Proteins nutritional requirements

Miller, E.L. (2004) Protein nutrition requirements of farmed livestock and dietary supply, in Protein Sources for the Animal Feed Industry, (ed. Changchui He), Publishing Management Service, Information Division, FAO. 

Nutritional Requirements. The nutrient requirements of mammalian cells are many, varied, and complex. In addition to typical metaboHc requirements such as sugars, amino acids (qv), vitamins (qv), and minerals, cells also need growth factors and other proteins. Some of the proteins are not consumed, but play a catalytic role in the cell growth process. Historically, fetal calf semm of 1—20 vol % of the medium has been used as a rich source of all these complex protein requirements. However, the composition of semm varies from lot to lot, introducing significant variabiUty in manufacture of products from the mammalian cells. 

When normal enteral feeding in not possible or is inadequate to meet an individual s nutritional needs, intravenous (IV) nutritional therapy or total parenteral nutrition (TPN) is required. Products used to meet the IV nutritional requirements of the patient include protein substrates (amino acids), energy substrates (dextrose and fat emulsions), fluids, electrolytes, and trace minerals (see the Summary Drug Table Electrolytes). 

Patient case A patient s daily nutritional requirements have been estimated to be 100 g protein and 2,000 total kcal. The patient has a central venous access and reports no history of hyperlipidemia or egg allergy. The patient is not fluid restricted. The PN solution will be compounded as an individualized regimen using a single-bag, 24-hour infusion of a 2-in-1 solution with intravenous fat emulsion (IVFE) piggybacked into the PN infusion line. Determine the total PN volume and administration rate by calculating the macronutrient stock solution volumes required to provide the desired daily nutrients. The stock solutions used to compound this regimen are 10% crystalline amino acids (CAA), 70% dextrose, and 20% IVFE. 

Soy Protein Concentrates. Both non-functional (low or no solubility) and functional (good solubility, emulsification capacity, and dispersibility) soy protein concentrates (70% protein, dry basis) are commercially available for use in meat products (2-4, 6, j), 15) Normally, a highly functional product with no harsh or bitter flavors is desirable. When used to replace lean meat, non-hydrated concentrate can be used at levels up to 6-7% in finished nonspecific emulsion meats Higher replacement levels or formulas with specific cost/nutrition requirements may use soy protein concentrate with a judicious amount of textured soy protein (6). Excellent yields, cost savings, texture, flavor and nutrient profiles are possible. However, most soy protein concentrates lack sufficient solubility or sufficiently low viscosities to be used in brines for absorption or injection into whole muscle tissue. When legal standards for protein content exist (13), more concentrate must be used to achieve legal minimums. Brine viscosities increase and uniform distribution of brine components throughout the specific whole muscle piece is restricted. Finished product appearance and flavor are easily compromised. Thus, use of soy protein concentrates in whole muscle applications is limited. 

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)... 

Animal feeds are a major market, especially for monogastric animals. This is because their nutritional requirements are high and the lysine content of traditional feed such as soy or maize is low. A supplementation of feeds with individual essential amino acids is necessary because a high protein contents lead to excessive manure production, especially by pigs. 

Biotin 515, 516,711, 721, 723 - 730,723s biosynthesis of 718, 745 in enzymes, table 724 mechanism of action 725 - 729 nutritional requirement 756 Biotin-binding proteins 728 Biotin carboxylase 724 Biotin carboxyl carrier protein 724 Biotin holoenzyme synthetase 724... 

The genetic manipulation of animal cells allows the production of therapeutic proteins in animal cell culture systems. Mammalian cells such as Chinese hamster ovarian cells and baby hamster kidney cells are commonly used. These mammalian hosts produce recombinant proteins that have almost identical properties to those made by human cells. However, the use of mammalian cells does have disadvantages. As noted earlier, they are expensive to use. This is influenced by their more complex nutritional requirements, their slower growth, and their increased susceptibility to physical damage (Walsh, 2003). 

Unstabilized bran and polish have been used almost exclusively for animal feed, due to the bitter flavor that develops from the lipolytic action of enzymes on the oil found in them. However, development of a thermal process that inactivates the lipases has resulted in a stabilized rice bran product that is suitable for the food industry. The impressive nutritional qualities of the oil, fiber, carbohydrate and proteins of rice bran have made it a valuable food material. Removal of fiber from the bran by physical K,J7or enzymic1819 processes produces a milk-like product having desirable nutritional and functional properties. The nutritional composition of the rice bran milk product described by California Natural Products has been shown to match the nutritional requirements of an infant formula. Originally, the anti-nutritional factor of the residual phytates was of concern. However, as of 2005, phytase enzymes are suitable for use to break down these phytates. 

We are concerned here with the enzymatic liberation of products that convert chemicals to less utilizable forms. The idea is to employ plant enzymes to strike directly at the insect s most critical needs, essential nutrients. In general, plant tissues are low in total nitrogen and pose a "nutritional hurdle" for insect herbivores (94). Plant proteins normally have low sulfhydryl and lysine content (95), which are nutritional requirements for insects (90,91). The nucleophilic properties of these limiting amino acids make them particularly susceptible to covalent binding by strongly electrophilic molecules such as o-quinones, hydroperoxides, ben-zoxazinones, and isothiocyanates formed in damaged plant tissues. 

Our results have been recapitulated with other proteins of varying nutritional value to S. exigua and H. zea they include soy protein, tomato foliar protein, corn gluten and zein. In all cases, more than 2.5% dietary protein was required to alleviate antinutritional effects, because these proteins are less nutritious than casein (Table III). The ability of a protein to alleviate the toxicity of o-quinones is proportional to its nutritional value to the insect (Table III). The proteins ability to function as an alkylatable sink (alleviation of antinutritive effects) is correlated with the relative amounts of alkylatable amino acids (e.g., lysine, cysteine, histidine, methionine Felton and Duffey, unpublished data). 

The digestion of heated or unheated soybean proteins by various enzymes is schematically compared with the nutritive values in Figure 18. Pattern A is typical of pepsin where, because of low pH of the reaction, the protein does not have to be denatured prior to addition to the reaction. Pattern B is typical of enzymes such as papain, bacterial neutral protease etc. where prior de-naturation of the substrate protein is required but there are no inhibitors of the enzyme present. Pattern C is typical of trypsin where prior heat treatment of the substrate protein is required to destroy inhibitors of trypsin as well as to denature the protein for digestion. The decrease in digestibility with prolonged heating in all three cases is due to modification of the substrate protein as described above. 

Ideally microbial cells should be consumable directly as food or food ingredients. However, because of their nucleic acid content the presence of undesirable physiologically active components the deleterious effects of cell wall material on protein bioavailability and the lack of requisite and discrete functional properties, rupture of cells and extraction of the protein is a necessary step. Importantly, for many food uses (particularly as a functional protein ingredient) an undenatured protein is required. For these reasons and for many potential applications of yeast protein(s) it is very desirable to separate cell wall material and RNA from the protein(s) for food applications. Much research is needed to develop a practical method for isolation of intact, undenatured yeast proteins from the yeast cell wall material to ensure the requisite nutritional and functional properties. 

To evaluate nutrition requirements, the reader needs a basic understanding of nutrients and the parameters that affect their needs. Nutrients are chemical substances needed to maintain life which are supplied to the body in food or drinks. The nutrients include vitamins, minerals, carbohydrates, fats, proteins, and water. These classifications of nutrients encompass approximately 45 different chemicals that are involved in every function or structure of the body. Wiile some of these functions that are directly influenced by exercise will be discussed in the subsequent chapters, a complete listing of these functions is beyond the scope of this book. For a more thorouc(i review of nutrient functions, the reader is referred to any one of a number of excellent nutrition references (5-6,15-16). 

The remainder of this chapter takes on a more "nutritional" aura, ft concerns the concepts of growth and maintenance- The material may be especially intcresling to those involved in infant nutrition, animal science, and weight reduction by low-energy diets. The material reveals the tecliniques used for determining the protein requirement and the recommended daily allow ancc (RDA) for protein. Clinical issues involving protein nutrition, such as renal disease and gput, arc also Outlined. 

A number of reviews have now appeared on the subject. It has been known since 1900 that differences exist between the intestinal flora of breast-fed babies and those fed on cows milk, the flora of the former being composed almost exclusively of L. bifidus. In 1926, it was shown that a growth factor for L. bifidus occurs, associated with the lactose fraction in whey, in human milk, but it was not found in cream, in the proteins, or in the inorganic material. Later the nutritional requirements of L. bifidus were reinvestigated and, in the course of this work, there was isolated, from the feces of infants, a variant of L. bifidus which gave only a scanty growth on the normal media, but which responded to the addition of human milk. This variant was named Lactobacillus bifidus var. pennsyl-... 

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