Table 2. Effects of intravenous administration of L-tryptophan on serum melatonin and gastrointestinal hormones concentrations in Hanwoo steers

Control L-tryptophan
28.9 mg/kg 57.8 mg/kg
Melatonin (pg/mL) Before1) 51.70 ± 4.970 58.85 ± 4.455 64.30 ± 5.185
After2) 58.25 ± 2.985b 64.25 ± 3.125ab 72.10 ± 3.020a
Mean3) 56.95 ± 2.595b 63.15 ± 2.650ab 70.55 ± 2.655a
Increment4) 6.55 ± 2.985 5.40 ± 3.125 7.80 ± 3.020
Cholecystokinin (ng/mL) Before 7.09 ± 0.419 8.11 ± 0.684 9.73 ± 2.164
After 8.06 ± 1.012b 10.39 ± 0.712b 17.24 ± 2.416a
Mean 7.86 ± 0.813b 9.93 ± 0.605b 15.74 ± 2.044a
Increment 0.97 ± 1.012b 2.28 ± 0.712b 7.52 ± 2.416a
Secretin (ng/mL) Before 7.93 ± 2.542 7.93 ± 2.606 7.94 ± 2.565
After 7.52 ± 1.268b 9.78 ± 0.924b 15.02 ± 2.790a
Mean 7.60 ± 1.116b 9.41 ± 0.892ab 13.60 ± 2.333a
Increment −0.41 ± 1.268b 1.85 ± 0.924b 7.08 ± 2.790a
Ghrelin (ng/mL) Before 16.19 ± 1.987 14.65 ± 4.500 21.45 ± 3.452
After 19.99 ± 1.419 15.88 ± 1.814 17.90 ± 1.366
Mean 19.23 ± 1.222 15.63 ± 1.672 18.61 ± 1.290
Increment 3.80 ± 1.419a 1.23 ± 1.814a −3.55 ± 1.366b
Before, average −60 to zero min before jugular vein injection of L-tryptophan.
After, average zero to 300 min after jugular vein injection of L-tryptophan.
Total, average −60 to 300 min during jugular vein injection of L-tryptophan.
Increment, after and before.
in rows p < 0.05.