Validated procedures play an important role to obtain accurate information about individual amino acid requirement data. The aim of the present study was to assess lysine (Lys) requirement of growing chicken both by classical supplementation tech nique and principles of diet dilution technique as applied with “Goettingen ap proach”. During the starter period (1 - 21 d), a growth study with male meat type chicken (Ross 308) was conducted making use of five graded dietary Lys-levels (3 repetition boxes with 3 birds/box). L-Lys × HCl was gradually added to a diet based on wheat, soybean protein concentrate, wheat gluten and fishmeal to yield 80%, 87.5%, 95%, 102.5% and 110% of the expected requirement level (13 g Lys/kg as fed). Diets were iso-energetic (12.8 MJME/kg) and iso-nitrogenous (21.65% crude protein). Birds were fed on free choice level also to assess the feed intake (FI) effects as important factor on traditional response criteria. Analyzed body composition at start and end of the growth study yielded N deposition (ND) data for further data assessment using exponential approximations depending on dietary Lys content or observed Lys intake. The results indicated significant differences (p < 0.05) in response on body weight gain (BWG) and observed dietary protein quality with unexpected consequences for the derived Lys requirement data. According to the independent variable (Lys in % of diet versus daily Lys intake) and aimed level of daily ND, the needed in-feed content of Lys varied between 1.24% and 1.46%. Application of the exponential modelling by “Goettingen approach” overcame these misleading conclusions by modelling the relationship between required Lys intake and observed response data (BWG, ND) taking also into account the expected real feed intake to formulate the needed in-feed concentration.
Inaccurate formulation of dietary amino acid supply will impair protein utilization and increase the total nitrogen output to the environment. In consequence, validated protein evaluation systems are a “must be” for improved efficiency of protein conversion process to satisfy current needs both for management of resources and for sustainability of the process to convert feed into food protein for human nutrition.
Mathematical models and statistical methods of data analysis have been created to improve the procedure for assessment of individual amino acid (AA) requirement data [
Gebhardt [
Lysine (Lys) is generally the second limiting amino acid after methionine and cystine (Met + Cys) in soybean-based mixed feeds for chicken [
The purpose of this study was a comparative evaluation of Lys requirement data of growing chicken based both on supplementation technique and principles of the diet dilution technique (“Goettingen approach”).
The experiments were conducted at Division Animal Nutrition Physiology at the Georg- August-University of Goettingen and approved by the the Animal Welfare Committee of Lower Saxony, Germany.
A total number of 45 male meat-type chickens (Ross 308) were obtained from a commercial hatchery and prepared for the experiment during starter period (1-21d). Birds were housed in wire floor cages with 3 birds per box (1 m × 1 m × 0.5 m) and 3 boxes per treatment. The cages were equipped with individual feeders and self-drinking system. Housing temperature was maintained at 32˚C (day old chicken) and sub sequenly continuously decreased to 25˚C up to the end of the experimental period. Humadity was maintained between 60% - 70% and warm red light was provided for 24 h per day.
Experimental diets (
At the start of the experiment, three birds of one day old chicken were sampled for body analyses and further calculation of N-deposition. Birds were weighed and randomly allotted to the experimental diets. The chicks were fed ad libitum to assess the feed intake effects which are an important factor of influencing on traditional response criteria. Feed supply was recorded daily and spilled feed was quantified for correction of daily feed intake. During the growth study, birds were individually weighted weekly. At the end of experiment, all birds were fasted for 24 hours and euthanized by carbon dioxide exposure. All samples were stored at −20˚C for further body nitrogen analysis.
Diets were analyzed for dry matter (DM), crude nutrients, starch and sugar according to the German VDL UFA standards [
Item | Diet1 | ||||
---|---|---|---|---|---|
L1 (80%) | L2 (87.5%) | L3 (95%) | L4 (102.5%) | L5 (110%) | |
Wheat | 480.00 | 480.00 | 480.00 | 480.00 | 480.00 |
Wheat starch | 220.23 | 220.43 | 220.62 | 220.85 | 230.05 |
Soy protein concentrate | 60.75 | 60.75 | 60.75 | 60.75 | 60.75 |
Fish meal | 50.00 | 50.00 | 50.00 | 50.00 | 50.00 |
Wheat gluten | 50.00 | 50.00 | 50.00 | 50.00 | 50.00 |
Soybean oil | 20.97 | 20.85 | 20.73 | 20.58 | 20.45 |
DCP | 10.63 | 10.63 | 10.63 | 10.63 | 10.63 |
CaCO3 | 5.00 | 5.00 | 5.00 | 5.00 | 5.00 |
NaCl | 1.80 | 1.80 | 1.8 | 1.80 | 1.8 |
Premix2 | 10.00 | 10.00 | 10.00 | 10.00 | 10.00 |
L-Glutamic acid | 34.60 | 32.60 | 30.60 | 38.6 | 36.60 |
L-Lysine×HCl | 5.00 | 6.30 | 7.50 | 8.80 | 10.0 |
DL-Methionine | 4.50 | 4.50 | 4.50 | 4.50 | 4.50 |
L-Valine | 3.80 | 3.80 | 3.80 | 3.80 | 3.80 |
L-Threonine | 3.30 | 3.30 | 3.30 | 3.30 | 3.30 |
L-Tryptophan | 0.50 | 0.50 | 0.50 | 0.50 | 0.50 |
L-Arginine | 5.40 | 5.40 | 5.40 | 5.40 | 5.40 |
L-Isoleucine | 2.90 | 2.90 | 2.90 | 2.90 | 2.90 |
L-Leucine | 3.30 | 3.30 | 3.30 | 3.30 | 3.30 |
L-Phenylalanine | 2.60 | 2.60 | 2.60 | 2.60 | 2.60 |
L-Histidine | 0.90 | 0.90 | 0.90 | 0.90 | 0.90 |
Phytase3 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 |
Xylanase4 | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 |
1L1 = 80%, L2 = 87.5%, L3 = 95%, L4 = 102.5%, L5 = 110% of the expected dietary lysine concentration as needed (13 g Lys/kg diet). 2Provided (per kilogram of diet): vitamin A, 5000 IU; vitamin D3, 1000 IU; vitamin E, 30 IU; thiamine, 2.6 mg; riboflavin, 4.8 mg; vitamin B6, 3.2 mg; vitamin B12, 20 μg; vitamin K3, 3 mg; capantothenate, 10 mg; nicotinic acid, 50 mg; folic acid, 0.9 mg; biotin, 100 μg; choline chloride, 1000 mg; Mn, 120 mg (source: MnO); Zn, 70 mg (ZnO); Fe, 50 mg (FeSO4); Cu, 15 mg (copper sulfate pentahydrate); I, 1.4 mg (Ca-iodate-hexahydrate); Se, 0.28 mg (Na2SeO3); Co, 0.17 mg [basic cobalt (II) carbonate monohydrate], and butylated hydroxytoluene, 100 mg. 3ZY Phytase 5.000, activity per g: 5000 FYT 6-phytase. 4ZY 68, activity per g: 1000 FXU Endo-1,4-β-xylanase.
with and without oxidation step for quantitative determination of the sulphur-con- taining AAs Met + Cys. The ether extract was analyzed following HCl-hydrolysis of the feed samples.
For body analyses birds were carefully defrosted, autoclaved for 4 h at 110˚C (HMC Europe, GmbH, Germany) and homogenized. Subsequently, representative samples were taken for DM and N analyses (Tru-Mac, LECO, Moenchengladbach, Germany).
Parameters of the conducted growth study were mean initial BW (IBW), final BW
Nutrients1 | Diets | ||||
---|---|---|---|---|---|
L1 | L2 | L3 | L4 | L5 | |
Crude protein | 24.6 | 24.3 | 24.7 | 24.7 | 24.7 |
Ether extract | 5.4 | 5.3 | 5.1 | 4.8 | 4.7 |
Crude fibre | 1.6 | 1.6 | 1.5 | 1.5 | 1.5 |
Crude ash | 5.4 | 5.3 | 5.3 | 5.4 | 5.2 |
N-free extract | 62.8 | 63.3 | 63.3 | 63.5 | 63.7 |
Starch | 56.6 | 56.9 | 57.3 | 57.4 | 57.6 |
Sugar | 1.5 | 1.7 | 1.4 | 1.4 | 1.2 |
ME (MJ/kg DM)2 | 14.0 | 14.0 | 14.1 | 14.1 | 14.1 |
Lysine | 1.14 | 1.25 | 1.36 | 1.46 | 1.57 |
Methionine + Cystine | 1.05 | 1.05 | 1.05 | 1.05 | 1.06 |
Threonine | 0.93 | 0.93 | 0.93 | 0.93 | 0.93 |
Tryptophan | 0.24 | 0.24 | 0.24 | 0.24 | 0.24 |
1All samples were analyzed at least as duplicate, values were averaged afterward. 2Calculated according to equation of WPSA [
(FBW), BW gain (BWG), total feed intake (FI) and feed conversion ratio (FCR). Average daily N deposition (ND) was calculated as analyzed final body N mass minus initial body N mass divided by 21 experimental days. The Lys requirement data were estimated from achieved daily ND depending on dietary Lys concentration or appropriate daily Lys intakes based on nonlinear regression analyses.
According to Schutte and Pack [
where: y is the daily N deposition (
The Lys requirement is defined as abscissa value corresponding to the point of the fitted response curve at 95% of the upper asymptote [
According to several studies [
where: NR is daily N retention (
Lys requirement data were calculated based on Equation (5):
where: LAAI is daily intake of limiting amino acid (
Model parameters NMR (113
Results are presented as mean values ± standard error of the mean (±SEM). Statistical analyses run with the SPSS software package program (version 19.0 for Windows, IBM SPSS Statistics Inc., Chicago, IL, USA). Differences between variables were compared by one-way analysis of variance (ANOVA). Verification of variance homogeneity and identification of statistical significance was applied by Tukey and Games-Howell tests. Observed differences between variables with p ≤ 0.05 were considered to be statistically significant. Individual outlier data (p ≤ 0.05) were identified according to Dixon and Massey [
Summarized results of the growth study are presented in
According to numerous studies [
Parameter | Diet2 | p | ||||
---|---|---|---|---|---|---|
L1 (80%) | L2 (87.5%) | L3 (95%) | L4 (102.5) | L5 (110%) | ||
IBW3 (g) | 44.8a ± 0.3 | 43.9a ± 0.2 | 44.4a ± 0.5 | 44.1a ± 0.2 | 45.9a ± 0.2 | 0.142 |
FBW4 (g) | 624.9c ± 29 | 918.5b ± 21 | 1159.0a ± 15 | 1120.3a ± 12 | 1103.4a ± 49 | 0.000 |
BWG5 (g) | 580.1c ± 29 | 874.65b ± 21 | 1114.45aa ± 15 | 1076.23a ± 12 | 1057.54a ± 49 | 0.000 |
FI6 (g) | 729.4c ± 18 | 1028.8b ± 29 | 1335.9a ± 13 | 1249.5a ± 5 | 1235.4a ± 50 | 0.000 |
FCR7 | 1.26a ± 0.03 | 1.23a ± 0.00 | 1.20a ± 0.02 | 1.16a ± 0.01 | 1.17a ± 0.01 | 0.186 |
1Mean values (three replicates ± SEM) with similar superscripts within rows are not significantly different (p > 0.05). 2L1 = 80%, L2 = 87.5%, L3 = 95%, L4 = 102.5%, L5 = 110% of the expected dietary lysine concentration as needed (13 g Lys/kg diet). 3Initial body weight. 4Final body weight. 5Body weight gain (FBW-IBW). 6Feed intake (total FI during 21 d). 7Feed conversion ratio (total FI (g): BWG (g)).
protein deposition (PD) as demonstrated in
The results of daily ND (
It has to be noted that this type of requirement estimates based on an arbitrary graduation to make use of the maximum ND response without considering the real feed intake as factor of influence [
In consequence, the observed individual ND data were fitted depending on averaged Lys intake levels of each experimental diet (
Furthermore, if observed ND data were fitted as function of real individual Lys intakes (
Parameter | Diet2 | p | ||||
---|---|---|---|---|---|---|
L1 (80%) | L2 (87.5%) | L3 (95%) | L4 (102.5%) | L5 (110%) | ||
PD (g/d) | 4.42c ± 0.22 | 6.84b ± 0.17 | 8.43a ± 0.12 | 8.90a ± 0.10 | 8.69a ± 0.39 | 0.000 |
Protein quality (b)3 | 158b ± 4.6 | 182a ± 0.9 | 186a ± 2.9 | 193a ± 2.6 | 188a ± 2.3 | 0.004 |
Lys efficiency (bc−1)4 | 34.2a ± 1.0 | 35.6a ± 0.2 | 33.9a ± 0.5 | 32.5ab ± 0.4 | 29.5b ± 0.4 | 0.009 |
1Mean values (three replicates ± SEM) with similar superscripts within rows are not significantly different (p > 0.05). 2L1 = 80%, L2 = 87.5%, L3 = 95%, L4 = 102.5%, L5 = 110% of the expected dietary Lys concentration as needed (13 g Lys/kg diet). 3b = Model parameter assessing the dietary protein quality (b × 106). 4bc−1 = Model parameter assessing the dietary efficiency of the limiting AA Lys (
importance of methodical standardization for valid conclusions in AA requirement studies.
The summarized results of modelling Lys requirement data according to Equation (5) for graded daily PD resp. BWG responses and predicted FI levels are presented in
adequate dietary AA concentration.
In consequence, a high variation of Lys requirement estimates also can be found in the literature [
BWG | PD | ND | Lys requirement | Optimal Lys content in the starter diet (%) at feed intake of | |||
---|---|---|---|---|---|---|---|
(g/d) | (g/d) | ( | ( | (mg/d) | 50 g/d | 60 g/d | 70 g/d |
48.5 49.1 49.7 50.3 50.9 51.5 52.1 52.7 53.3 53.9 54.5 | 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 9.0 | 1932 1956 1980 2004 2028 2053 2077 2101 2125 2149 2173 | 1030 1046 1063 1080 1097 1114 1131 1148 1166 1184 1202 | 682 693 704 715 727 738 749 761 772 784 796 | 1.36 1.39 1.41 1.43 1.45 1.48 1.50 1.52 1.54 1.57 1.59 | 1.14 1.16 1.17 1.19 1.21 1.23 1.25 1.27 1.29 1.31 1.33 | 0.98 0.99 1.01 1.02 1.04 1.05 1.07 1.09 1.10 1.12 1.14 |
1Measured mean body weight of birds during the experimental period of 21 days fed diets L3 to L5 according to data of
dietary protein concentration and AA balance as well as factors of AA bioavailability as affected by anti-nutritional factors may act as important factors of influence. In addition, according to the selected response criteria (performance characteristics, feed efficiency data, physiological parameters) varying requirement data are observed. Furthermore, the applied statistical models for assessing AA requirements (broken-line models, non-linear regression analyses, response surface methods, empirical approaches, etc.) considerably impact on validity of concluded AA requirement data [
Possibilities and limitations of different procedures for AA requirement studies were already discussed elsewhere [
The applied “Goettingen approach” makes use of an exponential function and describes the physiological process of N utilization in growing animals depending on N intake or LAA intake. The modelling procedure involves both the BW and graded performance data (PD, BWG) as reference criteria for estimating of growth dependent AA requirement data. Additionally, graded data of dietary Lys efficiency and predicted feed intake data can be taken into account for a wide scale of requirement data corresponding to the most important factors of influence. Consequently, remarkable modulation of the derived optimal dietary Lys concentration for modern meat-type chickens is not surprising (
The presented modelling of Lys requirement based on data evaluation by “Goettingen approach” is demonstrating that an adequate dietary Lys supply to yield optimal performance data and feed efficiency in broiler chicken production is modulated by different animal factors like age period, aimed growth (PD) performance and the realized FI. In addition, dietary factors influencing the Lys efficiency need more consideration. The observed high variation of Lys recommendations in meat type chicken is partly subjected to this important factor and requires more investigations, but also more standardized experimental conditions for more validated conclusions.
Generally, a fine structured network of recommendations could be achieved by modelling of requirement data which are adequate for integration into feeding systems continuously adapted to changes in BW, growth, FI and in-feed Lys requirements. However, more reliable data due to the expected variation of AA efficiency in feed ingredients are needed. By this way, application of physiologically based new procedures like “Goettingen approach” might contribute to more validated recommendations in the future and to reduce the currently observed high variation in Lys requirement data.
The authors thank German Academic Exchange Service (DAAD) and Experts4Asia program for financial support of travel and living expenses of Samadi.
Samadi, Wecke, C., Pastor, A. and Liebert, F. (2017) Assessing Lysine Requirement of Growing Chicken by Direct Comparison between Supplementation Technique and “Goettingen Approach”. Open Journal of Animal Sciences, 7, 56-69. http://dx.doi.org/10.4236/ojas.2017.71006