Utilization of Non-specific Nitrogen Sources
نویسندگان
چکیده
The rat repletion method of assay of protein value, developed by Cannon’s group at the University of Chicago (24), has been applied to liquid protein hydrolysates and amino acid mixtures in this laboratory (5, 6). The method has the advantage of convenient volumetric portioning of the amino acid components of the diet. With properly conditioned depleted animals, there is quantitative acceptance of liquid protein hydrolysates of high biologic value over a wide range of nitrogen intake; i.e., up to 400 mg. of N per rat day. Whole, dry, powdered proteins fed in cups separate from the non-protein diet are also quantitatively consumed, and provide convenient standards of protein value for comparison with amino acid solutions (7). In the present studies, solutions of ‘mixtures of pure amino acids were generally fed at a level to supply 100 to 120 mg. of available N per rat day. This is equivalent to approximately 1 per cent of N in the diet, or only about 6 to 7 per cent of protein. This level is well below the minimum level at which maximum growth responses are obtained even with proteins of high biologic value such as lactalbumin, whole egg, and fibrin, and is, therefore, highly critical with regard to limit.ing deficiencies of individual amino acids. Rose (8) suggested many years ago, and reemphasized recently, that it may be possible with the exact knowledge of individual essential amino acid requirements to devise mixtures of extraordinary value for parenteral hse. Such mixtures must obviously contain those eight amino acids which Rose has shown essential for maintenance of N balance in adult men. In addition, one must consider appropriate sources of nitrogen to supply the body needs for the non-essential amino acids plus other nitrogen metabolites ordinarily supplied by food. The eight essential amino acids account for only 40 to 50 per cent of the composition of proteins of the highest biologic value. The proteins of lower biologic value have an even lesser ratio of the essential to non-essential amino acids. The question arises, then, as to the optimum nutritive ratio between essential and non-essential
منابع مشابه
Effects of Two Sources of Tannins on Performance, Nitrogen Utilization and Efficiency of Microbial Nitrogen Synthesis in Dairy Goats
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متن کاملSynchronization of Energy and Protein on Supply Synthesis Microbial Protein
Synchronization of rumen available protein and energy is one of the conceptual methods to increase the efficiency of utilization of nutrients by the ruminants The concept of synchronization energy and protein was first by Jhonson, Implying that maximum microbial protein synthesis could be achieved by matching the rate of Organic Matter and protein degradation. Synchronization of rumen available...
متن کاملSynchronization of Energy and Protein on Supply Synthesis Microbial Protein
Synchronization of rumen available protein and energy is one of the conceptual methods to increase the efficiency of utilization of nutrients by the ruminants The concept of synchronization energy and protein was first by Jhonson, Implying that maximum microbial protein synthesis could be achieved by matching the rate of Organic Matter and protein degradation. Synchronization of rumen available...
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تاریخ انتشار 2003