Maintenance energy requirements of goats: predictions based on observations of heat and recovered energy

Abstract

A database including 80 treatment means, based on energy balance publications, was constructed and analyzed to estimate fasting heat production (FHP) and ME required for maintenance (ME m) of goats. Experiments entailed comparative slaughter, respiration calorimetry or CO 2 entry rate techniques. Goats were of eight breeds and five physiological states (preweaning; growing; mature and non-lactating; early and mid-pregnancy; and lactating). Assuming that heat increment was 40% of total heat energy, unweighted, and weighted (number of observations per treatment mean) log–log regressions ( n = 74 following removal of observations to increase explained variation) of FHP against BW resulted in FHP (kJ) = 299 × BW 0.762 ( R 2 = 0.82) and 244 × BW 0.826 ( R 2 = 0.75), respectively. The 0.762 and 0.826 BW scaling factors did not differ ( P < 0.17) from 0.75. The slope and intercept of a regression of recovered energy (RE) against ME intake (MEI) for preweaning goats differed ( P < 0.01) from those for other physiological states. A linear regression analysis of RE on MEI (both kJ/kg BW 0.75) was conducted with the remaining 71 observations, after removing two observations with SD greater than 2.5 residual SD. The resultant equation was: RE = −298.0 (SE = 22.38) + (0.691 (SE = 0.028) × MEI) [ n = 69; R 2 = 0.90]. These estimates of FHP and efficiency of ME use yielded an estimate of ME m of 431 kJ/kg BW 0.75. In summary, FHP and ME m of 298 and 431 kJ/kg BW 0.75, respectively, appear appropriate as general descriptors of the maintenance energy requirement of goats consuming diets at, near or above maintenance.