To estimate the dietary ME concentration, often feed tags list the Total Digestible Nutrient (TDN) concentration. Likewise, most commercial feed laboratories estimate the TDN concentration based on various analyses, such as for crude protein and fiber fractions.
The approach used to develop predictions of voluntary DM intake by goats
was based on an assumption of constant overall efficiency of utilization of ME. Therefore, ME requirements from other studies of this project were employed, along with assumptions of efficiencies of ME utilization. In accordance, inputs necessary to predict intake entail factors influencing the partitioning of energy for use in various physiological functions, including production level. Although this calculator will predict feed intake with body weight loss, the majority of observations in the dataset used to develop the prediction equations has positive average daily gain or values near or slightly less than zero. Hence, caution should be employed when predicting intake with substantial body weight loss. It is also important to note that input of an unreasonably high level of production given the characteristics of the animal and nature of the diet will result in a comparable unlikely estimate of feed intake.
The concentration of crude protein (CP) in the diet did not have
a significant effect on intake in the prediction equation
development process. Therefore, accuracy of intake prediction
is contingent upon the diet supplying adequate ruminally available
CP for normal growth and digestion by ruminal microbes and
an amount of metabolizable protein (MP) and array of amino
acids absorbed in the small intestine sufficient to achieve
the level of performance input.
Data on which this calculator is based were from
goats in pens or stalls and not in late gestation or experiencing
appreciable compensatory growth or effects of acclimatization.
Correspondingly, adjustments of the maintenance ME requirements
available in other calculators are not employed here. Therefore,
caution should be exercised if using this calculator to determine
if an estimate of feed intake based on a ME requirement calculator
with the maintenance requirement being substantially affected
by adjustments is likely or not. However, adjustments can be used with the Option B Calculator "Feed Intake with Adjustments of the Maintenance Energy Requirement - Growing Goats".
Our example would require a voluntary DM intake of a 30-kg growing meat goat consuming a diet with 11 MJ/kg DM of ME and gaining 50, 150, and 250 g/day are 0.72, 0.91, and 1.06 kg/day, respectively.