Metabolizable Protein (MP) And Crude Protein (CP) Requirements Of Mature Goats

Use this Protein Requirement Calculator to calculate the daily protein requirement for mature goats. Enter the data into the table below and then click the Calculate Protein 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 Protein Requirement Calculator. The MP requirement will then be added to the total maintenance requirement.


We will use a 40-kg doe consuming diet dry matter (DM) at 2.5% BW (1 kg intake). If an estimate of DM intake is not readily available, the Feed Intake Calculator can be used.
1. Enter body weight (kg)
2. Enter average daily gain (g/day)
3. Enter expected DM intake (% of body weight)

(maintenance energy based on body weight alone)

(adjusted maintenance energy)
(last 56 days of gestation)
(0= default)
To convert from English to metric system,
enter your values here.
They will be automatically entered into the table to the left.


Our example would require a total of 44.9 g MP for maintenance (26.7 g for metabolic fecal CP + 16.4 g for endogenous urinary CP + 1.8 g for scurf CP), which equates to a dietary MP concentration of 4.5% of DM.

DM intake (kg):
Metabolic fecal MP (g):
Endogenous urinary MP (g):
Scurf MP (g):
MP requirement for maintenance (g):
Dietary MP used for maintenance (g):
MP requirement for gain (g):
MP requirement for gestation (g):
Total dietary MP requirement (g):
Total dietary MP requirement (% DM intake):

The maintenance MP requirement for mature (≥ 1.5 years of age) meat (≥50% Boer), dairy (selected for milk production, such as Alpine and Saanen), and indigenous or local goats, non-lactating and lactating, is based on estimates of metabolic fecal (Moore et al., 2004; 0.0267 g/g DM intake) and endogenous urinary crude protein (Luo et al., 2004; 1.031 g/kg body weight0.75), as well as the scurf protein loss of beef cattle (NRC, 1984; 0.2 g/kg body weight0.6). In addition, it was assumed that the efficiency of MP use for these maintenance proteins is 100% (AFRC, 1998).

Body weight (BW) is necessary to determine MP required for endogenous urinary and scurf proteins. Conversely, metabolic fecal CP is predicted from DM intake. The simplest way to address DM intake is expression as a % of BW, which can be entered directly or derived from a feed intake calculator. However, feed intake prediction equations were derived with goats not in the last 56 days of gestation. Therefore, use of this calculator for goats in late gestation should be with caution.

MP requirements are preferable compared with CP because they consider how feedstuffs vary in the extent to which proteins are degraded in the rumen (or the extent of passage to the small intestine of intact feed protein) and dietary and animal characteristics that impact the quantity of microbial protein that is synthesized in the rumen and flows to the small intestine.

However, in many instances there may not be adequate knowledge about these factors to directly predict the amount of MP resulting from a given level of consumption of a particular diet. If such information is know, then the Calculator entitled "Metabolizable Protein (MP) Intake Based on Estimates of Ruminally Undegraded Protein (UIP) and Microbial Protein Synthesis" can be employed. If not, then a simple means of determining how requirements for MP relate to those for CP can be used. In this regard, NRC (2000) suggested that MP requirements can be reasonably well translated or projected to CP needs for most practical purposes with some assumptions regarding the extent of ruminal degradation of dietary CP. It was suggested that CP requirements can be determined through dividing MP needs by values from 0.64 to 0.80, which apply to diets with 0 and 100% rumen undegraded protein (UIP), respectively. Typically, diets with 0 or 100% of CP degraded (or undegraded) in the rumen are not fed. Thus, CP requirements have been calculated from MP for diets containing CP that is digested in the rumen (DIP; degraded intake protein) with extents of 80, 60, and 40%, which equate to concentrations of UIP of 20, 40, and 60%, respectively. A diet with 20% UIP would probably be one of fresh forage that typically has CP extensively degraded in the rumen. A diet with 40% UIP might be one with a mixture of concentrate (e.g., high level of corn) and forage. A diet with 60% UIP would have a moderate to high level of concentrate, and perhaps would contain some feedstuffs such as blood, feather, fish, or corn gluten meals that have considerable protein passing from the rumen intact. Likewise, pelletizing usually increases the dietary UIP concentration.

Based on the example above, the requirement for 44.9 g of MP equates to CP requirements of 66.8, 63.8, and 61.0 g, and 6.7, 6.4, and 6.1% of dietary DM, for 20, 40, and 60% UIP diets, respectively. These values reflect that, as long as ruminally available CP is adequate for normal microbial protein growth and digestion, CP requirements decrease as the dietary UIP concentration increases.

Total dietary CP requirement, diet with 20% UIP and 80% DIP (g):
Total dietary CP requirement, diet with 40% UIP and 60% DIP (g):
Total dietary CP requirement, diet with 60% UIP and 40% DIP (g):
Total dietary CP requirement, diet with 20% UIP and 80% DIP (% DM):
Total dietary CP requirement, diet with 40% UIP and 60% DIP (% DM):
Total dietary CP requirement, diet with 60% UIP and 40% DIP (% DM):

The calculations above were for no change in the body protein content other than possibly for gestation. However, often mature goats decrease in BW, such as with low feed availability during dry seasons. Similarly, after a period of appreciable BW loss, including proteineous tissue (lean) in addition to adipose (fat), with a higher nutritional plane BW and protein stores can be replenished. Therefore, this calculator also is fitted to estimate reduced maintenance MP needs during periods of BW loss as well as MP requirements for BW gain by goats, which does not pertain to pregnancy tissues. This is achieved by assuming 14.3% protein in tissue loss or gain, an efficiency of mobilized tissue protein for maintenance of 1.0 (AFRC, 1998). The requirement of MP for BW gain was determined by assuming 14.3% protein in tissue gained and an efficiency of MP use for tissue protein accretion of 0.59% (AFRC, 1998).

This calculation method was based on the following sources:

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

Luo, J., A. L. Goetsch, J. E. Moore, Z. B. Johnson, T. Sahlu, C. L. Ferrell, M. L. Galyean, and F. N. Owens. 2004. Prediction of endogenous urinary nitrogen of goats. Small Ruminant Research 43:293-308.

Moore, J. E., A. L. Goetsch, J. Luo, F. N. Owens, M. L. Galyean, Z. B. Johnson, T. Sahlu, and C. L. Ferrell. 2003. Prediction of fecal crude protein excretion of goats. Small Ruminant Research 53:275-292.

NRC. 1984. Nutrient Requirements of Beef Cattle, 6th edition. National Academy Press, Washington, DC.

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.