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Animal Science Journal (2015) 86, 189–193
doi: 10.1111/asj.12262
ORIGINAL ARTICLE The effects of the dark house system on growth, performance and meat quality of broiler chicken Rafael Humberto CARVALHO,1,4 Adriana Lourenço SOARES,2 Moisés GRESPAN,3 Rafael Sanches SPURIO,2 Fábio Augusto Garcia CORÓ,1 Alexandre OBA5 and Massami SHIMOKOMAKI1,4 1
Paraná Federal Technological University in Londrina, 2Graduate Program in Food Science Department of Food Science and Technology, Londrina State University, 4Graduate Program in Animal Science Department of Veterinary Preventive Medicine and 5Department of Animal Science, Londrina State University, Londrina, PR, Brazil, and 3Veterinary Doctor, Cascavel, PR, Brazil
ABSTRACT Meat production with minimum animal suffering is a humanitarian concern. Thus, the objective of this work was to observe the performance of Cobb broiler chickens from 7 to 46 days of age when raised under different installations: dark house system (DHS), conventional yellow system (CYC) and conventional blue system (CBC). The feed conversion ratio for the birds raised on the DHS was 3.8% and 2.7% lower than those for the CYC and CBC systems, respectively. Compared with the CYC and CBC systems, average daily gain under the DHS was 11.4% and 9.3% higher, respectively, and body weight at 46 days was 11.4% and 9.3% higher, respectively (P ≤ 0.05). The birds’ welfare was assessed based on their stress by determining the amount of pale, soft and exudative (PSE) meat in the breast fillets. The CYC and CBC birds had 24.3% and 25.3% PSE meat, respectively, whereas the DHS birds had 37.0%. We concluded that the DHS has a greater potential to produce broiler chickens, with superior performance to conventional systems, despite the higher stress faced by the birds during the maneuvers just before slaughter.
Key words: animal welfare, aviary, dark house, PSE broiler chicken meat.
INTRODUCTION The modern model of the industrial production of broiler chicken meat requires knowledge and investments in the areas of nutrition, genetics, health, environment, handling and slaughter technologies. The system used for raising broilers is a crucial factor affecting the birds in terms of comfort, welfare, health and production efficiency. Worldwide, chickens are raised in a variety of production systems that vary according to different factors, including environmental conditions, production scale and availability of financial funds (Fouad et al. 2008). The modern bird setup system described by Glatz and Pym (2007) has updated barns and equipment and allows for considerable control over the ambience. However, these barns require a high financial investment to build and operate and, therefore, require a large turnover of birds to make them economically feasible. Over the years, the so-called conventional installations, with open ends, natural ventilation, positive pressure (fans) and manual feeders and drinkers, have been replaced by innovative installations. Currently, © 2014 Japanese Society of Animal Science
controlled environments are created by using ventilators, nebulizers, exhausters, cooling systems, automatic drinkers and feeders as well as temperature, humidity and ventilation controls through electronic monitoring with computerized records (Costa et al. 2010). Nevertheless, the currently used feedlot regimen installations can subject the birds to stress (Jones & Mills 1999), with consequent adverse behavioral and physiological responses (Marin et al. 2001), and serious health problems affecting animals’ welfare (Hall 2001). This environmental stress increases mortality and reduces the installation’s production performance by affecting chicken meat quality due to the higher incidence of pale, soft and exudative (PSE) meat (Shimokomaki & Olivo 2006; Smith & Northcutt 2009). Correspondence: Massami Shimokomaki, UTFPR-Paraná Federal Technological University in Londrina, Av. dos Pioneiros, 3131, Londrina, Paraná CEP 86036-370, Brazil. (Email: [email protected]) Received 28 November 2013accepted for publication 2 May 2014.
190 R. H. CARVALHO et al.
This work aimed to evaluate the broiler chicken livestock index of birds reared under the dark house system with longer dark periods, compared with the conventional systems of yellow and blue curtains. The stress conditions of the birds was measured by determining the occurrence of PSE meat, which indicated meat quality.
used in this study. At 1 day of age, the birds were randomly housed on 27 lots (aviaries) that each contained approximately 20 000 birds. The different systems of production were evaluated in three treatments, with nine lots each as follows: 1) Treatments CYC and CBC: the conventional yellow and blue curtain systems both had lighting programs as listed in Table 1. The housing final density was 21 kg/m2 at 46 days of age and the final average body weight was 2600 g. 2) Treatment DHS: the dark house system had a lighting program as listed in Table 1. The housing final density was 24 kg/m2 at 46 days of age and the final average body weight was 2900 g.
MATERIALS AND METHODS Animals and production evaluation This experiment was conducted in the state of Paraná, Brazil, in a commercial cooperative and integrated system during the summer of 2011 under conditions of 31°C and 51% relative humidity, measured during the days of the experiment using the instrument Kestrel 4000 (Nielsen-Kellerman, Boothwyn, PA, USA). A total of 540 000 Cobb-500 lineage birds of both genders were raised at 1 to 46 days of age were
The rations were formulated based on pelleted corn and soybean meal (Table 2) in automatic feeders according to the birds’ lineage nutritional demands provided ad libitum throughout the experimental period of 46 days as well as
Table 1 Lighting program used for raised birds under the dark house system (DHS), a conventional yellow curtain system (CYC) and a conventional blue curtain system (CBC)
CYC and CBC
Artificial light (40 lux) Artificial light (5 lux) Natural light (75 lux) Black-out (dark)
DHS
0–7 days old
8–46 days old
0–7 days old
8–46 days old
00.00 to 22.59 hours – – 23.00 to 23.59 hours
18.00 to 01.00 hours 01.01 to 06.00 hours 06.01 to 17.59 hours –
00.00 to 22.59 hours – – 23.00 to 23.59 hours
08.00 to 12.00 hours 12.01 to 07.59 hours – –
Table 2 Ingredient composition and nutrient content of diets
Ingredients (%)
Pre-initial (1–7 days)
Initial (8–21 days)
Growth (22–38 days)
Final (39–46 days)
Corn Soybean meal Soybean oil Dicalcium phosphate Limestone Sodium chloride Premix† DL-methionine L-lysine HCl L-threonine Calculated nutrient level CP (%) ME (Mcal/kg) Lys (%) Met + Cys (%) Thr (%) Ca (%) Available P (%)
55.294 38.197 2.122 1.847 0.921 0.459 0.400 0.359 0.288 0.113
59.418 34.705 2.092 1.443 0.937 0.437 0.400 0.287 0.218 0.063
62.011 31.503 3.089 1.205 0.882 0.417 0.400 0.256 0.194 0.043
66.621 27.303 2.949 0.998 0.794 0.409 0.400 0.240 0.234 0.052
22.20 2.95 1.310 0.944 0.852 0.920 0.47
20.80 3.00 1.174 0.846 0.763 0.819 0.391
19.50 3.10 1.078 0.787 0.701 0.732 0.342
18.00 3.15 1.010 0.737 0.656 0.638 0.298
†Premix contained the following materials per kg: Pre-initial and Initial phase – vitamin A, 2571 IU; vitamin D3, 571 IU; vitamin K3, 446 mg; vitamin B1, 560 mg; vitamin B2, 1600 mg; vitamin B6, 849 mg; vitamin B12, 3428 μg; vitamin E, 8857 IU; pantothenic calcium, 2986 mg; niacin, 8960 mg; folic acid, 194 mg; biotin, 20 mg; choline, 83 143 mg; methionine, 424 286 mg; zinc, 17 785 mg; iron, 13 800 mg; copper, 2811 mg; manganese, 22 063 mg; iodine, 275 mg; selenium, 9643 mg; cobalt, 51 mg; Growth phase – vitamin A, 1900 IU; vitamin D3, 480 IU; vitamin K3, 374 mg; vitamin B1, 510 mg; vitamin B2, 1280 mg; vitamin B6, 703 mg; vitamin B12, 3000 μg; vitamin E, 7000 IU; pantothenic calcium, 2660 mg; niacin, 7546 mg; folic acid, 176 mg; biotin, 18 mg; choline, 75 000 mg; methionine, 380 160 mg; zinc, 16 500 mg; iron, 12 600 mg; copper, 2640 mg; manganese, 17 680 mg; iodine, 248 mg; selenium, 76,50 mg; cobalt, 50 mg; Final phase – vitamin A, 1428 IU; vitamin D3, 393 IU; vitamin K3, 297 mg; vitamin B1, 378 mg; vitamin B2, 960 mg; vitamin B6, 566 mg; vitamin B12, 2286 μg; vitamin E, 5286 IU; pantothenic calcium, 1900 mg; niacin, 5600 mg; folic acid, 131 mg; biotin, 14 mg; choline, 56 571 mg; methionine, 301 242 mg; zinc, 12 857 mg; iron, 9428 mg; copper, 2057 mg; manganese, 13 371 mg; iodine, 188 mg; selenium, 57 mg; cobalt, 50 mg. CP, crude protein; ME, metabolizable energy.
© 2014 Japanese Society of Animal Science
Animal Science Journal (2015) 86, 189–193
DARK HOUSE AND BROILER MEAT
drink water from a nipple waterer. The spilled feed was neglected due to feeder automation as its waste was minimal. The feeder space was adjusted for the different densities during growth of birds for all treatments. This feeding program was performed under four rearing treatments according to the birds’ ages: pre-initial (1 to 7 days), initial (8 to 21 days), growth (22 to 38 days) and final (39 days to slaughtering age at 46 days). Rice husk bedding was routinely provided to the animals in the aviary. All birds were weighed at the beginning and at the end of experimental period. The feed amount was also weighed at the beginning and at the end of each phase to determine cumulative feed consumption for each treatment. The temperature and relative humidity (RH) inside the aviary were measured using brand HOBO data loggers (Onset® model: U10-003; Onset Computer Corporation, Bourne, MA, USA) during the experimental period and the averages were calculated every 10 days. The parameters measured for the birds’ performances were: daily feed intake measurement, daily weight gain at 46 days of age, feed conversion ratio (calculated as the amount of feed consumed per unit of daily weight gain) and rearing viability (calculated as total number of birds produced divided by the initial number of chicks × 100).
Transport The birds were captured and manually placed in boxes containing 10 birds each; the average capture time was 40 min, and they were subsequently transported for 50 km (70 min) in an open truck. Birds of all treatments were transported approximately at 13.00 hours and the temperature and relative humidity during the transport was 31 ± 4°C and 51 ± 8%, respectively, measured by Kestrel 4000 Instrument. Upon arrival at the slaughterhouse, the birds were submitted to a water mist and ventilation for about 60 min before slaughtering.
Meat quality evaluation For the meat quality evaluation, four lots (n = 70) were randomly chosen from each treatment, totaling 840 birds. They were sacrificed following the routine commercial procedure as reported previously, which consisted of nebulization, hanging, electric stunning, bleeding, scalding, defeathering, evisceration, chilling and cooling (Oba et al. 2009; Simões et al. 2009). After deboning the breast fillet samples, Pectoralis major m., were cooled down to 5°C and refrigerated for 24 h for subsequent analyses of color and pH.
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PSE classification The fillet meat samples were classified as PSE or normal meat based on previously established parameters associated with pH and L* values. Samples with pH values less than 5.8 and L24 h* values greater than 53.0 were classified as PSE, and samples with pH values greater than 5.8 and L24 h* between 44.0 and 53.0 were classified as normal (Owens et al. 2000; Soares et al. 2003).
Statistical analysis The statistical analysis was conducted using the STATISTICA 8.0 program (StatSoft, Tulsa, OK, USA). Tukey’s test at a 5% probability level (P ≤ 0.05) was used to compare the temperature and RH of aviary, animal’s performance and meat quality evaluation in the three treatments.
RESULTS AND DISCUSSION Figure 1 shows the temperature and RH inside the aviaries throughout the experiment. In the DHS, the temperature was 2.3°C and 3.3°C significantly lower than CYC and CBC systems (P ≤ 0.05) after 30 and 40 days of growth, respectively. These results were in accordance with other recent reports in which the heavy birds reared in DHS were kept in the thermoneutral zone (Olanrewaju et al. 2010). Under these circumstances, these chickens would maintain their body temperature. Conversely, the birds under CBC and CYC aviaries systems were exposed to temperature higher than the thermoneutral zones. As pointed out by Olanrewaju et al. (2010), the consequences of these conditions were increase of body weight (BW) as the temperature value of 21°C under DHS was in the range of their values in their experiment.
pH and color measurement The pH values were determined by inserting electrodes into the breast muscle (Boulianne & King 1995) using a contact pH meter system model Testo 205 (Testo AG, Lenzkirch, Germany). The analysis was performed in triplicate at 24 h post mortem as previously described by Olivo et al. (2001). A colorimeter Konica Minolta (CR400; Minolta Sensing Inc., Osaka, Japan) was used to evaluate the color parameters, including L* (lightness), a* (redness) and b* (yellowness), on the posterior surface of the intact skinless breast muscles. The color values were measured at three different sites on the same sample. These sites were the proximal extremity of the muscle, distal extremity of the muscle and medial side at the halfway point between the proximal and distal extremities (Soares et al. 2003). Animal Science Journal (2015) 86, 189–193
Figure 1 Average value of temperature (T) and relative humidity (RH) inside the three aviaries: DHS, dark house system; CBC, conventional blue curtain system; CYC, conventional yellow curtain system during the growth of birds. *a–b indicate difference among aviaries by Tukey’s test at a 5% significance level (P ≤ 0.05).
© 2014 Japanese Society of Animal Science
192 R. H. CARVALHO et al.
Table 3 Performance of broiler chickens reared under the dark house system (DHS), a conventional yellow curtain system (CYC) and a conventional blue curtain system (CBC)
Parameter
Treatments
ADFI (g) ADG (g) BW (g) FCR V%
P
CYC
CBC
DHS
104.32a ± 8.63 56.68b ± 0.95 2607b ± 44.03 1.82a ± 0.04 96.67a ± 0.75
106.81a ± 7.35 57.79b ± 1.45 2658b ± 66.76 1.80a ± 0.47 96.18a ± 0.54
110.57a ± 4.82 63.14a ± 1.40 2904a ± 21.47 1.75b ± 0.33 96.88a ± 0.48
0.312 0.00001 0.00001 0.0048 0.143
a,b Means followed by different superscripts in the same row differ by the Tukey’s test at a 5% significance level (P ≤ 0.05). ADFI, average daily feed intake; ADG, average daily gain; BW, body weight at 46 days; FCR, feed conversion ratio; V, rearing viability.
Table 4 Meat quality parameters (L *, a *, b *, pH and PSE meat) used to evaluate the welfare of broilers reared under the conventional yellow curtain (CYC), conventional blue curtain (CBC) and dark house (DHS) systems
L* CYC CBC DHS
a*
53.11 ± 0.41 53.07b ± 0.10 54.80a ± 0.17 b
b*
1.54 ± 0.51 1.43a ± 0.49 1.53a ± 0.29 a
pH
9.76 ± 0.36 9.54a ± 0.73 9.64a ± 0.21 a
PSE %
5.83 ± 0.01 5.84a ± 0.01 5.78b ± 0.01 a
24.33b ± 2.05 25.33b ± 1.25 37.00a ± 0.82
a,b Means followed by different superscripts in the same row differ by Tukey’s test at a 5% significance level (P ≤ 0.05). L*, lightness; a*, redness; b*, yellowness; PSE, pale, soft and exudative.
RH did not differ among housing systems. These results indicated that the birds in DHS were under lower stress conditions. Table 3 shows that the birds reared under the DHS presented better production performance compared with the CYC and CBC systems, as the birds reared under the DHS showed respectively 11.4% and 9.3% higher average daily gain, 11.4% and 9.3% higher body weight and 3.8% and 2.7% lower feed conversion ratio (P ≤ 0.05). However, no significant differences were observed in the values for the average daily feed intake or rearing viability. In addition, no significant difference was observed between the birds reared in the CYC and CBC systems. Once the broiler chickens had been acclimatized to the DHS and were in the growing phase, the broiler chickens were under less stressful conditions, resulting in a higher body comfort and thus influencing their performance and meat quality. Nowicki et al. (2011) found higher feed conversion ratios in broiler chickens reared under dark house conditions compared with conventional aviaries, corroborating our results. Several maneuvers during the rearing period can expose birds to stressors that trigger stress reactions, and the aviary installation model is one of these maneuvers. The levels of ambient light, temperature and husbandry practices (Jones & Mills 1999; Marin et al. 2001) may cause serious problems for animal welfare (Hall 2001; NRC 2008). However, in aviaries under the DHS, these parameters are controlled, providing better welfare for the birds. Abreu and Abreu (2011); Costa et al. (2010) also reported that the outer insulation of the dark house’s internal barn provides better results. Table 4 shows the results of meat quality under these three treatments. These results clearly show that © 2014 Japanese Society of Animal Science
the samples under the DHS treatment were different in relation to the other treatment groups (CYC and CBC). It presented the highest value of L* and lowest pH value (P ≤ 0.05); however, no difference was observed between CYC and CBC treatments. As noted by Soares et al. (2003), lower post mortem pH (≤ 5.8) and higher L* (≥ 53) values were indicative of worse animal welfare, as measured by the incidence of PSE meat. Indeed, the PSE incidence for DHS treatment (37.0%) was higher (P ≤ 0.05) than CYC and CBC treatments, 24.3% and 25.3%, respectively. The a* and b* values did not differ among these three treatments. The DHS ambience provided a better environmental control within the barn, offering a better welfare for the birds as demonstrated by the temperature results (Fig. 1). However, when the birds were subjected to stress during the pre-slaughter treatments of fasting, harvesting, transporting and hanging (Sams 1999; Guarnieri et al. 2004; Petracci et al. 2004; Langer et al. 2009), they developed physiological responses to stress, causing as a consequence a higher incidence of PSE meat. Another significant factor to be considered were the transport activities from the farm to the commercial abattoir, and this experiment was conducted under summer conditions of temperatures at 31°C and 51% relative humidity. Simões et al. (2009) and Oba et al. (2009) conducted a recent survey under Brazilian summer conditions and obtained results indicating an incidence of PSE meat of 35% and up to 75%, under routine commercial management and under full stress management, respectively. Other reports worldwide have also shown that during the summer season, the incidence of PSE meat was higher compared with that during winter (Shimokomaki & Olivo 2006; Langer et al. 2009; Simões et al. 2009). Animal Science Journal (2015) 86, 189–193
DARK HOUSE AND BROILER MEAT
In conclusion, the broiler chickens reared under DHS showed higher values of PSE meat incidence, indicating that the birds produced under these conditions were more intensively affected by stress promoted by the pre-slaughtering maneuvers and conversely they presented a better growth performance.
REFERENCES Abreu VMN, Abreu PG. 2011. Os desafios da ambiência sobre os sistemas de aves no Brasil. Revista Brasileira de Zootecnia 40, 1–14. Boulianne M, King AJ. 1995. Biochemical and color characteristics of skinless, boneless pale chicken breast. Poultry Science 74, 1693–1698. Costa FGP, Silva JHV, Lima RC, Oliveira CFS, Rodrigues VP, Pinheiro SG. 2010. Scientific progress in the production of monogastric in the first decade of the twenty-first century. Revista Brasileira de Zootecnia 9, 288–302. Fouad MA, Razek AHA, Badawy ESM. 2008. Broilers welfare and economics under two management alternatives on commercial scale. International Journal of Poultry Science 7, 1167–1173. Glatz P, Pym R. 2013. Poultry housing and management in developing countries. Poultry development review. Food Agricultural Organization 1–5. Guarnieri PD, Soares AL, Olivo R, Schneider J, Macedo RM, Ida EI, Shimokomaki M. 2004. Preslaughter handling with water shower spray inhibits PSE (pale, soft, exudative) broiler breast meat in a commercial plant. Biochemical and ultrastructural observations. Journal Food Biochemistry 28, 269–277. Hall AH. 2001. The effect of stocking density on the welfare and behaviour of broiler chickens reared commercially. Animal Welfare 10, 23–40. Jones RB, Mills AD. 1999. Divergent selection for social reinstatement behavior in Japanese quail: effects on sociality and social discrimination. Poultry Avian Biology Review 10, 213–223. Langer ROS, Simões GS, Soares AL, Oba A, Rossa A, Matsuo T, et al. 2009. Broiler transportation conditions in a Brazilian commercial line and the occurrence of breast PSE (pale, soft, exudative) meat and DFD-like (dark, firm, dry) meat. Brazilian Archives Biology Technology 53, 1161–1167. Marin RH, Freytes P, Guzman D, Jones RB. 2001. Effects of an acute stressor on fear and on the social reinstatement
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responses of domestic chicks to agemates and strangers. Applied Animal Behavior Science 71, 57–66. Nowicki R, Butzge E, Otutumi LK, Júnior RP, Alberton LR, Merlini LS, et al. 2011. Desempenho de frangos de corte criados em aviários convencionais e escuros. Arquivos Ciencias Veterinarias Zoologia 14, 25–28. NRC and Committee on Recognition and Alleviation of Distress in Laboratory Animals. 2008. Recognition and Alleviation of Distress in Laboratory Animals. National Academy Press, Washington, DC. Oba A, Almeida M, Pinheiro JW, Ida EI, Marchi DF, Soares AL, Shimokomaki M. 2009. Management of transport and lairage conditions on broiler chicken breast meat qualities and DOA (death on arrival). Brazilian Archives Biology Technology 52, 205–211. Olanrewaju HA, Purswell JL, Collier SD, Branton SL. 2010. Effect of ambient temperature and light intensity on physiological reactions of heavy broiler chickens. Poultry Science 89, 2668–2677. Olivo R, Soares AL, Ida EI, Shimokomaki M. 2001. Dietary vitamin E inhibits poultry PSE and improves meat functional properties. Journal of Food Biochemistry 25, 271– 283. Owens CM, Hirschler EM, McKee SR, Martinez-Dawson R, Sams AR. 2000. The characterization and incidence of pale, soft, exudative turkey meat in a commercial plant. Poultry Science 79, 553–559. Petracci M, Bianchi M, Betti M, Cavani C. 2004. Color variation and characterization of broiler breast meat during processing in Italy. Poultry Science 83, 2086–2092. Sams AR. 1999. Meat quality during processing. Poultry Science 78, 798–803. Shimokomaki M, Olivo R. 2006. Carne PSE em frangos. In: Shimokomaki M, Olivo R, Terra NN, Franco BDGM (eds), Atualidades em Ciência e Tecnologia de Carnes, pp. 95–104. Varela, São Paulo, Brazil. Simões GS, Oba A, Matsuo T, Rossa A, Shimokomaki M, Ida EI. 2009. Vehicle thermal microclimate evaluation during Brazilian summer broiler transport and the occurrence of PSE (pale, soft, exudative) meat. Brazilian Archives Biology Technology 52, 195–204. Smith DP, Northcutt JK. 2009. Pale poultry muscle syndrome. Poultry Science 88, 1493–1496. Soares AL, Ida EI, Miyamoto S, Blazquez FJH, Olivo R, Pinheiro JW, Shimokomaki M. 2003. Phospholipase A2 activity in poultry PSE, pale, soft, exudative. Journal of Food Biochemistry 27, 309–319.
© 2014 Japanese Society of Animal Science
Animal Science Journal (2015) 86, 189–193
doi: 10.1111/asj.12262
ORIGINAL ARTICLE The effects of the dark house system on growth, performance and meat quality of broiler chicken Rafael Humberto CARVALHO,1,4 Adriana Lourenço SOARES,2 Moisés GRESPAN,3 Rafael Sanches SPURIO,2 Fábio Augusto Garcia CORÓ,1 Alexandre OBA5 and Massami SHIMOKOMAKI1,4 1
Paraná Federal Technological University in Londrina, 2Graduate Program in Food Science Department of Food Science and Technology, Londrina State University, 4Graduate Program in Animal Science Department of Veterinary Preventive Medicine and 5Department of Animal Science, Londrina State University, Londrina, PR, Brazil, and 3Veterinary Doctor, Cascavel, PR, Brazil
ABSTRACT Meat production with minimum animal suffering is a humanitarian concern. Thus, the objective of this work was to observe the performance of Cobb broiler chickens from 7 to 46 days of age when raised under different installations: dark house system (DHS), conventional yellow system (CYC) and conventional blue system (CBC). The feed conversion ratio for the birds raised on the DHS was 3.8% and 2.7% lower than those for the CYC and CBC systems, respectively. Compared with the CYC and CBC systems, average daily gain under the DHS was 11.4% and 9.3% higher, respectively, and body weight at 46 days was 11.4% and 9.3% higher, respectively (P ≤ 0.05). The birds’ welfare was assessed based on their stress by determining the amount of pale, soft and exudative (PSE) meat in the breast fillets. The CYC and CBC birds had 24.3% and 25.3% PSE meat, respectively, whereas the DHS birds had 37.0%. We concluded that the DHS has a greater potential to produce broiler chickens, with superior performance to conventional systems, despite the higher stress faced by the birds during the maneuvers just before slaughter.
Key words: animal welfare, aviary, dark house, PSE broiler chicken meat.
INTRODUCTION The modern model of the industrial production of broiler chicken meat requires knowledge and investments in the areas of nutrition, genetics, health, environment, handling and slaughter technologies. The system used for raising broilers is a crucial factor affecting the birds in terms of comfort, welfare, health and production efficiency. Worldwide, chickens are raised in a variety of production systems that vary according to different factors, including environmental conditions, production scale and availability of financial funds (Fouad et al. 2008). The modern bird setup system described by Glatz and Pym (2007) has updated barns and equipment and allows for considerable control over the ambience. However, these barns require a high financial investment to build and operate and, therefore, require a large turnover of birds to make them economically feasible. Over the years, the so-called conventional installations, with open ends, natural ventilation, positive pressure (fans) and manual feeders and drinkers, have been replaced by innovative installations. Currently, © 2014 Japanese Society of Animal Science
controlled environments are created by using ventilators, nebulizers, exhausters, cooling systems, automatic drinkers and feeders as well as temperature, humidity and ventilation controls through electronic monitoring with computerized records (Costa et al. 2010). Nevertheless, the currently used feedlot regimen installations can subject the birds to stress (Jones & Mills 1999), with consequent adverse behavioral and physiological responses (Marin et al. 2001), and serious health problems affecting animals’ welfare (Hall 2001). This environmental stress increases mortality and reduces the installation’s production performance by affecting chicken meat quality due to the higher incidence of pale, soft and exudative (PSE) meat (Shimokomaki & Olivo 2006; Smith & Northcutt 2009). Correspondence: Massami Shimokomaki, UTFPR-Paraná Federal Technological University in Londrina, Av. dos Pioneiros, 3131, Londrina, Paraná CEP 86036-370, Brazil. (Email: [email protected]) Received 28 November 2013accepted for publication 2 May 2014.
190 R. H. CARVALHO et al.
This work aimed to evaluate the broiler chicken livestock index of birds reared under the dark house system with longer dark periods, compared with the conventional systems of yellow and blue curtains. The stress conditions of the birds was measured by determining the occurrence of PSE meat, which indicated meat quality.
used in this study. At 1 day of age, the birds were randomly housed on 27 lots (aviaries) that each contained approximately 20 000 birds. The different systems of production were evaluated in three treatments, with nine lots each as follows: 1) Treatments CYC and CBC: the conventional yellow and blue curtain systems both had lighting programs as listed in Table 1. The housing final density was 21 kg/m2 at 46 days of age and the final average body weight was 2600 g. 2) Treatment DHS: the dark house system had a lighting program as listed in Table 1. The housing final density was 24 kg/m2 at 46 days of age and the final average body weight was 2900 g.
MATERIALS AND METHODS Animals and production evaluation This experiment was conducted in the state of Paraná, Brazil, in a commercial cooperative and integrated system during the summer of 2011 under conditions of 31°C and 51% relative humidity, measured during the days of the experiment using the instrument Kestrel 4000 (Nielsen-Kellerman, Boothwyn, PA, USA). A total of 540 000 Cobb-500 lineage birds of both genders were raised at 1 to 46 days of age were
The rations were formulated based on pelleted corn and soybean meal (Table 2) in automatic feeders according to the birds’ lineage nutritional demands provided ad libitum throughout the experimental period of 46 days as well as
Table 1 Lighting program used for raised birds under the dark house system (DHS), a conventional yellow curtain system (CYC) and a conventional blue curtain system (CBC)
CYC and CBC
Artificial light (40 lux) Artificial light (5 lux) Natural light (75 lux) Black-out (dark)
DHS
0–7 days old
8–46 days old
0–7 days old
8–46 days old
00.00 to 22.59 hours – – 23.00 to 23.59 hours
18.00 to 01.00 hours 01.01 to 06.00 hours 06.01 to 17.59 hours –
00.00 to 22.59 hours – – 23.00 to 23.59 hours
08.00 to 12.00 hours 12.01 to 07.59 hours – –
Table 2 Ingredient composition and nutrient content of diets
Ingredients (%)
Pre-initial (1–7 days)
Initial (8–21 days)
Growth (22–38 days)
Final (39–46 days)
Corn Soybean meal Soybean oil Dicalcium phosphate Limestone Sodium chloride Premix† DL-methionine L-lysine HCl L-threonine Calculated nutrient level CP (%) ME (Mcal/kg) Lys (%) Met + Cys (%) Thr (%) Ca (%) Available P (%)
55.294 38.197 2.122 1.847 0.921 0.459 0.400 0.359 0.288 0.113
59.418 34.705 2.092 1.443 0.937 0.437 0.400 0.287 0.218 0.063
62.011 31.503 3.089 1.205 0.882 0.417 0.400 0.256 0.194 0.043
66.621 27.303 2.949 0.998 0.794 0.409 0.400 0.240 0.234 0.052
22.20 2.95 1.310 0.944 0.852 0.920 0.47
20.80 3.00 1.174 0.846 0.763 0.819 0.391
19.50 3.10 1.078 0.787 0.701 0.732 0.342
18.00 3.15 1.010 0.737 0.656 0.638 0.298
†Premix contained the following materials per kg: Pre-initial and Initial phase – vitamin A, 2571 IU; vitamin D3, 571 IU; vitamin K3, 446 mg; vitamin B1, 560 mg; vitamin B2, 1600 mg; vitamin B6, 849 mg; vitamin B12, 3428 μg; vitamin E, 8857 IU; pantothenic calcium, 2986 mg; niacin, 8960 mg; folic acid, 194 mg; biotin, 20 mg; choline, 83 143 mg; methionine, 424 286 mg; zinc, 17 785 mg; iron, 13 800 mg; copper, 2811 mg; manganese, 22 063 mg; iodine, 275 mg; selenium, 9643 mg; cobalt, 51 mg; Growth phase – vitamin A, 1900 IU; vitamin D3, 480 IU; vitamin K3, 374 mg; vitamin B1, 510 mg; vitamin B2, 1280 mg; vitamin B6, 703 mg; vitamin B12, 3000 μg; vitamin E, 7000 IU; pantothenic calcium, 2660 mg; niacin, 7546 mg; folic acid, 176 mg; biotin, 18 mg; choline, 75 000 mg; methionine, 380 160 mg; zinc, 16 500 mg; iron, 12 600 mg; copper, 2640 mg; manganese, 17 680 mg; iodine, 248 mg; selenium, 76,50 mg; cobalt, 50 mg; Final phase – vitamin A, 1428 IU; vitamin D3, 393 IU; vitamin K3, 297 mg; vitamin B1, 378 mg; vitamin B2, 960 mg; vitamin B6, 566 mg; vitamin B12, 2286 μg; vitamin E, 5286 IU; pantothenic calcium, 1900 mg; niacin, 5600 mg; folic acid, 131 mg; biotin, 14 mg; choline, 56 571 mg; methionine, 301 242 mg; zinc, 12 857 mg; iron, 9428 mg; copper, 2057 mg; manganese, 13 371 mg; iodine, 188 mg; selenium, 57 mg; cobalt, 50 mg. CP, crude protein; ME, metabolizable energy.
© 2014 Japanese Society of Animal Science
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drink water from a nipple waterer. The spilled feed was neglected due to feeder automation as its waste was minimal. The feeder space was adjusted for the different densities during growth of birds for all treatments. This feeding program was performed under four rearing treatments according to the birds’ ages: pre-initial (1 to 7 days), initial (8 to 21 days), growth (22 to 38 days) and final (39 days to slaughtering age at 46 days). Rice husk bedding was routinely provided to the animals in the aviary. All birds were weighed at the beginning and at the end of experimental period. The feed amount was also weighed at the beginning and at the end of each phase to determine cumulative feed consumption for each treatment. The temperature and relative humidity (RH) inside the aviary were measured using brand HOBO data loggers (Onset® model: U10-003; Onset Computer Corporation, Bourne, MA, USA) during the experimental period and the averages were calculated every 10 days. The parameters measured for the birds’ performances were: daily feed intake measurement, daily weight gain at 46 days of age, feed conversion ratio (calculated as the amount of feed consumed per unit of daily weight gain) and rearing viability (calculated as total number of birds produced divided by the initial number of chicks × 100).
Transport The birds were captured and manually placed in boxes containing 10 birds each; the average capture time was 40 min, and they were subsequently transported for 50 km (70 min) in an open truck. Birds of all treatments were transported approximately at 13.00 hours and the temperature and relative humidity during the transport was 31 ± 4°C and 51 ± 8%, respectively, measured by Kestrel 4000 Instrument. Upon arrival at the slaughterhouse, the birds were submitted to a water mist and ventilation for about 60 min before slaughtering.
Meat quality evaluation For the meat quality evaluation, four lots (n = 70) were randomly chosen from each treatment, totaling 840 birds. They were sacrificed following the routine commercial procedure as reported previously, which consisted of nebulization, hanging, electric stunning, bleeding, scalding, defeathering, evisceration, chilling and cooling (Oba et al. 2009; Simões et al. 2009). After deboning the breast fillet samples, Pectoralis major m., were cooled down to 5°C and refrigerated for 24 h for subsequent analyses of color and pH.
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PSE classification The fillet meat samples were classified as PSE or normal meat based on previously established parameters associated with pH and L* values. Samples with pH values less than 5.8 and L24 h* values greater than 53.0 were classified as PSE, and samples with pH values greater than 5.8 and L24 h* between 44.0 and 53.0 were classified as normal (Owens et al. 2000; Soares et al. 2003).
Statistical analysis The statistical analysis was conducted using the STATISTICA 8.0 program (StatSoft, Tulsa, OK, USA). Tukey’s test at a 5% probability level (P ≤ 0.05) was used to compare the temperature and RH of aviary, animal’s performance and meat quality evaluation in the three treatments.
RESULTS AND DISCUSSION Figure 1 shows the temperature and RH inside the aviaries throughout the experiment. In the DHS, the temperature was 2.3°C and 3.3°C significantly lower than CYC and CBC systems (P ≤ 0.05) after 30 and 40 days of growth, respectively. These results were in accordance with other recent reports in which the heavy birds reared in DHS were kept in the thermoneutral zone (Olanrewaju et al. 2010). Under these circumstances, these chickens would maintain their body temperature. Conversely, the birds under CBC and CYC aviaries systems were exposed to temperature higher than the thermoneutral zones. As pointed out by Olanrewaju et al. (2010), the consequences of these conditions were increase of body weight (BW) as the temperature value of 21°C under DHS was in the range of their values in their experiment.
pH and color measurement The pH values were determined by inserting electrodes into the breast muscle (Boulianne & King 1995) using a contact pH meter system model Testo 205 (Testo AG, Lenzkirch, Germany). The analysis was performed in triplicate at 24 h post mortem as previously described by Olivo et al. (2001). A colorimeter Konica Minolta (CR400; Minolta Sensing Inc., Osaka, Japan) was used to evaluate the color parameters, including L* (lightness), a* (redness) and b* (yellowness), on the posterior surface of the intact skinless breast muscles. The color values were measured at three different sites on the same sample. These sites were the proximal extremity of the muscle, distal extremity of the muscle and medial side at the halfway point between the proximal and distal extremities (Soares et al. 2003). Animal Science Journal (2015) 86, 189–193
Figure 1 Average value of temperature (T) and relative humidity (RH) inside the three aviaries: DHS, dark house system; CBC, conventional blue curtain system; CYC, conventional yellow curtain system during the growth of birds. *a–b indicate difference among aviaries by Tukey’s test at a 5% significance level (P ≤ 0.05).
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192 R. H. CARVALHO et al.
Table 3 Performance of broiler chickens reared under the dark house system (DHS), a conventional yellow curtain system (CYC) and a conventional blue curtain system (CBC)
Parameter
Treatments
ADFI (g) ADG (g) BW (g) FCR V%
P
CYC
CBC
DHS
104.32a ± 8.63 56.68b ± 0.95 2607b ± 44.03 1.82a ± 0.04 96.67a ± 0.75
106.81a ± 7.35 57.79b ± 1.45 2658b ± 66.76 1.80a ± 0.47 96.18a ± 0.54
110.57a ± 4.82 63.14a ± 1.40 2904a ± 21.47 1.75b ± 0.33 96.88a ± 0.48
0.312 0.00001 0.00001 0.0048 0.143
a,b Means followed by different superscripts in the same row differ by the Tukey’s test at a 5% significance level (P ≤ 0.05). ADFI, average daily feed intake; ADG, average daily gain; BW, body weight at 46 days; FCR, feed conversion ratio; V, rearing viability.
Table 4 Meat quality parameters (L *, a *, b *, pH and PSE meat) used to evaluate the welfare of broilers reared under the conventional yellow curtain (CYC), conventional blue curtain (CBC) and dark house (DHS) systems
L* CYC CBC DHS
a*
53.11 ± 0.41 53.07b ± 0.10 54.80a ± 0.17 b
b*
1.54 ± 0.51 1.43a ± 0.49 1.53a ± 0.29 a
pH
9.76 ± 0.36 9.54a ± 0.73 9.64a ± 0.21 a
PSE %
5.83 ± 0.01 5.84a ± 0.01 5.78b ± 0.01 a
24.33b ± 2.05 25.33b ± 1.25 37.00a ± 0.82
a,b Means followed by different superscripts in the same row differ by Tukey’s test at a 5% significance level (P ≤ 0.05). L*, lightness; a*, redness; b*, yellowness; PSE, pale, soft and exudative.
RH did not differ among housing systems. These results indicated that the birds in DHS were under lower stress conditions. Table 3 shows that the birds reared under the DHS presented better production performance compared with the CYC and CBC systems, as the birds reared under the DHS showed respectively 11.4% and 9.3% higher average daily gain, 11.4% and 9.3% higher body weight and 3.8% and 2.7% lower feed conversion ratio (P ≤ 0.05). However, no significant differences were observed in the values for the average daily feed intake or rearing viability. In addition, no significant difference was observed between the birds reared in the CYC and CBC systems. Once the broiler chickens had been acclimatized to the DHS and were in the growing phase, the broiler chickens were under less stressful conditions, resulting in a higher body comfort and thus influencing their performance and meat quality. Nowicki et al. (2011) found higher feed conversion ratios in broiler chickens reared under dark house conditions compared with conventional aviaries, corroborating our results. Several maneuvers during the rearing period can expose birds to stressors that trigger stress reactions, and the aviary installation model is one of these maneuvers. The levels of ambient light, temperature and husbandry practices (Jones & Mills 1999; Marin et al. 2001) may cause serious problems for animal welfare (Hall 2001; NRC 2008). However, in aviaries under the DHS, these parameters are controlled, providing better welfare for the birds. Abreu and Abreu (2011); Costa et al. (2010) also reported that the outer insulation of the dark house’s internal barn provides better results. Table 4 shows the results of meat quality under these three treatments. These results clearly show that © 2014 Japanese Society of Animal Science
the samples under the DHS treatment were different in relation to the other treatment groups (CYC and CBC). It presented the highest value of L* and lowest pH value (P ≤ 0.05); however, no difference was observed between CYC and CBC treatments. As noted by Soares et al. (2003), lower post mortem pH (≤ 5.8) and higher L* (≥ 53) values were indicative of worse animal welfare, as measured by the incidence of PSE meat. Indeed, the PSE incidence for DHS treatment (37.0%) was higher (P ≤ 0.05) than CYC and CBC treatments, 24.3% and 25.3%, respectively. The a* and b* values did not differ among these three treatments. The DHS ambience provided a better environmental control within the barn, offering a better welfare for the birds as demonstrated by the temperature results (Fig. 1). However, when the birds were subjected to stress during the pre-slaughter treatments of fasting, harvesting, transporting and hanging (Sams 1999; Guarnieri et al. 2004; Petracci et al. 2004; Langer et al. 2009), they developed physiological responses to stress, causing as a consequence a higher incidence of PSE meat. Another significant factor to be considered were the transport activities from the farm to the commercial abattoir, and this experiment was conducted under summer conditions of temperatures at 31°C and 51% relative humidity. Simões et al. (2009) and Oba et al. (2009) conducted a recent survey under Brazilian summer conditions and obtained results indicating an incidence of PSE meat of 35% and up to 75%, under routine commercial management and under full stress management, respectively. Other reports worldwide have also shown that during the summer season, the incidence of PSE meat was higher compared with that during winter (Shimokomaki & Olivo 2006; Langer et al. 2009; Simões et al. 2009). Animal Science Journal (2015) 86, 189–193
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In conclusion, the broiler chickens reared under DHS showed higher values of PSE meat incidence, indicating that the birds produced under these conditions were more intensively affected by stress promoted by the pre-slaughtering maneuvers and conversely they presented a better growth performance.
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