Adjustment of the ME requirement for maintenance for acclimatization
Goats are raised in many different environments throughout the world. Although there has been less research of environmental effects on nutritional needs of goats compared with cattle or sheep, the same general principles should apply, such as those discussed by NRC (2000). A 2.9 kJ/kg Body weight (BW)0.75 change in fasting heat production (i.e., net energy requirement for maintenance) for each degree C that average daily ambient temperature in the previous month (PREVTEMP) differed from 20° C was suggested. The temperature of 20° C is the mid-point of the thermoneutral zone (MTNZTEMP). Assuming an efficiency of ME utilization for maintenance of 0.70, the change in the ME requirement for maintenance is 4.14 kJ/kg BW0.75. A similar adjustment can be applied with goats, but perhaps with consideration of using a MTNZTEMP specific for the particular goat genotype of interest rather than always 20° C.
As an example, with a MTNZTEMP of 20° C the maintenance ME requirement would be 8.3 kJ/kg BW0.75 lower with a PREVTEMP of 22°
C and 8.3 kJ/kg BW0.75 higher with a PREVTEMP of 18° C. The adjustment factor has a unit
of MJ/kg BW0.75 and, thus, is multiplied by
kg BW0.75, with the product added to the maintenance
Sources used (discussion and recommendations) for this calculation method are:
NRC. 2000. Nutrient Requirements of Beef Cattle, Update 2000. National Academy Press, Washington, DC.
Sahlu, T., A. L. Goetsch, J. Luo, I. V. Nsahlai, J. E. Moore, M. L. Galyean, F. N. Owens, C. L. Ferrell, and Z. B. Johnson. 2004. Nutrient requirements of goats: developed equations, other considerations and future research to improve them. Small Ruminant Research 53:191-219.