Experiment 2 were similar to experiment 1, except for a basal diet which contained 8% of skim milk and for initial body weight (6.8±0.4kg).
In experiment 1 and 2, there were no significant differences in growth performance between two groups. Average daily gain in experiment 1 and 2 were 409g/d and 455g/d, respectively. Feed efficiency in experiment 1 tended to be lower in arginine group than in control group. BUN in experiment 1 and 2, arginine group tended to be higher than in control group and BUN/feed intake was significantly higher in arginine group than in control group. In nitrogen balance, total (feces＋urine) nitrogen excretion (g/d) in experiment 1 and urinary nitrogen excretion (g/d) were significantly higher in arginine group than in control group. However, there was no significant difference in nitrogen retention (g/d) between two groups. In experiment 2, plasma free arginine and ornithine concentrations in arginine group were significantly higher than in control group. These changes in two amino acids and BUN response means that excessive arginine were degraded to ornithine, leading to synthesize urea.
In conclusion, arginine supplementation has no effect on growth performance of weaning pigs when initial body weight is about 6.8∼8.2kg and weight gain shows 400∼450 g/day.

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The absorption spectra of a reduced meat extract indicated heme pigments which determine the absorption characteristics to quite likely be myoglobin, hemoglobin and cytochrome c (Cyt. c). The absorption spectra of any other heme pigments in the meat extract were too weak to permit detection. A CO treated meat extract was found to contain CO myoglobin (COMb), CO hemoglobin (COHb) and reduced Cyt. c, each of these having a characteristic absorption spectrum differing from that of any other. The following absorption peaks observed:COMb:541 and 578 nm;COHb:539 and 568nm;Cyt. c:520 and 550nm. Spectrophotometrically, COMb, COHb and Cyt. c were in the most readily detachable forms. To devise a system equation based on the Beer-Lambert law, three wavelengths were optionally selected from among eleven wavelengths which showed 6 peaks for 3 heme pigments and 5 isosbestic points for COMb and COHb. The accuracy of the system equation was assessed for solutions of known-concentrations and meat extracts. The concentrations of Mb, Hb and Cyt. c could be determined with the greatest accuracy using the system equation derived based on weight absorption coefficients at 538, 568 and 578nm.

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