Digestible crude protein

Rate of incorporation of feedstuff in the diet or dietary nitrogen content 

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The nitrogen value of feed materials represents the quantity of amino acids from dietary and microbial origin absorbed in the digestive tract It is expressed in digestible crude protein for the horse, called MADC (INRA, 1984 INRA, 1990 Tisserand and Martin-Rosset, 1996). 

Digestibility of nitrogen (Nd) in the digestive tract and calculation of digestible crude protein (MAD)... 

A pig was given 2.0 kg/day DM of a food containing 150 g/kg DM crude protein and excreted 0.4 kg/day DM of faeces containing 175 g/kg DM protein. Calculate both the DM and the crude protein digestibility and the digestible crude protein (DCP) content of the food. 

Crude protein is a measure of food protein calculated as nitrogen content multiplied by 6.25. Digestible crude protein is calculated as 6.25 times the difference between nitrogen intake and nitrogen voided in the faeces. 

For horses, evaluation of protein sources is based on crude protein or digestible crude protein. 

The net protein requirement for milk production is the protein content of the milk. Up to day 22 of lactation, the crude protein content of milk (g/kg) can be estimated as 10 X (3.43 - 0.066 d), where d = days in milk. After day 22, milk protein concentration is assumed to be 19.6 g crude protein/kg. Using an efficiency of utilisation of 50 per cent and a digestibility of 79 per cent results in a dietary crude protein requirement for milk production of approximately 50 g/kg milk. Previous protein requirements were based on digestible crude protein, but more recently NRC (2007) argues that the lack of information regarding digestible crude protein content of feed-stuffs commonly fed to horses does not justify its use, and that requirements should be based on dietary crude protein. The crude protein requirement (g/day) for maintenance is therefore calculated as 1.44 W and total requirements for milk production as CP requirement = 1.44W + 50Y. For a 500 kg mare producing 15 kg of milk, the daily crude protein requirement (g/day) is estimated as 720 + 750 = 1470. 

No. of samples Crude fibre (g/kg) Crude protein (g/kg) Digestible crude protein (g/kg) Metabolisable energy (MJ/kg)... 

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