Effects of crude protein levels on egg quality traits of brown layers raised in two production systems

Eduardo de Faria Viana José Henrique Stringhini Fabyola Barros de Carvalho Débora Macedo Paronetto Viana Miliane Alves da Costa About the authors

ABSTRACT

The objective of this study was the evaluation of egg quality of 30 to 45-week-old brown layers, raised in cages or on floor, supplemented with amino acids, using the ideal protein concept with levels of 14, 15, 16, and 18% crude protein. A total of 400 birds (Hy-sex Brown) were used, distributed into two breeding systems (conventional cage or floor). The evaluated variables were the yolk relative weight, yolk height, albumen relative weight, albumen height, specific gravity, eggshell thickness, and eggshell weight. Treatments consisted of reduced levels of crude protein and were provided to both groups equally. We adopted a completely randomized design, in a factorial scheme, composed of two breeding systems and four levels of crude protein, totaling eight treatments. Five replicates per treatment and 10 birds per experimental unit were used. The breeding system on floor was configured as an option in the breeding of brown layers, of Hy-sex Brown commercial lineage, in the period between the 30th and the 45th week of age, since it presents results equivalent to the ones obtained in the breeding system in cages, having the egg quality as parameter. The system of production on floor is configured as an option in the farming of brown layers, of the commercial lineage Hy-sex Brown.

brown layer; cage; egg; floor

Introduction

Layer poultry farming presented a considerable development in the last decade thanks to technological innovations in the areas of genetics, nutrition, environment, and management (Barbosa Filho et al., 2006Barbosa Filho, J. A. D.; Silva, M. A. N.; Silva, I. J. O. and Coelho, A. A. D. 2006. Egg quality in layers housed in different production systems and submitted to two environmental conditions. Revista Brasileira de Ciência Avícola 8:23-28.). However, new technologies and market demands have stimulated the development of new breeding systems, aiming to promote animal welfare support, maintaining egg quality and productivity.

Protein and amino acid requirements may vary depending on body weight, growth rate, and egg production. Despite that, most recommendations found in the literature and published in the breeding manuals are based on studies that consider only the performance of the bird according to certain levels of intake, without evaluating the effects of the environment where they are raised.

The nutritional requirements may not be compatible with the demands of the different breeding systems, which justifies the implementation of studies to know specific nutritional requirements and more adequate nutrient levels (Angeles and Rosales, 2005Angeles, M. L. and Rosales, S. G. 2005. Efecto del nível de lisina digestible e del perfil ideal de aminoácidos sobre el requerimiento de lisina en gallinas HY-line W36 ao final del primer período de postura. Veterinária México 36:279-294.).

Most of the protein recommendations issued by the breeding manuals are based on studies conducted under different conditions from those found by birds at the places where they are explored. The choice of the adequate level of protein is favorable both for the bird, which might perform its metabolic functions in a potentiated way, as well as for the producer, who might maximize its financial resources through saving with protein sources (Sakomura et al., 2002Sakomura, N. K.; Basaglia, R. and Resende, K. T. 2002. Modelo para determinar as exigências de proteína para poedeiras. Revista Brasileira de Zootecnia 31:2247-2254.; Laudadio et al., 2012aLaudadio, V.; Passantino, L.; Perillo, A.; Lopresti, G.; Passantino, A.; Khan, R. U. and Tufarelli, V. 2012a. Productive performance and histological features of intestinal mucosa of broiler chickens fed different dietary protein levels. Poultry Science 91:265-270.; Laudadio et al., 2012bLaudadio, V.; Dambrosio, A.; Normanno, G.; Khan, R. U.; Naz, S.; Rowghani, E. and Tufarelli, V. 2012b. Effect of reducing dietary protein level on performance responses and some microbiological aspects of broiler chickens under summer environmental conditions. Avian Biology Research 5:88-92.).

According to Zhang and Coon (1997)Zhang, B. and Coon, C. N. 1997. The relationship of calcium intake, source, size, solubility in vitro and in vivo, and gizzard limestone retention in laying hens. Poultry Science 76:1702-1706. and Mizumoto et al. (2008)Mizumoto, E. M.; Canniatti-Brazaca, G. S. and Machado, F. M. V. F. 2008. Avaliação química e sensorial de ovos obtidos por diferentes tratamentos. Ciência e Tecnologia de Alimentos 28:60-65., nutrition and breeding system influence egg quality. For laying hens, the level of protein in the diet is important for the formation of the yolk and especially of the albumen. Since the ability of laying hens to store protein is limited, the protein concentration in the feed should be equated to achieve the desired egg production (Pesti, 1992Pesti, G. M. 1992. Temperatura ambiente e exigências de proteína e aminoácidos para poedeiras. p.208. In: Anais do Simpósio Internacional de Não Ruminantes, Lavras, MG.).

The study of different protein levels in diets for laying hens is of fundamental importance, since egg production and size are dependent on protein intake (Sakomura et al., 2002Sakomura, N. K.; Basaglia, R. and Resende, K. T. 2002. Modelo para determinar as exigências de proteína para poedeiras. Revista Brasileira de Zootecnia 31:2247-2254.). The objective of this study was the evaluation of egg quality in brown layers of Hy-sex Brown commercial lineage from 30 to 45 weeks of age, receiving diets with reduced levels of crude protein.

Material and Methods

This research project was approved by the Ethics Committee on Animal Use (CEUA), under case no. 312/11. The experiment was carried out in Urutaí, Goiás, Brazil (latitude: 17º27'49"S, longitude: 48º12'06"W, and altitude: 807 m). Four hundred brown layers of Hy-sex Brown lineage were used, in the laying phase, between the 30th and the 45th week of age.

Two sheds were used simultaneously, in which 200 birds were housed in pits lined with sawdust and other 200 in conventional cages. Individual weighing of the birds was performed for distribution in a completely randomized design. The birds were handled according to recommendations proposed in the breeding manual (Globoaves, 2006Globoaves Agropecuária Ltda. 2006. Manual de manejo – Hisex Brown. GloboAves, Cascavel, PR.). The densities of 500 cm2/bird in the cages and 3,333 cm2/bird on the floor were adopted.

In the shed of the floor raising system, the birds were distributed in 20 boxes. Each box had a water fountain, a feeder, and a nest. The boxes were lined with sawdust up to a height of 10 cm and measured 2.2 × 1.5 × 3 m (length × width × height).

The water fountain used was of the pendular type with a coupled valve and the feeder, of the tubular type, had the capacity for 15 kg of feed. The nest, built of wood, had three partitions (33 × 40 × 45 cm) and an elevation of 10 cm in relation to the substrate.

The management of eggs and nests was carried out according to the recommendations of EMBRAPA Swine and Poultry (Albino et al., 2005Albino, J. J.; Avila, V. S. and Sangói, V. 2005. Construção de ninhos para galinhas de postura criadas em sistemas de piso, coberto com cama. Embrapa Suínos e Aves, Concórdia.).

The experimental diets were formulated based on the ideal protein concept, isoenergetic (2.900 kcal/kg of metabolizable energy) and isonutritive, using basic ingredients (corn and soybean meal) and industrial amino acids (Table 1) to meet the nutritional requirements according to Rostagno et al. (2011)Rostagno, H. S.; Albino, L. F. T.; Donzele, J. L.; Gomes, P. C.; Oliveira, R. F.; Lopes, D. C.; Ferreira, A. S.; Barreto, S. L. T. and Euclides, R. F. 2011. Brazilian tables for poultry and swine: food composition and nutritional requirements. 3rd ed. UFV/DZO, Viçosa, MG, Brazil..

Table 1
Composition of experimental rations

The studied variables were Haugh unit, yolk relative weight, yolk height, albumen relative weight, albumen height, specific gravity, eggshell thickness, and eggshell relative weight. Four experimental periods of 28 days (30th to 33rd, 34th to 37th, 38th to 41st, and 42nd to 45th week of age) were adopted.

Data on the environment temperature inside the experimental sheds were obtained by means of maximum and minimum, using thermometers of the Incoterm brand, positioned in the center of the sheds at the height of the birds. The reading of the thermometers was performed daily, always at 08:00 h.

A sample of four eggs per experimental unit was collected in the morning (08:00 h), identified, and used for determination, yolk height, albumen height, Haugh unity, and specific gravity.

The specific gravity was determined by the salt flotation method, according to the methodology described by Hamilton (1982)Hamilton, R. M. G. 1982. Methods and factors that affect the measurement off egg shell quality. Poultry Science 61:2022-2039.. At the end of each experimental period, representative samples of four eggs per plot were selected; then, the eggs were immersed in saline solutions (NaCl) with the appropriate adjustments for the volume of 10 L of water, with densities ranging from 1.065 to 1.100 with a range of 0.005, calibrated with a densimeter of the Incoterm brand. The eggs were placed in buckets with solutions, from the lowest to the highest density, and were removed as they floated; then, the densities corresponding to the solutions of the containers were recorded.

Haugh unit was calculated using the expression HU = 100 Log (h - 1.7 ew + 7.6), in which HU = Haugh unit, h = dense albumen height (mm), and ew = egg weight (Haugh, 1937).

Eggshell thickness (mm) was determined according to the methodology described by Barbosa Filho et al. (2006)Barbosa Filho, J. A. D.; Silva, M. A. N.; Silva, I. J. O. and Coelho, A. A. D. 2006. Egg quality in layers housed in different production systems and submitted to two environmental conditions. Revista Brasileira de Ciência Avícola 8:23-28..

The data were analyzed in a completely randomized design in a 2 × 4 factorial scheme, with two breeding systems (cage and floor) and four levels (14, 15, 16, and 18%) of crude protein in the rations. Five replicates and ten birds were used per plot. For the crude protein levels, the polynomial regression model was adjusted when there was significance. Statistical analyses were performed using the SAEG 9.1 program. The data obtained were subjected to analysis of variance and when statistically different, were compared by Tukey’s test (5%).

Variables were analyzed according to the following mathematical model:

Yijk = μ + Fi + Nelj + FNelij + eijk,

in which Yijk = observation k of experimental unit subjected to treatments Fi and Nelj; μ = general constant; Fi = effects of production systems (floor and cage); Nelj = effects of rations with 14, 15, 16, and 18% crude protein; FNelij = effects of the interaction levels of Ca × P levels; and eijk = random error associated to each observation.

Results

The maximum and minimum temperature valuesobserved and their respective averages were in the expected range for the place where the experiment was conducted (Urutaí, GO) (Table 2).

Table 2
Means of ambient temperature (ºC) for the laying period in floor and cage raising systems

There was an effect (P<0.05) of the crude protein levels on yolk height (mm) in the first and fourth production periods (Table 3). In these periods, birds fed ration containing 15% crude protein had a higher yolk height, 14.60 and 14.23 mm, respectively.

Table 3
Yolk height (mm) per production period and raising system

Egg weight was influenced by breeding systems only in the second production period (34th to 37th week of age) and it was not possible to verify their relation with other quality parameters.

In the second production period, there was an effect (P<0.01) of the breeding systems (Table 4). In this period, eggs from the breeding system without cages presented higher yolk relative weight. In the fourth production period, there was a linear effect (P<0.01) of crude protein levels without yolk relative weight, according to equation Y = 23.09 + 0.19X.

Table 4
Yolk relative weight per production period and raising system

There was an effect (P<0.05) of crude protein levels on albumen height in the third production period. However, birds fed a 16% crude protein diet presented lower albumen height when compared with birds from other treatments. Birds raised in cages presented higher albumen height (P<0.01) (Table 5).

Table 5
Albumen height (mm) per production period and raising system

For the albumen relative weight, there was an effect (P<0.05) of the breeding systems only in the fourth production period. In this period, eggs from birds raised in cages had a higher albumen relative weight (Table 6).

Table 6
Albumen relative weight (%) per production period and raising system

There was no interaction (P>0.05) of crude protein levels of rations and raising systems. There was no effect (P>0.05) of crude protein levels and raising systems on the Haugh unit (Table 7).

Table 7
Haugh unit per production period and raising system

There was no interaction (P>0.05) of crude protein levels of rations and raising systems. There was also no isolated effect of crude protein levels and raising systems on specific gravity throughout the experimental period (Table 8).

Table 8
Specific gravity per laying period and raising system

There was no interaction (P>0.05) between crude protein levels and breeding systems. There was no isolated effect of crude protein levels and breeding systems on shell thickness throughout the experimental period (Table 9).

Table 9
Eggshell thickness (mm) per production period and raising system

Regarding the bark relative weight, there was an effect (P<0.01) of breeding systems in the second production period. In this period, birds raised in cages presented higher shell relative weight (Table 10).

Table 10
Eggshell relative weight (%) per production period and raising system

Discussion

Sekeroglu and Altuntas (2009)Sekeroglu, A. and Altuntas, E. 2009. Effects of egg weight on egg quality characteristics. Journal of Science of Food and Agriculture 89:379-383., when evaluating the effects of egg weight of laying hens (Lohmann Brown) raised in conventional cages in the period between 33 and 45 weeks of age on parameters of internal egg quality, observed a direct effect of the egg weight on the yolk height. However, Gharahveysi et al. (2012)Gharahveysi, S.; Niaki, S. M. F and Irani, M. 2012. The effect of broiler breeder ages on the qualitive and quantitive properties of the egg. American Journal of Animal and Veterinary Sciences 7:136-140., evaluating the effects of age on egg quality, observed an increase of yolk height with advancing age, as well as its decrease from the 43rd week of age.

Regarding the yolk relative weight, our results do not agree with Mousavi et al. (2013)Mousavi, S. N.; Khalaji, S.; Ghasemi-Jirdehi, A. and Foroudi, F. 2013. Investigation on the effects of various protein levels with constant ratio of digestible sulfur amino acids and threonine to lysine on performance, egg quality and protein retention in two starins of laying hens. Italian Journal of Animal Science 12:9-15., who investigated the effects of different levels of crude protein (15.5, 16.5, 17.5, and 18.5%) on the quality of the eggs of Lohmann LSL and Hy-Line W-36 lines between 25 and 33 weeks of age. These authors used diets formulated from the concept of ideal protein and stated that there was an interaction between protein levels and commercial lines and that the yolk relative weight decreased when reducing the protein level from 18.5 to 15.5%. The results of this work also diverge from those obtained by Varguez-Montero et al. (2012)Varguez-Montero, G.; Sarmiento-Franco, L.; Santos-Ricalde, R. and Segura-Correa, J. 2012. Egg production and quality under three housing systems in the tropics. Tropical Animal Health and Production 44:201-204., who worked with hen breeding (Rhode Island Red) in alternative systems (shed with access to open areas, closed shed, or conventional cages) in a hot climate region. The authors evaluated the effects of systems on egg quality and productive performance in two periods (30 to 35 weeks and 40 to 45 weeks of age) and reported that the yolk relative weight was higher for the breeding system in conventional cages.

The internal quality of the egg decreases as the layer age advances, this being an irreversible phenomenon (Llobet et al., 1989Llobet, J. A. C.; Pontes, M. P. and Gonzalez, F. F. 1989. Características del huevo fresco. p.54. In: Producción de huevos. Tecnograf S.A., Barcelona.). Van Den Brand et al. (2004)Van Den Brand, H.; Parmentier, H. K. and Kemp, B. 2004. Effects of two housing systems (cages vs outdoor) on external and internal egg characteristics were investigated. British Poultry Science 45:745-752., evaluating the effects of two production systems (conventional cages and shed with free-range access) on internal and external characteristics of brown layer eggs (Isa Brown) between 25 and 59 weeks of age, observed a decrease in albumen height with advancing age (between the 30th and 45th weeks of age) and higher albumen height for the floor raising system with free-range access. Silversides et al. (2004), when studying the relationship between quality parameters and functional albumen properties in eggs of brown layers (Isa Brown) collected at 32, 50, and 68 weeks of age and stored for five or 10 days, observed that the albumen height decreased with the increase of age and storage time.

Van Den Brand et al. (2004)Van Den Brand, H.; Parmentier, H. K. and Kemp, B. 2004. Effects of two housing systems (cages vs outdoor) on external and internal egg characteristics were investigated. British Poultry Science 45:745-752. evaluated the effects of two production systems (conventional cages and shed with access to free areas) on internal and external characteristics of eggs of semi-heavy laying hens (Isa Brown) between 25 and 59 weeks of age and found responses to albumen relative weight such as 60.05, 58.39, 58.95, and 57.39%, respectively, for the 33th, 37th, 41st, and 45th week of age. In a study of the effect of protein levels (15.5, 16.5, and 17.5% crude protein) on the relative weight of albumen, Costa et al. (2004)Costa, F. G. P.; Souza, H. C.; Gomes, C. A. V.; Barros, L. R.; Brandão, P. A.; Nascimento, G. A. J.; Santos, A. W. R. and Amarante Junior, V. S. 2004. Níveis de proteína bruta e energia metabolizável na produção e qualidade dos ovos de poedeiras. Ciência e Agrotecnologia 28:1421-1427. determined that birds fed a diet containing 17.5% crude protein presented higher values for this variable. Similarly, Rombola et al. (2004)Rombola, L. G.; Rizzo, M. F.; Faria, D. E.; Deponti, B. J.; Silva, F. H. A. and Araújo, L. F. 2004. Alimentação de poedeiras com diferentes níveis de proteína e lisina: desempenho e qualidade dos ovos. p.23. In: Anais da Conferência Apinco de Ciência e Tecnologia Avícolas, Santos. also found that the increase in dietary protein level increased the albumen relative weight, with the 18% level giving the best result.

The most commonly used parameter for expressing albumen quality is the Haugh unit, which is a mathematical expression that relates the weight of the egg to the height of thick white. In general, the higher the value of the Haugh unit, the better the egg quality (Rodrigues, 1975Rodrigues, P. C. 1975. Contribuição ao estudo da conversão de ovos de casca branca e vermelha. Dissertação (M.Sc.). Universidade de São Paulo, Piracicaba.). Alleoni and Antunes (2001)Alleoni, A. C. C. and Antunes, A. J. 2001. Unidade Haugh como medida da qualidade de ovos de galinha armazenados sob refrigeração. Scientia Agrícola 58:681-685. stated that the composition of the ration and the lineage of the birds may affect the Haugh unit values. Meanwhile, the season and the production system do not seem to affect this parameter. The effects of different levels of crude protein (14, 15, 16, and 17%) on the performance of brown layers (Bovans) in the initial stage of laying (20 to 40 weeks) were studied by Abioye et al. (2012)Abioye, S. A.; Aderemi, F. A. and Adeyemo, G. O. 2012. The effect of varied dietary crude protein levels with balanced amino acids on performance and egg quality characteristics of layers at first laying phase. Food and Nutrition Sciences 3:526-530., who obtained higher values for Haugh unit using ration with 17% crude protein.

The specific gravity is highly related to the shell quality, especially in relation to the thickness (Hamilton, 1982Hamilton, R. M. G. 1982. Methods and factors that affect the measurement off egg shell quality. Poultry Science 61:2022-2039.). However, this relationship was not observed in this study. Peebles and McDaniel (2004)Peebles, E. D. and McDaniel, C. D. 2004. A practical manual for understanding the shell structure of broiler hatching eggs and measurements of their quality. Mississipi State University, Huddersfield. considered the value of 1,080 as reference to classify the shell as good or bad. However, Barbosa Filho et al. (2006)Barbosa Filho, J. A. D.; Silva, M. A. N.; Silva, I. J. O. and Coelho, A. A. D. 2006. Egg quality in layers housed in different production systems and submitted to two environmental conditions. Revista Brasileira de Ciência Avícola 8:23-28., when studying the welfare of commercial brown layers in different production systems and environmental conditions, observed that this limit was valid only for the condition of thermal comfort (26 °C). Koelkebeck et al. (1993)Koelkebeck, K. W.; Parsons, C. M. and Leeper, R. W. 1993. Effect of supplementation of a low-protein corn molt diet with amino acids on early postmolt laying hen performance. Journal Poultry Science 72:1528-1536. also observed no effect of protein levels on specific egg gravity. In a study comparing two breeding systems (floor and cages), Alves et al. (2007)Alves, S. P.; Silva, I. J. O. and Piedade, S. M. S. 2007. Avaliação do bem-estar de aves poedeiras comerciais: efeitos do sistema de criação e do ambiente bioclimático sobre o desempenho das aves e a qualidade de ovos. Revista Brasileira de Zootecnia 36:1388-1394. observed that eggs from hens raised in cages presented thinner shells and, consequently, lower specific gravity, which implied differences between raising systems.

Alves et al. (2007)Alves, S. P.; Silva, I. J. O. and Piedade, S. M. S. 2007. Avaliação do bem-estar de aves poedeiras comerciais: efeitos do sistema de criação e do ambiente bioclimático sobre o desempenho das aves e a qualidade de ovos. Revista Brasileira de Zootecnia 36:1388-1394. evaluated the performance and egg quality of semi-heavy laying hens and heavy-weight laying hens raised in conventional cages or floor and observed a lower hull thickness in eggs of laying hens raised in cages. These authors attributed this condition to the greater stress and difficulty of birds in losing heat in the cages. They also clarified that the semi-heavy laying hens, due to their greater size, present greater heat intolerance. Evaluating the production and egg quality of heavy-weight laying hens and semi-heavy laying hens housed in two production systems (conventional cages or floor), Abrahamsson and Tauson (2009)Abrahamsson, P. and Tauson, R. 2009. Aviary systems and conventional cages for laying hens: effects on production, egg quality, health and bird location in three hybrids. Acta Agriculturae Scandinavica 45:191-203. observed lower production and feed conversion for birds raised on the floor. Regarding the internal quality of the eggs, there were no differences (P>0.05) between the production systems. Likewise, there was no difference (P>0.05) for shell thickness between these systems. According to Barbosa Filho et al. (2006)Barbosa Filho, J. A. D.; Silva, M. A. N.; Silva, I. J. O. and Coelho, A. A. D. 2006. Egg quality in layers housed in different production systems and submitted to two environmental conditions. Revista Brasileira de Ciência Avícola 8:23-28., the cage rearing system provides a thinner eggshell, especially for semi-heavy laying hens under thermal stress conditions. Another relevant point is presented by Jacob et al. (2000)Jacob, J. P.; Miles, R. D. and Mather, F. B. 2000. Egg quality. Institute of Food and Agricultural Sciences, University of Florida, Gainesville., who warned that the problems in the shell may result in low egg classification, affecting its market value.

Evaluating the internal and external quality of the eggs of semi-heavy laying hens (Lohmann Brown) between 43 and 55 weeks of age, Costa et al. (2004)Costa, F. G. P.; Souza, H. C.; Gomes, C. A. V.; Barros, L. R.; Brandão, P. A.; Nascimento, G. A. J.; Santos, A. W. R. and Amarante Junior, V. S. 2004. Níveis de proteína bruta e energia metabolizável na produção e qualidade dos ovos de poedeiras. Ciência e Agrotecnologia 28:1421-1427. observed the effect of crude protein levels (15, 16, 17, and 18 %) on shell weight, in which the eggs of semi-heavy laying hens fed diets containing 16% of crude protein presented the highest weight of the eggshell. Oliveira et al. (2011)Oliveira, E. L.; Gomes, F. A.; Silva, C. C.; Delgado, R. C. and Ferreira, J. B. 2011. Desempenho, características fisiológicas e qualidade de ovos de poedeiras Isa Brown criadas em diferentes sistemas de produção no Vale do Juruá – Acre. Enciclopédia Biosfera 7:339-347. studied several physicochemical properties of eggs from conventional and organic production systems and reported lower shell relative weight in the organic production system when compared with the conventional system (cages).

Conclusions

The production of the commercial lineage Hy-sex Brown on floor, between the 30th and the 45th week of age presents results equivalent to the obtained in the raising cages, having variables related to egg quality and the crude protein levels as reference.

References

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Publication Dates

  • Publication in this collection
    Nov 2017

History

  • Received
    19 June 2017
  • Accepted
    23 July 2017
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