3 NUTRIENT REQUIREMENTS OF ANIMALS
NUTRIENT REQUIREMENTS OF POULTRY
WRF3MJ1 ICAR
Indian Council of Agricultural Research New Delhi
PRINTED : JULY 2013 THIRD EDITION 2013 i
Project Director Incharge (English Editorial Unit) Editor
Chief Production Officer Technical Officer (Production) Cover Design
Dr Rameshwar Singh Dr R P Sharma Reena Kandwal Dr V K Bharti Punit Bhasin Dr V K Bharti and Punit Bhasin
Correct Citation: Nutrient Requirements of Animals - Poultry (ICAR-NIANP), 2013
Š 2013, All rights reserved Indian Council of Agricultural Research, New Delhi
ISBN: 978-81-7164-138-3
Price: ?200
Published by Dr Rameshwar Singh, Project Director, Directorate of Knowledge Management in Agriculture, Indian Council of Agricultural Research, New Delhi 110 012; Lasertypeset at M/s Dot & Design, D-35, Ranjeet Nagar Comm. Complex, New Delhi 110 008 and printed at M/s Royal Offset Printers, A-89/1 , Naraina Industrial Area, Phase I, New Delhi 110 028.
CONTENTS SI. No. Title
Page No.
1.
Introduction
1
2. 3.
Feeding System Components of Poultry Diets Energy
2 3
Protein and Amino Acids
6
4.
5. 6. 7. 8. 9. 10. 11.
12. 13.
Feed supplements Nutrient Requirements of Chicken Commercial White and Coloured Broiler Chickens Broiler Breeders Egg Type Pullets Improved Native Chickens Nutrient Requirements of Japanese Quails Nutrient Requirements of Turkeys Nutrient Requirements of Ducks Nutrient Requirements of Guinea fowl Nutrient Requirements of Emus Feed Formulation Feed Additives
3
11 12 13 16 17 22
25 28 30 32 34
35
Conclusion
36 39 41
References
41
Mycotoxins
Annexures A1 Ingredient and nutrient composition of broiler diets A2 Ingredient and nutrient composition of chick diet of layer and native chicken A3 Ingredient and nutrient composition of layer diets A4 Ingredient and nutrient composition of quail diets
48 49 49
50
NUTRIENT REQUIREMENTS OF POULTRY
A5 A6
A7 A8 A9
Ingredient and nutrient composition of turkey diets Chemical composition and nutritive value of certain feedstuffs (as fed basis) Chemical composition and nutritive value of green forages or meals (DM basis) Composition of minerals in different feedstuffs (as fed basis) Amino acid composition of certain feedstuffs (as fed basis)
List of Tables
51
51 53 54
55 58
NUTRIENT REQUIREMENTS OF ANIMALS
1
Introduction
Poultry production in the country has gained momentum during the last four decades. Consequently, it has taken the shape of a full-fledged industry. At present, this industry has emerged as the most dynamic and fastest expanding segment in animal husbandry sector. The percent annual growth rate was 6 in 1980s, 11 in 1990s and 19 in 1997-2002 in broiler chickens, and 5-6 in egg production during this period (Mandal et al., 2005a). The overall combined growth rate was 7.23% during 2003-2007. With an annual production (BAHS, 2010) of around 61.45 billion eggs (95.2% chicken, 2.5% duck and 2.3% from other species) and 2.03 million metric tonnes of poultry meat, India ranks 3rd and 5th in egg and meat production, respectively, in the world. The estimated poultry population in 2007 was 648.8 million comprising 617.7 million chicken, 27.6 million ducks and 3.5 million diversified poultry birds such as Japanese quails, turkeys, guinea fowls, emus, etc. (BAHS, 2010). The performance of birds in terms of meat and egg production has also improved significantly in the recent years. Poultry birds being reared inIndia include commercial chickens (white and coloured broilers, and laying hens), improved chickens for low-input rural poultry production (CARI-Nirbheek, HITCARI, UPCARI, CARIDevendra, CARI Shyama, Vanaraja, Giriraja, Gramapriya, Krishna J, Nandanam-99, Gramalakshmi, etc.), native and exotic ducks (Khakhi Campbel, White Pekin, Pati, Indian Runner, etc.), Japanese quails (egg type and meat type), turkeys (white andblack plumage), guinea fowls (Pearl, Lavender and White) and emus. There is vast  scope for growth of poultry industry in j9 future as per caput annual availability i of (51 eggs numbers) and meat (3.43 kg out of ' which 1.73 kg in Jj poultry meat) is gg much less against B the requirement of Vanaraja hen Vanaraja cock 180 eggs and 11.8 kg meat. India’s export share of poultry produce may go up to 5% in future. However, in the recent years, poultry industry has been affected due to rising feed cost, export-import prices, fluctuating market price and several other factors. The requirement of poultry feed is around 16 million
V|
2
NUTRIENT REQUIREMENTS OF POULTRY
and is likely to increase to 35 million tonnes by 2025 assuming 6-7% growth. The availability and cost of maize and soybean meal generally determine the feed cost. Countries producing maize and soybean meal produce broilers with low feed cost like Brazil followed by India and the USA. Though the average annual growth of maize and soya production corroborates well with the growth rate of poultry production, the fluctuation in their production due to monsoon failure, diversification to human and industrial use, export, etc. leads to scarcity of these principal commodities. As there is scarcity of both maize and soybean meal at reasonable price, locally available feed ingredients are being utilized more and more in least cost efficient mixed feed. India, due to its highly variable landscape, rainfall and agro-climate, produces large number of raw materials for feeding; however, only a narrow range of raw materials are used in poultry feed formulations due to lack of reliable data on their nutritive quality, feeding value and safe or effective levels of inclusion. More careful approaches to sustain the poultryindustry in the competitive market, either domestic or international, should be the reduction of cost of production, production of safe and quality products to meet the consumers’ demands and to address environmental concern. tonnes at present,
Feeding Systems
Poultry birds are generally rearedeither under intensive, semi-intensive or extensive systems. The commercial broilers, layers, breeders and Japanese quails are reared under intensive production system. In intensive system of production, birds may be reared either on deep litter or cage system. Commercially, the broilers are reared on deep litter system mainly due to low investment and labour cost. Layer chickens can be reared under both deep litter and cage systems; however, the most commonly followed method is the cage system. The cage system of rearing layer chickens has been considered as a super-intensive system with 1-4 birds in a cage, arranged in single or double or triple rows (California cage system). The advantages of cage system are rearing of larger number of birds per unit area, better feed conversion efficiency, production of clean eggs, culling of nonÂŹ productive birds, control of vices such as cannibalism and egg eating, control of parasitic diseases like coccidiosis and worm infestation, and reduction of feed wastage and spoilage. The major disadvantages include difficulties in ensuring proper ventilation to birds especially in summer season and under very high dense conditions, incidence of leg problem, cage layer fatigue, fatty liver syndrome, flies and increased obnoxious gases in the house. Free range system or extensive methodis the oldest of all andhas been used for centuries by general farmers where there is no shortage of land.
NUTRIENT REQUIREMENTS OF ANIMALS
3
Semi-intensive system is adopted where the area under scavenging is limited. Improved native chickens, guinea fowls and ducks are reared in extensive or semi-intensive system. Emu and Turkey, depending upon the flock size are reared in either of above types. The number of birds reared under extensive system mainly depends upon the available feed resources, area under scavenging, type of birds, etc.
Components of Poultry Diets
Energy Energy and protein (amino acids) are two major items of poultry feed that need special consideration as both can bring a continued andincreased production of eggs and meat with the entry of improved genetic stock (Mandal et al., 2004c). Energy is required to maintain all biological activities (movement, walking, heartbeat, respiration, panting, etc.), vital processes (consumption, digestion, absorption, transportation, etc.) and chemical reactions occurring in the body for synthesis of proteins, fats, glycogen, eggs, organic molecules, etc. It is also deposited in the body in the form of protein as structural component, and fat and glycogen as readymade available source of energy whenever required for vital activities and processes, and chemical reactions. Thus, the gain in body weight is the gain of energy and the egg production is conversion of dietary energy to egg energy. Energy concentration in the diet or its requirement is expressed either as calorie (cal) or joule. One kilocalorie (kcal) is equivalent to 4.184 kilojoules (kj), alternatively one kj is equivalent to 0.239 kcal. There are certain terms associated with expression of dietary energy concentration. Gross energy (about 4,400 kcal/kg in typical poultry feed) is the total heat produced after complete ignition of unit sample in a bomb calorimeter. Some part of energy consumed is excreted through faeces (Faecal Energy-FE, about 22.7% of gross energy in normal diet): the digested part is called digestible energy (DE =GE - FE). Some part of DE is excreted through urine (UE, 4.5% of gross energy). The remaining part of consumed energy retained in the body (about 72.7%) is called metabolizable energy (ME = DE-UE). Some part of ME is lost as heat increment (HI) due to ingestion, digestion, nutrient metabolism (specific dynamic action-SDA or heat due to nutrient metabolism-HNM) and excretion. SDA is the major contributor of HI. HI is mere waste and also exerts stress on birds, except in winter wherein it is beneficial to keep body warm. HI for different functions is; maintenance 0.4 kcal/g, protein synthesis 1.4 kcal/g, fat synthesis 1.0 kcal/g, and egg production 1.1 kcal/ g of feed. After deducting HI from ATE value of the feed, that remains is called net energy (NE). As activity and type of function greatly affect HI,
4
NUTRIENT REQUIREMENTS OF POULTRY
the NE value ranges from 41.0 to 61.4% of gross energy (Farrel, 1974). The net energy is again partitioned for maintenance (NEm), gain (NEg), and production (NEp). As faeces andurine pass together, ME is the best measure offeed energy expression in poultry. Energy requirements are also expressed in terms of ME. The term ME that is used under all practical purposes is apparent metabolizable energy-nitrogen corrected (AMEn). The classical ME represents GE minus energy lost through excreta. If classicalME is corrected to zero nitrogen balance, it is called AMEn. If feed intake is normal, the AME corrected at zero nitrogen balance is more or less constant. The classical experimental protocol developed by Hill and Anderson (1958) is still in use for estimating AMEn. AMEn = GE - excreta energy - 8.22 X N-retained Where, GE = GE of 1kg feed dry matter, Excreta energy = Energy voided /kg of feed dry matter intake. It is calculated as (total dry excreta voided x calorific value of excreta)/ feed dry matter
intake,
N-retained = Nitrogen retained (g) / kg feed dry matter intake. 8.22 = calorific value of 1 g uric acid nitrogen True ME (TME) differs from AME, as the former corrects the loss of energy, which is endogenous in origin (from the body of the bird, not feed). There is constant loss of energy through faeces andurine (collectively excreta) even when the bird is under starvation. TME is always higher than AME but both are highly correlated. However, TME is not in use either for expressing feed energy value or requirements of birds due to several demerits in assumption and assay procedure. However, TME method is utilized for assessing nutrient availability (amino acids and minerals). Productive energy is very similar to net energy value of feed, i.e. it is that amount of feed energy utilized for maintenance and production. This system of energy evaluation is not in operation. AMEn values of different feedstuffs are generally evaluated using practical diet replacement method, in which a practical diet is formulated (reference diet) and part of it is replaced by the feedstuff subjected to evaluation for AMEn generally at two substitution levels (test diets) as suggested by Sibbald and Slinger (1963). Protein contents of diets are generally kept nearer to the requirement, and diets are supplemented with vitamins and minerals. Different methods (glucose replacement methods, prediction from chemical composition, organic matter metabolizability or dry matter metabolizability) have been suggested. Dry matter metabolizability can be estimated if quantity of feed dry matter consumed and quantity of dry matter voided in excreta are recorded in a definite period of time (48 to 72 hr).
NUTRIENT REQUIREMENTS OF ANIMALS
5
DMM = (Dry matter intake - dry matter outgo in excreta)/ dry matter intake x 100 DMM has close relationship with AME and AMEn (Mandal and Pathak, 1996) in mixed feed and thus can be calculated as follows: Chicken: AME (kcal/kg) = 855.3 + 32.66 DMM% (n=66 sets, r = 0.85, P<0.001) AMEn (kcal/kg) = 1258.2 + 26.09 DMM% (n=66 sets, r = 0.75, P<0.001) Guinea fowl: AME (kcal/kg) = 849.6 + 37.15 DMM% (n=66 sets, r = 0.89, PcO.001) AMEn (kcal/kg) = 792.0 + 32.72 DMM% (n=66 sets, r = 0.85, P<0.001) As energy is the limiting factor in poultry diets, its accurate supply is a must to achieve desired response. Chickens have the remarkable ability to control energy intake by regulating feed intake, especially at thermo¬ neutral zone. However, under heat stress or sudden change in dietary energy concentration the adjustment is less precise. Therefore, dietary energy level is fixedfirst and thereafter based on energy concentrationthe other nutrients are set. Expression of daily energy requirement per bird is more accurate than of dietary concentration expressed as kcalME/kg diet; however, because of daily variation in feed intake in growing birds due to change in body weight, the energy value is expressed as kcal ME/kg diet. In layers, the daily requirement is calculated from body weight, egg mass, environmental temperature and ultimately translated to kcal/kg based on feed intake. Feed conversion ratio (FCR, feed: gain) is an important economic parameter. Dietary ME concentration directly influences FCR, i.e. better FCR is achieved at higher ME concentration in the diet. Maximizing energy intake in commercial broilers, especially in winter, leads to ascitis and in summer sudden death syndrome (SDS) due to high body heat load. Deposition of abdominal and carcass fat is also more in high energy diets. Environmental temperature plays an important role in feed and energy intake. A reduction of 1.5 g feed intake per °C is observed at temperature beyond 30°C and it may be even higher (2 to 4g/°C) if temperature exceeds 35°C. As a result, weight gain, feed utilization efficiency and survivability decrease during summer. ME intake declines by 2.5 % on every degree increase in ambient temperature from 20 to 30°C. Normal feed consumption is reduced by 10-15% during summer. Therefore, chicks hatched during summer suffer from low feed intake and it becomes very difficult to achieve optimum body weight of about 1350gatl8 weeks of age. Moreover, at the onset of egg production, feed intake is reduced in pullets and energy intake becomes a limiting factor for growth and egg
production.
6
NUTRIENT REQUIREMENTS OF POULTRY
The AMEn values suggested for chickens can safely be used for other poultry species. Several trials have been conducted in India (Mandal and Pathak, 1996, Mandal et al. 2005b, 2006a; Elangovan et al., 2006) on different cereals and their byproducts, and oilcakes in different poultry species (chicken, guineafowl and Japanese quails), but differences in AMEn values due to species did not exist. Maize is the most common source of energy in poultry diets. However, sorghum, pearl-millet, broken wheat, broken rice, rice polish, deoiled rice bran, etc. can also be used alone or in combination according to the specified safe or effective level of inclusion. Fats and oils (8,200 to 8,600 kcal ME/ kg) are also rich sources of energy and are used to enrich diets with energy. Soya lecithin is also a very good source of energy (5,600 kcal ME/kg) and choline, a phospolipid present in it, helps in improving digestibility of fats.
Protein and Amino Acids Proteins play an important role in body structural functions, muscle contraction, transportation of nutrients and oxygen, regulating acid-base balance, catalyst in chemical reactions (enzymes), immuno-competence (antibodies), chemical regulation (hormones), blood clotting, dim light vision, growth and production. Growth is a functionof protein and energy deposition. The egg contains many proteins (albumen, globulin, ovomucin, avidin, etc.), and 1 egg of 58 g contains 7 g of protein. Poultry birds require all the 20 amino acids for protein synthesis and other biological functions. Essential amino acids are those that are not synthesized in the animal body at a rate required for normal growth and other production functions, hence must be supplied through diet. These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tyrosine and valine. In addition, glycine and proline are also essential for broilers. The quality of protein depends upon the composition or assortment of essential amino acids. The assortment of essential amino acids of a feed protein, very nearer to body protein, is considered very good quality proteins. The limiting amino acids are those essential amino acids which are usually deficient in diet. Lysine (Lys) is the first limiting
amino acid in most of the soya-free diets. Controversy continues
to
exist
on the level of dietary Lysine for optimal body weight gain, feed conversion
and breast meat development. Breast meat is the major part of edible meat (about 25%) andcontains high concentration of Lysine. Lysine requirement for optimum feed conversion ratio (FCR) is higher than that for optimum body weight gain. Under practical conditions, nutritionists aim also for optimum FCR. Methionine (Met) is the first limiting amino acid in broilers on conventional corn-soya-based diets. Thus Met supplementation
NUTRIENT REQUIREMENTS OF ANIMALS
7
improves dietary amino acid balance and promotes greater protein build up, increases breast yield and decreases fat deposition. Difference in feather development in different breeds or strains of broiler also influences the demand for Cysteine, thus total sulphur containing amino acids requirement. Threonine (Thr) is the third limiting amino acid for broilers, second limiting amino acid in growing Japanese quails and first limiting amino acid in starting egg-type pullets. Threonine is closely associated with the digestive enzymes and mucus in the digestive tract. It is retained by intestine and used for mucin formation or catabolized by enterocytes (Stoll et al., 1998). Threonine requirement for amylase synthesis is particularly high at approximately 11 % of protein. It is also involved with amylase secretion. Threonine content of feather protein is relatively high. Broilers differing in feathering rate may have different dietary requirements. In ovo injection of 20 to 30 mg of threonine into yolk-sac of embryo modulated post-hatch growth and breast meat yield in broilers at marketable age (Kadam et al., 2008). The ideal protein concept (Bhanja and Mandal, 2005; Kaur et al., 2006, 2007, 2008) may play an integral role in precision protein nutrition to minimize the loss of N and dietary P indirectly by improving growth and production. Judicious use of protein and amino acids (amino acid) required for maximum growth and production also saves the birds from heat stress by minimizing heat increment. Production can also be reduced through reduction of dietary protein incorporating most limiting amino acids. Reduction of dietary protein lowers the feed cost besides providing space for energy supplements. As defined by Batterham (1992), availability refers to the portion of total amino acid that is digested and absorbed in the form suitable for protein synthesis. The two terms digestibility and availability are often considered synonymous. Nitrogen metabolism in the hind gut comprises both the degradation of nitrogenous substances (dietary and non-dietary origin) andthe synthesis of microbial proteins. The balance between the two activities determines whether the recovery of amino acid in excreta, relative to the ileum, will decrease or increase. Deamination of amino acid leads mainly to the formation of ammonia, which may be absorbed but not utilized by the bird and almost completely excreted in the urine as uric acid and urea (feed arginine is the only source of urea). When the net result is degradation, the output of amino acid in excreta will be decreased, resulting in the overestimation of amino acid digestibility. On the other hand, when the net result of microbial activity is synthesis, the reverse situation will occur resulting in under- estimation of digestibility. As caeca is the major site for microbial degradation and synthesis of amino acids, caecetomized cockerels have also been used for determination of true amino acid digestibility of major cereals, oilseed meals, and animal protein supplements at CARI (Vasan et al., 2007, 2008ab).
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NUTRIENT REQUIREMENTS OF POULTRY
Digestible amino acid values are becoming important for poultry feed formulations. However, formulations of diets based solely on digestible amino acid are few. The major reasons include: (1) wide variations in published digestible amino acid values from different sources, arising from differences in sample variation, type of birds, assay diets and assay methodology, (2) insufficient knowledge of the batch-to-batch variation of amino acid digestibility values, and (3) limited published information on broiler responses to diets formulated on the basis of digestible amino acid. Reports indicate that broilers fed diets formulated on a digestible amino acid basis had significantly improved performance and breast meat yield (Bhanja, 2003; Vasan, 2006). Meat yield increased further with additional dietary methionine supplementation. Formulation of broiler diets on a digestible amino acid basis may permit higher dietary inclusion of cheaper, alternative protein sources and decrease nitrogen excretion by the bird. Application of ideal protein concept and meeting digestible amino acids in practical feed formulation may help in utilizing costlier protein supplements efficiently and, if formulated with minimum requirements based on digestible amino acids rather than total, the total amino acids couldbe adjusted downward by 5 to 10% (Waldroup, 2001, Vasan, 2006). Amino acid and immunity: Amino acids and other nutrients play an important role in the development and functioning of immune system. Glick et al. (1981, 1983) reported that the thymus is very sensitive to periods of feed deprivation, especially amino acid deficiency. This results in lower IgG production. CD4+ cells act as the source for IL-4 and IL-6 cytokines, which by activating B cells causes the proliferation and differentiation of immunoglobins. Konashi et al. (2000) reported that isoleucine deficiency impairs thymus development, and decreases the delayed cutaneous hypersensitivity response and circulating levels of T cell coÂŹ
+ T cells. The requirement of amino acid for growth and maximal immune response are not identical. Research in rats indicated that lysine does not have any significant effect on antibody litres though it affects growth (Lotan et al., 1980). The dietary limitations of lysine gave rise to only a slight depression of immune response. Moderate reduction of threonine in the diet produced profound depression of humoral immune response but the cytotoxic cell-mediated immunity remained intact. Methionine is known for its cellular immunity (Bhanja et al., 2004ab; Thakur, 2007). Swain and Johri (2000) found that methionine supplementation has higher leucocyte migration inhibition value and enhanced antibody titre of Newcastle disease virus. Konashi et al. (2000) reported that the branched chain amino acids (iso-leucine, leucine and valine) affect the humoral and cell-mediated immune response by affecting antibody production. Amino
receptors, CDS
NUTRIENT REQUIREMENTS OF ANIMALS
9
acid composition of immunoglobulin revealed that threonine, leucine and valine contents were comparatively higher in immunoglobulin (Tenenhouse and Deutsch, 1966). Bhargav et al. (1970, 1971) also observed that deficiency of valine and threonine reduced the antibody production against ND virus in chicken. Gastro-intestinal tract amino acid metabolism: The tissues of the gastro-intestinal tract play a major role in the metabolism of protein and amino acid in growing animals. Intestinal tissue has a high rate of protein metabolism, which is directly linked to the high rates of proliferation, protein secretion, cell death, and desquamation of various epithelial and lymphoid cells within the mucosa. Because the small intestine is the first tissue exposed to the diet, it has a key regulatory role in the digestion, absorption, metabolism and availability of dietary protein and amino acids for growth. The major oxidative fuels for the intestine are glutamate, glutamine, aspartate and glucose; however, some essential amino acids, such as lysine, leucine and phenylalanine are also oxidized. Dietary threonine and cysteine are utilized by the intestinal mucosa for mucin and glutathione synthesis. From a nutritional perspective, although threonine is considered essential, cysteine is not. However, cysteine can be synthesized from methionine, an essential amino acid. Therefore, increasedmetabolism of methionine to meet cysteine needs may become limiting for growth, and hence has nutritional significance. In ovo threonine supplementation increased villi height (Kadam et al., 2008) of broiler chickens. Amino acidand embryonic growth: Positive effect on growth at hatch was observed from eggs that receivedin ovo injection of amino acids (Bhanja et al., 2003ab, Ohta et al., 2001). Injecting amino acid into an egg might stimulate amino acid utilization by increasing amino acid synthesis and concomitant decrease of amino acid degradation by the embryo. Although the protein fraction is partly constitutive (albumen), a large fraction of the egg protein consists of antibodies the hen synthesized during the immune responses it experienced at the time the egg was laid. It is important to note that, during incubation, the developing embryo must be supplied with amino acids, but these do not come from maternal antibodies. Under normal circumstances, maternal antibody is not digested during the incubation process, leaving these immunoglobulins intact and fully functional at the time of hatch. Dietary amino acid profile and ratios (relative to Lysine) for broilers: The optimum lysine concentrations vary from 1.10 to 1.30 in starting diets (0-3 weeks) and 1.00 to 1.20% in finisher diets (3-6 weeks). Thereafter (6-9 weeks) the requirements vary from 0.75 to 0.85 % for optimum growth and feed conversion ratio. The requirements of methionine andmethionine plus cysteine for the corresponding phases are
10
NUTRIENT REQUIREMENTS OF POULTRY
0.48 -0.50 and 0.75-0.90, 0.38-0.45 and 0.78-0.88, and 0.32-0.35 and 0.60-0.72%. The threonine requirements are 0.75-0.80, 0.60-0.70 and 0.59-0.68% for 0-3, 3-6 and 6-9 weeks of age respectively. Arginine affects utilization of lysine, thus its concentration needs to be considered. The requirements of arginine are 1.18-1.25, 0.97-1.10 and 0.83-1.0% for the corresponding phases of broiler growth. The consideration of ratio of different dietary amino acids is important in broiler nutrition so as to avoid the chances of deficiency, imbalances, toxicity and antagonism of amino acids. Moreover, an ideal protein is one that supplies all the amino acids in proper ratio required for protein synthesis and should result in minimum heat increment. Different dietary proteins have different ratios of amino acids, but ideal amino acid ratios or profile should be one that promotes maximum gain and feed conversion efficiency. The ideal ratios for lysine to protein (% lysine: % CP) are 0.0552, 0.0540 and 0.0522 for 0-3, 3-6 and 6-9 weeks of age respectively. The ideal ratios (in relation to % of Lysine) as reported (Thomas et. al., 1992; NRC, 1994; Baker, 1996; Waldroup, 1999; Bhanja etal., 2002a,b; Bhanja, 2003) for gain and FCE are lysine (100), methionine 36 to 44 (average 40), methionine+cysteine 69 to 75 (average 72), tryptophan 16 to 17 (average 17), threonine 55 to 67 (average 61), isoleucine 61 to 71 (average 66), arginine 93 to 108 (average 103), leucine 94 to 117 (average 107) andvaline67 to 81 (average 76). Dietary aminoacidprofilefor egg-typepullets-. The dietary requirements of amino acids in egg-type starting chicks are: lysine 0.85%, methionine 0.30%, methionine + cysteine 0.62% and threonine 0.68% at 2850 kcal ME/kg diet (NRC, 1994). The value of lysine was lower than 0.9% as specified by BIS (1992). Study carried out at CARI, Izatnagar also indicated that the requirements specified for these amino acids by NRC (1994) are applicable for tropical condition of India. A diet with 2,600 kcal ME/kg, 14.6% CP, 0.62% lysine, 0.28% methionine and 0.56% threonine was found optimum for growing pullets during 6-12 weeks of age. The daily needs of lysine, methionine, methionine + cysteine and threonine for laying hens producing more than 90% eggs are 690 mg, 300 mg 580 mg and 470 mg, respectively (NRC, 1994). Meeting amino acid requirements: The requirements of majority of amino acids are met out even at lower level of dietary protein than the specified one. The limiting amino acids in poultry nutrition depend on the source of protein used in the diet. These amino acids are also available commercially. Methionine has been the most limiting one in diets based on soybean meal. Its requirement is met either by supplementing synthetic DL-methionine or DL-2-hydroxy 4-methylthiobutanoic acid (DL-HMB), more commonly referred to and known as methionine hydroxy analogue.
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