Intraperitoneal Administration of Tryptophan Decreases Liquid Diet Intake in Early Weaned Piglets (original) (raw)

1996, Acta Veterinaria Brno

The aim of the present study was to investigate the effect of intraperitoneal tryptophan (Trp) administration on liquid diet consumption in early weaned piglets. Furthermore, the effects of two chemical forms of the amino acid were compared. Single doses (100 mg.kg-l) ofL-tryptophan (480 mmol.kg-l) or L-tryptophan methyl ester (392 mmol.kg-l) (Sigma, USA) were L p. administered at 07.00 h to 2 groups of 5 piglets each at the age of 3,9, 12, 14 and 16 days. The piglets were weaned on d I, housed individually in cages and offered a commercial diet (Selasan) for suckling from feeding bottles between 06.00 and 22.00 h 9 times a day at 2-h intervals with an 8-h break at night. Control piglets (n=5) were left intact. Compared with intact controls, L-Trp decreased the relative sizes of individual meals in piglets aged 3 d only 5 h (P < 0.02) after its administration, in the 9-d-old ones 1,3 and 5 h (P < 0.05; P < 0.01; P < 0.05, respectively), and in the 16-d-old piglets 3 h (P < 0.01) later. No significant differences between control and L-Trp-treated animals occurred on days 12 and 14. L-Trp methyl ester decreased the diet consumption of piglets at all ages as follows: in 3-, 9-and 16-d-old piglets 3 h (P < 0.05; P < 0.05; P < 0.01, respectively) post-injection, in the 12-d-old animals I h (P <0.01), 3 h (P< 0.001) and 7 h (P< 0.05), and in the 14-d-old piglets I h (P<O.OI) and 3 h (P < 0.01) after L-Trp methyl ester administration. In 12-and 14-d-old piglets its effect was also reflected in 24-h diet intake that was significantly decreased. Similar differences in diet consumption were found when the relative sizes of individual meals were compared to the first morning consumption, Le. I h before Trp treatment. In conclusion, Trp did suppress food consumption in early weaned piglets as soon as on day 3 after birth, indicating that the aminostatic component of their food intake regulation is functional at this age. At the same time it was found that this effect ofL-ttp methyl ester (the actual dose of which was smaller than that ofL-Trp) occurs earlier, is more profound and lasts longer than that ofL-Trp.