Metabolizable Energy (ME) for Mature Goats

Use this Energy Requirement Calculator to calculate the daily energy requirement for mature goats. Enter the data into the table below and then click the Calculate Energy Requirement button. The results will be displayed in the table at the bottom of the page. If the doe is in the last 2 months of gestation, click on the Gestation Energy Requirement Calculator. The ME requirement will then be added to the total requirement.


We will use a 50-kg mature dairy doe with no change in body weight (0 g average daily gain (ADG)) and a dietary ME concentration of 10.0 MJ//kg DM.
1. Choose biotype of the goat meat, 50% or more Boer
indigenous or local
2. Choose gender of goat female or wether
intact male
3. Enter body weight (kg)
4. Enter average daily gain (g/day)
Enter dietary ME concentration (MJ/kg DM)
You can use the TDN calculator below and the ME concentration will be entered automatically.
(1 = no adjustment; multiplicative)
(1 = no adjustment; multiplicative)
(0 = no adjustment; additive, MJ)
(last 56 days of gestation)
(0 = default; additive, MJ)
10. Enter % DM in diet (default is 90%)
To convert from English to metric system,
enter your values here.
They will be automatically entered into the table to the left.


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 ME concentration can be calculated with these simple formulas:
ME (MJ/kg) = TDN (%) × 0.15104 and
ME (Mcal/kg) = TDN (%) × 0.0361.

Enter TDN (%)
ME (MJ/kg)
ME (Mcal/kg)

Our example would require a total of 9.43 MJ/day and that for a meat doe is 7.95 MJ/day. With an ADG of 20 g/day, these requirements increase to 10.00 and 8.52 MJ/day for the dairy and meat doe, respectively (0.57 MJ required for 20 g ADG).

ME requirement for maintenance (MJ):
Dietary ME used for maintenance (MJ):
ME requirement for gain (MJ):
Dietary ME used for maintenance and gain (MJ):
ME requirement for gestation (MJ):
Total dietary ME requirement (MJ):
Dry matter intake for dietary ME requirement:
Dry matter intake for dietary ME requirement (% body weight):
As fed intake for dietary ME requirement:
As fed intake for dietary ME requirement (% body weight):

With knowledge of the dietary ME concentration to estimate the efficiency of dietary ME use for maintenance and the concentration of energy in mobilized tissue, it is also possible to project the ME requirement for mature goats decreasing in BW. In this regard, 23.9 MJ/kg of mobilized tissue and a maintenance ME efficiency equal to 0.503 + (0.019 × dietary ME concentration, MJ/kg DM) were assumed. With a loss of 20 g/day of BW, the total ME requirement would be 8.73 and 7.26 for the mature dairy and meat goat doe, respectively. However, most observations in the database used to determine the ME requirements entailed positive body weight change. Therefore, caution should be exercised when using this calculator to determine requirements with body weight loss. To calculate the amount of dietary DM to provide these amounts of ME, the total ME requirement is divided by the dietary ME concentration. As an example, for the 50-kg dairy doe without change in body weight and a dietary ME concentration of 10.0 MJ//kg DM (2.39 Mcal/kg DM), this is 9.42 MJ / 10.0 MJ/kg = 0.942 kg DM. The ME requirement for mature goats determined by Luo et al. (2004) were 462 kJ/kg body weight0.75 for maintenance and 28.5 kJ/g for body weight gain. The database used was smaller in size than that employed for growing goats. Therefore, the difference in the maintenance energy requirement among biotypes of growing goats was applied to the maintenance energy requirement determined for mature goats. Furthermore, because most mature goat observations were with females or wethers, the requirement for intact males was assumed 15% greater. By use of the Grazing Factor Calculator, the maintenance ME requirement can be adjusted for a predicted grazing activity energy cost. A default of 1 is included for housing in a pen or stall setting. In addition, there are similar adjustments for previous nutritional plane and acclimatization. These are optional adjustment factors with default values of 1 (no adjustment). Because of the manner in which data were reported in the the studies used to determine these requirements, it was not possible to directly assess possible differences among genders. Hence, based on NRC (2000), it was assumed that the maintenance ME requirement for females and male castrates was 92.5% of the estimated value, and that for intact males was 107.5% Because mature goats usually consume forage-based diets and are not rapidly gaining body weight, DM intake needed to meet ME requirements is not adjusted for influences of dietary ME concentration or efficiencies of ME utilization as performed for growing goats. To determine if consumption of a calculated amount of a specific diet necessary to meet the ME requirement is possible, the Feed Intake Calculator can be used. However, the Mature Goat Feed Intake Calculator was based on data from non-pregnant goats. Thus, caution should be employed if use is for goats in the last 56 days of pregnancy.

(maintenance energy based on body weight alone)

(adjusted maintenance energy)

Sources used in this calculation method are:

AFRC. 1998. The Nutrition of Goats. CAB International, New York, NY.

Luo, J., A. L. Goetsch, T. Sahlu, I. V. Nsahlai, Z. B. Johnson, J. E. Moore, M. L. Galyean, F. N. Owens, and C. L. Ferrell. 2004. Prediction of metabolizable energy requirements for maintenance and gain of preweaning, growing, and mature goats. Small Ruminant Research 53:231-252.

NRC. 2000. Nutrient Requirements of Beef Cattle, 2000 Update. National Academy Press, Washington, DC.

Nsahlai, I. V., A. L. Goetsch, J. Luo, Z. B. Johnson, J. E. Moore, T. Sahlu, C. L. Ferrell, M. L. Galyean, and F. N. Owens. 2004. Metabolizable energy requirements of lactating goats. Small Ruminant Research 53:253-273.

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.