Nitrogen intake

In the net protein ratio (NPR) calculation (17), 15-day growth and protein intake data of animals on the PER diets were used. Nitrogen digestibility (percent of nitrogen intake absorbed) was determined on each animal on pooled data from the 8th through the 15th day of the PER test. 

A protein that is unduT7 rich in the ten essential amino acids would not provide sufficient nitrogen for other metabolic processes without obligatory catabolism of the essential amino acids. Thus, the proportion of the total nitrogen intake that essential amino acids form indicate how a given protein fulfills nutritional requirements for proteins. This proportion, the E/T ratio (54), indicative of the amount of protein nitrogen supplied by essential amino acids, is (in g of essential amino acids per g of nitrogen)... 

Calculate the net protein utilization (NPU), which is the proportion of nitrogen intake that is retained as is equivalent to BV x true digestibility, by comparing the carcass nitrogen content of a group of animals fed the test-protein diet to that of animals fed a zero-protein diet ... 

The effects of injury and corticoid administration on protein metabolism differ significantly in animals. The content of liver nitrogen is increased by giving cortisone to rats but fracture of the femur does not have this effect in spite of increased levels of cortisol in the blood (M13). The administration of cortisone has a constant effect on nitrogen balance at all levels of nitrogen intake whereas the catabolic response to injury is reduced or even abolished by diminished protein intake and weight loss prior to injury (M12). 

Dietary period (days) Daily nitrogen intake (g) Daily nitrogen output (g) Average daily nitrogen balance... 

The answer is c. (Murray, pp 123-148. Scriver pp 2367-2424. Sack, pp 159-175. Wilson, pp 287-317.) The daily intake of 62.5 g of high-quality protein is above the minimum daily requirement for a 70-kg adult (45 g protein per day). As the obligatory nitrogen losses are covered by the dietary intake, this man will be in nitrogen balance (i.e., 0) and nitrogen loss will equal nitrogen intake. 

Topping DC, Visek WJ. 1976. Nitrogen intake and tumorigenesis in rats injected with... 

Oukessou M, Toutain PL, Effect of dietary nitrogen intake on gentamicin disposition in sheep, J. Vet. Pharmacol. Ther. 1992 15 416-420. 

FIG. 2. Relative values of corn gluten meal (CGM), Mormon cricket meal (MCM), and CGM-MCM mixtures at 0, 50, or 95% of (Finke f <0.. 1987b). The 40% CGM-60% MCM protein mixture was used as the control (relative value = 100%). The relative values of the other proteins and protein mixtures were calculated as the nitrogen intake required to achieve a specific nitrogen gain for the control mixture divided by the intake required for the identical response by rats fed the test proteins. 

FIG. 5. Plots of /] and fz vs daily dietary protein nitrogen intake. The solid line represents casein, the broken line represents peanut protein, and the dashed tine represents wheat gluten. 

Humans require certain minimal quantities of essential amino acids from a biologically available source as part of a larger protein/nitrogen intake. The required amounts of these amino acids vary with age, physiological condition, and state of health. It is therefore important to be able to discriminate with both accuracy and precision the relative efficiency with which individual protein sources can meet human biological needs. This efficiency also has direct implications for the commercial value of the protein product [101,107]. 

A is the absorbed nitrogen F is the fecal nitrogen F-ki the metabolic nitrogen I is the nitrogen intake... 

Essential to all life processes is the supply of nitrogen. This supply is achieved by operation of the nitrogen cycle which utilises the vast quantities of the element available in the atmosphere. The natural cycle includes fixation, nitrification and denitrification processes, aU of which are carried out by the appropriate bacterial organisms (Figure 11.25). Plants can usually assimilate their nitrogen solely in the form of NH3 or NOf, while with higher animals at least some of their nitrogen intake must be in the form of amino adds supplied by food protein. 

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