Changes in free amino acid concentrations in the blood, brain and muscle of heat-exposed chicks.

An experiment was conducted to analyse the changes in free amino acid concentrations in the blood, brain and muscle of chicks in response to 15 or 30 min exposure to high ambient temperature (HT). Food intake and body weight were not affected, while rectal temperature was significantly increased by short-term HT exposure. Several free amino acid concentrations increased in the blood, brain and muscle even with short-term HT, whereas levels of a few amino acids declined significantly. As well as the nonessential amino acids, essential amino acids also significantly increased with exposure to HT. 3-Methylhistidine, a marker of proteolysis, significantly declined in the muscle of HT chicks, implying a reduction of protein breakdown under HT. These results indicate that alteration of protein metabolism may occur in chicks even with short-term heat exposure.

Lauroyl-L-aspartate decreased food intake and body temperature in neonatal chicks.

We hypothesized that the effects of L- and D-amino acids might be influenced when conjugated with fatty acid. Thus, the effects of oral administration of lauroyl-L-aspartate (Lau-L-Asp) as well as lauroyl-D-aspartate (Lau-D-Asp) were examined. In Experiment 1, oral administration of both Lau-L-Asp and Lau-D-Asp decreased food intake while L- or D-Asp did not influence food intake. Interestingly, only Lau-L-Asp decreased body temperature. Experiment 2 was conducted to determine whether non-conjugated mixture of L-Asp plus lauric acid has same effects under ad libitum feeding conditions. Lau-L-Asp decreased food intake and body temperature, but L-Asp plus lauric acid did not show any effect studied. In Experiment 3, we found that Lau-L-Asp declined food intake as well as time-dependently suppressed the body temperature in fasted chicks. However, L-Asp plus lauric acid did not show any effect. These results suggest that Lau-L-Asp may exert anorexigenic and hypothermic actions in chicks.