Thermal Response of Three Strains of Hens Housed in a Cage-Free Aviary at the Amazon Rainforest

ABSTRACT

This study aimed to evaluate the thermal response of three strains of hens housed in a cage-free system at the Amazon rainforest in order to evaluate how feather coverage influences thermal exchange with the environment. The experimental method was completely randomized and treatments comprised three strains of hens (Rhode Island Red (red feathers with feathers on the neck), alternative strain FCI (red feathers without feathers on the neck), and alternative strain FCIII (white feathers without feathers on the neck)), with 20 hens (replicates) analyzed per strain. Thermal images of each bird were captured in order to record the birds’ surface temperatures on five points in five targets. All data collected in this study were subjected to ANOVA and subsequently to the Tukey test at p≤0.01 and p≤0.05. The aviary’s left wall presented a lower average temperature, indicating lower heat accumulation, while the floor presented higher heat accumulation. FCIII hens (white feathers) presented higher (p<0.05) heat accumulation on the head and legs, and lower (p<0.05) heat accumulation on the neck and back in relation to other analyzed hens, indicating increased heat exchange efficiency and high concentration of this process in specific body areas. FCI and FCIII hens (without feathers on the neck) presented lower (p<0.05) heat accumulation on the neck and higher (p<0.05) heat accumulation on the head and legs, indicating that the feather coverage directly influenced heat exchange mechanisms, and an increased area without feathers provided great heat exchange zones for birds in a tropical climate.

Keywords:
Amazon; animal welfare; cage-free; Gallus gallus domesticus; thermal comfort

INTRODUCTION

The Amazon rainforest is an important regulatory mechanism of the tropical atmosphere and its climate variation, performing important functions in the climate equilibrium of several ecosystems and their inhabitants. The region also has unique climate and environment characteristics (Fisch et al., 1998). The development of poultry production in the region thus presents several challenges related to birds’ environmental comfort, depending on the type of housing system used and birds’ response to these environmental characteristics (Cruz et al., 2016).

Chickens are homeothermic animals, being directly affected by climate changes (Kolb, 1984; Cunningham, 2004). They are in continuous thermal exchange with the environment, characterizing an interaction between environmental factors and birds’ physiology. However, this mechanism is effective only when the bird’s temperature presents disequilibrium in relation to the environment (Abreu & Abreu, 2011). Thus, changes in the birds’ physiological mechanism caused by environmental conditions may affect performance responses (Bueno & Rossi, 2006).

Similar to other species, birds’ thermal comfort zone may be defined as a range of temperatures where the metabolic rate is minimal and energy needs are low (Nascimento et al., 2014). Birds’ ability to dissipate heat tends to decrease as ambient temperature and relative humidity leave the thermoneutral zone (air temperature at 24°C (75.2 ºF) and relative air humidity at 70%). In this sense, significant changes in the bird’s body temperature cause caloric stress (Yahav et al., 2005; Curto et al., 2007; Slimen et al., 2015).

Such caloric stress imposed by excessive heat is the great barrier faced by the poultry industry when trying to reach an ideal condition of animal welfare in tropical regions, especially considering the control of environmental conditions within and outside of the aviary, among other factors (Tinôco, 2001). It is known that the poultry industry had significant changes to its animal welfare protocols along the last decades, mainly adopting alternative management systems such as free-range, cage-free, agroecological, and organic. In this context, there are a lot of management protocols that should be studied and improved to provide data regarding birds’ adaptability to their environmental conditions and how adaptability may affect bird performances (Al-Ajeeli et al., 2018). As a model to provide a better environmental condition to birds, the cage-free aviary system is highly variable, and needs to present adequate management practices and design. But this system may provide the birds with a good environmental condition, free of behavioral restriction and stress problems, with an efficient heat exchange with the environment (Hartcher & Jones, 2017).

Studies of birds’ thermal response are important to provide the poultry industry with data regarding its adaptability to environmental conditions and how these effects may affect bird performances. Considering these aspects, this study was developed to evaluate the thermal response of three strains of hens housed in a cage-free system in the Amazon rainforest, in order to evaluate the feather coverage’s influence on the thermal exchange with the environment.

MATERIAL AND METHODS

This study was conducted in the facilities of the Poultry Sector, Faculty of Agrarian Sciences, Federal University of Amazonas, Manaus, Amazonas State, Brazil. Animals’ management procedures followed the guidelines established by the Ethics Committee in Animals’ Use of the Federal University of Amazonas.

The aviary was located on the following geographic coordinates: latitude 3° 06’ 14’’ S, longitude 59° 58’ 46’’ W, at an altitude of 92 m. The climate in the region was classified as humid tropical, presenting an annual rainfall of 2,286 mm, temperature ranging between 27 and 32 °C, and relative air humidity between 65 and 75% (Rufino & Martorano, 2020). According to Martorano et al. (2017), it is possible to identify variations with three patterns (Af₁, Af₂, and Af₃) in the state of Amazonas, but in Manaus the typology Af₃ predominates. The aviary (25 x 8 m) was built east-west and divided into 14 pens (3 x 3 m). The floor was covered with 8 cm of sawdust, presenting cement roof tiles, open skylights for natural ventilation and illumination, with no curtains or forced ventilation. The birds were already housed in the aviary before analyzes were carried out.

The experimental method was completely randomized and treatments were comprised three strains of hens Rhode Island Red (red feathers with feathers on the neck), alternative strain FCI (red feathers without feathers on the neck), and alternative strain FCIII (white feathers without feathers on the neck)), with 20 hens (replicates) being analyzed per strain. Hens (60 weeks-of-age) were housed at a density of 4 birds/m² and fed diets formulated according to the requirements proposed by Rostagno et al. (2017), with food and water available ad libitum.

The data were collected in two periods (9:00 a.m. and 4:00 p.m.) using a FLIR^® infrared thermographic camera, with a window of one hour for data collection. Thermal images of 10 points of the aviary’s roof, walls (right and left in the east-west way), and floor were initially captured to evaluate its environmental conditions. In order to record the birds’ surface temperatures, thermal images of randomly selected birds were captured for the following targets: (i) head; (ii) neck; (iii) back, (iv) wing and (v) legs. The temperature was evaluated on five points for each target (Figures 1 and 2). Based on the results obtained in the FLIR® software for thermographic images’ processing, the Average Surface Temperature (AST) was calculated according to the equation proposed by Richard (1971).

Figure 1
Thermal image of a Rhode Island Red hen indicating the evaluated targets.

Figure 2
Thermal image of a FCIII hen indicating the evaluated targets.

All data collected in this study were analyzed using the GLM procedure of SAS (Statistical Analysis System, v. 9.2) and estimates of the strains were subjected to ANOVA and subsequently to the Tukey test. Results were considered significant at p≤0.01 and p≤0.05.

RESULTS AND DISCUSSION

Thermal condition results inside the aviary showed that the left wall presented a lower temperature, which may be associated with the aviary architecture in the east-west direction, thus providing less exposure to the sun on this side (Table 1). In contrast, the floor presented both high temperature accumulation and variation in temperature. These results may be associated with the birds’ presence and distribution along the aviary and the variation in the concentration of the sawdust used to coat the floor where the birds were housed. Even though all pens have the same number of birds per m², variations in sawdust height and distribution along each pen may occur.

Table 1
Thermal response of the aviary used to house the birds.¹

Place	Average Temperature (ºC)	Min. Temperature (ºC)	Max. Temperature (ºC)
Roof	28.14±0.11	28.00	28.30
Right wall	28.04±0.13	27.90	28.20
Left wall	27.94±0.08	27.80	28.00
Floor	28.88±0.71	28.00	29.60

• ¹
  Mean values ± SE are presented.

As expected, the roof tended to present a higher temperature accumulation due to its direct exposure to the birds. However, the studied location had a great number of trees along its edge, creating a good microclimate that resulted in lower heat accumulation in aviary structures.

In Brazil, for economic reasons or lack of information, little attention is given to aviaries’ architectural planning and design, or to structures that are compatible with each region’s climatic reality. As a consequence, the aviary can be very hot in the summer, resulting in almost continuous thermal discomfort for the birds (Tinôco, 1995). Both the Amazon environment and the internal conditions of the aviary housing environment directly affect the birds’ comfort and thermal experience. This impacts the maintenance of thermal balance inside the facilities and the hens’ natural behavior expression (Nazareno et al., 2009).

The management of aviary structures and environmental conditions are important to provide comfort for the birds (Näas et al., 2007). Diseases and injuries are usually developed due to inadequate conditions in the aviary, which are the major causes of carcasses abnormalities in slaughterhouses (Pinto et al., 1993). Perdomo (1998) reported that acclimatization issues tend to cause serious problems for the broilers, suggesting that the use of simple thermal diagnosis methodologies for aviary structures and broilers may provide data and enable responses that solve a lot of problems in bird management.

Hens with white feathers presented higher temperature accumulation on the head and legs, and lower temperature accumulation on their neck and back (Table 2). Previous studies showed that feather color directly affects birds’ thermal comfort (Scarinci & Marineli, 2014), as they are responsible for body heat absorption and accumulation. Fragata et al. (2015) reported that surfaces with high absorptivity in the heat wavelength range tend to reach higher equilibrium temperatures than those with less absorptivity. Thus, dark color surfaces absorb 50% more incident heat than white surfaces (Kreith, 1973).

Table 2
Birds’ thermal response in different body targets.

Strains	Variables
	Head (ºC)	Neck (ºC)	Back (ºC)	Leg (ºC)
Rhode Island Red	36.14±0.38b	39.88±0.91a	31.50±2.39b	32.30±0.85b
FCI	36.76±2.23ab	39.48±0.96ab	34.18±3.29a	32.38±1.17b
FCIII	37.12±1.45a	32.07±1.77b	29.99±0.76c	35.54±2.02a
p-value	0.03**	0.01*	0.01*	0.01*
CV (%)	3.29	4.28	4.12	2.45

• CV - Coefficient of Variation. * Significant Effect (p≤0.01). ** Significant Effect (p≤0.05).

Furthermore, it was observed that birds without feathers on the neck presented lower temperatures on the neck and high temperatures on the head and legs, indicating a direct relation between feather cover and heat accumulation. Lack of feathers on the neck indicated great heat dissipation along this surface and concentration of heat on the head and the legs, regions that present high heat accumulation, in spite of mechanisms to dissipate this heat (Deschutter & Leeson, 1986).

The head, neck, and some areas around the abdomen have a naturally poor feather coverage as compared to other regions of the hens, causing heat accumulation and creating zones with more sensibility to this heat flow (Li & Yamamoto, 1991; Choi et al., 1997; Naas et al., 2010). Hens with low feather coverage tend to present a more efficient natural capacity of exchanging heat with the environment than other strains, especially due to their mechanisms of metabolic rate control being most effective and their own thermoregulation (Deschutter & Leeson, 1986). Feathers play a critical role in heat accumulation and dissipation, directly affecting the hens’ productivity (Leeson & Morrison, 1978; Deschutter & Leeson, 1986).

The average surface temperature results showed that birds without feathers on the neck presented lower (p<0.05) heat accumulation, especially the alternative strain FCIII, which combines the absence of feathers on the neck and white colored feathers. These results may indicate these birds’ greater capacity of dissipating heat (Table 3).

Table 3
Average thermal response of birds’ surfaces.

Strains	Temperature (ºC)
Rhode Island Red	44.37±1.69a
FCI	42.71±3.02b
FCIII	41.31±1.06c
p-value	0.01*
CV (%)	4.33

• CV - Coefficient of Variation. * Significant Effect (p≤0.01).

Based on these results, we suggest that a larger area available for heat exchange with the environment improves birds’ thermal comfort; and birds without feathers on the neck have an increased area to perform this heat loss. It is therefore important to point out that two major points should be considered when analyzing the influence of animal welfare in bird handling: a) feather coverage is related to the bird’s accumulation of body heat and its heat exchange with the environment; and b) blood flow is related to the body’s heat production (Yahav et al., 2004; Silva et al., 2007; Marchini et al., 2018).

According to Nascimento et al. (2011), heat loss is related to specific feather coverage in each body part. Fukayama et al. (2005) also reported that feather coverage in specific places may provide an extension of the heat loss surface, improving the thermal comfort range of the birds and allowing for some strains to better adapt to temperature ranges rather than others. In this sense, Yahav et al. (1998) reported better adaptation to tropical climates by chickens without feathers in the neck, precisely due to this extra heat dissipating region on the neck.

Other studies still point out that modern strains’ feather coverage along most of the body surface led to the development of a greater heat sensibility, creating more efficient mechanisms to detect environmental heat changes and concentrate heat exchanges in specific body areas, (especially those without feathers) such as shanks, feet, neck (in some strains) and so on (Cangar et al., 2008; Naas et al., 2010; Abreu & Abreu, 2011).

On the other hand, blood flow is the major responsible for regulating homeostasis processes (Yahav et al., 2001; Yahav et al., 2004; Cangar et al., 2008; Marchini et al., 2018). If the environmental temperature is higher than the body temperature, blood flow tends to decrease in order to reduce the body’s heat production. However, if the environmental temperature is lower than body temperature, blood flow tends to increase in order to increase the body’s heat production (Richards, 1971; Tessier et al., 2003; Shinder et al., 2007; Naas et al., 2010).

Thus, great variations in the environmental temperature (high or low) and a inefficient body heat exchange by the birds tend to negatively impact the performance, carcass and noble cut yields. These losses may be represented by reduction of feed intake (from 12% to 28%) and weight gain (from 18% to 44%), consequently affecting energy retention, protein and fat deposition in the carcass, and viscera growth (Abu-Dieyeh, 2006; Al-Fataftah and Abu-Dieyeh, 2007; Mello et al., 2015; Marchini et al., 2018).

CONCLUSIONS

Birds without feathers on the neck housed in a cage-free system presented lower body heat accumulation, especially on the neck, indicating this region to be a great zone for heat exchange and the creation of better thermal comfort conditions. Birds with white color feathers also presented lower body heat accumulation.

REFERENCES

• Abreu VMN, Abreu PG. Os desafios da ambiência sobre os sistemas de aves no Brasil. Revista Brasileira de Zootecnia 2011;40:1-14.
• Abu-Dieyeh ZHM. Effect of high temperature per se on growth performance of broilers. International Journal of Poultry Science 2006;5(1):19-21.
• Al-Ajeeli MN, Miller RK, Leyva H, Hashim MM, Abdaljaleel RA, Jameel Y, et al. Consumer acceptance of eggs from Hy-Line Brown layers fed soybean or soybean-free diets using cage or free-range rearing systems. Poultry Science 2018;97(5):1848-1851.
• Al-Fataftah AA, Abu-Dieyeh ZHM. Effect of chronic heat stress on broiler performance in Jordan. International Journal of Poultry Science 2007;6(1):64-70.
• Bueno L, Rossi LA. Comparação entre tecnologias de climatização para criação de frangos quanto a energia, ambiência e produtividade. Revista Brasileira de Engenharia Agrícola e Ambiental 2006;10(2):497-504.
• Cangar Ö, Aerts J-M, Buyse J, Berckmans D. Quantification of the spatial distribution of surface temperatures of broilers. Poultry Science 2008;87:2493-2499
• Cunningham JG. Tratado de fisiologia veterinária. Rio de Janeiro: Guanabara Koogan; 2004.
• Curto FPF, Nääs IA, Pereira DF, Salgado DD. Estimativa do padrão de preferência térmica de matrizes pesadas (frangos de corte). Revista Brasileira de Engenharia Agrícola e Ambiental 2007;11:211-216.
• Deschutter A, Leeson S. Feather growth and development. World's Poultry Science Journal 1986;42(3):259-267.
• Fragata F, Sens M, Sebrão M. Influência da cor de tintas de poliuretano na absorção e na dissipação de calor. Corrosão e Protecção de Materiais 2015;34(2):53-59.
• Fisch G, Marengo JA, Nobre CA. Uma revisão geral sobre o clima da Amazônia. Acta Amazônica 1998;28(2):101-126.
• Fukayama EH, Sakomura NK, Neme R, Freitas ER. Efeito da temperatura ambiente e do empenamento sobre o desempenho de frangas leves e semipesadas. Ciência e Agrotecnologia 2005;29:1272-1280
• Hartcher KM, Jones B. The welfare of layer hens in cage and cage-free housing systems, World's Poultry Science Journal 2017;73:1-15.
• Kreith F. Princípios da transmissão de calor. São Paulo: Edgard Blücher; 1973.
• Kolb E. Fisiologia veterinária. Rio de Janeiro: Guanabara Koogan; 1984.
• Leeson S, Morrison WD. Effect of feather cover on feed efficiency in' laying birds. Poultry Science 1978;57:1094-1096.
• Marchini CFP, Fernandes EA, Nascimento MRBM, Araújo EG, Guimarães EC, Bueno JPR, et al. The effect of cyclic heat stress applied to different broiler chicken brooding stages on animal performance and carcass yield. Brazilian Journal of Poultry Science 2018;20(4):765-772.
• Martorano LG, Vitorino MI, Silva BPP, Moraes JR, Da SC, Lisboa LS, Sotta ED, et al. Climate conditions in the eastern Amazon:Rainfall variability in Belem and indicative of soil water defict. African Journal of Agricultural Resarch 2017;12:1801-1810.
• Mello JLM, Boiago MM, Giampietro-Ganeco A, Berton MP, Vieira LDDC, Souza RA, et al. Periods of heat stress during the growing affects negatively the performance and carcass yield of broilers. Archivos de Zootecnia 2015;64(248):339-345.
• Naas IA, Romanini CEB, Neves DP, Nascimento GR, Vercellino RA. Broiler surface temperature distribution of 42 day old chickens. Scientia Agricola 2010;67(5):497-502.
• Nascimento GR, Pereira DF, Naas IA, Rodrigues LHA. Índice fuzzy de conforto térmico para frangos de corte. Engenharia Agrícola 2011;31:219-229.
• Nascimento GR, Näas IA, Baracho MS, Pereira DF, Neves DP. Termografia infravermelho na estimativa de conforto térmico de frangos de corte. Revista Brasileira de Engenharia Agrícola e Ambiental 2014;18:658-663.
• Näas IA, Miragliotta MY, Baracho MS, Moura DJ. Ambiência aérea em alojamento de frangos de corte: poeira e gases. Engenharia Agrícola 2007;27(2):326-335.
• Nazareno AC, Pandorfi H, Almeida GLP, Giongo PR, Pedrosa EMR, Guiselini C. Avaliação do conforto térmico e desempenho de frangos de corte sob regime de criação diferenciado. Revista Brasileira de Engenharia Agrícola e Ambiental 2009;13:802-808.
• Perdomo CC. Mecanismos de aclimatação de frangos de corte como forma de reduzir a mortalidade no inverno e verão. Anais da Conferência APINCO de Ciência e Tecnologia Avícolas, Simpósio Internacional sobre Instalações e Ambiência; 1998; Campinas, São Paulo. Brasil. Campinas: FACTA; 1998. p.229-240.
• Pinto FG, Curi PR, Toledo M. Evolução da condenação avícola no Estado de São Paulo (1985 a 1990): tendências anuais e estacionais. Veterinária e Zootecnia 1993;5:45-50.
• Richards SA. The significance of changes in the temperature of the skin and body core of the chicken in the regulation of heat loss. Journal of Physiology 1971;216:1-1.
• Scarinci AL, Marineli F. O modelo ondulatório da luz como ferramenta para explicar as causas da cor. Revista Brasileira de Ensino de Física 2014;36:1-14.
• Shinder D, Rusal M, Tanny J, Druyan S, Yahav S. Thermoregulatory response of chicks (Gallus domesticus) to low ambient temperatures at an early age. Poultry Science 2007;86:2200-2209.
• Silva MAN, Barbosa Filho JAD, Silva CJM, Silva IJO, Coelho AD, Savino, JM. Avaliação do estresse térmico em condição simulada de transporte de frangos de corte. Revista Brasileira de Zootecnia 2007;36(4 suppl):1126-1130.
• Slimen IB, Najar T, Ghram A, Abdrrabba M. Heat stress effects on livestock:molecular, cellular and metabolic aspects, a review. Journal of Animal Physiology and Animal Nutrition 2015;100(3):401-412.
• Tessier M, Du Tremblay D, Klopfenstein C, Beauchamp G, Boulianne M. Abdominal skin temperature variation in healthy broiler chickens as determined by thermography. Poultry Science 2003;82:846-849.
• Tinôco IFF. Estresse calórico: meios artificiais de condicionamento. Anais do Simpósio Internacional de Ambiência e Instalações na Avicultura Industrial; 1995; Campinas, São Paulo. Brasil. Campinas: FACTA; 1995. p.99-108.
• Tinôco IFF. Avicultura industrial:novos conceitos de materiais, concepções e técnicas construtivas para galpões avícolas brasileiros. Revista Brasileira de Ciência Avícola 2001;2(1):1-26.
• Yahav S, Luger D, Cahaner A, Dotan M, Rusal M, Hurwitz S. Thermoregulation in naked neck chickens subjected to different ambient temperatures. British Poultry Science 1998;39:133-138.
• Yahav S, Straschnow A, Vax E, Razpakovski V, Shinder D. Air velocity alters broiler performance under harsh environmental conditions. Poultry Science 2001;80:724-726.
• Yahav S, Straschnow A, Luger D, Shinder D, Tanny J, Cohen S. Ventilation, sensible heat loss, broiler energy, and water balance under harsh environmental conditions. Poultry Science 2004;83:253-258.
• Yahav S, Shinder D, Tanny J, Cohen S. Sensible heat loss:the broiler's paradox. World's Poultry Science Journal 2005;61:419-434.

Publication Dates

• Publication in this collection
  10 Sept 2021
• Date of issue
  2021

History

• Received
  08 Dec 2020
• Accepted
  06 June 2021