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Least cost feed rations on your personal computer

Wed, 28 Jul 2010 21:38:00 +0000 — Wed, 28 Jul 2010 21:38:00 +0000

Mathematical programming models are routinely used to calculate everything from minimum-cost feed rations to scheduling plane flights and blending petroleum products in refineries. A revolution in the software necessary to solve these powerful models has occurred in the past couple of years. Now anyone owning the latest version of most commercial spreadsheets such as Microsoft Excel or Quattro Pro has computational power which only Fortune 500 companies possessed a decade ago. Putting this enhanced computational power to work, however, requires the ability to put together a useful mathematical programming model. All mathematical programming models have two critical elements: something to be maximized or minimized, and constraints or limitations which reflect production requirements and the availability of resources. In the minimum- cost feed ration, the costs of mixing a nutritional feed are minimized. The constraints in the feed mix problem are the nutritional requirements necessary to maintain good health and assure weight maintenance or gain. Once the objective to be maximized or minimized is identified, the constraints or limitations directly affecting the objective must be recognized. Most constraints identify scarce resources and biological, physical, or financial requirements. Scarce resources are often easily recognized. In a grazing operation, the extent of available range land limits the number of head that can be grazed. The number of acres a farmer owns and leases limit the area planted in crops. Biological, physical, and financial requirements are sometimes more difficult to quantify. Finding the nutritional requirements for targeted weight gain may not be easy. Determining the proper fertilizer dosage for the targeted yield may require some searching. A SIMPLE EXAMPLE Most real life problems involve many complex interrelationships. The simple example presented here should give you an idea of the kinds of problems which could be solved. The details of the example are necessarily simplified. The problem is the classic feed mix problem. The objective is to find a feed formulation that meets given nutritional requirements at minimum cost. Our possible ingredients are hay, corn, barley and meal. Their nutritional analysis is as shown in the spreadsheet table below. The hay used for this simple example is assumed to have 15 percent protein and 50 percent TDN by weight. The nutritional analysis for corn, barley and meal are 8, 7, and 40 percent protein and 85, 78, and 75 percent TDN, respectively. A simple spreadsheet can be set up to calculate the protein energy and cost of any possible ration by simply defining the appropriate formulas for the ration column. If % protein is in A2 then a formula of: (B2*B$5+C2*C$5+ D2*D$5+E2*E$5)/F$5 will define the % of protein in the ration and if copied down will mutate to define the % energy and cost per pound as well. The pounds in ration (F5) is simply the sum of the pounds of each individual ingredient, i.e., (B5+C5+D5+E5). Once you have this simple spreadsheet set up you could then simply try different combinations of ingredients until you found a combination of ingredients that met the nutritional requirements at a reasonable cost. Such a solution is shown in the above table. However, this brute force approach might take a fair amount of time. A much better way is to use the “solver” option of your spreadsheet. The mechanics of using this option in Microsoft Excel are as follows: (other brands of spreadsheets with solver options have very similar mechanics) 1. Set up your spreadsheet to calculate the necessary values, as described above. 2. Choose the Solver Option from the menu. 3. Enter the cell you want to minimize in the Set Cell Box (F4, ration cost per pound). 4. Click on the Minimize Button. 5. Enter the cells you want to solve for in the By Changing Cells Box (B5:E5, the pounds of possible ingredients). 6. Add the following constraints by clicking on the Add Button: F2 > = .12 (Protein level must be greater than or equal to 12 percent) F3 > = .60 (Energy level must be greater than or equal to 60 percent) F5 = 100 (You want to mix 100 pounds of ration) B5:E5 > = 0(Negative weights are hard to measure out in formulating a ration. This insures only positive or zero values) At this point, you have told the computer what cell describes your objective function (F4). You have given it instructions to minimize this value subject to a set of constraints by varying the amount of the various ingredients in your ration. Click on solve and the computer should return the following results. As you can see, the computer found a cheaper ration meeting all requirements than was found by simply fiddling with the original spreadsheet. Further, additional information is available in the form of a sensitivity report. What is a Reduced Gradient or a Lagrange Multiplier? These terms are just techno babble for expressing what happens if you make a small adjustment to the optimum solution the computer found. For example, if you were to add one pound of meal to the solution and let the computer recalculate the ration so that the original constraints were still met the cost per pound of this modified ration would be .000732134 $/lb higher than the original ration. Adding a pound of corn would increase the cost even less. If instead of adjusting the ingredients you made small changes in the constraints the Lagrange multipliers indicate how the optimum cost would change. For example a small increase in the protein requirement (say to 12.1 percent) would not change the cost at all. This is because the optimal solution already has more than 12.1 percent protein. A larger change to any value above 12.4 percent would increase the cost and the model would need to be re-optimized to calculate the new optimum and its associated new sensitivity values. Increasing the energy requirement to .61 percent would raise the ration cost .001071 $/lb. (We raised the constraint by .01 units so we must multiply the Lagrange multiplier by .01.) Could this mathematical modeling stuff be of any real use on a ranch? Is it as easy as the simple model above? The answer to the first question is yes. The simple ration mix problem might even be useful on your ranch. The answer to the second question is Nope. Even the simple ration problem becomes more complex in reality. For example, are the analyses based on dry matter weights or at the feed scale weights? How many different ingredients are reasonable to consider? Most importantly, how should I decide on what the protein, energy, minerals, etc. content of the ration should be. The bottom line is that the current high end spreadsheets have capabilities to help you think about and solve some of the management problems common in ranching today. by Russell Gum and Gary Thompson - Arizona Cooperative Extension

Dietary protein – from amino acid supply to bioactive peptides

Tue, 27 Jul 2010 07:27:00 +0000 — Tue, 27 Jul 2010 07:27:00 +0000

The word protein is derived from the Greek proteios, meaning primary or foremost. This is fitting in that proteins, being the molecular instruments through which genetic information is expressed (one gene – one enzyme), are central to the life process. There is a huge diversity of proteins. The key to the structure of different proteins is the group of relatively simple building block molecules, the amino acids. It is indeed remarkable that the cell can join what is a relatively small number of amino acids in many different combinations and sequences, yielding either peptides or proteins having strikingly different properties and activities. Over the years, research in animal nutrition has moved from describing the protein content of feedstuffs to the amino acid content, through to the absorption and metabolic utilisation of amino acids. Recently, attention has turned toward describing peptides that can be derived from food proteins during natural digestion. As is true for the remarkable diversity of protein types, there is also a plethora of these peptides, many of which have quite potent activity and significant biological roles. In this chapter, I intend to draw largely upon results from my own laboratory at Massey University, New Zealand in an attempt to highlight developments in amino acid and peptide nutrition. Current understanding on how to describe the amounts of amino acids in diverse feedstuffs and their ‘availability’ to monogastric animals will be outlined, leading on to a discussion of bioactive peptides, which is an area that may very well herald a ‘new frontier’ in animal research. Dietary amino acid supply AMINO ACIDS IN FEEDSTUFFS As late as the 1960s it was still common to find compounded diets for the growing pig formulated on the basis of total crude protein. With the more widespread use of chromatographic techniques, however, formulation on the basis of gross amino acid contents became more common, such that by the late 1970s diets were almost exclusively formulated with regard to gross amino acid content. The work of W.C. Rose and co-workers in the early 1950s led to the definition of essential (indispensable; must be ingested) and non-essential (can be synthesised in the body) amino acids. Consequently, much emphasis has been placed on the essential amino acids considered to be the most limiting in formulated diets. More recently, however, the essential/ non-essential classification has been queried, as it does not allow for gradations of essentiality brought about by different physiological circumstances, and the distinction is highly dependent upon the criteria of evaluation. If, for example, maximum growth rate is taken as a criterion, then glycine and proline may be considered ‘essential’ for young avian species. Another example, is that cysteine may be considered ‘essential’ in the human infant as the trans-sulphuration pathway is poorly developed. These considerations have led to a proposed reclassification (Reeds, 1990) to include as many as four different categories of ‘essentiality’. Such a change in thinking has led to more studies into the individual properties of specific amino acids. This has led to major findings, such as the effect of tryptophan on food intake, the role of glutamine as a preferred gut metabolite, or the role for taurine in infant nutrition. As our understanding of the metabolic roles of individual amino acids increases, opportunities will present for nutraceutical solutions for both animals and humans. Studies at my own Institute have recently centred on the sulphurous amino acid felinine, a unique metabolite found only in members of the cat family (Felidae). Curious as to the biological role for and the nutritional significance of felinine, we undertook to review current knowledge on the compound (Hendriks et al., 1995a) and to set up an HPLC analytical procedure. In attempting the latter, we found that several published chemical synthesis procedures for felinine actually produce an amino acid isomeric with felinine, but not felinine itself. This finding casts doubt over much of the published information on felinine and has opened the door for a re-definition of its metabolism and physiological roles. Moreover, a new high-yielding method for the synthesis of felinine (Hendriks et al., 1995b) has been developed. Our work has demonstrated (Figure 1) a sex-linked and very high excretion of felinine in the urine of the domestic cat. Such a rate of excretion has nutritional implications, with felinine excretion in the tom cat accounting for around 30% of dietary sulphur amino acid requirement. The presence or absence of this amino acid in urine can also be used to reassess phylogenetic relationships within the cat family. Some of our preliminary data are shown in Table 1. There is currently much speculation as to a biological role for felinine. Perhaps it is involved in the regulation of sterol metabolism or it may have a pheromonal role. Our studies of felinine are on-going and seek to elucidate a biological function. Such information could lead to the development of new biotechnology products for the companion animal industry. Figure 1. Mean 24 hr excretions of felinine in entire male, castrated male, entire female and spayed female cats (from Hendriks et al., 1995c). Table 1. The detection of felinine in the urine of Felidae. 1Unpublished data, The assistance of the Auckland, Wellington, Melbourne, Adelaide, Antwerp, Rotterdam, Amsterdam, Rhenen, Cincinnati, Paris, San Diego and Singapore Zoological Gardens is acknowledged. Advances in the chemical analysis of amino acids have been the subject of recent review (Williams, 1994; Rutherfurd and Moughan, 2000). While some refinements have occurred, the essential preferred methodology has not changed greatly over the last few decades, and during this time masses of information on the gross amino acid contents of feedstuffs have accumulated. Such data sets have served to highlight the considerable degree of variation in amino acid content that exists even within well-defined feedstuffs. Figure 2 provides an example illustrating significant variation in the lysine content of soyabean meal, even when differences in crude protein content are taken into account. Also, and particularly for the amino acid lysine, it has been known for some time that when protein sources have been subjected to processing, conventional estimates of lysine content may considerably overestimate lysine present in the feedstuff in a chemical form that can be utilised by the animal (Tables 2 and 3). For such feedstuffs, assays such as Carpenter’s fluoro dinitrobenzene (FDNB) lysine have provided invaluable data on the ‘available’ lysine content. Figure 2. Soyabean meal lysine content in crude protein (% Lys in CP) (Adapted from Gill, (2000). Table 2. Total lysine and ‘available’ (FDNB-reactive)1 lysine in 12 samples of meat and bone meal. 1Fluorodinitrobenzene lysine; Carpenter’s Method. – adapted from Moughan et al. (1989) with permission of the Society of Chemical Industry. Table 3. Total lysine and ‘available’ lysine (FDNB – reactive)1 contents of soyabean meal extruded at different temperatures (T) and moisture levels (M). 1Fluorodinitrobenzene lysine; Carpenter’s Method. – adapted from Hendriks et al. (1994). Absorbed amino acids Whereas the formulation of diets based on gross amino acid content was a major advance over crude protein, so too was a move in the early 1980s toward formulation based on digestible amino acids. Not only does amino acid content of feeds vary, but also amino acid digestibility varies, often quite markedly, both within and across feedstuffs. Traditionally, amino acid digestibility measurement was based on analysis of the faeces or in the chicken, excreta. However, and because of the profusion of microorganisms in the hindgut that metabolise protein entering from the small intestine, faecal output does not accurately reflect the excretion of unabsorbed dietary and endogenous (of body origin) amino acids. It has been estimated (Mason, 1980) that 80% of the nitrogen present in the faeces of the pig is of bacterial origin. Similar estimates have been made in the chicken and other animals. In fact, faecal protein bears little resemblance to undigested dietary material. The flow of amino acids at the terminal ileum is more representative of the unabsorbed dietary amino acid flow; and development of ileal digestibility measures has been another milestone in animal nutrition. Generally, faecal digestibility is considered to overestimate the actual digestibility of dietary protein in simple-stomached mammals and birds (Table 4). Moreover, ileal amino acid digestibility coefficients have been shown in a number of studies to provide suitably accurate data for the purposes of practical dietary formulation. Little is known of the potential effect of microorganisms present in the upper tract on the derivation of ileal digestibility coefficients; and this is a topic urgently requiring investigation. When dietary amino acid digestibility is determined at the end of the small intestine, it is important that correction is made for the endogenous amino acids, as endogenous protein makes up a sizeable proportion of the protein present in ileal digesta. Major strides have been made in the technology of determining ileal endogenous amino acid flows and these have been the subject of recent review (Moughan et al., 1998; Hodgkinson and Moughan, 2000). True ileal digestibility (whereby correction has been made for the endogenous component) is now well established as a preferred method for describing the uptake of dietary amino acids from the digestive tract. Table 4. Comparison of the ileal and faecal digestibility of dietary protein for the chicken and several simple-stomached mammals. From Moughan and Donkoh (1991). 1Piglets (6 kg) fed bovine milk (Moughan et al. 1990). 2Pig (45 kg) given meat and bone meal based diet (Moughan et al. 1984). 3Milk fed calf (45 kg) (Moughan et al. 1989). 4Adult human (65 kg) consuming a meat, vegetable, cereal, dairy product diet (Moughan and Rowan 1989). 5Overall mean amino acid digestibility for 9 amino acids and 16 diets given to 10 week old chickens (Raharjo and Farrell 1984) and based on a collection of ileal digesta or excreta. 6Rat (80 g) given a meat and bone meal based diet (Moughan et aI. 1984). A matter not widely appreciated is that for feedstuffs that have been subjected to processing or storage, (and with consequent chemical change of the constituent amino acids) the conventional ileal amino acid digestibility assay should not be expected to be accurate (Moughan, 1991; Moughan et al., 1991). This is well exemplified for lysine. During amino acid analysis whereby protein is hydrolysed with strong hydrochloric acid, early Maillard compounds are known to partially revert to lysine. Such reversion does not occur, however, in the animal’s alimentary canal during gastric digestion. Consequently, estimates of dietary and ileal digesta lysine will be in error leading to biased ileal digestibility coefficients. Although, and at least for lysine, structurally unaltered molecules can be accurately determined chemically (e.g. FDNB lysine assay), there is evidence (Hurrell and Carpenter, 1981) that the unaltered or chemically available molecules may not be fully absorbed from the damaged proteins. The absorption (measured at terminal ileum) of reactive lysine has been determined in a recent study (Moughan et al., 1996) with the growing pig (Table 5). A casein-glucose mixture was heated to produce early Maillard compounds, and the amount of epsilon-n-deoxy-fructosyl-lysine (blocked lysine) and lysine regenerated after acid hydrolysis in the resulting material was calculated from the determined level of furosine. The amount of unaltered or reactive lysine was found by difference between the total lysine (acid hydrolysis) and regenerated lysine. The FDNB method allowed accurate assessment of the amount of chemically reactive lysine, which was grossly overestimated by conventional amino acid analysis (acidhydrolysed lysine), but the reactive lysine was not completely absorbed. Table 5. Amounts of acid-hydrolysed lysine, FDNB lysine, reactive lysine and absorbed reactive lysine in a heated casein-glucose mixture. 1After conventional amino acid analysis. 2FDNB = fluorodinitrobenzene. 3Lysine units remaining chemically reactive after heating, determined from furosine levels. 4Reactive lysine absorbed by the end of the small intestine. Moughan and Rutherfurd (1996) have developed a new digestibility bioassay to circumvent some of these problems. The new assay places emphasis on determining the uptake of chemically available lysine molecules from the gut, rather than the earlier preoccupation of trying to describe the uptake and utilisation of chemically altered lysine. With the new assay, the feedstuff (in its natural state) is fed to the test animal and samples of ileal digesta are collected. The reactive lysine in samples of the feedstuff and digesta are then determined after reaction with the agent o-methylisourea under controlled conditions by analysing the diet and digesta for the amino acid homoarginine. The true ileal digestibility of ‘reactive lysine’ is then calculated. The new bioassay has been shown to be more accurate than assays based on conventional amino acid analysis as an indicator of digestible reactive lysine (Rutherfurd et al., 1997a). Overall for processed feedstuffs, digestible reactive (available) lysine will be overestimated using the conventional approach. (Table 6). Table 6. Values for ‘available’ lysine (g/kg sample) in heat processed feedstuffs as determined conventionally or using a new (digestible reactive lysine) assay. From: Rutherfurd et al., 1997b. Over the years, much progress has been made in allowing a description in feedstuffs of the amino acids available for fuelling metabolism within the animal. Attention now needs to turn toward adapting these baseline assays to allow rapid, real time measurement of amino acid availability. In this way, considerable further cost savings can be secured. Bioactive peptides – a potential new frontier in biotechnology Recently, an exciting new era in protein research has emerged. This has come about from a realisation that during the digestion of proteins in the alimentary canal, variously sized peptides are released that have a wide range of physiological effects. Food proteins contain sequences of amino acids that are cleaved free during enzymatic digestion and then may be resistant to further breakdown. These peptides may act locally in the gut, or be absorbed and act systemically, to bring about a wide range of physiological effects. It is now known that there are many such peptides (often referred to as bioactive peptides) released during the digestion of food, but our understanding of these peptides and their effects is really still very limited. Most research to date has investigated milk proteins and numerous bioactive peptides have been identified. Other food proteins, although not yet widely studied, are also known to contain biologically active amino acid sequences. Bioactive peptides have been shown to elicit behavioural, hormonal, immunological, neurological, vasoregulatory and nutritional responses in animals. It has been clearly demonstrated that peptides generated from casein, lactoferrin and ß-lactoglobulin are able to effect a range of responses such as ACE inhibition (casokinins), antimicrobial activity (casecidin, lactoferricin), anti-thrombotic activity (casoplatelins), calcium absorption (caseinphosphopeptide) and immunomodulatory activity (casein, whey and lactoferrin hydrolysates). Moreover, effects on food palatability, gut function and the digestive processes have also been documented. Bioactive peptides are not only released naturally during digestion, but are also present in commercially produced protein hydrolysates. Thus there is a significant opportunity for the biotechnology industry to produce crude hydrolysates or semi-purified hydrolysate fractions that may be used to support more efficient animal production. Commercial peptides (eg. casein derived phosphopeptides) are already being used as food supplements (Meisel, 1997a) and the pharmacological application of peptides has been investigated. As the research sector progressively screens the potentially enormous range of protein hydrolysates and unravels their physiological influences, there will be an opportunity for the biotechnology and feeds industries to capitalise on the knowledge generated and to produce innovative products. Early results are promising, and given the ubiquity of protein sources, the biotechnology industry faces a significant new frontier and what appears to be a major opportunity. For the feeds industry, immune enhancement and antibiotic activity are properties of bioactive peptides that would appear to hold immediate promise for commercial exploitation. Documented effects on food palatability and the control of the digestive process are also highly relevant in practice but may present a somewhat longer-term opportunity. The immunostimulatory and antimicrobial properties of various milk-derived bioactive peptides have been reviewed in detail (Meisel, 1997b; Xu, 1998; Clare and Swaisgood, 2000). A peptide from trypsin hydrolysed milk has been shown (in vitro) to stimulate the phagocytosis of sheep red blood cells by murine peritoneal macrophages and to enhance the resistance of mice to Klebsiella pneumoniae infection when given intravenously. A peptide from casein has shown protective action in mice against Staphylococcus aureus and Candida albicans. The same peptide has been shown to safeguard sheep and cows against mastitis when injected into the udder at levels comparable to those observed with standard antibiotic treatment. Current work from our own laboratory with rodents confirms the immunomodulatory activity of hydrolysates. Recently, Donnet-Hughes et al. (2000) have reported that Transforming Growth Factor (TGF-ß), polypeptides occurring naturally in milk, are effective in inducing remission and mucosal healing in patients suffering from Crohn’s disease. Direct evidence in the literature that orally administered casein-derived casomorphins are able to regulate gastrointestinal motility, affect the rate of gastric emptying and exert anti-diarrhoeal action, has led our research group to investigate the effects of food derived peptides on digestive function in general. Already, our work has confirmed the earlier findings of others that the rate of gastric emptying can be influenced by the oral ingestion of peptides. Moreover, and of considerable interest, have been the results from a number of experiments in the pig and other simple-stomached animals clearly demonstrating an effect of protein hydrolysates on overall gut protein dynamics as measured by the flow at the terminal ileum (ileal flow) of endogenous nitrogen or amino acids. It seems that dietary peptides influence gut protein secretory activity and/or endogenous amino acid absorption, leading to a substantial net increase in endogenous protein entering the large bowel from the small intestine. Such an effect has implications for dietary amino acid and energy requirements (leading to heightened requirements), to overall productive efficiency and to optimising digestive function. Identification of the active peptides and the gut processes affected offers promise for means of manipulating the physiological processes at play. Intriguingly it appears that the breakdown products of dietary proteins themselves may assist in regulating the digestive processes. The influence of dietary peptides on endogenous ileal amino acid flow is highlighted by the data presented in Tables 7 and 8. The results shown in Table 7 are from a study (Darragh et al., 1990) in which the endogenous ileal flows of serine, glutamic acid and alanine were determined in the growing rat given a semisynthetic diet where the sole source of nitrogen was either an hydrolysate of casein or synthetic amino acids. The animals also received a nitrogenfree diet as a control. The animals receiving the synthetic amino acid-based diet were in positive body nitrogen balance and the gut cells received a supply of dietary amino acids. In spite of this, the net endogenous amino acid flows at the end of the small intestine were no higher than those found for animals receiving a diet completely devoid of nitrogenous material. However, the presence of dietary peptides in the gut brought about a very sizeable increase in net unabsorbed endogenous ileal amino acids. It is concluded that the peptides derived from casein have a major effect upon overall gut protein dynamics. It would appear that the peptides have a quantitatively significant influence on the secretory and absorptive processes. The comparable results shown in Table 8 are from a similar study (Butts et al., 1993) in the growing pig and it is now also established that this effect of peptides is dose-dependent (Table 9). Clearly, given the quantitative importance of gut protein dynamics in overall body protein metabolism (Moughan, 1999), there are opportunities here to manipulate the gut processes. One can imagine, for example, enhanced digestive function arising from dietary peptide supplementation or significant improvements in growth efficiency brought about by a reduction in endogenous amino acid loss consequent upon removing or reducing the effects of key bioactive peptides. Opportunities abound in what is an exciting new area of nutritional research. Table 7. Mean endogenous amino acid flows (μg/g dry matter intake) at the terminal ileum of the growing rat. Means with differ ent superscripts were significantly different (P<0.05). Adapted from Darragh et al., 1990. Table 8. Endogenous amino acid flows (mg/kg dry matter intake) at the terminal ileum of the growing pig given either a synthetic amino acid or enzyme hydrolysed casein-based diet. Adapted from Butts et al. (1993). Table 9. Endogenous flows of lysine and total nitrogen (mg/kg dry matter intake) at the terminal ileum of the growing pig receiving purified diets containing graded levels of enzyme hydrolysed casein (EHC). Adapted from Hodgkinson et al. (2000). Quite in addition to their bioactive role, hydrolysates, and specifically peptides, are useful nutritional supplies of amino acids and are used in many human functional foods for this purpose alone. Recently, protein hydrolysates have become available as feed ingredients for animals, especially young pigs. These hydrolysates may have some specific nutritional properties. Firstly, the digestibility and availability of the amino acids in such hydrolysates is very high and there is unlikely (because the material is ‘pre-digested’) to be any limitation due to incomplete digestion and absorption. The uptake of peptides is based on a H+ -coupled mechanism, and if with the hydrolysates proportionally more (compared to intact protein) amino acid is absorbed in the peptide form, less energy may be expended by the animal in absorption. Peptides from hydrolysates are known to be taken up into the portal blood more rapidly than the comparable intact protein, which may mean that there is less microbial degradation of key limiting amino acids. Finally, the commercial enzymatic breakdown of the protein and accompanying processing may reduce the amounts of active antinutritional factors known to be present in some plant materials. Some preliminary production trials have been undertaken with hydrolysates as feed supplements for young pigs and these have shown promising results. Studies recently conducted at Ohio State University and Michigan State University, reported by Tibbetts (2000) have shown that an enzymatic hydrolysate (of a non-animal protein source) can successfully replace spraydried blood plasma in the diets of young pigs. In one particular study, the hydrolysate supported better performance in comparison to a plasma protein control. In a further trial reported by Tibbetts (2000), conducted in the United Kingdom, the effect of replacing fish meal and full-fat soya by the hydrolysate was investigated. Over the entire period of the trial (21 days) the performance of the pigs receiving the hydrolysate was superior, although the result did not achieve statistical significance. More information is required from controlled studies before definite conclusions can be drawn; but as can be expected, it does appear that hydrolysates have a valuable nutritional role. In addition to this nutritional role, the specific physiological/nutraceutical properties of peptides can also be exploited, which means that there is considerable potential for the development of new and superior value-added products. As our scientific understanding of bioactive peptides increases, more sophisticated and targeted hydrolysate products will be developed. The concept that a mixed feed provides more than nutrients, and in fact has functional/nutraceutical properties, will become more widely accepted in animal production, as is already the case in the foods industry. Products such as Alltech’s NuPro2000 is an interesting development. In addition to containing highly digestible protein and trace elements, it also contains peptides and nucleotides and contains a relatively high amount of glutamine. This and similar products emerging on the world markets are pioneer functional foods for animals. Conclusion The ability to formulate diets in such a way as to supply the animal with a balanced array of available amino acids for body protein synthesis is central to efficient animal production. Over recent years technologies have been developed and refined such that this can now be achieved with a high degree of accuracy. A single remaining challenge is to develop analytical methodologies that are very rapid so as to allow a more flexible, dynamic, real-time approach to formulation. Research efforts are currently being directed toward this goal. Because of the central importance of amino acids in fuelling protein metabolism in the animal, much research has been centred on dietary protein from a nutritional perspective. However, the discovery of bioactive peptides has opened up a whole new field of study in relation to protein. There is potentially a very large number of bioactive peptides, and as new peptides are discovered and their activities become understood, there will undoubtedly be opportunities for pharmacological and nutraceutical applications within livestock production. by Paul J. Moughan - Institute of Food, Nutrition and Human Health, Massey University

Guide to Collide: GTC (tm) technology

Tue, 27 Jul 2010 07:24:00 +0000 — Tue, 27 Jul 2010 07:24:00 +0000

There are two key reasons for high-energy consumption, low throughput and a rise in temperature of ground materials coming from a hammer mill. They are: 1. Poor hammer milling capacity Large amounts of colliding energy is wasted as heat due to the high rate of eccentric collision. This only makes materials spin and bounce around in grinding chamber, and does not lead to further size reduction. 2. Poor screening capacity There’s definitely a material circulation layer being swept along the inner surface of the screen, hindering correctly sized particles from getting through the screen holes in time. As these particles rub against the screen, and each other and crushed by hammers, their size is continually reduced by attrition and collision. Energy is wasted in the production of heat, while throughput is restricted and particles sizes become too small. Guiding the fluidized bed of material GTC Technology is a size reduction method that manages to guide the fluidizedbed of material to collide with hammers. It greatly increases the probability of frontal collision between materials and hammers requiring the same energy consumption . It makes full use of the kinetic energy within the fluidized-bed of material, and succeeds in enlarging impact capacities 31 times that of single rotor hammer mill, which could dash material into shatters once even eccentric collision . It stops the formation of a material circulation layer effectively. It highly improves the efficiency of screening capacity by enlarging by 20 percent the effective screening area and keeps agitating the fluidized-bed of material, thereby reducing the density of the material layer against the screen surface It promises to produce more than 40 percent more throughput under same energy consumption; in other words, it saves more than 30 percent on the energy requirement under same production capacity It promises temperature rises of less than 15°C when grinding aquatic and poultry feed. Poor hammer milling capacity Materials, such as corn could be broke up by using little energy when frontal collision. However, much power is needed for eccentric collision. This is because when eccentric collision happens, a moment of gyration is generated between the impact point and the barycenter of corn. In general, it only makes the corn spin but does not necessarily break it up. That falls into the category of elastic collision; the impact power turns into the form of heat which is wasted. However, corn could be broke up along its mid-point and maximum length due to the bending movement if the impacting speed is fast enough. During the process of milling with hammer mills, eccentric collision happens mostly, with large amounts of energy being wasted. Therefore, methods used manage to increase the probability of frontal collision between the materials and hammers and also enlarge the impact velocity that improve the efficiency of hammer mills. To see what’s going on in a working hammer mill, researchers designed experiment by using high speed photography technology. High-speed photography required a specially designed hammer mill (see Figure 1) in order to study these effects. One side of hammer mill was equipped with plexiglass, whole the grinding chamber was visible through a 10mm outside screen. The camera’s shutter rate was 5,000fps, exposure was 1/25,000s and the hammer mill’s rotation speed was 3314rpm, with the hammer tip speed at 69m/s when photographed. Two videos were captured separately when grinding corn at normal load and below normal load. Videos were analysed and processed in professional image processing system. Some typical corn particles were tracked and their movements were captured (see Figure 2-3). It could be seen from the video that there is definitely a material circulation layer formed on the screen surface in chamber. The corn particles first tracked did not fall into hammer impacting area. They moved on to the hammer impacting area along the hammer rotating direction, and rebounded into the hammer impacting area after colliding with the screen. Reason for this phenomenon include corn fed into a hammer mill with low speed cannot pass through the material circulation layer. The first tracked corn particle was broke up within 0.4ms at a relative speed 57.45m/s when frontal colliding with hammer. The second tracked corn particle rebounded into hammer impacting area after collided with screen, as the first one had done. However, it spun and bounced in the chamber when there is eccentric conllision, colliding with hammer. It needed further impacting in order to achieve size reduction. Eccentric collision happens mostly in the two videos. Poor screening capacity According to traditional size reduction theory in working hammer mill chambers, and due to centrifugal force, bigger particles circustay tight and close to the inner screen surface while the smaller particle are further from the screen. Big heavy particles are difficult to exit through the screen holes and block the holes, while small light particles are far from the screen hole. They also cannot easily exit through the screens, thus forming a material circulation layer with outer big particles and inner small ones. In view of the above, various shapes of grinding chambers were developed to disrupt the material circulation layer, such as hexagonal, elliptical, water-drop etc. However, some researchers carried out corn grinding experiments to compare every chamber shapes and they found that feeding was at a low speed, compared with round chamber, hexagonal, elliptical, water-drop shaped chambers’ capacity per kilowatt were higher; but when feeding at a higher speed, capacity per kilowatt of hexagonal, elliptical chambers were lower than round one, while water-drop one was similar to round one. This is because when feeding at a higher speed, stagnated materials appear at every corner of the hexagon, at the two ends of ellipse and top frontal impacting screen area of the water-drop chamber (see Figure 4). Stagnated materials reduce real screening area and as big particles find it hard to bounce at these places, capacity drops. If you continue to increase the speed of feeding, the stagnated materials will grow in size to fill the chamber so that it becomes a round one, and the real screening area is reduced sharply. In truth, however, big and small particles are distributed evenly in the material circulation layer; density distribution is near the inner screen surface as density is increased, so that the material circulation layer is looser on the inner area and tighter on the outer area. Therefore, reducing the density of material on inner screen surface can largely improve the screening capacity of hammer mills. Researchers designed a special hammer mill (see Figure 5) to acquire material circulation layer distribution data directly, which revealed the truth. There’s a fixed partition between grinding chamber and fan chamber. Eight sampling probes (four as a group) were installed in a radial direction evenly spaced on a fixed partition (see Figure 6). Sampling probes connect grinding chamber and fan chamber (negative pressure), high breathability sampling bags covered to end of sampling probes to the fan chamber side. Then distribution data of material circulation layer along radial direction could be acquired. Main technical parameter of hammer mill Width of screen: 200mm Diameter of screen hole: 2mm Motor power: 5.5kW Hammer tip speed: 60m/s Feeding speed: 700kg/h Corn moisture content: 12.5 percent Single grinding quantity: 9.5kg Researchers checked the materials in each sampling probes and found that average particle sizes was similar along entire radial direction, all around ensemble average size of sample, 1.12±0.04mm. (Ensemble average size of sample was tested by mixing all samples from the probes.) Density (material mass per unit volume) distribution of the material circulation layer along the radial direction was low to high. That is, the bottom of material circulation layer, which was close to the inner screen surface, density was high; the closer to the center of chamber the lower it became. GTC Technology GTC Guide (fluidized-bed of material diversion plate) ensures high probability of frontal collision between fluidizedbed of material and hammers. GTC Guide is a plate similar to a cuboid, whose section is a parallelogram with two sides bowing inward. It is installed between two rotors and through the center of grinding chamber, which separates the whole chamber into chamber A and B. It blocks the whole chamber’s center space; chamber A and B could communicate through the tunnel at the top and bottom of GTC guide. So the GTC Guide can guide as well as divert. Guide: GTC Guide guides material into neighbouring chamber’s hammer impacting area at a suitable angle, making moving direction of the fluidized-bed of material in the opposite direction to that of the hammer. Divert: GTC Guide avoids low efficiency collision between two fluidized-bed of material in two chambers, and ensures high probability of frontal collision between fluidizedbed of material and hammers. GTC Technology enlarges impacting capacity Fluidized-bed of material collides with hammers of neighbouring chamber in opposite direction; at a speed around 70 percent of hammer tip speed. Enlarging GTC hammer mills’ impacting capacity 31 times those of single rotor hammer mills. It could dash materials into shatters once even eccentric collision. Hammer milling capacity and efficiency highly improved, temperature rise of ground material obviously lowered. GTC Technology improves the efficiency of screening capacity As mentioned before, the density distribution of fluidized-bed of material is that the near the inner screen surface the greater the density, so the fluidized-bed of material is loose near the inside and tighter on the outside. Consequently, reducing the density of material on the inner screen surface can largely improve the screening capacity of hammer mills. The GTC hammer mill has double grinding chambers and a GTC Guide. Its unique frame structure keeps agitating the fluidized-bed of materials, guiding it into neighbouring chamber and colliding it with the hammers. Continually disrupted, the trend of the fluidized-bed forms an inner loose layer and an outer tight layer in terms of density distribution. Thus, it reduces the density of material layer against the screen surface, greatly increases the screening capacity. Meanwhile, the unique double chamber frame structure enlarges by 20 percent the effective screen area at the bottom, which also contributes much to reduction in the density of material layer against the screen surface, thereby improving the efficiency of the screening capacity. by Jonathan Woo

Evaluation of a new Egyptian probiotic by African Catfish Fingerlings

Tue, 27 Jul 2010 07:06:00 +0000 — Tue, 27 Jul 2010 07:06:00 +0000

Dietary live yeast improved (p<0.01) fish body weight, reduced muscular fat and serum triglycerides and cholesterol but increased RBC's, Hb, PCV and serum glucose. So, dietary live yeast may improve growth performance and hematological picture in fish (Kobeisy and Hussein, 1995). Moreover, Abdelhamid et al . (2000) reported significant positive effects of the combination of dried live yeast and lacto-sacc on tilapia growth, feed conversion and nutrients utilization. The highest level of these separate or combined additives (20 g kg-1) was the best for improving fish body weight and feed conversion. Also, Magouz et al . (2002) and Abou Zied et al . (2003) came to the same conclusion that dietary supplementation of lacto-sacc (0.1% of the diet) produced high growth rate, survival rate and feed and protein utilization of Nile tilapia. Lacto-sacc had also positive effect on economical efficiency of tilapia production. However, Olvera-Novoa et al . (2002) reported that fish fed 25-30% (of the dietary protein) yeast diets showed the best growth performance, feed conversion, protein efficiency ratio, nitrogen utilization, incidence cost and profit index. Additionally, Khattab et al . (2004) found that Biogen(R) (0.1% of the diet), as a feed supplement, had improved growth performance, feed conversion, chemical composition of the whole fish body as well as the blood profile of Nile tilapia fish. Recently, Allam (2007) found that Pronifer(R) (lactic acid bacteria and its fermentation metabolites) as feed additive at 3% level improved tilapia growth and their blood profile. It reduced fish fat content and alleviated the hazard effects of A. hydrophila on mortality rate. The African catfish Clarias gariepinus is distributed throughout Africa. It is of growing economic value in the African aquaculture industry (Goda et al ., 2007; Osman et al ., 2007; Abdelhamid, 2009a). Probiotics are pure cultures of one or more living microorganisms given in feed that proliferates in the host gastrointestinal (GI) tract. They ensure that the host maintains a beneficial microbial population in the GI tract (Linge, 2005). They confer a healthy effect on the host as significant microbial food supplements in the field of prophylaxis (Geovanny et al ., 2007). The research of probiotics for aquatic animals is increasing with the demand for environment-friendly aquaculture. Some probiotics were designed to treat the rearing medium, like biocontrol when the treatment is antagonistic to pathogens or bioremediation when water quality is improved. Most probiotics have been undertaken by isolating and selecting strains from aquatic environment (Gatesoupe, 1999). Also, probiotics have found use in aquaculture as a means of disease control, supplementing or even in some cases replacing the use of antimicrobial compounds (Irianto and Austin, 2002; Sahu et al ., 2008). Since, the use of expensive chemotherapeutants for controlling diseases have been widely criticized for their negative impacts (Sahu et al ., 2008).Therefore, the objectives of the present study were to evaluate effects of graded levels of a new-local probiotic on African catfish concerning their growth performance, feed utilization, carcass composition, histometric characteristics of the dorsal muscles, blood profile as well as effect of this probiotic on some pathogenic bacteria of fish. MATERIALS AND METHODS Experimental Management A field study was conducted to evaluate the effects of dietary inclusion of graded levels of a newly local produced probiotic (T-Protphyt 2000: It is a local product with a patent No. 23593. It consists of 15% zinc salts, 10% inorganic phosphorus, 5% dried fermentation products of Aspergillus oryzae growth and starch as carrier up to 1 kg. Each gram of this product contains 100 unit of phytase, 75 unit of protease, 25 unit of lipase and 15 unit of amylase) on African catfish ( Clarias gariepins ). For this reason, 4 net Hapas (1x3x1.5 m diameters) were constructed and implanted in 1 Feddan (Egyptian area unit = 4200 m2) earthen pond in a private fish farm at Tolompat 7, Alriad, Kafr El-Sheikh Governorate, Egypt. The Hapas' net was 1 cm opens, from Tailand. The pond was irrigated via a pump from an agricultural drain. Eighty similar-size catfish were purchased from a private neighbor farm, regardless to their sex, with an average body weight of 90 g. The feeding trial started on the 20th of July 2008 and ended on the 20th of November 2008 (120 days) using a commercial diet (25% crude protein, from Almorshedy for Trading and Development, Meet Ghamr-Dakhalia-Zagazig Road, Egypt). This commercial diet contained yellow corn, soybean meal (44%), wheat bran, fish meal (65%), corn gluten (60%), lime stone, common salt, dicalcium phosphate and molasses and had not less than 25% crude protein, 3% crude lipids, 3935 Kcal gross energy kg-1 diet and not more than 5.30% crude fiber, according to the manufacture's formula. Table 1 shows the proximate analysis of the basal diet which was carried out according to AOAC (1995). The diet was ground to add the tested propiotic (at levels of 0, 1, 2 and 3 g kg-1 diet, referred to treatments No. T1, T2, T3 and T4, respectively). Molasses at 5% of each diet was used to spread the propiotic and then all diets were repelleted. The tested diets were offered once daily (10 am) at 5% of the fish biomass at each Hapa. The feed quantity was adjusted periodically according to the actual body weight changes. Fish Performance and Quality Measurements used for the evaluation included fish weight and length and water quality parameters (i.e., temperature using centigrade thermometer, salinity using conductivity TDS meter model 470, pH using pH meter model 340, dissolved oxygen using oxygen meter model 970, all instruments were from Jenway-England). At the start and at the end of the experiment, fish samples were collected and kept frozen till the proximate analysis of the whole fish body according to AOAC (1995).Their gross energy contents were calculated according to NRC (1993). At the end of the experiment some fishes from each treatment were sacrificed and fish dorsal muscles were sampled. Samples were fixed in 10% neutralized formalin solution to histometric examination according to Pearse (1968). Blood Parameters At the end of the experiment blood samples were collected from the fish caudal peduncle of the different groups. Adequate amounts of whole blood in small plastic vials containing heparin were used for the determination of hemoglobin (Hb) using commercial colorimetric kits (Diamond Diagnostic, Egypt). Also, total erythrocytes (RBCs), platelets and total leucocytes (WBCs) were counted according to Dacie and Lewis (1995) on an Ao Bright-Line Haemocytometer model (Neubauer improved, Precicolor HBG, Germany). Other blood samples were collected and transferred for centrifugation at 3500 rpm for 15 min to obtain blood plasma for determination of plasma total protein according to Gornall et al . (1949), albumin according to Weichsebum (1946) and globulin by difference according to Doumas and Biggs (1972). Bacterial Strains Nine of Gram-negative bacteria, namely Aeromonas hydrophilla , Pseudomonas aeruginose , Pseudomonas fluorescens and Vibrio sp., in addition to the Enterobacteriaceae ( Klebsiella , Shigella , Salmonella , Proteus and Escherichia coli ) were used in this study, these bacteria were isolated from Nile tilapia fish and identified by specific media and biochemical testes, except Aeromonas hydrophilla that was identified by primed Polymerase Chain Reaction (PCR). Assessment of Antibacterial Activity of the Probiotic Powder samples of probiotic and (OTC) antibiotic (because of its wide antibacterial spectrum and high potency, OCT is the most commonly used antibiotic against various diseases caused by Gram-negative and Gram-positive bacteria in fish farming) were suspended in sterile water and used at two concentrations each (120 and 240 μg of probiotic and 30 and 60 μg of OTC). Four wells were punched with a cork borer (6 mm in diameter) in plates of nutrient agar (NA) freshly seeded with 0.1 mL of 24 h old of each tested bacterial cultures. Different concentrations of probiotic and antibiotic were put into the wells, left 1 h to allow diffusion, plates were incubated for 24 h at 37°C. The diameter of clear zones surrounding the wells were measured and recorded expressing the antibacterial activity. Statistical Analysis The obtained data were statistically analyzed using SAS (1996) procedures for personal computer. When F-test was positive, least significant difference (Duncan, 1955) was calculated for the comparisons among means. RESULTS Experimental Diet The chemical analysis of the basal diet used in the present experiment is given in Table 1. Calculated gross energy based on factors of 5.65, 9.45 and 4.11 Kcal g-1 protein, fat and carbohydrate, respectively according to NRC (1993) was 395.5 Kcal 100 g-1, protein/energy (P/E) ratio was 58.76 mg Kcal-1. Water Quality Criteria Water parameters were measured twice daily (10 am and 10 pm). There were no significant differences among Hapas' water throughout the experimental period because all Hapas were in the same pond. Therefore, the means of the whole period are given in the following Table 2. Growth Performance Growth performance parameters shows in Table 3 shows that T2 (1 g T-Protphyt 2000 kg-1 diet) was the best among various dietary treatments concerning body weight gain, daily body weight gain, RGR, SGR and condition factor as well as PER and PPV (even feed conversion ratio which not given in the Table 3). Yet, all data in this Table 3 are lower than those in literature (El-Haroun, 2007) probably for low dietary protein and fat determined (23.24 and 2.87%, respectively) as well as for poor experimental rearing conditions, e.g., stocking rate, feeding rate and frequency and using Hapas which restricted the fish growth and negatively affected feed conversion and nutrients utilization. Therefore, the evaluation will continue in a serial paper under other good ambient conditions.T2 gave significantly (p≤0.05) the highest final body weight and condition factor. However, all supplemental diets with the tested probiotic (T2, T3 and T4) reflected better results than the control (T1). T4 did not differ significantly (p≥0.05) than either T2 or T3. Table 1: Proximate chemical analysis of the basal diet (% as fed) Table 2: Water quality parameters (Means±SE) of the whole experimental period, regardless to the treatments Table 3: Growth performance of catfish after 120 days of feeding the experimental diets (Means±SE) a-c: Means in the same row with different superscripts are significantly (p≤0.05) different; NS: Not significant at p≥0.05; *RGR: (Final body weight-Initial body weight)/Initial body weight; **SGR: (In final weight-In initial weight)x100/experimental period; ***PER: Body weight gain/consumed feed protein; ****PPV: Retained proteinx100/consumed feed protein; *****EU: Retained energyx100/consumed feed energy Carcass Composition Proximate chemical analysis of the whole fish body at the start and at the end of the 120 day experimental period is summarized in Table 4. These data indicated that moisture content was higher and ether extract as well as energy content were lower at start than at the experimental end; otherwise, no remarkable changes were recorded. Concerning dietary treatments, there were slight increases in crude protein and ether extract percentages but lower ash content due to the dietary inclusion of T-Protphyt 2000. Table 4: Proximate chemical analysis (% fresh basis) of whole fish body at the start and at the end of the feeding period Histometric Examination of Fish Dorsal Muscles There were no significant (p≥0.05) differences of all histomestic parameters (smallest diameter (μm), mean diameter (μm), smallest/largest ratio, intensity of muscular bundles mm-2, the percentage of muscular bundles area mm-2 and the percentage of connective tissue mm-2) of African catfish dorsal muscles among all treatments. However, fish fed diet supplemented with commercial probiotic T-Protphyt 2000 at level of 1 g kg-1 diet (T2) realized slight improvement of these histometric characteristics of fish dorsal muscles compared with the control (T1) or other treatments (T3 and T4). It is of interest to note that, T2 treatment realized the best growth performance (Table 3) and carcass composition (Table 4) of fish compared with the control and other treatments. This means that supplementation of commercial probiotic T-Protphyt 2000 at level of 0.1% to fish diets led to improvement of most histometric characteristics of the dorsal muscles of African catfish (Table 5, Fig. 1a-d). Blood Profile Data of hematological and biochemical parameters are given in Table 6, which clears that there were no significant (p≥0.05) effects of the tested probiotic on hemoglobin (Hb) content and white blood cells count (WBCs) comparing with the control. Yet, there were significant (p≤0.05) positive effects on platelets count and A/G ratio and negative effects on total protein and globulin contents; otherwise, no clear trend was recorded for the effect of probiotic inclusion levels. Fig. 1: Cross-section of muscular bundles and interstitial connective tissue of the dorsal muscles of catfish in the (a) 1st, (b) 2nd, (c) 3rd and (d) 4th treatments respectively. (X 400, H and E stains) Table 5: Effect of dietary supplementation of T-Protphyt 2000 on histometric characteristics of dorsal muscles of catfish (Means±SE) NS: Not significant at p≥0.05; * % of muscular bundles area mm-2 = ([3.14 X (mean diameter/2)2]xIntensity of muscular bundles mm-2)x100, whereas: the muscular bundles were considered in approximately circular shape; ** % of connective tissue mm-2 = (1- muscular bundles area, mm-2)x100 Table 6: Hematological and biochemical analysis of catfish blood after 120 days experimental feeding (Means±SE) a-d: Means in the same row with different superscripts are significantly (p≤0.05) different; RBCs: Red blood cells (Erythrocytes); WBCs: White blood cells (Leucocytes); *A/G ratio: Albumin/Globulin T4 did not differ significantly (p≥0.05) with T3 in most parameters, except A/G ratio, but differ (p≤0.05) with T2 in both red blood cells count (RBCs) and A/G ratio. T3 did not differ significantly (p≥0.05) with T2 in platelets count and A/G ratio. The increased A/G ratio is related to the decrease in globulin values. Antagonism to Pathogens The results in Table 7 and Fig. 2 A-D showed the positive effect of the probiotic at the two concentrations against all the tested bacteria and showed nearly no clear difference between the two concentrations of probiotic. Also, it has a similar effect of the antibiotic (OTC) especially with the pathogenic bacteria, Aeromonas and Pseudomonas , which showed sensitivity towards probiotic, while the Vibrio sp., showed resistance to OTC at the two concentration (Fig. 2D). Table 7: The antibacterial activity of aqueous probiotic compared with OTC Fig. 2: (a-d) The inhibition zones of some bacteria by the action of probiotic compared with OTC. (A) A. hydrophilla , (B) P. aeruginose , (C) P. fluorescenus , (D) Vibrio sp. 1 = 120 μg probiotic, 2 = 240 μg probiotic, 3 = 30 μg OTC, 4 = 60 μg OTC DISCUSSION The values of water parameters are within the acceptable ranges recommended for pisciculture (Abdelhamid, 1996, 2009b; Abdelhakim et al ., 2002). However, the optimum growth of African catfish requires 28-30°C, <5 ppt salinity, <15 mg L-1 dissolved oxygen, 6.5-9.0 pH and 50-100 mg L-1 hardness in the rearing water (Chapman, 2000). Craig and Helfric (2002) reported that protein levels in aquaculture feeds generally have an average of 28-32% for catfish. Protein requirements are lower for omnivorous fish and for larger fish than carnivorous and smaller ones. Feeding rate affects also fish requirements of protein (Jauncey, 1998). However, Machiels and Henken (1985) reported 40% crude protein, 19.2 KJ DE g-1 and 13 mg protein/KJ as optimal requirements for C. gariepinus (40-120 g). Recently, Eid (2007) recommended a diet containing 25% protein, 6% fat and 72 mg protein Kcal-1 for adult catfish. Also, El-Gendy (2009) found that the best dietary crude protein and fat levels were 35.9 and 11.7% (465.88 Kcal 100 g-1), respectively and 77.1 P/GE ratio for the African catfish fingerlings (13 g initial body weight). Robinson et al . (2009) reported that even though catfish have been cultured for many years, there is still considerable variation in feeding practices on commercial catfish farms. Catfish are generally fed once daily to what is commonly called saturation. Catfish (27 g) feed is generally recommended to contain 28-32% protein, starting with a 32% protein feed in spring and change to a 28% feed as the temperature increases. Abdelhamid et al . (1996) and Attia et al . (2007) confirmed the economical-environmental benefits of using the dietary supplemental microbial-phytase. It increases (p<0.05) body weight, feed efficiency, carcass % and serum contents of P, Ca, Mg and Zn. Also, El-Dakar and Gohar (2004) found that growth and survival of Peneaus japonicus post larvae fed probiotic diet was higher than those fed the basal diet. The in vitro study revealed that the probiotic ( Bacillus subtilis ) decreased the proteolyses activity of the bacterial pathogens ( Aeromonas hydrophila , Edwardsiella tarda and Vibrio proteolyticus ). Bacillius subtilis had a positive effect against the pathogens and on reducing the antibiotic susceptibility when presented in culture water or in feed of shrimp. Moreover, Salem et al . (2004) reported that bacterial and yeast probiotics ( Bacillus subtilis and Saccharomyces cerevisiae ) improve the activity of lactic acid bacteria which could inhibit the pathogenic bacteria ( E. coli ). Castillo (2008) also concluded that certain Bacillus strains act as probiotic bacteria and block the communication system of Enter pathogens such as Yersinia and Salmonella sp. Yet, Hidalgo et al . (2006) concluded that no significant effects on growth and survival were found following the addition of Bacillus toyaoi , T and B. cereus , E as probiotics to dentex diets. However, some lactic acid bacteria isolated from the gastrointestinal tract of fish can act as probiotics. These candidates are able to colonize the gut and act antagonistic against Gram negative fish pathogens. These harmless bacteriocin-producing strains may reduce the need to use antibiotics in future aquaculture (Ringo and Gastesoupe, 1998). Generally, the probiotics actively inhibit the colonization of potential pathogens in the digestive tract by antibiosis or by competition for nutrients and/or space, alteration of microbial metabolism and/or by the stimulation of host immunity. Probiotics may stimulate appetite and improve nutrition by the production of vitamins, detoxification of compounds in the diet and by breakdown of indigestible components (Irianto and Austin, 2002). Additionally, Abd El-Rahman and El-Bana (2006) used Micrococcus luteus as a bacterial probiotic which presented in vitro and in vivo antagonistic effects against the pathogenic bacteria Aeromonas hydrophila . The inhibition zone to A. hydrophila was 40 mm in diameter due to M. luteus . The dietary inclusion of this probiotic improved significantly the final weight, weight gain, specific growth rate, feed conversion, protein efficiency ratio erythrocytic counts, hemoglobin content and survival rate of O. niloticas fish. Rollo et al . (2006) reported an improvement in tolerance to acute stress of sea bream fry fed with probiotics. Also, Taoka et al . (2006) indicated that probiotics treatment is promising as an alternative method to antibiotics for disease prevention in aquaculture. Additionally, Attalla (2007) found that supplementation of dietary bacteria or yeast produced significantly better weight gain, specific growth rate and feed utilization in tilapia cultivation. Biobuds® and yeast or Biogen® as probiotics led to improving the growth performance, feed conversion, protein efficiency ratio and feed costs for tilapia fingerlings (Mohamed, 2007; Mohamed et al ., 2007). Moreover, El-Ashram et al . (2008) concluded that, super Biobuds® can improve body gain, survival and enhance resistance to challenge infection. Yet, Abdelhamid and Elkatan (2006) found that dietary supplementation of Biobuds® slightly improved body weight gain but reduced the survival rate of tilapia fingerlings. El-Haroun et al . (2006) and El-Haroun (2007) reported that Biogen® dietary supplementation improved growth performance and feed utilization, carcass protein and fat percentages as well as economical profit in Nile tilapia and catfish culture, respectively. Wongsa and Werukhamkul (2008) came to the same conclusion, since they found that catfish fed diets containing probiotics plus phytase enzyme showed 35% higher weight gain and better feed conversion by more than 25% in comparison to catfish fed control diets in a three-month trial. However, during the past two decades, the use of probiotics as an alternative to the use of antibiotics has shown to be promising in aquaculture, particularly in fish and shellfish larviculture (Tinh et al ., 2008). Recently, Aly et al . (2008a) found that some Bacillus and Citrobacter strains isolated from Nile tilapia ( B. pumilus, B. firmus and C. freundii ) showed inhibitory effects against A. hydrophila . Also, Aly et al . (2008b) reported that the probiotic activity of two bacteria ( Bacillus subtilis and Lactobacillus acidophilus ) was evaluated by its effect on the immune response of Nile tilapia ( Oreochromis niloticus ), beside its protective effect against challenge infection. Furthermore, their in-vitro inhibitory activity was evaluated. The in vitro antimicrobial assay showed that Bacillus subtilis and Lactobacillus acidophilus inhibited the growth of A. hydrophila . The B. subtilis inhibited the development of P. fluorescens while L. acidophilus inhibited the growth of Strept. iniae . The B. subtilis and L. acidophilus proved harmless when injected in the O. niloticus . The feed, containing a mixture of B. subtilis and L. acidophilus or B. subtilis alone, showed significantly greater numbers of viable cells than feed containing L. acidophilus only after 1, 2, 3 and 4 weeks of storage at 4 and 25°C. The survival rate and the body-weight gain were significantly increased in the fish given B. subtilis and L. acidophilus for one and two months after application. The hematocrit values showed a significant increase in the group that received the mixture of B. subtilis and L. acidophilus compared with the control group. The nitroblue tetrazolium (NBT) assay, neutrophil adherence and lysozyme activity, showed a significant increase in all the probiotic-treated groups after 1 and 2 months of feeding, when compared with the untreated control group. The serum bactericidal activity was high in the group that was given a mixture of the two bacteria. Also, Marzouk et al . (2008) reported that probiotics ( B. subtillis and Saccharomyces cerevisae ) revealed significant improvement in growth parameters and showed failure in re-isolation of some pathogens. Varley (2008) cited also that probiotics show real benefits in the synergistic effects with the beneficial bacteria in making inroads into improving gut health. So, probiotics may improve the growth performance and immune response of fish (Wang et al ., 2008). The increased count of WBCs may be caused by protein resorption (Merck, 1976). Hypoproteinemia may be due to protein loss, decreased albumin, or to increased globulin (Merck, 1974). An insufficient amount of protein in the diet may lead to a low total protein of blood. This is the case in starvation. In other cases, although adequate protein is being taken in the feed, absorption from the alimentary tract may be defective. This may occur in vitamin deficiencies particularly of the B-vitamins (Varley, 1978). In the field of physical structure of tilapia muscles, Abdelhamid et al . (2004) found that probiotics (Betafin® and Biopolym®) not only increased body weight, growth rates and total productivity, but also improved muscular protein percentage, radius of the muscular bundles, total surface area occupied by the muscular bundles mm-2 (least thickness of connective tissues between muscular bundles and thickness of skin and subcutaneous layer) and net return. CONCLUSION In conclusion, this preliminary study revealed that this probiotic under study is useful for enhancing fish growth, feed and nutrients utilization, fish chemical composition and muscular structure, besides fish resistance for pathogenic bacteria, i.e. it may be useful also from the economic point of view. Yet, it is to recommend also more research work on this probiotic under various conditions, e.g., different fish species, initial weight, stocking rates, feeding rates, dietary protein levels and sources, etc. by Abdelhamid, A.M., A.I. Mehrim, M.I. El-Barbary, S.M. Ibrahim and A.I. Abd El-Wahab, 2009. Evaluation of a New Egyptian probiotic by African catfish fingerlings. J. Environ. Sci. Technol., 2: 133-145. DOI: 10.3923/jest.2009.133.145 URL: http://scialert.net/abstract/?doi=jest.2009.133.145

Use of soybean products in aquafeeds: a review

Tue, 27 Jul 2010 06:58:00 +0000 — Tue, 27 Jul 2010 06:58:00 +0000

Introduction The world demand for sea food is increasing dramatically year by year, although an annual upper limit of 100 million tons is set so as not to exhaust reserves. It is for this reason that there is a considerable move towards modernizing and intensifying fish farming. To be economically viable, fish farming must be competitive, which means that feed costs amongst others must be carefully monitored as the operational cost goes 60% for feed alone .Therefore selection of cheaper and quality ingredients is of paramount importance for sustainable and economical aquaculture. Identification of suitable alternate protein sources for inclusion in fish feeds becomes imperative to counter the scarcity of fish meal. In addition to its scarcity and high cost, often fish meal is adulterated with sand, salt and other undesirable materials. All these factors have forced fish feed manufactures all over the world to look for alternate sources. In this context they have been left with no protein but to substitute animal protein with plant protein sources. A variety of plant protein sources including soybean meal, leaf protein concentrate and single cell protein have been tested. The tests have shown that these can be included as alternatives to fish meal (Ogino et al, 1978, Appler and Jauncy, 1983). Of various plant protein sources, soybean meal (SBM) is one of the most promising replacements for part or whole of fishmeal. Soybean meal is the by-product after the removal of oil from Soya beans (glycine max). At present soybean meal is the most important protein source as feed for farm animals and as partial or entire replacement of fish meal. The products obtained from soybeans and their processing are as follows:- - Soybean meals, solvent extract - Soybean meal from dehulled seeds, solvent extracted, - Soybean expeller - Soybean expeller from dehulled seeds - Full fat soybean meal - Full fat soybean meal from dehulled seeds The chemical composition of soybean meal is fairly consistent (Figure 1). Figure.1 Chemical composition of soybean meal The crude protein level depends on the soybean meal quality. Soybean has one of the best amino acid profiles of all vegetable oil meals (Table.1).The limiting amino acids in soybean meal are methionine and cystine while arginine and phenylalanine are in good supply (New, 1987). The fat content of the solvent extracted soybean meal is insignificant but soybean expeller has oil content between 6.0 and 7.0%, while full fat soybean expeller has oil content between 18 to 20%. Soybean meal and soybean expeller are lower in macro and trace elements than fish meal. There is no substantial difference between the individual soybean meal products (Table. 2).The calcium content is low and the phosphorus level is rather higher. However, the phosphorus is bound to phytic acid and its availability for aquatic animals is, therefore, limited. Soybean meals and expellers are reasonable source of B- vitamins. For most vitamins there are insignificant differences between the different products. However the full fat soybean meal tends to be higher in some vitamins. While the products are mainly higher in choline content, the vitamin B 12 content is low and pantothenic acid is mainly damaged by heat treatment (Table-3). The digestible energy of soybean meal over all fish species ranges from 2572 to 3340 Kcal/kg (10.8 to 14.0 MJ/kg) (Table. 4). The metabolizable and digestible energy of full soybean meal increases with the increase heating temperature at a given time due to the inactivation of trypsin inhibitors. DELETERIOUS CONSTITUENTS OF SOYBEAN PRODUCTS Trypsin inhibitors: - About 6.0 % of the total protein of soybeans reduces activities of trypsin and chymotrysin, which are pancreatic enzymes and involved in protein digestion (Yen et al ., 1977). The activity of trypsin inhibitor is not fully understood, but is responsible for the poor performance of certain fish species (Alexis et al., 1985, Balogum and Ologhobo., 1989). Lectins: - This type of toxic protein is chemically hem agglutinin, which causes agglutination of RBC's (Liener, 1969). There are indications that lectins reduce the nutritive value of soybean meal for Salmonids but are inactivated by treatment of the meals (Ingh et al , 1991). Other properties: - Soybean is unpalatable for some fishes such as Chinook salmon. While as herbivorous and omnivorous species are less choosy. The size or age of the fish may also affect the palatability of soybean meal. Utilization of Soybean Products in Aquaculture: Comprehensive research work has been done to evaluate soybean meals as a replacement of animal protein sources in diets for fishes but the replacement of all fishmeal by soybean meal has not been very successful perhaps due to the limiting amino acids and insufficient heat treatment of the soybean meals. Smith et al (1980) claimed success in feeding rainbow trout a diet based almost entirely on raw materials of vegetable origin containing 80% full fat roasted soybean. In a similar report, Brandt (1979) evaluated a diet based entirely on plant ingredients (containing 50% heated full fat soybean + 10 % maize gluten meal to overcome a possible deficiency of S-amino acids). Reinitz et al (1978) observed that rainbow trout fry fed a diet containing 72.7% full fat soybean had a greater daily increase in length and weight with an improved feed conversion ratio compared with those fed a control diet based on 25% herring meal, 5% fish oil 20% soybean oil meal. The mortality rate for both groups was similar. Taste panel studies indicated that there was no effect of dietary treatment on firmness and flavour of the fish. Kaneko (1969) reported that 1/3rd of white fish meal could be replaced by soybean meal with no negative effects on growth of warm water fishes. Viola (1977) iso-nitrogenously reduced the fishmeal content in the diet of carps containing 25% protein supplemented by soybean meal with the addition of amino acids, vitamins and minerals and opined that soybean diet did not induce good growth in carp. Similarly Atack et al (1979) reported poor utilization of soybean protein by carp when it formed the sole protein source. Gracek (1979) used different qualities of soybean meal to supplement ground maize for feeding carp fry and recorded better survival. No difference in growth was observed when common carp ( Cyprinus carpio ) were fed either with 45% soybean meal (+10% fishmeal) or 20% soybean meal (+22% fishmeal). Other trails however showed that the growth performance and feed efficiency of common carp were reduced when dietary fish meal was replaced by soybean meals. There were no differences in performance between extruded full fat soybean meal and oil reconstituted soybean meal (Inghet et al ; 1991). A better weight gain was reported when soybean meal was incorporated in the diets of carp fish (Cristoma et al; 1984). Similarly sklyrov et al (1985) successfully used soybean meal in rearing carp fish commercially. It is claimed that soybean meal is deficient in available energy and lysine as well as methionine for carps. Supplementation of soybean meal diets with methionine coated with aldehyde treated caesin significantly improved utilisation of amino acid by common carp (Murai et al ; 1982). Lack of phosphorus rather than the sulphur amino acids may be the cause for poor performance of common carps when 40% soybean meal diets were fed to them. Addition of 2.0% sodium phosphate did not improve their performances (Viola et al ; 1986).Kim and Oh (1985) attributed the poor performance of common carp fed with a diet containing 40% soybean to lack of phosphorus rather than sulphur and amino acids, since addition of 2% sodium phosphates to soybean meal diet improved their performance to a level obtained with the best commercial feed. Nour et al (1989) studied the effect of heat treatment on the nutritive value of soybean meal as complete diet for common carp by autoclaving the soybean seeds for 0, 15, 30, or 90 minutes and recorded maximum average daily weight gain with diets containing soybean seeds autoclaved for 30 minutes. Nandeesha et al (1989) incorporated soybean meal in the diets of Catla and indicated the possibility of utilizing soybean meal in carp diets. Keshavapa et al (1990) used soybean flour in the diet of carp fry and recorded better survival. Senappa (1992) studied protein digestibility from soybean incorporated diets and recorded better digestibility when fed to fingerlings of Catla. Naik (1998) studied the effect of Soya flour and fish meal based diets in the diet of Catla catla & Labeo rohita and observed a better growth and survival of carps when reared together and also in combination with fresh water prawn. Channel cat fish ( Ictalurus punctatus ) fed on all plant protein diets grew significantly less than fish fed diets containing fish meal (Lyman et al , 1944). Growth was substantially reduced when menhaden fish meal was replaced by soybean meal at an isonitrogenous basis (Andrews and Page, 1974) Full fat soybean meal heat treated differently replaced fish meal at low levels in diets for channel cat fish showed that replacement gave satisfactory results (Saad, 1979). Growth and feed efficiency of fingerling hybrid tilapia ( Oreochromis niloticus ) was significantly depressed when soybean meal replaced fish meal at the optimum level (30%) in their diet (Shiau et al, 1988). The growth depression of the hybrid tilapia was reduced when a 30% crude protein diet containing soybean meal but by adding 2-3% dicalcium phosphate to the diet, growth rate of tilapia was comparable to the control (Viola et al, 1986). Soybean meal with supplemental methionine could replace up to 67% fish meal in the diets for milk fish ( Chanos chanos ) (Shiau et al , 1988). Growth, feed conversion and survival of tiger prawn ( Penaeus monodon ) juveniles fed two levels of soybean meal under laboratory conditions were lower with higher levels of soybean meal (Piedad, Pascual and Catacutan, 1990). No significant differences in growth and survival could be established when soybean meal at levels from 15- 55% replaced partially or completely fish meal in the diets for tiger prawns stocked in cages in ponds at 10 to 20 shrimps per square meter (Piedad, Pascual et al, 1991). Lim and Dominy(1991) obtained comparable results in feeding Penalus Vannamel with diets containing up to 17% of dry extruded full fat soybean meal as a partial replacement for fish protein. Generally the studies outlined above together with several others indicate that there is an advantage to be gained from using properly processed soybean products for formulating diets for fish due to their better quality protein and higher dietary energy value in full fat soybean which is more advantageous with cold water fish species because warm water fish (Carp, Catfish etc) can utilize carbohydrates more efficiently. The only recommendation relating to the limit of inclusion of full fat soybean in fish diets is not to exceed the known practical limits relating to fats in general in order to avoid problems of feed preparation and to reduce the risk of high fat levels in the meal. Recommended Inclusion Rates Soybean may replace animal protein in diets for aquatic animals to a certain extent. However, with increasing substitution of e.g. fish meal by soybean meal the performance of fish decline. Herbivores may tolerate higher levels of soybean meal than carnivores. It appears that full fat soybean meal is more beneficial for cold water fish than for warm water species due to the better utilization of the energy from the soybean products. Only properly heat treated soybean products should be used for aquatic feeds. Furthermore, it is advisable to use only soybean meals processed from dehulled seeds in order to reduce the crude fisher content in the diet. The rates of soybean products are given in table 5. by T. H.Bhat, M. H.Balkhi and M.T.Banday