Review article
A MODEL FOR ESTIMATING PROTEIN VALUE OF RUMINANT FEEDINGSTUFFS: METABOLIZABLE PROTEIN
Darko Grbeša
; Agronomski fakultet Sveučilišta u Zagrebu, Zavod za hranidbu domaćih životinja, Zagreb, Republika Hrvatska
Abstract
Based on a review of present system of evaluation of protein value feedstuffs for ruminants, the exchange of the existing digestible crude protein system with metabolizable protein is suggested in Croatia. The method of evaluation follows protein metabolism in ruminants described as a model in AFRC (1992). Metabolizable protein (MP) is the unit of protein value of feedingstuffs consisting of in the small intestine digestible undegraded protein (DUP) and microbial crude protein (MCP). Synthesis of MCP is evaluated in two ways: (1) based on the effective degradable protein (EDP) and (2) the amount of fermentable metabolizable energy (FME) of feedstuffs. When the amount of synthesized MCP from EDP is – MCP from FME, then EDP = MGP and the reverse; that is valid for feedingstuff as a component of a diet. lf the ruminants are fed only single feedingstuffs (pasture) without supplements, then the value is lower. Rumen digest outflow rate (r = 0.R05/h) is constant because ruminants in Croatia are fed only forage of forage (r = 0.045) to concentrate (r = 0,058 ratio) 60:40% in diet DM, and r is 0.6*0.045+0.4*0.058 = 0.05; so the corresponding feeding level is not higher than 2x maintenance. The amount of FME (MJ/kg DM) = ME - (0.035xMEfat + 0.015 x UDP + MEferm) and synthesis of MCP (g/kg DM) = 10xFME (MJ/kg DM).Table of requirement coefficients (%) for calculation of MP is suggested: solubility of protein effective degradability of insoluble protein and acid detergent insoluble protein (indigestible undegradable protein) for common feedingstuffs in Croatia.
Keywords
Hrčak ID:
164813
URI
Publication date:
15.9.1993.
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