Growth
Estimates for the energy costs of protein retention
(MEpr) range from 6.8 to 14.0 Mcal of ME/kg, with a
mean of 10.6 Mcal of ME/kg (Tess et al., 1984). Literature
estimates of the energy costs of fat deposition (MEf) range
from 9.5 to 16.3 Mcal of ME/kg, with a mean of 12.5 Mcal
of ME/kg (Tess et al., 1984). Although the mean energy
costs/kg of protein or fat deposited are approximately equal
(Wenk et al., 1980), 1 kg of lean muscle tissue is only 20
to 23 percent protein, whereas 1 kg of adipose tissue is 80
to 95 percent fat. Therefore, the energy cost for muscle
tissue production is considerably less than that for fat tissue
deposition.