Protein required for maintenance

The protein requirements for maintenance adopted by CSIRO (2007) are based on ARC (1980), but they specify separate estimates for EUP and MFP and recognise that MFP varies directly with level of feeding. For B. taurus breeds of cattle, EUP is predicted as follows ... 

As indicated above, most of the protein systems for ruminants (see Chapter 13) used around the world base their estimates of protein requirements for maintenance on endogenous losses of nitrogen but use different factors to translate endogenous losses into dietary requirements. For example, using the UK metabolisable protein... 

Protein requirements for maintenance are estimated from endogenous urinary nitrogen and metabolic faecal nitrogen excretion. There are also small losses of nitrogen in hair and scurf. In ruminants the protein requirement for maintenance can generally be met by microbial protein synthesis. 

It is clear from the above that unlike in AFRC (1993), calculation of the protein requirement for maintenance is not possible unless the DM intake and predicted microbial protein synthesis in the rumen are known. In practice, most commercial dairy cow diets will result in a DMTP ranging from 1000 g/day to 1200 g/day, and a reasonable mid-point of 1100 g/day may be used if a computer rationing program is not available. The MP requirement for pregnancy, milk and body weight change in FiM are the same as that proposed by AFRC (1993). An example of a metabolisable protein requirement calculated according to FiM is provided in Box 16.7. 

The mare s protein requirement for maintenance is related to metabolic liveweight and breed. Production requirement depends primarily on stage of lactation. 

Wong, E. D., Wagner, J. A., Gorsich, S. W., McCaffery, J. M., Shaw, J. M., and Nunnari, J. (2000). The dynamin-related GTPase, Mgmlp, is an intermembrane space protein required for maintenance of fusion competent mitochondria. J. Cell Biol. 151, 341-352. 

Chizzotti, M.L., L.O. Tedeschi and S.C. Valadares Filho, 2008. A meta-analysis of energy and protein requirements for maintenance and growth ofNellore cattle. J. Anim. Sci. 86, 1588-1597. 

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