The following technical article is related to the event:
XXII Latin American Poultry Congress 2011

Quality of eggs from isa brown laying hens

Production performance and internal quality of eggs from isa brown laying hens in various production systems in hot/ humid weather

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Brazilian egg production industry keeps growing and, consequently, concerns have increased about poultry performance and welfare. The purpose of this study was to evaluate the performance and egg quality of eggs from Isa Brown layers using both the conventional production system in cages and the floor system, with and without forced ventilation, in hot/humid weather. The experiment was conducted in experimental units with flocks in production, using 4 different house construction models. Different production systems were selected (cages or on floor) and two environmental systems (with or without forced ventilation) and each treatment included 4 repetitions in time (4 time periods of 7 days each), at one week intervals. A total of 200 Isa Brown laying hens, in production, between 23 and 42 weeks of age. The performance evaluation of these birds (feed intake, feed conversion rate, and egg production) was performed by collecting the information daily, at two pre-determined times (from 09:00 to 10:00; and from 15:00 to 16:00 h). The effects of the production systems on internal egg quality were evaluated on the day of lay, using the following parameters: egg weight, Haugh units, yolk index, and eggshell thickness. The floor systems, regardless of forced ventilation, resulted in improved productive performance and improved egg quality as compared to the system based on suspended cages.
Key words: Feed conversion rate, Yolk index, Haugh units.


As awareness increases about the importance of the environment on the performance of the laying hen, more and more concerns arise about improving the production systems and environment in order to provide improve both animal welfare and final egg quality. Considering the inexistence of well defined seasons in the Brazilian Amazon region, particularly the microclimate in the state of Acre, relative humidity (RH) and temperature in which layers are produced, are remarkably high. This is why it is crucial to undertake research leading to better understand the physiological and productive responses of birds to their production environment. According to (2000), the ideal temperature for egg production is 21-26°C. Between 26 and 29°C a mild decrease occurs in egg size and eggshell quality, while between 29 and 32°C these two parameters are badly deteriorated, and the same is valid for egg production levels. Between 35 and 38°C, severe egg s occur and the birds get prostrated. The purpose of this study was to evaluate egg performance and quality in Isa Brown layers under a conventional production system in cages, or on the floor, with or without forced ventilation in a hot, humid climate.

Materials and Methods

The experiment was conducted in Acre Federal University (UFAC), Multidisciplinary Center of Cruzeiro do Sul, AC, Brazil, between august and November 2010. In agreement with Koppen´s classification, the climate in the region is considered tropical humid Af, with rain precipitation well distributed throughout the year, and with no dry season. The mean altitude is 170 meters and yearly raining rate is 2,074 mm. For this study, experimental units with commercial flocks in production were used. The study was carried out in aviaries of 4 different models. A total of 200 Isa Brown laying hens was used. Considering that the experiment was undertaken in a commercial farm, birds between 23 and 42 weeks of age were used. The experimental feed was the same used in the farm at that time, formulated based on corn and soybean meal, as per strain's nutritional requirements. Both feed and water were provided ad libitum. The experimental treatments were represented by the production systems, and consisted of two farming systems (cages or on the floor), with two ambient systems (with or without forced ventilation). Each treatment had 4 time repetitions (four times of seven days, one week apart). Each production/environment system included 50 representative birds. Data corresponding to all variables was collected daily throughout the trial, regardless of rainfall, at pre-established times (from 09:00 to 10:00, and from 15:00 to 16:00 hours, local time), Forced ventilation consisted of using one fan with a capacity of 1 m3/sec. Bird performance (feed intake, feed conversion rate, end egg production) was evaluated by collecting the data every day. Regarding egg quality, the following parameters were evaluated: mean egg weight, Haugh units, yolk index, and eggshell thickness. The experiment was designed with random blocks, and data was analyzed using Tukey´s test with a 5% probability.

Results and Discussion

Performance results with these brown layers subjected to the various systems of production and environments are described in Table 1.

Table 1. Feed intake (FI), feed conversion rate (FCR) and egg production of the ISA Brown layers subjected to various production/environment systems


Treatments (Houses/Production Systems)*

CV (%)

Cage with Ventilation

Floor with/ Ventilation

Cage w/o Ventilation

Floor w/o Ventilation

FI (g/bird/day)






FCR (Kg/Kg)






Production (%)






* Means followed by different letters in a line are statistically different as per Tukey´s test  (P<0.05).

Results show a higher FI in the birds housed on the floor, with forced ventilation, with statistically-significant differences with the other systems. In this case, the higher FI is directly related with the lower stocking density as compared to cage systems which, in turn, results in lower ambient comfort and increased stress for the birds. This improvement in comfort was translated into a lower need to dissipate heat in the production environment and allowed the birds to naturally regulate their hunger/satiation center, thus promoting access to the feed, and allowing hormone control to work directly in the hypothalamus. All other treatments, particularly tat with cages and no forced ventilation, had lower FI and, not being directly justified by the effect of the increased stocking density, such reduction seems to be related with direct physiological effects i.e., higher body temperature as a result of increased heat/RH in the house.
FCR also showed improved results among the hens held on the floor (with or without ventilation). These results are directly related with increased egg weight in these groups. Birds in all other treatments showed undesirable FCR increases, which is explained by the possible nutrient shortfall in the levels of nutrient intake in function of the lower FI which, in turn, resulted in reduced mean egg weight. No significant effects were found when the FCR in the suspended cage systems were analyzed (P>0.05). These results corroborate those by Pavan et al. (2005) who studied stocking density and found no FCR differences in caged layers subjected to forced ventilation.
Regarding egg production results, these were very consistent with FI levels. Improved productivity was remarkable in the birds maintained on the floor, with or without ventilation. Once again, this data match the theory of higher egg production related to animal comfort and welfare. The non-ventilated cage system caused a reduction in lay, which cannot be directly attributed to the stocking density factor, but it might possibly be related with the effects of the micro-climate inside the house.
Egg production results in cages (with and without forced ventilation) reported herein, are consistent with those reported by Carey et al. (1995), who found no significant differences in the birds with different heat dissipation rates resulting from various stocking densities. It is considered that the production similarity in the cage systems with and without forced ventilation can be limited to 3 birds per cage, and this productivity can be negatively affected if higher stocking densities were used.
Egg quality results in these brown layers subjected to various production/environment systems are shown in Table 2.

Table 2. Mean egg weight (MEW), Haugh units (HU), yolk index (YI) and eggshell thickness (EST) in brown layers under various production/environment systems


Treatments (Houses/Production Systems)*

CV (%)

Cage w/ Ventilation

Floor w/ Ventilation

Cage w/o Ventilation

Floor w/o Ventilation



















EST (mm)






* Means followed by different letters in a line are statistically different as per Tukey´s test  (P<0.05).

The statistical analysis of MEW showed a significant differences, particularly in the birds held on floor models.
Results showed a significant decrease (P<0.05) in MEW when the birds were subjected to a possible condition of heat stress, especially in the cage with no ventilation system. These results confirm those reported by Mashaly et al. (2004), who found a 7.5 g difference between the eggs from comfortable conditions vs. those from heat-stressed  hens. Results also show a more evident reduction in the MEW under cage conditions, which can probably be explained by the increased stress imposed by this system in conditions of high temperature, considering the level of confinement and the higher difficulty of the birds to dissipate the heat.
Haugh units (HU) classify the quality of eggs as follows: excellent, HU >90; very good, HU 80 - 90; acceptable, HU  70 - 80; and mean, HU 65 - 70. The quality parameter HU showed a significant difference (P<0.05) with regard of the environmental conditions studied. For the caged environment, HU were significantly lowed than on floor,  which downgraded these eggs to "very good" which still means a considerable internal egg quality. Nevertheless, this reduction could be due to the stress experienced by the birds as a result from high temperatures. This result confirms that of Barbosa et al. (2008), who reported that HU values decreased when compared with those obtained prior to exposing the birds to heat stress. It is important to mention that, even with a lower performance, eggs from cages were classified as " very good" . Regardless of the environmental conditions and the production systems all eggs had a considerable egg quality when the parameter albumin was considered.
With regard to the yolk index (YI) significant differences were obtained (P<0.05) in association with the production. A significant decrease (P<0.05) can be seen in the mean YI values for the eggs produced by the hens housed in suspended cages. In the floor birds, no YI statistical differences existed, even though YI in these birds was higher than those in the other systems. Possibly, this condition is a reflection of the thermal comfort zone in which these birds were maintained.
Eggshell thickness (EST) had statistical differences (P<0.05), depending on the production system, with a well defined decrease in the suspended cage model. In agreement with authors like Barbosa et al. (2008) this situation reflects a reduction in Ca blood balance, since it is well known that Ca balance is affected in the face of heat stress, resulting in decreased amounts of plasma Ca and adversely affects eggshell formation.


Under the conditions of this experiment, the birds maintained on the floor (regardless of forced ventilation) had improved productive performance and improved egg quality when compared with the suspended cage system. Further studies are needed as to verify the economic feasibility of egg production under these different production systems.


Barbosa NAA, Sakomura NK, Mendonça MO, Freitas ER, Fernandes JBK. 2008. Qualidade de ovos comerciais provenientes de poedeiras comerciais armazenados sob diferentes tempos e condições de ambientes. ARS Veterinária 24(2):127.

Carey JB, Kuo FL, Anderson KE. 1995. Effects of cage population on the productive performance of layers. Poultry Science 74(4):633-637.

Mashaly MM, Hendricks GL, Kalama MA. 2004. Effect of heat stress on production parameters and immune responses of commercial laying hens. Poultry Science 83:889-894.

Pavan AC, Garcia EA, Mori C. 2005. Efeito da Densidade na Gaiola sobre o Desempenho de Poedeiras Comerciais nas Fases de Cria, Recria e Produção. Revista Brasileira de Zootecnia 34(4):1320-1328.

Silva RG. 2000. Introdução a bioclimatologia animal. São Paulo: Nobel. 286p.



Hassan B. Yusuf Hassan B. Yusuf
Animal Nutritionist
August 27, 2013
I am right now working on the effects of energy protein ratio on the performance of layer chickens in the northern guinea savanna zone of nigeria. i am also using the isa brown chicken for my research. Any additional information to update my review of literature will be highly appreciated.
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