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Comp Biochem Physiol A Mol Integr Physiol. 2017 Feb;204:48-56. doi: 10.1016/j.cbpa.2016.10.013. Epub 2016 Nov 11.

l-Leucine acts as a potential agent in reducing body temperature at hatching and affords thermotolerance in broiler chicks.

Author information

1
Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Sciences, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
2
Division for Experimental Natural Science, Faculty of Arts and Science, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 819-0395, Japan. Electronic address: vc-sur@artsci.kyushu-u.ac.jp.

Abstract

Thermal manipulation (TM) of incubation temperature causes metabolic alterations and contributes to improving thermotolerance in chicks post hatching. However, there has been no report on amino acid metabolism during TM and the part it plays in thermotolerance. In this study, we therefore first analyzed free amino acid concentrations in the embryonic brain and liver during TM (38.6°C, 6h/d during embryonic day (ED) 10 to ED 18). It was found that leucine (Leu), phenylalanine and lysine were significantly decreased in the embryonic brain and liver. We then chose l-Leu and other branched-chain amino acids (l-isoleucine (L-Ile) and l-valine (l-Val)) for in ovo injection on ED 7 to reveal their roles in thermoregulation, growth, food intake and thermotolerance in chicks. It was found that in ovo injection of l-Leu, but not of l-Ileu or l-Val, caused a significant decline in body temperature at hatching and increased food intake and body weight gain in broiler chicks. Interestingly, in ovo injection of l-Leu resulted in the acquisition of thermotolerance under high ambient temperature (35±1°C for 180min) in comparison with the control thermoneutral temperature (28±1°C for 180min). These results indicate that the free amino acid concentrations during embryogenesis were altered by TM. l-Leu administration in eggs caused a reduction in body temperature at hatching, and afforded thermotolerance in heat-exposed young chicks, further suggesting that l-Leu may be one of the key metabolic factors involved in controlling body temperature in embryos, as well as in producing thermotolerance after hatching.

KEYWORDS:

Body temperature; Chicks; In ovo injection; Thermal manipulation; Thermotolerance; l-Leucine

PMID:
27840178
DOI:
10.1016/j.cbpa.2016.10.013
[Indexed for MEDLINE]

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