Introduction

Sines amino acids are extensively metabolized (see Chapters 4 and 5), it is widely assumed that any surplus ingested by animals is disposed of without adverse effects. It has also been suggested that the ruminant is endowed with protective detoxification mechanisms by virtue of considerable microbial metabolism of amino acids within the rumen. However, there is now unequivocal evidence demonstrating that amino acids may precipitate profound deleterious effects in diverse classes of farm...

The Modelling of Dietary Amino Acid Utilization

Mathematical models which simulate the uptake, metabolism and partitioning of dietary nutrients, can be used ultimately to derive relationships between the monetary value of production and levels of nutrient intake for different types of pigs growing under different physical and financial conditions. Several biological models simulating growth in the pig have been developed and applied in commercial practice (Whittemore and Fawcett, 1976 Stombaugh and Oko, 1980 Moughan, 1981 Phillips and...

Factors Affecting Responses to Amino Acids

The responses of growing poultry to individual amino acids are influenced by a wide range of factors. These include environmental temperature, immunological stress, sex, age, species and several dietary factors. Critical evaluation indicates that these factors readily resolve into those that influence food intake and those that reduce efficiency of utilization of the amino acid in question. The distinction between the two categories of factors only emerges if responses are considered in...

References

Abebe, S. and Morris, T.R. (1990a) Note on the effects of protein concentration on responses to dietary lysine by chicks. British Poultry Science 31. 255-260. Abebe, S. and Morris, T.R. (1990b) Effects of protein concentration on responses to dietary tryptophan by chicks. British Poultry Science 31. 267-272. Alleman, F., Michel, J., Chagneau, A.M. and Leclereq, B. (1999) Comparative responses of genetically lean and fat broiler chickens to dietary threonine concentration. British Poultry...

Biosynthesis of Amino Acids and Nutritional Classifications

The title of this book now reflects the fact that, in addition to traditional farm animal species, additional chapters have been included to address the amino acid nutrition of cats and fishes. In light of this, it is necessary to revisit the classification of amino acids in the context of the physiological state of each species in question, the productive and health management goals and how this influences our nutritional decisions (see Chapter 1). There are 20 amino acids commonly found in...

Arginine Metabolism

Arginine has only comparatively recently emerged as an intriguing amino acid in animal metabolism. Following the establishment of its pivotal role in the urea cycle in the 1930s, arginine remained in the background for many decades. It was not until the 1990s that important developments were made with respect to its function as a precursor of polyamines and nitric oxide (NO). Many authors have yet to record these developments in their biochemistry textbooks. In the urea cycle (Fig. 4.2), the...

The relative quantitative importance of physiological processes underlying dietary amino acid utiliz

An important application of a model of amino acid metabolism is to provide a deeper quantitative understanding of the inherent metabolic and physiological processes. A model can be used to quantify the significance of different aspects of the growth process. Having broadly described the processes in protein metabolism, a mechanistic model, describing amino acid flow in the 50 kg live weight pig and embodying the concepts discussed in this chapter, is now applied to give an overall appreciation...

Amino Acid Composition of Microbial Protein

Formulation of non-ruminant diets for amino acid requirements is easier than that of ruminant diets since amino acid requirements of non-ruminant animals are provided only by dietary protein. In contrast, amino acid requirements of ruminants are met by a mixture of dietary protein and microbial protein. Briefly, the challenge is to predict (i) what the requirements of the animal are, and (ii) the amino acids available for absorption in the small intestine. Therefore, the amino acid composition...

Methionine and cystine

The methionine-sparing effects of cystine are well documented (Chapter 8). The methionine-cystine conversion is of practical importance since many feeds contain more cystine than methionine. Consequently, diets may be relatively high in total SAA but low in methionine. In assessing the extent to which cystine may spare dietary methionine requirements, it is important to ascertain whether values being considered are on a weight or molar basis. In addition, it is necessary to recognize that...

Efficiency of Dietary Protein Use for Wool Growth

The efficiency of utilization of dietary protein for ruminant livestock can be quantified using factorial analysis (Agricultural Research Council, 1984). The net efficiency for wool production is defined as the ratio of wool protein increment to the absorbed amino acids partitioned to wool growth. Absorbed amino acids for wool growth are calculated by subtracting the maintenance and weight gain requirement from the total absorption in non-reproductive animals (Standing Committee on Agriculture,...

Amino Acid Utilization by Sheep

Amino acid utilization by growing sheep is somewhat more difficult to assess than that by cattle because the impact of wool growth must be considered. Wool production represents an irreversible loss of amino acids which might otherwise be used for tissue deposition. Additionally, wool contains a high concentration of cysteine, and, as such, its production requires a large amount of sulphur amino acids, either as cysteine directly or as methionine for the production of cysteine. In a classic...

Animal Nutrition References

Agricultural Research Council (1981) The Nutrient Requirements of Pigs. Commonwealth Agricultural Bureaux, Farnham Royal. UK. Almquist, H.J. and Grau, C.R. (1944) The amino acid requirements of the chick. Journal of Nutrition 28. 32 5 33 X. Baker, D.H. (1997) Ideal amino acid profiles for swine and poultry and their applications in feed formulation. Biokyowa Technical Review 9, 1-24. Baker, D.H. and Han, Y. (1994) Ideal amino acid profile for broiler chicks during the first three weeks...

Branchedchain amino acids

The branched-chain amino acids continue to attract much attention as regards oxidation, molecular roles and dynamics. The catabolism of branched-chain amino acids (BCAA) is initiated by a reversible aminotransferase reaction (Chapter 4) leading to the formation of branched-chain keto acids (BCKA). These intermediates may then undergo irreversible oxidative decarboxylation to yield acyl-CoA compounds, with further catabolism occurring via reactions analogous to those in oxidation of fatty acids....

Adjusting animal and dietary factors to predict actual performance

The previous discussion indicates accurate prediction of energy and amino acid supply depended on prediction of NDF, starch, CP and protein solubility pool sizes and their digestion and passage rates, and microbial amino acid composition. Prediction of absorbed energy and amino acid requirements depended on accurate prediction of protein retained, amino acid tissue composition, and efficiency of use of absorbed energy and protein. We believe that with adequate feed com position values and...

NRC model

Rumen digestion of crude protein (CP), and protein available at the intestinal absorptive site as metabolizable protein (MP), is predicted using static equations in the NRC model (NRC, 2001). There are a number of required feedstuff chemical analyses and feedstuff biological determinations, as well as some characteristics of the animals to which the feedstuffs and ration are to be fed, that are required as model input. The process proceeds stepwise to create numerous empirical equations that...

Amino Acid Antagonisms

An amino acid antagonism may be defined as a deleterious interaction between structurally similar amino acids. This category of adverse effects was devised to accommodate the unique and separate effects of lysine and leucine in the rat. Demonstrations of antagonisms have been extended to farm animals (D'Mello and Lewis, 1970a,b,c Papet et al., 1988a). In addition, it is now recognized that antagonisms may be precipitated by a wide range of analogues occurring naturally in crop plants as...

Mediated Absorption of Free Amino Acids

What Foods Have Amino Acids

Molecular and functional properties of proteins capable of biochemically defined free amino acid transport 'system' activities As indicated in Fig. 3.1, the mediated absorption of free amino acids across both apical and basolateral membranes is critical to the assimilation of luminal proteins. Remarkably, within the last 12 years, cDNA have been generated that encode proteins for six anionic, four cationic, 11 neutral, and five neutral and cationic free amino acid transporters. Except for...

Mammary metabolism of amino acids

Precursors for milk protein synthesis The arteriovenous net balance technique has been used to monitor mammary uptake of AA. The ratio of AA removal to milk protein secretion has been used to indicate limiting AA. Based on this comparison, it would appear that valine, leucine, isoleucine, arginine, lysine and threonine are not limiting since their extractions generally exceed milk protein outputs. In vivo data have demonstrated that leucine and lysine, which are extracted in excess, can be...

Prospects for ruminally protected amino acids

The concept of balancing rations for swine and poultry with pure amino acids has been a part of commercial feed formulation programmes for many years. This has led to lower nitrogen levels of diets, improved efficiencies of nitrogen utilization and, in general, lower ration costs. However the use of pure amino acids in ruminant rations has lagged far behind. There are a number of reasons that commercial application of amino acid nutritional concepts to ruminant ration formulation has not...

Amino Acids

Semi Essential Amino Acids

Essential amino acids and synthesis routes of semi-essential and non-essential amino acids. Fig. 9.1. Essential amino acids and synthesis routes of semi-essential and non-essential amino acids. the ARC 1981 lysine was used as reference for the other amino acids. Tryptophan has also been suggested as a reference for the other essential amino acids NRC, 1988 . However, it is now generally accepted that lysine is most suitable ARC, 1991 NRC, 1998 . Some very good reasons for using lysine...

Hepatic metabolism

Having traversed the complexity of the gut, AA absorbed into the portal vein flow to the liver where they may be subjected to further metabolism. The liver is equally metabolically active as the gut, accounting for 25 of whole body oxygen consumption, even though the liver represents only 2 of body weight Huntington and Reynolds, 1987 . In dairy cows, up to 2000 1 Ir1 of blood passes through the liver Reynolds et al., 1988 . The liver serves a critical role in maintaining AA homeostasis and in...

Sulphur Amino Acids

Mimosine Metabolism The Ruminant

The sulphur amino acids of particular relevance here are methionine and cysteine. In proteins, 2 mol of cysteine may undergo oxidation to form a disulphide bridge, yielding another sulphur amino acid, cystine. Methionine plays a key role in metabolism as a donor of active methyl groups. It does so after conversion into S-adenosylmethionine. Following release of the active methyl group, S-adenosylhomocysteine is formed which may then undergo hydrolysis to produce homocysteine. The importance of...

Chromatographic separation and detection

Several recent review articles on amino acid analysis should first be mentioned here. Morr and Ha 1995 reported in general terms on analysis of protein and amino acids in food products, whereas Rutherfurd and Moughan 2000 focused on analysis of animal feeds. Molnar-Perl 2000 described chromatographic techniques for the determination of sugar, earboxylie acids and amino acids in foodstuffs and included references to techniques such as gas chromatography and capillary electrophoresis. Fekkes 1996...

Glucogenic and ketogenic amino acids

In the degradation of amino acids, the carbon skeletons follow distinct pathways see Chapter 4 . Those amino acids that are broken down to pyruvate or key intermediates of the tricarboxylic acid cycle have the potential to yield glucose via phosphoenolpyruvate. These amino acids are referred to as glucogenic. Those amino acids that yield acetyl CoA or acetoacetyl CoA are classified as ketogenic since the latter two compounds are the precursors of ketone bodies. Some amino acids are both...

Concept of providing amino acids during lactation ideal protein

As mentioned in Chapter 9, an ideal protein is the profile of amino acids that would be perfectly in 'harmony' with the pig's requirement that is a perfect balance. After Dr H.H. Michell at the University of Illinois developed the concept of ideal protein in the 1930s, there has been a large amount of research done to identify ideal protein in swine diets. The concept of ideal protein for lactating sows was understood and established more recently than those for pigs in other stages of life....

Transformation of apparent into true digestibility values

If one accepts that the determination of amino acid digestibility values should be based on the ileal analysis method, these digestibility coefficients should be consistent with two main specifications. First, they must allow feed ingredients to be accurately compared, thus being independent of experimental and dietary conditions. Secondly, they must include any variation of the endogenous fraction related to the feedstuff itself, which is one of its attributes and must be considered in diet...

Conclusions

The responses of growing poultry to individual amino acids may be determined empirically by the graded supplementation technique or by the diet-dilution method. Although initial evaluation procedures indicated considerable compatibility in growth responses derived by these methods, subsequent research revived the debate concerning the validity of the diet-dilution technique. It is a condition of this procedure that responses are not confounded by the unavoidable variation in protein contents of...

Net Portaldrained Visceral Flux of Amino Acids

Early research in dogs Elwyn et al., 1968 showed an increase in free amino acids appearing in hepatic portal blood during protein digestion following a meal. During the absorptive period, amino acids appearing in portal blood were similar in composition to those ingested with the meal, except that glutamic and aspartic acids, which were removed by the PDV, and lysine and histidine appeared in greater amounts. Interestingly, net portal absorption of total amino acids was greater than the amount...

Quantitative Amino Acid Requirements of Penaeid Shrimp

Successful studies have recently been completed on determining the amino acid requirements of penaeid shrimp Table 23.12 . Previous attempts to quantify the requirements had resulted in only limited success Deshimaru and Kuroki, 1974 Akiyama, 1986 . This was due primarily to the lack of a water stable diet that would resist leaching while being slowly consumed by the shrimp. Chen et al. 1992 were able to determine the arginine requirement by using a microencapsulated diet. Fox et a I. 1995...

Lysinearginine antagonism

The lysine-arginine antagonism provides a distinctive, but not unique, example of how one amino acid may reduce the efficiency of utilization of another. The results of one such study D'Mello and Lewis, 1970 are shown in Table 14.2. A basal diet marginally deficient in arginine but adequate in lysine was used. Addition of excess lysine to this basal diet to give concentrations of 13.5, 16.0 and 18.5 g kg-1, progressively reduced growth performance and enhanced the quantity of arginine required...

Contributors

Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK. Present address Department of Animal Science, Faculty of Agriculture, Canakkale Onsekiz Mart University, 17100 Canakkale, Turkey Baker, D.H. Department of Animal Sciences, University of Illinois, 132 Animal Sciences Laboratory, 1207 West Gregory Drive, Urbana, IL 61801, USA Baldwin, R.L. Department of Animal Science, University of California, Davis, CA 95616-8521, USA Bequette, B.J. Department of Animal...

Optimization of feed formulation

All diets for poultry and swine are today formulated to match the amino acid requirement of the species to achieve optimal growth and feed conversion. To do this the nutritionist needs reliable data on the amino acid composition of his feed raw materials. If NIR amino acid calibrations are available any quality fluctuations can be corrected by supplementation of amino acids. Due to the complexity and high cost of the technique, chromatographic amino acid analysis is usually not available to the...

Effects of Dietary Amino Acids on Carcass Composition

The effects of varying dietary concentrations of amino acids on body composition of growing poultry are imperfectly documented. However, the results of three studies indicated striking effects of dietary isoleucine and lysine on fat content of 3-week-old broiler chicks. Contrasting effects were observed, depending on the degree of deficiency of either amino acid Figs 14.18 and 14.19 . At very low levels of isoleucine or lysine, fat content was relatively low but this increased progressively...

Felinine

Felinine acid is a sulphur-containing amino acid present in the urine of certain members of the Felidae family including the domestic cat. Discovered by Datta and Harris 1951 , 24 h felinine excretion levels of entire male cats have been reported to be 25 mg kg-1 body weight whereas castrated male, entire female and spayed female cats excrete 8.5, 7.5 and 4.1 mg kg-1 body weight Hendriks et al., 1995 . Precursors of felinine synthesis were recently shown to include cysteine and methionine with...

Urea breakdown

Ammonia is formed extremely rapidly from the breakdown of urea in the rumen and can then be used for amino acid synthesis. This activity enables ruminants to utilize urea entering the rumen either with the feed Virtanen, 1966 Salter et al., 1979 Roffler and Satter, 1975 , or endogenous salivary secretion, or by diffusion across the rumen wall Kennedy and Milligan, 1980 . The enzyme mechanism is a simple hydrolysis by urease, which can be inhibited in vitro by acetohydroxamic acid Makkar et al.,...

Relationship of Methionine with Other Methyl Donors

In addition to its primary function as a constituent of proteins, methionine can be converted into S-adenosylmethionine and S-adenosylhomocysteine, as illustrated in Fig. 8.3. These reactions release a methyl group that is used in several metabolic processes, primarily DNA methylation and synthesis of carnitine from lysine, adrenaline from noradrenaline, and creatine from guanidine acetate Simon, 1999 . Thus, methionine is sometimes referred to as a 'methyl donor'. To regenerate methionine from...

Sex

The responses of male and female broilers to available lysine concentrations in the diet have been published by Thomas et al. 1977 . Viewed in terms of dietary concentrations of total lysine, two growth response curves are apparent Fig. 14.6 implying genuine differences in lysine utilization between males and females. Indeed, having arrived at this conclusion, Thomas et al. 1977 developed two regression equations for lysine requirements of male and female broilers. However, when the responses...

Phenylalanine

A relationship similar to that presented for methionine and cystine exists for phenylalanine and tyrosine, two important aromatic amino acids. Tyrosine is considered dispensable because it can be synthesized by the fish from the indispensable amino acid phenylalanine. If tyrosine is included in the diet, it reduces the amount of phenylalanine needed in the diet. Thus, fish have a total aromatic amino acid requirement. The phenylalanine or total aromatic amino acid requirement values for fish...

Requirement estimation from doseresponse experiments an empirical approach

The 'requirement' of an animal for a nutrient may be thought of as a point on a dose-response curve relating the level of intake of that nutrient and some measure of productivity of the animal or some indicator of metabolism. In the case of protein the 'requirement' is best considered as the requirement for individual amino acids rather than for the protein as a whole. Although accurate estimates of the amino acid requirements for growth in the pig are necessary for efficient dietary...

AE ratios and the ideal protein concept

Arai 1981 used A E ratios essential amino acid content total essential amino acid content including cystine and tyrosine x 1000 of whole body coho salmon fry to formulate test diets for this fish. Fish fed casein diets supplemented with amino acids to simulate the A E ratios of whole body tissue showed much improved growth and feed efficiency. Ogata et al. 1983 used A E ratios based on amino acid composition data from cherry salmon Oncorhynchus masou to design test diets for cherry salmon and...

Amino acids for mammary gland growth

The mammary glands are the key tissue organ that cannot be ignored in discussing lactating sows because of their metabolic importance in synthesizing and secreting milk that is directly related to litter weight gain and litter weaning weight. Mammary glands take up amino acids from the bloodstream, synthesize milk proteins and secrete milk to nursing pigs. Understanding the metabolism and biology of mammary glands is, therefore, a crucial initial point for improving reproductive performance of...

Threonine in broilers

For the essential amino acid threonine, there are not as much data available for response modelling. On the other hand, the commercial interest has increased considerably due to the availability of larger quantities of industrial L-threonine. Therefore, Fig. 25.7 displays another set of three experiments combined on a relative scale. Again, responses are non-linear and exponential functions fit the data well. Economic evaluations of these responses show a minimum feed cost per kg live weight...

Amino Acid Imbalance Definition

This term was defined by Harper 1964 as a change in the pattern of amino acids in the diet precipitating depressions in food intake and growth, which are completely alleviated by supplementation with the first-limiting amino acid. The prerequisite for a limiting amino acid may be satisfied by the use of a suitably deficient protein such as gelatin, but more generally this condition may be fulfilled by the use of low-protein diets. The definition of imbalance was devised as a result of...

Tryptophan Isoleucine Valine and Arginine

A semipurified diet Table 13.2 based on AA-fortified maize gluten meal CGM was developed in our laboratory Peter et al., 2000 for use in studying the requirements for several AA. True digestibility of AA was determined in the high-protein CGM sample used Table 13.3 , and the same sample of CGM was used for all AA bioassays. Using 10.7 g kg-1 digestible lysine as a requirement reference point Han and Baker, 1991, 1993 , the CGM basal diet was fortified with essential AA so that all essential AA...

Valine assay

Quadratic P lt 0.01 responses in weight gain Fig. 13.6 and feed efficiency occurred when graded doses 5.1-10.6 g kg-1 of digestible valine were fed Baker et al., 2002 . The broken-line digestible requirement estimates were 7.44 and 7.43 g kg-1 for weight gain and feed efficiency, respectively. The valine requirement 7.44 g kg-1 ratioed to the lysine requirement 10.0 Dietary digestible isoleucine g kg-1 Fig. 13.5. Fitted broken-line and quadratic plots of 13-day weight gain as a function of true...

Sensitivity of the CNCPS to various inputs

Priorities for research and routine feed analysis procedures that need to be implemented depend on cost to benefit ratios and the procedures available to measure sensitive variables. There is little value in developing more complex models for amino acid balancing until the first limiting factors can be accurately predicted. This was demonstrated when measured duodenal flows from 80 diets were not predicted as accurately with the dynamic, low level aggregation rumen model of Baldwin et al....

Prediction of Diet Amino Acid Balances Within the Structure of the CNCPS

The definition of a model by Gill et al. 1989 describes the CNCPS an integrated set of equations and transfer coefficients that represent the various physiological functions in cattle and sheep. Included are predictions of tissue requirements maintenance, growth, pregnancy, lactation and tissue reserves , and supply of nutrients to meet requirements feed carbohydrate and protein fractions, their characteristic digestion and passage rates, microbial growth, intestinal digestion and metabolism of...

Quality of Manure

Manure is a mixture of excreta urine and faecal matter . It is composed of undigested dietary components, endogenous components and products from indigenous microorganisms and the biomass of those microorganisms. Some odorous volatile components OVC , short-chain volatile fatty acids VFA , and other volatile carbon-nitrogen and sulphur-containing compounds from microbial fermentation in the GI tract can be emitted immediately. Others are emitted at various times after excretion. Around 200 or...

Amino Acid Toxicity

Unique toxic effects may be precipitated on feeding excess quantities of individual amino acids by virtue of their particular structural or functional properties. Benevenga and Steele 1984 reviewed the evidence derived principally from observations with laboratory animals. The acute growth depressions caused by excesses of some individual amino acids may be accompanied by profound and specific lesions in organs and tissues. Toxicities may also be demonstrated in farm livestock, and Baker 1989...

Valine

The valine requirement values of fish are presented in Table 23.6. There is reasonable agreement between the values reported for the species studied, indicating that the requirement ranges from about 30 to 40 g kg-1 of dietary protein. Studies showed that serum valine levels in the channel catfish responded to valine intake in a manner similar to that described for isoleucine Wilson et al., 1980 . Table 23.5. Leucine requirements g kg-1 of protein of various fish species. Table 23.5. Leucine...

Assessment of Amino Acid Needs of Growing Cattle

Several factors make straightforward approaches to the study of amino acid utilization by growing ruminants unsatisfactory. For responses to a single amino acid to be measured, that amino acid must be the sole limiting factor. Thus, the amino acid of interest must be deficient, but other nutrients, including other amino acids, must be supplied in adequate or excess amounts. Due to the synthesis of microbial protein in the rumen, it is difficult to supply adequate amounts of energy to the animal...

Establishment of the Ideal Dietary Amino Acid Profile for Pigs

Basically, it would be expected that sow's milk, which can be considered to be optimized for suckling piglets during evolution, would also provide the weaned piglets with an ideal amino acid profile. This assumption is supported by the fact that the profile is very constant in sow's milk and apparently not influenced by the dietary composition Boisen, 1997 . Furthermore, this composition is very close to the amino acid composition in the body as well as in the deposited protein during growth...

Net Portaldrained Visceral Flux of Peptides

Measurements of peptide and amino acid and other nutrients absorption and metabolism by tissues of the portal-drained viscera PDV gastrointestinal tract, pancreas, spleen and omental fat can be obtained using chronic indwelling catheters in animals which allows for simultaneous sampling of arterial and venous blood draining the PDV, or sections of the PDV, and measuring blood flow through the same tissues Reynolds, 2001 . Net rates of peptide or amino acid release or removal by the PDV or...

Empirical methods

The empirical method most commonly used to determine amino acid responses in growing poultry involves the addition of graded supplements of the amino acid under test to a basal diet deficient in that amino acid D'Mello, 1982 . These graded additions are accomplished with the crystalline form of the amino acid. A number of criteria must be fulfilled for satisfactory results. It is imperative that the basal diet is sufficiently deficient in the amino acid under investigation and that graded doses...

Optimum ET Ratio for Growth and Protein Deposition

Soon after experiments with purified diets had been started in the early 1940s, it became apparent that use of essential amino acids as a sole source of dietary N did not promote normal growth of rats Kinsey and Grant, 1944 or chicks Hegsted, 1944 Luckey et al., 1947 and that, to attain maximum growth rate, it was necessary to supplement the mixture of essential amino acids with one or several non-essential amino acids or another source of non-specific nitrogen Rose et al., 1948 Frost and...

Effect of ET Ratio on Protein and Amino Acid Utilization

In studies with isonitrogenous diets, the estimates of optimum E T ratios required for protein deposition did not differ from those for protein utilization Sugahara and Ariyoshi, 1968 Wang and Fuller, 1989 Heger et al, 1987, 1998 Gotterbarm et al, 1998 Lenis et al., 1999 . However, when essential N was held constant and E T ratio was altered by changing total dietary N, a considerably lower E T ratio was needed for maximum N reten tion than for optimum N utilization. Thus in rats fed on diets...

Black J. L. Robards G. E And Thomas R. 1973. Australian Journal Of Agricultural Research 24 399.

Adams, N.R., Liu, S.M., Briegel, J.R. and Greeff, J.C. 2000 Protein metabolism in skin and muscle of sheep selected for or against staple strength. Australian Journal of Agricultural Research 51, 541-546. AFRC Technical Committee on Responses to Nutrients 1993 Energy and Protein Requirements of Ruminants. CAB International, Wallingford, UK. Agricultural Research Council 1984 The Nutrient Requirements of Ruminant Livestock. Commonwealth Agricultural Bureaux, Slough, UK. Benevenga, N.J.,...

Second Edition

Formerly of the Scottish Agricultural College Edinburgh, UK CABI Publishing is a division of CAB International CABI Publishing CAB International Wallingford CABI Publishing 44 Brattle Street 4th Floor Tel 44 0 1491 832111 Fax 44 0 1491 833508 E-mail cabi cabi.org Tel 1 617 395 4056 Fax 1 617 354 6875 E-mail cabi-nao cabi.org CAB International 2003. All rights reserved. No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying,...

Improving Protein Efficiency

Reducing the contamination of soils, water and air caused by excessive build-up of animal wastes is now the priority of many nutritionists, land managers and lawmakers A recent evaluation of dairy farms in the eastern US states indicated that dairy farmers over feed protein by 7 , resulting in a 16 increase in urinary N excretion Jonker et ai, 2002 . The transfer of current nutritional information from research scientist to nutritionist to farmer may be the problem, but more than likely it...

Applications of the CNCPS model

One of the current concerns about academic research is that often it is not used by those who might benefit most from it. In part, this is because our usual products, journal articles, are not usually read by practitioners. When research data are incorporated into the CNCPS model, the information reaches the end-user, producers and nutrition consultants, quickly and in a form that is immediately useful. When the CNCPS model predictions do not agree with field observations, we usually get...

Difficulties in Defining Essential to Nonessential Amino Acid Ratio

Most of the disparity between published estimates of the optimum essential to non-essential amino acid ratios is attributable to the different ways of expressing the relations between the two amino acid groups, different classifications of amino acids with regard to their essentiality, and different methodological approaches. These issues are briefly discussed below. Expressing the relations between essential and non-essential amino acids There are various ways of expressing the relationships...

Free Aoac Methods For Analysis Of Animal Feed Premix

Albala-Hurtado, S., Bover-Cid, S., Izquierdo-Pulido, M., Veciana-Nogues, M.T. and Vidal-Carou, M.C. 1997 Determination of available lysine in infant milk formulae by high-performance liquid chromatography. Journal of Chromatography A 778, 235-241. Alb n, D.M., Wubben, J.E. and Gabert, V.M. 2000a Effect of hydrolysis time on the determination of amino acids in samples of soybean products with ion-exchange chromatography or precolumn derivatization with phenylisothiocyanate. Journal of...

Wet Chemical Analysis Sample preparation

The determination of amino acids requires the hydrolytic splitting of protein into its individual building blocks, which behave very differently during hydrolysis due to the functionality of the R side group. Asparagine and glutamine lose the amide residue in the side group and form aspartate and glutamate, respectively. The resulting ammonia can be determined chromatographically, but amino acid analysis always determines the sum Asx or Glx of these amino acid pairs. Tryptophan is largely...

The Limiting Amino Acid Concept and Modelling

It is not clear whether the relationship between AA supply and protein synthesis is simply a substrate effect or a reflection of regulatory events. Although acyl-tRNA are normally saturated in other tissues at prevailing intracellular AA concentrations Shenoy and Rogers, 1978 , the same does not appear to be the case for the udder Elska et ai, 1971 . If the tRNA-acylating enzymes are not saturated with AA under normal conditions, then provision of additional AA should result in an increase in...

Rumen fungi

The anaerobic fungi are an important component of the cellulolytic flora of the rumen Orpin and Joblin, 1997 . Ruminal fungi, unlike ruminal cellulolytic bacteria, are known to be proteolytic Wallace and Joblin, 1985 , which probably favours the disruption of the proteinaceous layer that prevents cellulolytic bacteria from gaining access to the secondary cell wall Engles and Brice, 1985 . Rumen fungi are able to grow in media lacking preformed amino acids and therefore must be able to form the...

Milkfish Amino Acid Requirements

Agricultural Research Council 1981 Protein and amino acid requirements. In The Nutrient Requirements of Pigs. Commonwealth Agricultural Bureaux, Farnham Royal, Slough, pp. 67-124. Akiyama, D.M. 1986 The development of a purified diet and nutritional requirement of lysine in penaeid shrimp. PhD dissertation, Texas A amp M University, College Station, Texas. Akiyama, T. and Arai, S. 1993 Amino acid requirements of chum salmon fry and supplementation of amino acid to diet. In Collie, M.R. and...