Metabolisable Protein System

The UK metabolisable protein system divides the requirement of an animal into that which is required for supplying the needs of the rumen microbes and that which is required at tissue level. After estimating the contribution of microbial protein to satisfying this demand, the requirement for undegraded dietary protein is calculated. 

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... 

Using the AFRC (1993) system, calculate the metabohsable energy (ME) and metabolisable protein (MP) requirements of a 300 kg bull of large breed gaining at 1.1 kg/day. Assume that the animal s diet has an M/D value of 11.0 MJ/kg DM. 

Diet composition and dry matter intake were required to calculate metabolisable protein supply (i.e. the amoimt of AA absorbed in the small intestinal) using the INRA (1989) feeding system and expressed in PDIE (protein truly digestible in the small intestine as allowed by available energy in the rumen). By pass starch and total C3 produced in rumen were estimated using the INRA (1988) feed tables and the calculations of Rigout et al (2003) to compare the present response curves to this previous work. The molar proportion of C3 in the rumen reported in each publication on GN supply was required (Rigout et al., 2003). 

With the increased consumer concerns about the impact of animal production on the environment, more attention has been directed in recent years to the nitrogen (N) efficiency of dairy production. Proper determination of animal protein requirements and evaluation of protein supply, usually expressed as metabolisable protein (MP), are critically important for optimizing production with minimum N input in dairy production systems. Although, depending on the basal diet, increasing N input may produce an increase in milk protein yield (MPY), the efficiency of conversion of dietary N into milk protein will predictably decrease (Cohnenero and Broderick, 2006). Dietary CP... 

It is readily absorbed from the GI tract, 99% bound to plasma proteins, distributed into synovial fluid, the central nervous system, placenta and breast milk. It is metabolised in the liver to glucuronide conjugates, excretion of metabolites is predominantly in the urine with some amount appearing in the faeces. 

After oral administration it is absorbed almost completely but a large portion of the dose is metabolised in liver before reaching systemic circulation as a result the bioavailability of propranolol is reduced. It is highly bound to plasma proteins. 

Cohen and co-workers combined the unique characteristics of acetyl-dextran (Ac-DEX) and spermine with small interfering RNA - a class of double-stranded RNA molecules, 20-25 base pairs in length - as a delivery system. Ac-DEX possesses several characteristics suitable for the delivery of bioactive agents such as proteins. The novel system combined ease of synthesis and biocompatibility with the advantage of controlled release, i.e., sensitivity to physiologically relevant acidic conditions. Acid-catalysed hydrolysis of spermine-Ac-DEX generated spermine-modified dextran, which could be further metabolised in vivo by enzymes [13]. 

It is a reasonable assumption that transport systems arose before chemotaxis. The sharing of the binding proteins between an attractant chemo-sensor and the transport system for that ligand confers several benefits. Ability to move towards higher chemical concentrations is advantageous only if that compound can be efficiently transported and metabolised. The binding protein for a transport system would carry out the receptor requirement of an evolving chemosensor. 

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