Theoretical considerations for partitioning nutrients between
muscle and adipose tissue
G.C. Waghorn and J.E. Wolff
Applied Biochemistry Division DSIR, Palmerston North and Ruakura
Animal Research Station, Ministry of Agriculture and Fisheries, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1984, 44: 193-200
To apportion the intake of metabolisable energy (MEI) used for
synthesis of lean and fat tissue, current knowledge of substrate
oxidation and substrate utilisation for biosynthetic reactions has been
combined with estimates of fat and protein turnover to develop models of
energy metabolism and nutrient fluxes in a lean 20 kg male and a fat 40
kg female sheep, each gaining 200 g/d. When the most efficient pathways
and lowest turnover rates are employed the biosynthetic reactions
account for 38 and 34% of MEI in the lean and fat animals. These values
rise to 45 and 43% of MEI respectively when higher estimates of turnover
and less efficient pathways are used in the calculations. Hormonal
regulations of metabolite utilisation is believed responsible for such
differences but hitherto, only glucose-insulin system has been
quantitated. Two techniques used for its quantitation are described to
provide examples of the methods needed to elucidate the control of
nutrient utilisation and ultimately body composition in ruminants.
Keywords: NZSAPAB;
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