Investigate the Magnitude of Differences on Total Metabolizable Protein among Different Genotypes of Barley Grown for Three Consecutive Years

Abstract

Several genotypes of barley have been developed by Crop Development Center. However, no quantitative evaluation of true protein supply to ruminants has been done in terms of protein degradation balance (PDB) and total metabolizable protein supply (or total truly absorbed protein in the small intestines). The objective of this study was to determine the magnitude of difference in terms of total metabolizable protein supply of five CDC feed-type barley cultivars in comparison to Canada’s most widely grown malting cultivar AC Metcalfe. Six, two row cultivars of spring sown barley, included AC Metcalfe, CDC Cowboy, CDC Dolly, CDC Helgason, CDC Trey and McLeod were grown in the research field of University of Saskatchewan, Saskatoon, SK, Canada for three consecutive years. The quantitative predictions were made in terms of: 1) Rumen synthesized microbial protein truly absorbed in the small intestine (AMCP); 2) Rumen undegraded protein truly absorbed in the small intestine (ARUP); 3) Endogenous protein in the digestive tract (AECP); 4) Total metabolizable protein supply in the small intestine. The results showed that CDC barley variety differed (P < 0.05) in AMCP ranging from 34 to 40 g/kg DMand AECP, but had no difference (P > 0.05) in ARUP with average of 48 g/kg DM. Total metabolizable protein ranged (P < 0.05) from 85 to 92 g/kg DM. In conclusion, CDC barley variety affected total predicted metabolizable protein supply, but not to large extend. All the barley varieties had negative degraded protein balance value.

Abbreviations

ADIP:

Acid detergent insoluble crude protein

AECP:

Endogenous protein in the digestive tract

AMCP:

Rumen synthesized microbial protein truly absorbed in the small intestine

ARUP:

Rumen undegraded protein truly absorbed in the small intestine

CP:

Crude Protein

D:

Potentially degradable fraction in situ

ECP:

Endogenous protein

EDCP:

Effective degradability of crude protein in situ

Kd:

Protein degradation rate in situ

Kp:

Protein passage rate in situ

MCPEDCP:

Potential Rumen synthesized microbial protein based on effective degradability of crude protein

MCPTDN:

Potential Rumen synthesized microbial protein based on total digestible energy

MCPSupplied:

Rumen synthesized microbial protein supply

MP:

Metabolizable protein

NDIP:

Neutral detergent insoluble crude protein

NPN:

Non-protein nitrogen

PA:

Fraction of CP that is instantaneously solubilized at time zero

PB1:

Fraction of CP that is soluble in borate-phosphate buffer and precipitated with trichloroacetic acid

PB2:

Calculated as total CP minus the sum of fractions PA, PB1, PB3 and PC

PB3:

Calculated as the difference between the portions of total CP recovered with NDF and ADF

PC:

Fraction of CP recovered with ADF and is considered to be undegradable. It contains proteins associated with lignin and tannins and heat-damaged proteins such as the Mailard reaction products

PDB:

Protein degradation balance calculated based on data from NRC 2001 model

RUCP:

Rumen undegradable feed protein

RUCPDVE:

Rumen undegradable feed protein estimated according to the DVE/OEB system

S:

Soluble fraction in situ

SCP:

Soluble crude protein

TP:

True Protein

U:

Undegradable fraction in situ

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Correspondence to Peiqiang Yu.

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Hart, K.J., Rossnagel, B.G. & Yu, P. Investigate the Magnitude of Differences on Total Metabolizable Protein among Different Genotypes of Barley Grown for Three Consecutive Years. CEREAL RESEARCH COMMUNICATIONS 40, 405–412 (2012). https://doi.org/10.1556/CRC.40.2012.3.9

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Keywords

  • total metabolizable protein
  • barley
  • genotypes
  • plant protein
  • ruminants