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Enzyme Supplementation of Broiler Feeds with Reduced Mineral and Energy Levels

ABSTRACT

An experiment was conducted with the purpose of evaluating enzyme blends on the performance, carcass traits, and bone mineralization of broilers. In total, 928 one-day-old Cobb 500 male chicks of were used. A completely randomized design with four treatments with eight replicates of 29 birds each was adopted. The evaluated treatments were: 1- Positive Control (PC), feed containing the nutritional recommendations of the genetic company's manual; 2- Negative Control (NC), feed with reductions of 75 kcal/kg AME and 0.10 and 0.12 percent points of phosphorus and calcium, respectively; 3 - NC + enzyme blend (amylase + b-glucanase, xylanase, and phytase; 250 g/t of feed) and 4 - NC + enzyme complex (phytase, amylase, xylanase, glucanase, pectinase, cellulase, and protease; 200 g/t of feed). Birds fed the diet with reduced nutrient levels (NC) presented the worst performance (p<0.05). The supplementation of the enzyme blend promoted similar (p<0.05) weight gain and feed conversion ratio as those obtained with the PC diet during the period of 1-21 days of age. During the phase of 22-42 days and the entire experimental period, weight gain and feed conversion ratio improved with the use of the enzyme combinations compared with the NC group, but remained lower than the PC group. Enzymes combinations did not affect (p>0.05) carcass or parts yields. The broilers fed the reduced-nutrient and energy diet presented lower (p<0.05) tibial ash, calcium, and phosphorus contents that the other treatments. The use of enzyme combinations improved the performance of broilers fed diets with reduced nutrient and energy levels.

Keywords:
Additives; bone mineralization; broilers; carcass; performance.

INTRODUCTION

In Brazil, poultry diets are based on corn and soybean meal which, in spite of presenting high digestibility, can be better utilized. Studies with broilers fed those ingredients have confirmed that the use of exogenous enzymes individually or in combination improves dietary nutrient utilization, resulting in more uniform animal performance (Cowieson & Adeola, 2005Cowieson AJ, Adeola O. Carbohydrase, protease, and phytase have an additive beneficial effect in nutritionally marginal diets for broilers chicks. Poultry Science 2005;84:1860-1867. ; Francesh & Geraert, 2009Francesch M, Geraert PA. Enzyme complex containing carbohydrases and phytase improve growth performance and bone mineralization of broilers fed reduced nutrient corn-soybean-based diets. Poultry Science2009;88:1915-1924.; Lu et al. 2013Lu H, Adedokun SA, Preynat A, Legrand-Defretin V, GeraertPA, Adeola, O, et al. Impact of exogenous carbohydrases and phytase on growth performance and nutrient digestibility in broilers. Canadian Journal of Animal Science 2013;93(2):243-249.).

According to Lima (2005Lima FR. Aditivos zootécnicos: enzimas.In: Palermo Neto J, Spinosa HS, Górniak Sl. Farmacologia aplicada à avicultura. São Paulo: ROCA; 2005. p.239-248.), the purpose of adding exogenous enzymes to non-ruminant feeds is to reduce the effects of the antinutritional factors of ingredients that are present in greater or lesser amounts in the diet. Enzymes increase, therefore, the availability of nutrients by breaking down specific chemical structures which endogenous digestive enzymes are not capable of breaking down or break down only partially.

According to Choct (2006Choct, M. Enzymes for the feed industry: past, present and future. World's Poultry Science Journal 2006;62:5-15. ), use of commercial enzymes in poultry feeds has evolved greatly in the last few years, based on the efficacy of the new products and a better understanding of the relationship between enzyme activity and substrates available.

Enzyme products containing single enzymes or enzyme blends are currently available in the market. According to Freitas et al. (2011Freitas DM, Vieira SL, Angel CR, Favero A, Maiorka A. Performance and nutrient utilization of broilers fed diets supplemented with a novel mono-component protease. Journal of Applied Poultry Research 2011;20:322-334. ), most of the available enzyme products include more than one enzyme activity. However, there are still some single-component products which possess only one enzyme activity, produced by a specific microorganism. Enzyme blends, a term used for products containing enzyme combinations, are obtained from the production of enzymes through the fermentation of several microorganisms individually, which enzymes are only subsequently blended. On the other hand, enzyme complex is derived from the fermentation with a single microorganism that synthesizes several enzymes.

Barbosa et al. (2012Barbosa NAA, Sakomura NK, Bonato MA, Oviedo-Rondon LHE. Enzimas exógenas em dietas de frangos de corte: desempenho. Ciência Rural 2012;42(8):1497-1502.), studying the efficacy of enzymes in broiler diets, found that the addition of phytase, amylase, xylanase, and protease in diets with reduced metabolizable energy, calcium, and phosphorus content, promoted similar feed intake and weight gain than a diet with adequate nutrient levels. According to the authors, enzyme blends can be added to diets with reduced nutrient levels aiming to maintain broiler growth performance.

The objective of the present experiment was evaluate the use of two different enzyme combinations (a blend and a complex) in diets with reduced nutrient and energy levels on the performance, carcass characteristics, and bone mineralization of broilers.

MATERIAL AND METHODS

The experiment was conducted in the Poultry Production Sector of the Centro de Ciências Agrárias, Ambientais e Biológicas of UFRB, in Cruz das Almas, Bahia, Brazil. A total number of 928 one-d-old male Cobb-500(r) chicks were acquired from a commercial hatchery. The birds were housed in a conventional poultry experimental facility. Each experimental unit (pen measuring 1.65 x 1.55 m), was equipped with wood-shavings litter, a bell drinker, and a tube feeder.

A completely randomized design with four treatments and eight replicates, totaling 32 experimental units with 29 birds each, was adopted.

The following treatments were evaluated: 1 - positive control (PC) diet, formulated according to the nutrient recommendations of the manual of the Cobb-500(r)line (Cobb, 2012Cobb-Vantress. Desempenho e nutrição para frangos de corte Cobb 500. Guapiaçu; 2012. Suplemento.); 2 - negative control (NC) diet, also supplying the recommendations of Cobb-500(r) manual, but with reductions of 75 kcal of AMEn, and 0.10 and 0.12 percentage points of available phosphorus and calcium, respectively; 3 - NC + enzyme blend (250g/t); 4 - NC +enzyme complex (200g/t). The dietary energy reduction was obtained by reducing soybean oil levels and making quantitative adjustments.

The enzyme blend included amylase (160 kNU/g) + b-glucanase (280 FGB/g), xylanase (160 FXU/g), and phytase (2000 U/g). These enzymes (single-component) derived from the following microorganisms: Bacillus amyloliquefaciens(amylase+b-glucanase), Thermomyces lanuginosus (xylanase), and Citrobacter braakii (phytase). The enzyme complex consisted of the combination of the enzymes phytase (300 U/g), protease (700 U/g), xylanase (100 U/g), b-glucanase (200 U/g), cellulase (40 U/g), amylase (30 U/g), and pectinase (4000 U/g), produced by solid-state fermentation of the microorganism Aspergillus niger.

The nutrient composition of corn, soybean meal, dicalcium phosphate, and limestone was determined and the results were used for the formulation of the experimental diets. The nutrient composition of the other ingredients, corrections for corn and soybean meal amino acids, as well as the metabolizable energy values used for diet formulation followed the recommendations of Rostagnoet al. (2011Rostagno HS, Albino LFT, Donzele JL, Gomes PC, Oliveira RF, Lopes DC, Ferreira AS, Barreto SLT, Euclides RF. Tabelas brasileiras para aves e suinos: composicao de alimentos e exigencias nutricionais. 3ed. Vicosa: UFV; 2011.). A feeding program (Table 1) with starter (1-10 days), grower (11-22 days) and finisher (23-41 days) diets was adopted.

Table 1
Ingredient composition and calculated nutrient levels of the experimental diets.

Both temperature (oC) and relative humidity (%) were daily monitored and recorded by means of a thermo-hygrometer. Based on the data collected daily, weekly maximum and relative humidity averages were calculated as 32.5oC and 58.9%; 34.3oC and 50.6%; 31.3oC and 66.1%; 33.3oC and 56.4%; 35.1oC and 54.3%; 33.2oC and 58.3%, respectively.

Birds and feed offer and residues were weighed on days 22 and 41 days to determine the performance variables feed intake, weight gain, and feed conversion ratio. Pen mortality was recorded daily to calculate livability and to correct feed intake.

On days 22 and 42 days old, one bird per unit, with an average weight of the experimental unit, was sacrificed and their tibiae collected for the determination of bone ash, calcium, and phosphorus contents. The birds slaughtered on day 42, which were selected on the previous day (day 41; until then submitted to the same management and feeding practices) during weighing, were also used for the determination of carcass yield, breast yield, leg (thigh and drumstick) yield, and liver relative weight. Birds were fasted for four hours, individually weighed, and sacrificed. Carcass yield was calculated as the ratio between live weight and carcass weight (carcass with no viscera, feet, head, and neck). Breast and leg yields were calculated as the ratio between carcass weight and their respective weights. Liver relative weight was calculated as the percentage of liver absolute weight relative to carcass weight.

In order to determine bone ash content, the tibiae were dried at 105oC, defatted in a fat extractor, ground, and samples were burnt at 600oC. Bone calcium content was determined by atomic absorption spectrophotometry, while bone phosphorus content was determined by UV/visible light spectrophotometry, according to the methodology proposed by the AOAC, method 965-17 (AOAC, 1990).

The results were evaluated for error normality by the Shapiro Wilk test and then submitted to analysis of variance, using SAS statistical package (SAS Institute, 2003). Means were compared by the SNK (Student-Newman-Keuls) test, adopting 5%maximum probability level.

RESULTS AND DISCUSSION

During the period of 1 to 22 days, the best (p<0.05) performance responses were obtained in the PC group and in broilers fed the diets supplemented with the enzyme combinations (enzyme blend or enzyme complex) relative to the other treatments. The birds fed the NC diet presented worse feed intake, weight gain, and feed conversion ratio (Table 2) compared with positive control broilers and equal to those fed the diets supplemented with the evaluated enzyme complex.

Table 2
Performance of 22- and 41-d-old broilers, and carcass yield, cuts yield, and liver relative weight of 42-d-old broilers fed diets supplemented or not with enzyme blends.

The supplementation of the enzyme blend from 1 to 22 days allowed for similar growth performance as the positive-control diet, which mineral and energy levels were not reduced, whereas the birds supplemented with the enzyme complex presented the same performance of those fed the NC diet. These results are consistent with the findings of Barbosa et al. (2012Barbosa NAA, Sakomura NK, Bonato MA, Oviedo-Rondon LHE. Enzimas exógenas em dietas de frangos de corte: desempenho. Ciência Rural 2012;42(8):1497-1502.), who observed that the supplementation of enzyme blends to diets with reduced mineral and energy levels promoted similar feed intake and weight gain that broilers fed a standard diet during the starter phase. Britoet al. (2006Brito CO, Albino LFT, Rostagno HS, Gomes PC, Dionizio MA, Carvalho DCO. Adição de complexo multienzimático em dietas à base de soja extrusada e desempenho de corte. Revista Brasileira de Zootecnia 2006;35(2):457-461.), using an enzyme complex containing amylase, protease, and xylanase, observed increased weight gain and improved feed conversion ratio in broilers between 1 to 21 days of age, as opposed to the findings of the present experiment. In addition, Leiteet al. (2011Leite PRSC, Leandro NSM, Stringhini JH, Café MB, Gomes NA, Jardim Filho RM. Desempenho de frangos de corte e digestibilidade de rações com sorgo ou milheto e complexo enzimático. Pesquisa Agropecuária Brasileira 2011;46(3):280-286.), who evaluated the same enzyme complex as the current study, found better feed conversion ratio 21-d-old broilers.

The results obtained on day 41 (Table 2) indicate performance differences (p<0.05) among broilers submitted to the different treatments. The birds fed the positive control diet and those fed the NC+EBdiet presented similar (p>0.05) feed intake. The NC group presented lower feed intake, while those fed the NC+EC presented similar feed intake as the PC and NC+EB groups.

Weight gain during the entire rearing period was the highest (p<0.05) in the broilers fed the PC diet, while those fed the NC diet presented the worst result. Regardless of the enzyme combination used, broilers fed enzymes did not achieve the same weight gain as those fed the standard diet.

The best feed conversion ratio (p<0.05) was obtained in birds fed the PC diet, while those fed the NC presented the worst feed conversion ratio. Relative to the broilers supplemented with the enzyme blends, those fed the EB presented worse feed conversion ratio (a difference of 1.55%) than those fed the EC diet (p<0.05). These results are in agreement with the findings of Toledo et al. (2007Toledo GSP, Costa PTC, Silva JH, Ceccantini ML, Poletto C. Broilers fed diets varying in energy and protein supplemented with a pool of enzymes. Ciência Rural2007;37:518-523.), who evaluated enzyme supplementation to diets with different nutrient densities and observed that the performance of broilers fed a low-density diet supplemented with enzymes was better relative to those fed a low-density diet, but did not achieve the same level as those fed a standard diet. A similar response was observed by Francesh & Geraert (2009), who found that the supplementation of an enzyme blend improved the weight gain and the feed conversion ratio of broilers fed nutrient-reduced diets.

Livability was not significantly different among treatments (Table 2), and the average mortality was below 3.2%.

The nutrient and energy reductions of the NC treatment effectively allowed for the statistical performance differentiation from the PC diet, which was an important initial proposal of this study. On the other hand, Fortes et al. (2012Fortes BD, Café MB, Stringuini JH, Brito JAG, Rezende PLP, Silva RD. Avaliação de programas nutricionais com a utilização de carboidrases e fitase em rações de frangos de corte. Ciência Animal Brasileira 2012;13:24-32.), testing the addition of carbohydrases and phytase to a standard diet and to a reduced-nutrient diet, observed that dietary enzyme supplementation promoted higher feed intake and weight gain in 42-d-old broilers, but did not affect feed conversion ratio.

Differently from the results of the present study, Cowieson & Ravindran (2008Cowieson AJ, Ravindran V. Effect of exogenous enzymes in maize-based diets varying in nutrient density for young broilers: growth performance and digestibility of energy, minerals and amino acids. British Poultry Science2008;49:37-44.) found higher weight gain and better feed conversion ratio in broilers fed diets with reduced energy and amino acid levels supplemented with an enzyme complex as compared with a standard diet with no enzyme supplementation. Lu et al.(2013Lu H, Adedokun SA, Preynat A, Legrand-Defretin V, GeraertPA, Adeola, O, et al. Impact of exogenous carbohydrases and phytase on growth performance and nutrient digestibility in broilers. Canadian Journal of Animal Science 2013;93(2):243-249.) supplementing a blend containing xylanase, b-glucanase, and phytase to diets deficient in energy, protein, calcium, and phosphorus, observed a significant improvement in the performance of broilers supplemented with enzymes.

The high temperatures recorded in weeks 4, 5, and 6 of the rearing period, with maximum temperatures higher than 33ºC, may have influenced broiler performance. According to Bertechini (2012Bertechini AG. Nutrição de monogástricos. 2.ed. Lavras: UFLA; 2012. ), it is difficult for broilers to exchange heat with the environment, and the main means of heat exchange is by panting. The increased respiratory rate in hot environments leads to a reduction in feed intake, which may affect weight gain. According Lu et al. (2007Lu Q, Wen J, Zhang H. Effect of chronic heat exposure on fat deposition and meat quality in two genetic types of chicken. Poultry Science2007;86(1):1059-1064.), chicken exposure to high temperatures causes a reduction in feed intake resulting in negative effects on growth rate. In spite of the highest feed intake (absolute) on day 41 obtained by the PC birds (4.556 kg/bird; Table 2), this value is lower than the feed intake estimated in the management guidelines of the broilers' genetic strain (Cobb, 2012Cobb-Vantress. Desempenho e nutrição para frangos de corte Cobb 500. Guapiaçu; 2012. Suplemento.), which is 4.766 kg/bird. The high environmental temperatures recorded during the grower phase possibly directly affected the birds' feed intake, resulting in lower weight gain.

Among other reasons, the enzyme supplementation may not have been efficient to allow for similar performance as that obtained with the standard diet due to the higher lipid (oil) level of the positive control diet, which has less impact on the heat increment compared with carbohydrates and proteins. The heat increment represents all energy lost during nutrient digestion, absorption, and metabolism (Sakomura & Rostagno, 2007Sakomura NK, Rostagno HS. Métodos de pesquisa em nutrição de monogástricos. Jaboticabal: Funep; 2007. ). Therefore, the broilers fed the PC diet may have been less affected by heat stress and responded better to heat stress during the grower period.

Carcass, breast, and leg yields, and liver relative weight of 42-d-old broilers were not affected (p>0.05) by the mineral differences (0.1 and 0.12 percent points of available phosphorus and calcium) or by the energy difference (75 kcal AME) among the diets, independently of enzyme supplementation. These results are consistent with those of Carvalho et al. (2009)Carvalho JCC, Bertechini AG, Fassani EJ, Rodrigues PB, Pereira , RAN. Desempenho e características de carcaça de frangos de corte alimentados com dietas à base de milho e farelo de soja suplementadas com complexos enzimáticos. Revista Brasileira de Zootecnia2009;38(2):292-298. and Fortes et al.(2012Fortes BD, Café MB, Stringuini JH, Brito JAG, Rezende PLP, Silva RD. Avaliação de programas nutricionais com a utilização de carboidrases e fitase em rações de frangos de corte. Ciência Animal Brasileira 2012;13:24-32.), who supplemented enzyme blends to diets based on corn and soybean meal and found no influence of the treatments on carcass or cuts yield. Santos et al. (2008Santos FR, Hruby M, Pierson EEM, Remus JC, Sakomura NK. Effect of phytase supplementation in diets on nutrient digestibility and performance in broiler chicks. Journal of Applied Poultry Research2008;17(2):191-201. ) evaluated the addition of xylanase, amylase, and protease to broiler diets and also did not observe any significant differences in liver relative weight.

Ash, calcium, and phosphorus contents and weights in the tibiae of 22- and 42-d-old broilers are shown in Table 3.

Table 3
Content (%) and weight (mg) of ashes, calcium and phosphorus in the tibiae of birds 22- and 42-d-old broilers fed diets containing or not enzyme blends.

There were no significant differences (p>0.05) in ash, calcium, or phosphorus contents in the tibiaeof 22- or 42-d-old broilers as a function of the diets evaluated.

Ash weights were significantly different (p<0.05) among treatments with PC broilers presenting the highest ash weight, and NC the lowest, whereas those supplemented with the enzyme blends (1 or 2) higher ash weight compared with the NC birds when evaluated at 22 days of age. Tibial ash, on a weight basis, showed similar behavior to that observed for weight gain of the birds at the end of the experimental period, as broilers presenting higher weight gain also had higher ash weight.

The broilers fed the NC diet presented the lowest tibial phosphorus (mg) and calcium (mg) weights measured at 22 days of age (p<0.05), while the highest values were obtained in the PC broilers. The tibial phosphorus weight obtained with the supplementation of the enzyme blend was similar to that of positive control diet, but was not different from that promoted by enzyme complex. Birds supplemented with enzymes presented similar tibial calcium weight.

Francesch & Geraert (2009Francesch M, Geraert PA. Enzyme complex containing carbohydrases and phytase improve growth performance and bone mineralization of broilers fed reduced nutrient corn-soybean-based diets. Poultry Science2009;88:1915-1924.) found that reducing dietary nutrient levels resulted in reduced bone ash, calcium, and phosphorus contents in comparison with a standard diet. In addition, those authors observed that supplementing the nutrient-deficient diet with a xylanase, glucanase, and phytase blend, improved the bone mineralization of 21-d-old broilers, promoting similar results as those obtained with a standard diet. However, in the present study, the treatments influenced the weight but not the contents (%) of ashes, calcium and phosphorus.

The tibial ash content obtained in 22-d-old broilers in the present study are different from the responses ash obtained by Shawet al. (2011Shaw AL, Hess JB, Blake JP, Ward NE. Assessment of an experimental phytase enzyme product on live performance, bone mineralization, and phosphorus excretion in broiler chickens. Journal Applied Poultry Research 2011;20:561-566.), who evaluated the addition of different levels of phytase to diets with three different phosphorus levels and found that the highest phytase addition level promoted similar ash content as those found in the broilers fed the highest dietary phosphorus level.

Tibial ash and phosphorus weights determined when broilers were 42 days of age presented similar behavior as those determined when broilers were 22 days old. At 42 days of age, tibial ash and phosphorus weights of the PC-fed birds and those supplemented with both enzyme blends were similar; however, the results obtained with the enzyme treatments were not different from those of the negative control groups. Tibial calcium weight was not affected (p>0.05) by the diets evaluated.

The tibial ash and phosphorus content results of the present study are in agreement with those obtained by Oliveira et al. (2008Oliveira MC, Marques RH, Gravena RA, Bruno LDG, Rodrigues EA, Moraes VMB. Qualidade óssea de frangos alimentados com dietas com fitase e níveis reduzidos de fósforo disponível. Acta Scientarum Animal Sciences 2008;30(3):263-268. ), who did not find any effect of the addition of phytase on the tibial ash and phosphorus content of broilers. On the other hand,Onyango et al. (2005Onyango EM, Bedford MR, Adeola O. Phytase activity along the digestive tract of the broiler chick: A comparative study of anEscherichia coli derived and Peniophora lycii phytase. Canadian Journal of Animal Science 2005;85:61-68.) reported that phytase supplementation of a low-phosphorus diet restored broiler growth rate, but ash content remained low. In addition, Walk et al. (2011Walk CL, Cowieson AJ, Remus JC, Novak CL, Mcelroy AP. Effects of dietary enzymes on performance and intestinal goblet cell number of broilers exposed to a live coccidia oocyst vaccine. Poultry Science2011;(90):91-98.), evaluating different of phytase, xylanase and protease combinations in broiler diets with reduced available phosphorus and calcium levels, found effect of enzyme supplementations on the ash content. Possibly, the reduced dietary calcium and phosphorus contents, as well as the reduced energy levels, limited not only muscle growth, but also skeletal growth. Birds may have presented smaller bones, but ash, calcium, and phosphorus contents were similar.

CONCLUSION

The supplementation of enzyme blends to diets with reduced calcium, phosphorus and energy levels allowed for the partial recovery of broiler growth performance and bone characteristics. The single-component enzyme blend (amylase (160 kNU/g) + b-glucanase (280 FGB/g), xylanase (160 FXU/g), and phytase (2000 U/g) provided better performance results than the enzyme complex, (phytase (300 U/g), protease (700 U/g), xylanase (100 U/g), b-glucanase (200 U/g), cellulase (40 U/g), amylase (30 U/g), and pectinase (4000 U/g)) in broilers fed marginal levels of minerals and energy.

Enzyme products did not affect carcass yield and cuts.

Further studies are needed, particularly considering, among other factors, the influence of climate onthe definition of nutrient and energy levels of diets with the inclusion of enzymes.

REFERENCES

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  • Bertechini AG. Nutrição de monogástricos. 2.ed. Lavras: UFLA; 2012.
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  • Cowieson AJ, Ravindran V. Effect of exogenous enzymes in maize-based diets varying in nutrient density for young broilers: growth performance and digestibility of energy, minerals and amino acids. British Poultry Science2008;49:37-44.
  • Fortes BD, Café MB, Stringuini JH, Brito JAG, Rezende PLP, Silva RD. Avaliação de programas nutricionais com a utilização de carboidrases e fitase em rações de frangos de corte. Ciência Animal Brasileira 2012;13:24-32.
  • Francesch M, Geraert PA. Enzyme complex containing carbohydrases and phytase improve growth performance and bone mineralization of broilers fed reduced nutrient corn-soybean-based diets. Poultry Science2009;88:1915-1924.
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  • Lu Q, Wen J, Zhang H. Effect of chronic heat exposure on fat deposition and meat quality in two genetic types of chicken. Poultry Science2007;86(1):1059-1064.
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  • Toledo GSP, Costa PTC, Silva JH, Ceccantini ML, Poletto C. Broilers fed diets varying in energy and protein supplemented with a pool of enzymes. Ciência Rural2007;37:518-523.
  • Walk CL, Cowieson AJ, Remus JC, Novak CL, Mcelroy AP. Effects of dietary enzymes on performance and intestinal goblet cell number of broilers exposed to a live coccidia oocyst vaccine. Poultry Science2011;(90):91-98.

Publication Dates

  • Publication in this collection
    Oct-Dec 2015

History

  • Received
    Aug 2014
  • Accepted
    Apr 2015
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