Levels Of dLys Research Articles

Development of artificial neural network models based on experimental data of response surface methodology to establish the nutritional requirements of digestible lysine, methionine, and threonine in broiler chicks

An artificial neural network (ANN) approach was used to develop feed-forward multilayer perceptron models to estimate the nutritional requirements of digestible lysine (dLys), methionine (dMet), and threonine (dThr) in broiler chicks. Sixty data lines representing response of the broiler chicks during 3 to 16 d of age to dietary levels of dLys (0.88–1.32%), dMet (0.42–0.58%), and dThr (0.53–0.87%) were obtained from literature and used to train the networks. The prediction values of ANN were compared with those of response surface methodology to evaluate the fitness of these 2 methods. The models were tested using R2, mean absolute deviation, mean absolute percentage error, and absolute average deviation. The random search algorithm was used to optimize the developed ANN models to estimate the optimal values of dietary dLys, dMet, and dThr. The ANN models were used to assess the relative importance of each dietary input on the bird performance using sensitivity analysis. The statistical evaluations revealed the higher accuracy of ANN to predict the bird performance compared with response surface methodology models. The optimization results showed that the maximum BW gain may be obtained with dietary levels of 1.11, 0.51, and 0.78% of dLys, dMet, and dThr, respectively. Minimum feed conversion ratio may be achieved with dietary levels of 1.13, 0.54, 0.78% of dLys, dMet, and dThr, respectively. The sensitivity analysis on the models indicated that dietary Lys is the most important variable in the growth performance of the broiler chicks, followed by dietary Thr and Met. The results of this research revealed that the experimental data of a response-surface-methodology design could be successfully used to develop the well-designed ANN for pattern recognition of bird growth and optimization of nutritional requirements. The comparison between the 2 methods also showed that the statistical methods may have little effect on the ideal ratios of dMet and dThr to dLys in broiler chicks using multivariate optimization.

Ratio needs of arginine relative to lysine of male broilers from 28 to 42 days of age during a constant, elevated environmental temperature regimen

SUMMARY The digestible Arg (dArg)-to-digestible Lys (dLys) ratio of broilers exposed to a constant, elevated ambient temperature was evaluated in commercial high-yielding male broilers. Common starter and grower diets were fed to all broilers from 0 to 28 d of age. Experimental diets were provided from 28 to 42 d of age. The experimental test diets were formulated with corn, soybean meal, corn distillers dried grains with solubles, and an animal by-product blend. The diets were formulated to satisfy all nutrient recommendations, with the exception of dArg. To create the experimental finisher diets, 2 experimental diets were formulated to contain 0.95 and 1.24% dArg and a common dLys level of 0.95%. These 2 diets were then blended to create 5 intermediate dArg:dLys levels (7 treatment diets in total), which were fed from 28 to 42 d of age. A diet made exclusively with conventional ingredients, with a dArg:dLys ratio of 107%, served as a positive control. Body weight gain was unaffected by the 7 experimental diets. Feed efficiency was improved in the experimental diets when the dArg:dLys ratio was 110%. However, no difference was observed for this parameter when compared with the FE of the control diet (dArg:dLys = 107%). Carcass traits were unaffected by the experimental treatments. Therefore, an adequate dArg:dLys ratio during a period of constant, elevated temperature was satisfied at a minimum of 110%.

Estimation of ideal ratios of methionine and threonine to lysine in starting broiler chicks using response surface methodology

In a dose-response study, dietary levels of standardized ileal digestible methionine (dMet), lysine (dLys), and threonine (dThr) were optimized by response surface methodology (RSM) using a central composite rotatable design in starting broiler chicks that were feed-deprived 2 d posthatch. In total, 60 floor pens of 6 birds each were assigned to 15 diets of central composite rotatable design containing 5 levels of dMet (0.42–0.58%), dLys (0.88–1.32%), and dThr (0.53–0.87%) from 3 to 16 d of age. Experimental levels of dMet, dLys, and dThr significantly affected bird performance. The second-order models for BW gain and feed conversion ratio (FCR) were generated. The response surface analysis showed significant quadratic models for BW gain and FCR. The crossproduct of amino acids was significant for FCR but not significant for BW gain. Canonical analyses on BW gain and FCR models showed that the maximum BW gain at the stationary point may be obtained with 0.54, 1.12, and 0.78% of dMet, dLys, and dThr in the diet, respectively, and the minimum FCR at the stationary point may be obtained with 0.53, 1.13, and 0.75% of dMet, dLys, and dThr in diet, respectively. Estimated ideal ratios of dMet and dThr to dLys were 48 and 70% for BW gain and 47 and 66% for FCR. Canonical analysis revealed the most important amino acids in the models of BW gain and FCR were Lys and Thr, respectively.

Digestible Lysine Requirement of Liuzhou Mahua Broilers at Different Growth Stages

Experiments were conducted to determine the digestible lysine (DLys) requirement of Liuzhou Mahua broilersfrom 1 to 21 d and from 22 to 42 d of age. Monofactorial design was adopted in this study. 1200 one-day-oldhealthy broiler chicks were divided randomly and evenly into five treatments, and were all fed with isoenergeticdiet (with ME of 3.0 Mcal/kg) but with graded levels of DLys: 1.22%, 1.12%, 1.02%, 0.91% and 0.81% duringthe period of 1 to 21 days; 1.13%, 1.02%, 0.92%, 0.82% and 0.71% during the period of 22 to 42 days. Theresults showed that the DLys level in diet had a quadratic relationship both with the average daily gain (ADG)and feed:gain ratio (F/G). For Liuzhou Mahua broilers from 1 to 21 d of age, ADG was the highest at the DLyslevel of 1.12%, which was not significantly different from those at the levels of 1.22% and 1.02% (P>0.05), andF/G was the lowest at the DLys level of 1.22%. For Liuzhou Mahua broilers from 22 to 42 d of age, at the DLyslevel of 1.02%, ADG was the highest, and F/G was the lowest, but not significantly different from those at thelevels of 1.13% and 0.92% (P>0.05). According to regression analysis results, for Liuzhou Mahua broilers from1 to 21 d of age, the optimum DLys requirement was 1.07% with ADG as the indicator, and was 1.13% with F/Gas the indicator. For Liuzhou Mahua broilers from 22 to 42 d of age, with ADG and F/G as the indicator, DLysrequirement were 0.89% and 0.84%, respectively. Liuzhou Mahua broilers were not as sensitive to DLysconcentration variation as fast-growing broilers from abroad.

Effects of digestible lysine levels on growth performance, serum metabolites and carcass composition in barrows

This study was conducted to investigate the effects of different levels of dietary lysineon growth performance, serum metabolites, and carcass composition in growing‐finishing barrows fed to achieve a body weight (BW) of about 70 kg from an initial weight of 40 kg. Forty‐eight barrows were randomly assigned to one of three dietary groups containing 0.59, 0.75 or 0.91% digestible lysine (DLys), respectively. Results showed that the ADG and G/F increased (P < 0.05) as the level of DLys increased. The dressing percentage of barrows in the 0.91% DLys treatment group was larger (P < 0.05) than that in the other two groups. Other chemical indexes of body composition, including protein, ash, lipid accretion rates, and estimated lean yields were also affected (P < 0.05) by the level of dietary DLys. Increases in of lysine intake elevated the concentrations of glucose and insulin (P > 0.05). The concentrations of serum urea nitrogen and T3 first decreased and then increased (P < 0.05), while T4 decreased (P < 0.05) with increasing levels of DLys. These findings suggest that barrows fed diets providing 14.21 MJ of DE/kg from over a period during which BW increases from 40 to 70 kg, show the maximum ADG and G/F when the concentration of DLys is 0.91%, which corresponds approximately to an intake of 18.4 g/day DLys and 0.63 g of DLys/MJ of DE, respectively.

Effects of Dietary Metabolizable Energy and Protein on Early Growth Responses of Broilers to Dietary Lysine

Two studies evaluated effects of metabolizable energy (ME), digestible Lys (dLys), and amino acid (AA) balance on broiler performance. In experiment 1 diets contained 3 levels of ME (3,000, 3,100, and 3,200 kcal/kg) in combination with 4 levels of dLys (1.05, 1.13, 1.21, and 1.29%). A fixed proportion of dLys relative to CP and key indispensable AA was maintained in graded increments of CP from 21.9 to 26.9%. There was no interaction of ME and dLys for 21 d BW gain or adjusted feed conversion ratio, which improved linearly with dietary dLys. Increasing the dLys or ME had no effect on feed intake, and the linear improvement in performance was attributed to a step-wise increase in dLys when diets contained a balance of AA and CP. Experiment 2 evaluated broiler response to 20 d of age when diets contained graded increments in dLys while maintaining a fixed proportion of dLys relative to CP and indispensable AA (balanced CP), or when dLys was increased in diets by supplementing synthetic l-Lys to 1 of 2 basal diets with 22.0% CP (low CP) or 27.0% CP (high CP) without adjusting concentrations of other AA or CP. The BW gain of broilers fed the low CP diet series followed a quadratic response, and the dLys requirement was estimated to be 1.19 ± 0.03% (1.30% total Lys). By contrast, BW gain on both the high CP and balanced CP diet series increased linearly. The higher BW gain and continued response to dLys above 1.19% when CP and AA concentrations were increased confirmed that the dLys requirement of broilers was dependent on the dietary CP. When a fixed ratio of dLys to CP was applied and indispensable and dispensable AA were not limiting, broiler BW gain and adjusted feed conversion ratio responded positively to incremental dLys up to at least 1.32% (27.2% CP) and was independent of the dietary ME over a range from 3,000 to 3,200 kcal/kg.