Nutritional requirement of digestible tryptophan for white-egg layers of 60 to 76 weeks of age

The objective of this study was to determine the nutritional requirement of digestible Trp for white egg layers in the period from 60 to 76 wk of age. A total of 180 Dekalb White layers with an average weight of 1,345 kg were distributed in a completely randomized design with 5 increasing levels of digestible Trp (0.167, 0.175, 0.183, 0.191, and 0.199%), 6 replicates, and 6 birds per experimental unit. The diets of the treatments contained 0.759% of digestible Lys, which was obtained using the prediction equation of the Brazilian Tables for Poultry and Swine, and each treatment consisted of a digestible Trp-to-Lys ratio of 22, 23, 24, 25, or 26%. The digestible Trp levels in the diet had a quadratic effect on egg production, egg mass, and conversion per mass and per dozen eggs, and a linear effect on egg weight. In conclusion, a diet with 0.192% digestible Trp, in a 25.33% ratio with digestible Lys or 212 mg/bird per day, can be recommended for white egg layers of 60 to 76 wk of age.     

Nutritional requirement of digestible threonine for white egg layers of 60 to 76 weeks of age

The objective of this study was to determine the requirement for digestible Thr for optimum performance of white egg layers in the period from 60 to 76 wk of age. DeKalb White Leghorn layers with an average weight of 1,345 kg were distributed 5 increasing levels of digestible Thr (0.523, 0.546, 0.569, 0.592, and 0.615%) in a completely randomized design, with 6 replicates and 6 birds per experimental unit for a total of 180 birds. The dietary treatments contained 0.759% of digestible Lys, which was obtained using the prediction equation of the Brazilian Tables for Poultry and Swine, and each treatment consisted of a digestible Thr-to-Lys ratio of 69, 72, 75, 78, or 81%. The digestible Thr levels had a linear effect on feed intake and a quadratic effect on egg production, egg mass, and feed conversion per mass and per dozen eggs. In conclusion, a digestible Thr-to-Lys ratio of 75.14% is recommended for White Leghorn of 60 to 76 wk of age, corresponding to the level of 0.570% in the diet and a daily intake of digestible Thr of 622 mg/bird.     

2‐Hydroxy‐4‐methylthio butanoic acid and DL‐methionine for Japanese quails in production

An experiment was performed using 1,000 laying Japanese quails to assess the availability of two alternative dietary methionine sources. Treatment 01 = Basal Feed that is deficient in digestible methionine + cystine (Met + Cys). The other treatments were constituted by Met + Cys levels of 0.8, 1.60 and 2.40 g/kg, supplemented with DL‐Methionine‐99%, HMTBA‐88% and HMTBA‐84%, being 10 treatments in total. The following characteristics were studied: feed intake (g/bird/day), egg production (egg/day × 100), egg weight (g/egg), egg mass (g/egg), feed conversion per egg dozen (kg feed/dozen eggs), feed conversion per egg mass (kg feed/kg eggs), relative yolk weight (g/100 g of egg), relative albumen weight (g/100 g of egg), relative shell weight (g/100 g of egg), shell thickness (mm) and specific gravity (g/cm³). In general result comment, supplemental methionine sources must be included in the poultry diet. The different methionine sources affect the performance of quails, and the increase in the levels within each source improves the performance variables. Significant effect was observable on performance variables and egg quality variables, being that DLM‐99% is superior to the other sources. The HMTBA‐88% source is superior to the HMTBA‐84% source for the same aforementioned variables. In conclusion, the bioefficacy values of the HMTBA‐88% and HMTBA‐84% sources compared to the DLM‐99% source on an equimolar basis were 81 and 79%, respectively, for the performance variables, and 83 and 74 while the methionine sources were equivalent for the variables related to egg quality.     

Digestible lysine requirement for growing Japanese quails

A total of 1,000 one-day-old Japanese quails were distributed at random, with 5 digestible lysine levels, in 10 replicates and with 20 birds per experimental unit. The basal diet was formulated based on corn and soybean, with 200.6 g CP/kg, 2900.00 kcal/kg ME, and 8.8 g digestible lysine/kg. This basal diet was supplemented with L-lysine HCl (784 g/kg), replacing glutamic acid, and corresponding to digestible lysine levels of 8.8 g/kg, 9.8 g/kg, 10.8 g/kg, 11.8 g/kg, and 12.8 g/kg. The increase in the levels of digestible lysine produced a greater weight gain in birds with up to 12.2 and 12.1 g of lysine/kg at 40 d of age. Carcass weight increased as levels were increased to up to 11.85 g of lysine/kg, and, similarly, egg production per bird housed increased up to 12.03 g of lysine/kg. A linear increase took place in the growing phase for feathering, fat, and crude protein deposits in the carcass, feed intake, and lysine intake. Egg production and egg mass per bird per d increased linearly in the laying phase with the weight gain of birds decreasing linearly until 100 d of age, and, similarly, the feed conversion per egg mass linearly improved in function of the lysine levels. A level of 11.85 g of digestible lysine/kg in the diet, which corresponded to a lysine intake of 120.5 mg/bird/d, provided better carcass weight at the end of the growing phase and better performance at the beginning of the laying phase for the Japanese quails.     

Exogenous enzyme complexes and linoleic acid to laying hens

The aim of this research was to evaluate how the decrease of fat inclusion (and therefore compounds essential for animal development, such as linoleic acid) and the use of exogenous enzyme complexes can affect the performance of layers. Treatments consisted of diets with different levels of linoleic acid, the negative control (NC) with 2.41 g/100g and positive control (PC) with 3.75g/100g. Treatment 3 (RLLA) was reformulated using enzymes and low levels of linoleic acid equal to the NC, treatment 4 (RILA) and treatment 5 (RHLA) were reformulated using enzymes, but with linoleic acid at moderate (3.08 g/100g) and high levels (3.75 g/100g), respectively. The formulation of treatments 3, 4, and 5 used enzymes reformulated using an enzyme nutritional matrix. The variables analyzed in each period were the feed intake (g/bird/day); egg production (%); egg weight (g); egg mass (g); feed conversion per egg mass (kg/kg) and per dozen eggs (kg/dozen); weight (g) of yolk, albumen, and shell; specific gravity (g/cm³); Haugh unit; and shell thickness (mm). The commercial enzyme supplementation was effective in supporting the productive performance of the laying hens. Nutritional reduction in diets reformulated with supplementation of the commercial enzymes can be an alternative to reduce production costs without compromising the productive performance of hens.     

Effect of dietary digestible lysine concentration on performance,egg quality,and blood metabolites in laying hens

An experiment was conducted to evaluate the effect of dietary digestible lysine concentration on productive performance, egg quality, and blood metabolites in laying hens. A completely randomized block design was performed with 5 treatments and 6 replicates of 8 Hy-line W-36 hens each, from 32 to 44 wk of age. The treatments were 5 digestible lysine concentrations (0.657, 0.707, 0.757, 0.807, and 0.857% of diet). Feed intake was significantly increased with each increment in dietary digestible lysine concentration. Significant improvement in egg production, egg weight, egg mass, Haugh unit, and FCR were observed by an increase in lysine intake. Dietary lysine concentration did not have a significant impact on percentage of egg components, specific gravity, eggshell thickness, DM, and protein constituents of eggs. Dietary digestible lysine concentration did not have a significant effect on triglyceride, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), uric acid, and total protein in plasma. The digestible lysine requirements for optimal egg production, egg mass, and egg weight (32 to 44 wk of age), based on the linear broken-line regression analysis, were 814, 810 and 778 (mg/b/d), respectively. Whereas, these values were 4, 3.9, and 6 percent less than those estimated by the quadratic broken-line model, respectively.     

Performance of lactating sows in response to the dietary valine supply

In order to determine the requirement of lactating sows for valine (Val) the effects of graded Val supplementations on feed intake, milk yield and changes of body weight of sows and piglets were examined using 54 multiparous sows over a total of 72 lactations (35 days). The sows were randomly assigned to six treatments (1-6). Each group received the same basic diet, covering the requirements of energy and nutrients except Val (4.5 g native Val, i.e. 3.5 g apparent ileal digestible Val). Adding crystalline l-Val dietary Val concentrations of 5.5, 6.5, 8.5, 10.5 and 14.5 g/kg, respectively, were realized. Feed intake of the sows was determined daily, body weight was determined on day 110 of gestation and day 1, 22 and 35 of lactation. The piglets were weighed on day 1, 21 and 35. The intake of piglet feed, which was offered from day 21, was determined at day 35 for each litter. Milk yield was determined using the weigh-suckle-weigh-method at day 13, 14, 20 and 21, fat and protein contents were analysed in hand-milked samples with infrared spectroscopy. Feed intake (kg/day) of the sows during lactation averaged 2.9, 4.3, 4.6, 4.6, 4.9 and 5.1 for treatments 1-6, respectively. For treatments 1 and 2 body weight losses of the sows during lactation were higher (1207 and 805 g/day, respectively) and milk production was lower (7076 and 8686 g/day, respectively), compared with the average of treatments 3-6 (625 g/day body weight loss; 9263 g milk/day). Daily weight gain of the piglets was also lower (146 and 171 g/day vs. 200 g/day) leading to lower weaning weights of 6.6 and 7.5 vs. 8.5 kg. As a consistent growth depression of the piglets in Val deficiency must be assumed, at least 6.5 g Val corresponding to 5.5 g apparent ileal digestible Val per kg lactation feed must be recommended.     

Evaluation of amino-acid supplemented diets varying in protein levels for laying hens

The ideal amino acid concept is increasing by being applied to laying hens. However, understanding the responses of modern laying hens to decreasing levels of dietary protein balanced with crystalline amino acids has yet to be examined. In this study, 5 dietary treatments varying in CP content (18.0, 17.5, 17.0, 16.5, and 16.0%) were formulated at a fixed dietary energy concentration of 2,825 kcal of ME/kg of feed. The crystalline amino acids, including Met, Thr, Ile, Val, Trp, and Lys, were supplemented according to an assumed ideal AA profile, and all diets contained 0.831% ileal digestible Lys. Irrespective of the CP levels, the ratio of Lys and the profile of different essential amino acids in relation to Lys remained similar in all the diets. A total of 540 21-week-old Hy-Line W36 hens were used with 6 replicates per treatment group. This trial was conducted for a period of 14 wk, ranging from wk 21 to 34. Egg production, daily egg mass, feed intake, and FCR were not affected in the low-protein groups. Egg weight and N excretion declined, whereas egg yolk color increased in the low-protein groups. Decreasing dietary CP was found to have no effect on blood ammonia and plasma uric acid. The application of the assumed ideal AA profile can lead to reduced dietary protein level, from 18 to 16%, without affecting the production performance of laying hens during 21 to 34 wk of age. The ratios of standardized ileal digestible Met, Met + Cys, Thr, Trp, Arg, Ile, and Val to standardized ileal digestible Lys were 50, 91, 70, 21, 104, 80, and 88%, respectively, in the assumed ideal AA profile. Excretion of nitrogen was significantly decreased from hens fed the protein-reduced diet without impairing BW.     

30～38周龄产蛋鸡理想氨基酸模式的研究

本试验旨在通过4个剂量-反应试验,研究30～38周龄产蛋鸡对赖氨酸(Lys)、蛋氨酸(Met)、色氨酸(Trp)和苏氨酸(Thr)4种必需氨基酸(AA)的需要量及其比例.每个试验均采用360只海兰灰产蛋鸡,设5个处理,分别采食5个AA梯度水平的试验饲粮,每个处理6个重复,每个重复12只鸡.采用蛋公鸡回肠食糜法测定饲料原料的标准回肠可消化(SID)值.试验预试期14 d,正试期56 d.结果表明:海兰灰产蛋鸡的产蛋率、蛋重、日产蛋量和料蛋比与SIDLys、SID Met、SID Trp和SID Thr的摄入水平均有较好的折线回归关系;以日产蛋量为自变量(x),AA摄入水平为依变量(Y)分别建立的回归方程为:YSID Lys=51.60-0.041 6(682.5-x),R2=0.96;YsID Met=51.43-0.085(314.1-x),R2 =0.95;YSID Trp =51.17-0.155 4(163.0-x),R2=0.97;YsID Thr=52.85-0.057 6(499.5-x),R2=0.93.在饲粮粗蛋白质12.8％的条件下,以日产蛋量为参照指标确定的30 ～ 38周龄产蛋鸡的SID Lys、SID Met、SID Trp和SID Thr需要量分别为684、313、171和506 mg/(只·d).以日产蛋量为指标建立的30～38周龄产蛋鸡理想SID AA模式为:Lys:Met:Trp:Thr=100∶46∶24∶73.     

Effect of dietary calcium and phosphorus concentrations on retention of these nutrients by caged layers

1. A 5 3 factorial experiment was carried out with caged White Leghorn hens with 5 concentrations of calcium (26.0, 29.0, 32.5, 36.0, 39.0 g/kg) and 3 concentrations of phosphorus (4.3, 5.0 and 6.0 g/kg) for 120 d. Variables observed were hen day egg production, food consumption, shell weight, shell weight per unit surface area (SWUSA) and egg content. 2. 36.0 g calcium (Ca) and 4.3 g phosphorus (P) kg were found to be the dietary concentrations that resulted in optimal hen day egg production, shell weight, SWUSA and egg content. 3. Lack of a significant interaction between the effects of calcium and phosphorus on production parameters showed that the dietary Ca: P ratio is not of great importance for the laying hen. 4. Absolute retentions of Ca and P were inversely related to percentage retentions. 5. A balance study of calcium and phosphorus also showed optima at 36.0 g Ca and 4.3 g P per kg. 6. It was inferred that 36.0 g Ca and 5.0 g total P per kg are the optimal concentrations in diets for caged layers in a tropical climate.     

Broiler responses to feeds formulated with or without minimum crude protein restrictions and using supplementall-valine andl-isoleucine

Comparisons of corn-soy-feeding programs formulated using different protein constraints were done in the present study. A total of 1,800 one-day-old, slow-feathering Cobb × Cobb 500 male broiler chicks were placed in 72 floor pens of 25 birds each with 9 birds/m². Feeding programs (PRG) were composed of prestarter (PST,1–7 d), starter (ST, 8–21 d), grower (GR, 22–35 d), and finisher (FN, 36–43 d) diets formulated as: PRG 1 = CP restricted to a minimum (22.4, 21.1, 19.8, and 18.4% for PST, ST, GR, and FN, respectively) with amino acid-to-Lys ratios only set for TSAA (0.72) and Thr (0.65); PRG 2 = CP not restricted, whereas ratios of amino acids to Lys were also extended to Val (0.77) and Ile (0.67); PRG 3 and PRG 4 were the same as PRG 2, but withl-Val added in PRG 3 andl-Val andl-Ile in PRG 4. Feeds were formulated to have digestible Lys of 1.324, 1.217, 1.095, and 1.006% for PST, ST, GR, and FN, respectively, or 5% higher. A completely randomized design was used with a 4 × 2 factorial (4 PRG and 2 digestible Lys) design with 9 replications per treatment. Overall, no interactions between PRG and digestible Lys were observed, with 1 exception observed for BW gain and FCR from 36 to 43 d. Birds fed PRG 2 showed improvements in BW gain and FCR when fed the diet 5% higher in digestible Lys. Cumulative BW gain and FCR results at 35 and 43 d, as well as in each individual feeding phase, showed broilers from PRG 2 having the best results, but without mean separation significant differences when compared with PRG 3 and 4. Feeding a dietary program with a 5% increase in digestible Lys resulted in improved cumulative FCR only when cumulatively measured from placement to 43 d. Abdominal fat, as a percentage of the eviscerated carcass at 43 d, was lowest for birds fed PRG 2 diets. Formulation of diets having traditional recommendations of digestible Lys with Val- and Ile-to-Lys ratios of 0.77 and 0.67, without restricting CP, led to the best results overall in performance and fat pad deposition; therefore, if the goal is to reduce CP, similar results should be achieved by addingl-Ile with further reductions in protein ifl-Val is also added. Data obtained in this study support the applicability of supplementation withl-Val andl-Ile when ideal AA ratios are followed.     

Effect of graded nitrogen supplements on egg protein synthesis and body protein retention in broiler hens

In the top laying period (29th/30th week of life) egg protein synthesis and protein retention in the bodies of laying hens were ascertained. Based on egg-N analyses, the relation between N-intake/live weight0.67kg and egg-N discharge/kg LW0.67kg was regressively calculated and described. The subtraction of egg-N discharge/LW0.67kg from N-balance/LW0.67kg made it possible to estimate N-retention/LW0.67kg in the body. From the intersection of this curve with the chi-axis it follows that the broiler hen meets the N-requirement for maintenance and egg production with a daily consumption of 1,264.7 mg N/LW0.67kg, which corresponds to 15.8 g crude protein, and then neither loses nor retains body protein. At a daily intake of this amount of CP (15.8 g) the broiler hen produces 44.1 g egg per day. An energy intake of more than 70 EFUhen/animal and day resulted in fat retention in the broiler hen.     

Performance and Egg Characteristics of Laying Hens Fed Diets Incorporated with Poultry By-Product and Feather Meals

The effects of poultry by-product meal (PBPM) and feather meal (FM) incorporated separately and in combination in the diet on laying hen performance and egg characteristics during postpeak production were determined. Bovans White strain laying hens, 42 wk of age, were fed diets with 0% PBPM and FM, 5% FM, 5% PBPM, or 4% FM + 4% PBPM. Egg production, feed intake, and egg mass were not significantly affected by dietary treatments, whereas egg weight and feed conversion ratio (FCR) were significantly affected. Egg weights of hens receiving 4% FM + 4% PBPM were significantly lower than those fed the control diet, whereas those fed 5% FM or 5% PBPM were intermediate. FCR was significantly improved by the diets containing 5% FM or 5% PBPM compared with the diet containing 4% FM + 4% PBPM. Dietary PBPM decreased Haugh units, but FM did not. Egg breaking strength, shell weight, and weights of albumen and yolk were not affected by treatments. The results suggested that FM or PBPM could be incorporated up to 5% singly or up to 8% in combination in layer diets but with possible detrimental effects on Haugh units, egg weight, and FCR.     

Optimum isoleucine requirement of laying hens and the effect of age

1. Medium weight laying hens were used for an assay to determine their isoleucine requirement between 26 and 36 weeks of age and again between 46 and 56 weeks of age. 2. Two isoleucine-limiting mixtures were formulated with similar amino acid profiles, one containing 198 g and the other 110 g crude protein per kg diet. These mixtures were blended to give a series of 11 diets with isoleucine contents ranging from 7.6 to 3.8 g/kg. The lowest protein diet was also fed with a supplement of L-isoleucine. Each of the 12 diets was given to 5 groups of 24 laying hens. 3. The daily isoleucine requirement of individual laying hens was estimated to be 9.48 mg/g egg output plus 44.47 mg/kg body weight per day for the 1st period and 12.11 mg/g egg output plus 6.86 mg/kg body weight per day for the 2nd period. Calculated optimum intakes of isoleucine for various ratios of cost of input to value of output are tabulated. For example, for a flock of medium weight hens producing an average of 50 g daily egg mass, the optimum isoleucine intake (mg/hen d) varied between 760 and 890 varying for ratios of costs to egg prices. 4. It is concluded that the isoleucine required per day does not decrease during the first laying year despite a decrease in rate of egg output.     

Feeding value of rice distiller’s dried grains with solubles as protein supplement in diet of laying hens

A feeding trial of 10 weeks duration was undertaken on laying hens (n = 240) to evaluate feeding value of rice distiller’s dried grains with soluble (rDDGS) with or without enzyme supplementation (α-amylase, β-glucanase, xylanase, carboxymethylcellulase, pectinase, proteinase, α-galactosidase, β-galactosidase, lipase, and phytase), following 4 × 2 factorial design, on egg production, nutrient utilization, and cost economics of egg production. The birds were randomly assigned to eight dietary treatments with 30 birds/treatment. The birds were housed individually in layer cages and each bird was taken as an experimental unit. Eight experimental diets were prepared by incorporating four levels (0, 50, 75, and 100 g/kg) of rDDGS with and without enzyme supplementation. The results revealed a significant (P < 0.01) increase of egg mass, feed intake, egg production, and body weight gain in dietary treatments with up to 75 g rDDGS though the values were statistically similar to the hens fed 100 g rDDGS. Enzyme supplementation resulted in significant (P < 0.01) improvement of egg mass, egg production, feed conversion ratio (FCR) per dozen eggs, FCR per kilogramme egg mass, and net FCR. The significantly (P < 0.01) higher yolk index was observed at 100 g rDDGS level, while shell thickness improved significantly (P < 0.01) up to 75 g rDDGS level. No significant effect of rDDGS inclusion was observed on shape index, albumin index, and Haugh unit. Enzyme supplementation significantly improved the shell thickness and yolk colour of eggs. Nitrogen, calcium, and phosphorus retention and dry matter metabolizability did not show any significant treatment effects. There was significant (P < 0.01) reduction in feed-cost per kilogramme egg mass or per dozen eggs with the increased DDGS levels and dietary enzyme supplementation. It was concluded that rDDGS can be used up to 100 g/kg diet of laying hens along with enzyme supplementation for better productivity of layer hens.

     

Effect of excess dietary threonine on laying performance,egg quality,serum free amino acids,and digestive enzymes activities of laying hens during the postpeak period

A total of 640 layer hens, 56 wk of age, were allocated to 4 dietary treatments groups, each of which included 5 replicates of 32 hens. Graded levels ofl-Thr were added to the basal diet at 0.0 (control), 1.0, 2.0, and 3.0 g/kg; determined Thr values were 5.7, 6.5, 7.4, and 8.7 g/kg of diet, respectively. In the 53-d feeding trial, egg production increased significantly due to dietaryl-Thr supplementation. Hens fed 2.0 g of Thr/kg of diet had significantly higher egg production than the control diet. Supplementing the diet withl-Thr did not affect egg weight or feed intake, but egg mass increased significantly. Also, FCR was improved significantly and the best FCR was exhibited by hens receiving 2.0 g of Thr/kg of diet. Feeding laying hens a diet containing 2.0 g ofl-Thr/kg of diet improved Haugh units linearly; however, egg shell thickness decreased linearly as the level of dietary Thr increased, and the lowest value was observed for hens fed 3.0 g of Thr/kg of diet. Serum free Thr increased linearly as supplemental Thr increased, but serum free Ile, Phe, and Tyr decreased. No differences attributable tol-Thr were found among groups in the activity of digestive enzymes (trypsin and amylase) in the mucosal homogenates of the jejunum. The activity of α-alkaline phosphatase in the jejunum was analyzed as a marker of mucosal enterocyte maturation and no differences due tol-Thr supplementation were noted. In conclusion, feeding laying hens from 56 to 64 wk of agel-Thr up to 2.0 g/kg can improve laying performance and Haugh units.     

Protein utilization as well as crude protein and amino acid requirements of broiler hens

After N-balance experiments with broiler hens in the top laying period and the feeding of soybean coarse meal/fish meal protein the protein utilisation values were calculated. The PNu curve and the PEW curve could be described as utilisation values from the N-retention curve (e-function). At an intake of N at which the hen neither decomposed nor retained protein, the utilisation (PNu) for maintenance and egg production was 55.3% and the utilisation of feed protein for egg production 49.4%. Maximum PEW 34.3% could only be ascertained at an N-intake/LW0.67kg of 1500 mg. The corresponding crude protein quota of 18.7 g recommended as crude protein requirement is calculated from this N-quota (xm) and a live weight of the broiler hen of 2804 g. For the same N-quota (xm) and the same live weight of the hens this results in a necessary quota of S-AA of 694 mg per hen and day. Provided the daily feed intake is 145 g and thus the intake of crude protein 18.7 g and that of S-AA 694 mg per hen, the necessary crude protein content of the feed is 130 g per kg original substance and an S-AA concentration which is equivalent to 3.7% of the crude protein (in g/16 g N).     

Estimation of the optimum standardized ileal digestible total sulfur amino acid to lysine ratio in late finishing gilts fed low protein diets supplemented with crystalline amino acids

A total of 90 gilts were used to investigate the effects of various standard ileal digestible (SID) total sulfur amino acid (TSAA) to lysine (Lys) ratios on the performance and carcass characteristics of late finishing gilts receiving low crude protein (CP) diets supplemented with crystalline amino acids (CAA). Graded levels of crystalline methionine (Met) (0, 0.3, 0.5, 0.8 or 1.1 g/kg) were added to the basal diet to produce diets providing SID TSAA to Lys ratios of 0.48, 0.53, 0.58, 0.63 or 0.68. At the termination of the experiment, 30 gilts (one pig per pen) with an average body weight (BW) of 120 kg were killed to evaluate carcass traits. Increasing the SID TSAA to Lys ratio increased average daily gain (ADG) (linear and quadratic effect, P < 0.05), improved feed conversion ratio (FCR) (linear and quadratic effect, P < 0.05) and decreased serum urea nitrogen (SUN) concentration (linear and quadratic effect, P < 0.05) of finishing gilts. No effects were obtained for carcass traits. The optimum SID TSAA to Lys ratios to maximize ADG as well as to minimize FCR and SUN levels were 0.57, 0.58 and 0.53 using a linear‐break point model and 0.64, 0.62 and 0.61 using a quadratic model.     

Ideal amino acid profile and dietary lysine specification for broiler chickens of 20 to 40 days of age.

1. The aim of the study was to determine the ideal ratio of the essential amino acids lysine (Lys), methionine (Met), threonine (Thr), tryptophan (Trp), arginine (Arg), valine (Val) and isoleucine (Ile) and to assess the required dietary lysine concentration for optimum performance in broiler chickens of 2 commercial strains from 20 to 40 d of age. 2. An identical basal diet was used throughout all experiments. It consisted mainly of maize and soyabean meal and contained 172 g crude protein and 13.2 MJ AME(N) per kg. For each experiment, the basal diet was adequately supplemented with all essential amino acids except the one to be tested, which was supplemented in 6 graded concentrations in exchange for maize starch. One (Met, Trp, Arg, Val, Ile) or 2 (Lys, Thr) growth trials were conducted per amino acid tested and the response in weight gain, food: gain ratio, breast meat yield and abdominal fat were examined. 3. The ideal amino acid ratio relative to Lys (expressed as a percentage) was calculated to be 75% Met+Cys, 63% Thr, 19% Trp, 112% Arg, 71% Ile and 81% Val on a true faecal digestible basis when the data were subjected to broken-line regression analysis. From both lysine studies the concentration for optimum food: gain ratio was calculated, by exponential regression analysis, to be 11.5 g true faecal digestible lys per kg diet.     

Protein and Energy Requirements of Pre-weaned West African Dwarf Goats Fed Soyabean Diet as a Replacement for Milk in a Tropical Environment

Twenty-one early-weaned West African dwarf goats weighing between 1.0 and 1.5 kg at birth were used to assess the protein and energy requirement of pre-weaned West African Dwarf (WAD) goats fed soyabean diet. Three isonitrogenous diets (24%) were prepared such that dried whole-milk protein was replaced by corn starch and soyabean concentrate protein at 0.0%, 25.0% and 50.0% levels such that a 14.5% total solid solution was obtained for each diet. Results indicated that a daily digestible energy (expressed as kcal/day/W0.75 kg) intake of 58.2, 63.7, 98.5 and 114.6 kcal was required for maintenance, while a corresponding value of 7.37, 4.50, 2.18 and 1.91 kcal was required per day per gram live weight gain by the kids at 4, 6, 9 and 13weeks old, respectively. Similarly, a digestible crude protein (DCP) intake of 3.59 g/day/W0.75 kg) appeared to be adequate for maintenance of the kids between 0 and 13 weeks, while 0.34 g/day/W0.75 kg of DCP intake was required per day per gram live weight.