Fasting heat production and metabolic body size in non-ruminant growing farm animals

Fasting heat production (FHP) of animals is indicative of their basal metabolic rate and is used to estimate the maintenance energy requirements and for calculating the net energy value of feeds. However, estimates of FHP vary with experimental conditions, as well as with measurement and calculation methods. In addition, FHP is often related to metabolic body weight (MBW) with the idea that FHP per unit of MBW is constant for a given group of animals over a large BW range. For comparing FHP in adult animals of different species, MBW is frequently expressed as BW0.75 but validity of the 0.75 exponent has been questioned for growing animals (Noblet et al., 1999; Labussiere et al., 2008). The objective of this study is to combine FHP measurements obtained according to a common methodology in four species of growing monogastric farm animals (veal calves, pigs, turkeys and broilers).