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Metabolizable Protein (MP) and Crude Protein (CP) Requirements for Maintenance and Growth of Growing Goats

(Meat, Dairy, and Indigenous)

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Use this Protein Requirement Calculator to calculate the daily protein requirement for young growing goats. Enter the data into the table below and then click the Calculate Protein Requirement button. If an estimate of DM intake is not readily available in order to determine the requirement as a percentage of the diet, requirements in g/day can still be derived. In addition, dry matter (DM) intake projections can be obtained from the Feed Intake Calculator. The results will be displayed in the table at the bottom of the page.

Example

We will use a 25-kg Spanish wether gaining 75 g/day with a DM intake of 3.25% of body weight.
1. Choose biotype of the goat meat, 50% or more Boer
dairy
indigenous or local
2. Enter body weight (kg)
3. Enter average daily gain (g/day)
4. Enter DM intake (% of body weight)
or

(maintenance energy based on body weight alone)
or

(adjusted maintenance energy)
To convert from English to metric system,
enter your values here.
They will be automatically entered into the table to the left.
BW
(lbs)
ADG
(lbs/day)

    

Our example would require a total of 56.1 g of MP (34.4 g for maintenance + 21.8 g for gain), and a 30-kg Boer wether gaining 125 g/day requires 89.9 g of MP (39.4 g for maintenance + 50.5 g for gain).

DM intake (kg):
MP requirement for maintenance (g):
Dietary MP used for maintenance (g):
MP requirement for growth or gain (g):
Total dietary MP requirement (g):
Total dietary MP requirement (% of DM intake):

Requirements for MP for maintenance and growth of growing (≤ 1.5 years of age) meat (50% Boer), dairy (selected for milk production, such as Alpine and Saanen), and indigenous or local goats were determined by multiple regression analyses (Luo et al., 2004). The maintenance requirement via this method (3.07 g MP/kg body weight0.75) is similar to that determined by the factorial approach for mature goats. There was a difference among biotypes in the MP requirement for gain or growth (0.409 g MP/g average daily gain for meat goats and 0.290 g MP/g average daily gain for dairy and indigenous goats). Thus, inputs necessary to estimate MP needs for maintenance and growth of growing goats are biotype, body weight (BW), and average daily gain (ADG).

Little research has been conducted regarding how body weight loss affects MP requirements. Nonetheless, with assumptions of AFRC (1998) regarding the protein concentration in live weight gain (Protein % = 15.722 - (0.069 x body weight in kg)) and an efficiency of use of mobilized tissue protein for maintenance of 1.0, estimates for BW loss can be derived.

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 examples above, the MP requirement for the Spanish wether, assuming DM intake of 3.25% of BW, equates to CP requirements of 83.5, 79.7, and 76.2 g, and 10.3, 9.8, and 9.4% of DM intake for diets with 20, 40, and 60% UIP, respectively. The MP requirement for the Boer wether, assuming DM intake of 3.5% of BW, equates to CP requirements of 133.8, 127.7, and 122.1 g, and 12.7, 12.2, and 11.6% of DM intake for diets with 20, 40, and 60% UIP, respectively.

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):

Sources for this calculation method are:

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

Luo, J., A. L. Goetsch, I. V. Nsahlai, T. Sahlu, C. L. Ferrell, F. N. Owens, M. L. Galyean, J. E. Moore, and Z. B. Johnson. 2004. Metabolizable protein requirements for maintenance and growth of growing goats. Small Ruminant Research 53:309-326.