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Nutrient oxidation and lipogenesis in hens
Author(s) -
Chwalibog A.,
Thorbek G.
Publication year - 1999
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1046/j.1439-0396.1999.00245.x
Subject(s) - lipogenesis , chemistry , nutrient , carbohydrate , metabolism , urine , biochemistry , energy metabolism , lipid metabolism , excretion , zoology , biology , endocrinology , organic chemistry
Introduction Indirect calorimetry based on measurements of gas exchange has been used successfully during the last century in order to estimate energetic values of feedstuffs and animals’ requirement for nutrients and energy. Recently, measurements of gas exchange have been used to calculate nutrient oxidation and lipogenesis in the intact body of man (T horbek et al. 1994), pigs (C hwalibog et al. 1992; C hwalibog and T horbek 1995), calves (C hwalibog et al. 1996; C hwalibog et al. 1997a), mink (T auson et al. 1997) and rats (C hwalibog et al. 1998). In the present paper a similar approach has been used to quantify nutrient metabolism in laying hens in accordance with a calculation method first proposed by C hwalibog et al. (1992) and later modified as outlined in Fig. 1. According to this biological model digested protein (DP) which is equal to PROT – group is utilized for retention in eggs (OP), ovary and body (OBP), whereas deaminated amino acids are oxidized (OXP) with concomitant excretion of energy with nitrogenous substances in urine (UE N ) and contribution of energy (GLUC) to carbohydrate metabolism. Digested carbohydrate (DCHO) together with GLUC constitute the CHO – group , which is retained in eggs (OCHO), oxidized (OXCHO) and used for lipogenesis (LIPO). Digested fat (DFAT) and lipids from lipogenesis constitute the FAT – group , which is incorporated into eggs (OF), ovary + body (OBF) and oxidized (OXF). Both CHO and FAT metabolism contribute with energy containing products excreted with urine (UE N‐free ). The energy from OXP, OXCHO and OXF make up the total heat production (HE). The validity of the method will be discussed later. The aim of this study was to demonstrate how data from gas exchange measurements in combination with nitrogen and energy balances can be applied in order to calculate nutrient oxidation and the quantities of substrates used for retention and lipogenesis processes, and furthermore, to elucidate differences in nutrient oxidation and lipogenesis in relation to different housing conditions and genotypes of laying hens.