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Current IssueSpecial IssueEditorial BoardOnline First ArticlesArchive

ABSTRACT

Background: The weather parameters influence the thermal comfort and productivity of commercial ‘Cobb 400’ broilers.  Hence, this study was conducted to evaluate the effect of seasonal weather on the growth, feed and water intake, FCR, body temperature and livability of broiler chickens.

Methods: The experiment was conducted for five weeks each during winter and summer on 200 number of broiler chicks. Environmental parameters (temperature and relative humidity) were recorded inside and outside the poultry house and the key physiological responses like feed intake, water intake, FCR and livability of the birds were observed and compared among summer and winter seasons.

Result: Results revealed winter season (mean maximum temperature of 30.4°C, relative humidity between 40-70 per cent) was found to be optimal for broiler performance, with, higher feed consumption, greater live body weight (2005 g vs. 1868 g), improved feed conversion ratio (1.80 vs. 1.90) and 100 per cent livability. In contrast, summer season (mean maximum 36.6°C and reduced relative humidity 33-49 per cent) increased the Temperature Humidity Index (THI), leading to reduced feed intake, higher water intake, poorer FCR and increased mortality during summer season. This shows winter season to be suitable for broiler growth, ensuring better production efficiency compared to summer season.

INTRODUCTION

Among the animal protein industry, broiler chicken production is one of the most rapidly growing sectors. India is the fifth largest producer of broiler producing countries of the world, with monthly over 400 million broiler chicks, contributing about 65.3 per cent to the total poultry industry output (Ghosal, 2020). This growth is attributed to the integration of improved genetic lines, specialized feed, better housing and management practices that have significantly reduced the age of market-ready birds to just 40 days, with an average live body weight of 2 kg (Cicek and Tandogan, 2016).
       
Despite of all the advancements, attaining the potential production of these homoeothermic birds is highly weather dependent, especially during the post brooding phase. Temperature and Relative Humidity (RH) within the poultry house are the critical parameters that influence the physiological responses, growth and feed efficiency of broilers. At higher temperatures, birds exhibit reduced feed intake, increased water consumption as well as respiratory rates, which can negatively impact growth and feed conversion efficiency (Vandana et al., 2021). High temperatures and low RH increases energy expenditure for thermoregulation, through increased respiration and heat dissipation. Furthermore, the simultaneous occurrence of high temperature and high humidity impairs heat dissipation, worsening the stress response (Krishnan et al., 2023).
       
Several THIs have been developed to quantify the thermal comfort and heat stress experienced by livestock and poultry by combining environmental variables such as dry-bulb temperature, wet-bulb temperature, relative humidity, air velocity and solar radiation (Moraes et al., 2008; Purswell et al., 2012; Omomowo, 2021; Narmilan et al., 2021; Kumar et al., 2025). The interpretation of THI values generally ranges from conditions of thermal comfort to mild, moderate and severe heat stress, although the specific thresholds vary depending on the index used. In broilers, increasing THI beyond the thermoneutral range is associated with reduced feed intake, impaired weight gain, poorer feed conversion, increased water consumption and, under severe heat stress, increased mortality (Lallo et al., 2018). Thus, THI provides a practical means of linking environmental conditions with physiological and productive responses.
       
Although there are several studies, there exist limited studies specifically about the seasonal impacts on broiler productivity under standard management conditions in South Indian tropical environments. Hence, the present study aims to assess the seasonal influence on broiler production by evaluating physiological indicators, performance indicators and THI.

MATERIALS AND METHODS

The experiment was conducted during the winter (November to December 2023) and summer (March to April 2024) seasons in Tamil Nadu Agricultural University, Coimbatore, TamilNadu. The experimental period lasted for five weeks in each season.
 
Experimental birds and design
 
The experiment was laid out in completely randomized design (CRD) with four replications, using pens (each measuring 4.2 m x 1.8 m) as experimental units. The long axis of the poultry house was oriented in an east-to-west direction and naturally ventilated.
       
For this study, 200 number of ‘Cobb 400’ strain broiler chicks were purchased from a private commercial hatchery and reared as experimental birds under standard management practices. All the chicks were weighted using digital electronic balance and raised in a deep litter system of management, with rice husks as the litter material for the entire duration of the experiment under standard management practices. The birds were fed with a pre-starter diet (0-7 days), a starter diet (8-21 days) and finisher diet (22-35 days) as per BIS (2007) guidelines was purchased from the private feed mill. The diets were tested for proximate analysis as per AOAC (2016) guidelines and results are tabulated (Table 1).

Table 1: Nutrient composition of broiler diet.


       
Ambient temperature inside and outside the broiler house was continuously measured, except during the brooding period (0-14 days of age), when standard spot-heating was provided using hover brooders. No thermal mitigation strategies were employed during the experimental period. Broiler chicks were vaccinated against Newcastle disease (LaSota strain) on day 5 and infectious bursal disease (MB/intermediate-plus strain) on day 14 of age.
 
Environmental data
 
Weather parameters of the poultry house were collected by fixing maximum, minimum, wet bulb and dry bulb thermometers inside and outside the poultry house. Data were recorded daily at 7.00, 14.30 and 16.30 hours. Inside the poultry house, the parameters were recorded at three heights viz., at bird’s level, middle of the house and roof level by using standard methods.
 
Physiological data
 
The growth parameters, like feed intake, water intake, body temperature and livability were measured. Feed conversion ratio (FCR), average weight gain and THI were calculated from the observed parameters.
 
Feed intake per bird
 
At weekly intervals average feed intake per bird was measured in grams. The feed intake was calculated by using the following formula.
  
 
  
Water intake per bird
 
The observation on water intake was measured in millilitres per bird on daily basis by using the following formula:
  
  
 
Average weekly weight gain (g)
 
The average weekly weight gain of broiler was calculated by subtracting subsequent week body weight from the previous week body weight in grams. 
 
Feed conversion ratio 
 
The FCR of broiler was calculated by using the following formula.
 
  
 
Livability
 
Livability is an expression used to describe the number of survivors in a flock and was expressed as percentage (per cent). 
 
 
  
Body temperature
 
The body temperature of broilers was measured at 07:30 and 14:30 hours by using cleaned and disinfected clinical thermometer by measuring the cloacal temperature and expressed in °C.
 
Temperature humidity index (THI)
 
(Moraes et al., 2008).
Tdb = Temperature of Dry bulb in oC.
RH= Relative humidity.
 

 
Statistical analysis
 
Data were analysed using IBM SPSS Statistics, with ANOVA used to compare means and variances at P<0.05.

RESULTS AND DISCUSSION

Temperature
 
During the winter season, maximum temperature inside the poultry house ranged between 28.3 to 31.6°C (Fig 1). The difference between the maximum temperature inside the poultry house and the outside condition was about 0.3 to 0.8°C. Whereas the minimum temperature inside the poultry house (24.0 to 25.8°C) was higher by 2.1 to 5.4°C compared with outside minimum air temperature. This increase in minimum temperature was because of the combined effects of structural buffering and continuous metabolic heat accumulation within the house during night time.

Fig 1: Temperature inside and outside poultry house (°C).


       
During the summer season, the maximum temperature inside the poultry house (35.7 to 37.0°C) was higher than that of the ambient maximum temperature (by 0.2 to 1.2°C). Similarly, in winter season, the minimum temperature inside the poultry house (18.8 to 23.7°C) was higher compared with ambient minimum temperature (by 1.9 to 2.5).
       
The diurnal temperature was found to be lower (winter 3.1 to 6.3°C and summer 0.7 to 2.3°C) inside the poultry house when compared outside. The temperature variation inside the poultry house was quite stable, with a daily variation of 9.6°C to 12°C. This suggests effective temperature control inside the broiler house. The daily variation outside was slightly higher, reflecting the more fluctuating and unpredictable nature of outdoor summer temperatures.
       
The higher minimum temperature inside the poultry house during both the seasons might be due to the trapping of the terrestrial radiation by increase in ammonia, CO2, carbon monoxide, nitrous oxide and methane gases inside the poultry house. The reduction in maximum temperature during the summer season inside the house might be because of the tree canopies surrounding the poultry house, acts as a micro climate modifier (Zaerpour et al., 2025). The smoothening of temperature was due to the presence of large green trees surrounding the poultry house (Bounoua  et al., 2000).
 
Relative humidity
 
During winter season, the average relative humidity inside and outside the poultry house was 60.2 and 70.4 per cent, respectively. There was a noticeable drop in humidity inside, as the age of the broilers increases, with the lowest humidity recorded during 4th week of age. Relative humidity outside follows a different trend. The relative humidity outside ranged from 63.4 per cent to 77.4 per cent.
       
During summer season the RH outside the poultry house ranged between 61.1 to 67.1 per cent and the RH inside ranged between 33 to 49 per cent.
       
This shows that during both the seasons, the outside relative humidity (RH) was higher than inside (Table 2). However, the variation was more pronounced in summer than in winter. The lower RH inside the poultry house, compared to outside, might be attributed to bird activity, metabolic heat production and ventilation. This difference was also influenced by the larger difference between maximum and minimum temperatures during summer.

Table 2: Relative humidity during summer and winter season in broiler house.


 
Vertical temperature distribution
 
The temperature was higher by 4.5°C, 6.2°C and 6.3°C at the roof level during morning, afternoon and evening time, respectively during the summer season when compared to the winter season. Similarly, compared to winter season, the temperature at the middle of the house was higher by 3.5°C, 6.4°C and 5.7°C during morning, afternoon and evening time, respectively during the summer season. It could be noticed that the temperature at the bird level was only higher by 2°C, 5.3°C and 5°C, respectively at the morning, afternoon and evening time during the summer season (Fig 2).

Fig 2: Temperature inside the poultry house at different heights and time.


       
Temperature fluctuations were clearly observed between seasons in the broiler poultry house. Roof temperature during both the seasons was lowest during early morning (7:00 am) and highest in the afternoon and evening, indicating rapid heating due to solar radiation and cooling at night. The asbestos roof material contributed to higher heat gain (Akinwemoye et al., 2025), as material properties influence radiation absorption (Fiorelli et al., 2010).
       
A buffering effect was noticed in the middle of the house, where wired mesh ventilation and surrounding vegetation helped reduce temperature by directing and filtering wind flow (Rojano et al., 2016).
       
At ground level, higher temperatures resulted from heat exchange between birds and the surrounding air. Proper airflow minimizes heat build-up and reduces inside-to-outside temperature differentials (Aengwanich, 2017).
 
Feed intake (g) 
 
During winter, the mean feed intake increased from 157.00±1.70 at one week to 1346.00±7.80 at five weeks, whereas during summer it increased from 140.00±1.18 to 1249.00±13.17, respectively (Fig 3).

Fig 3: Feed and water intake during summer and winter seasons.


       
The feed intake was relatively higher in winter season when compared with the summer season by 3 to 16 percentage. The higher reduction in feed intake during first week of growth (11%) indicates the sensitive of the young chicks to the thermal stress.
       
While in the subsequent weeks the comparative reduction in feed intake was lesser (3 to 4%) during summer season, indicating the ability of the birds to partially adapt to the environmental conditions. Analysis of variance revealed a significant effect of season on feed intake (P<0.05). A significant age vs. season interaction was also observed (P<0.05), indicating that the influence of season on feed intake varied with the age of the broilers.
       
The present findings agree with previous reports that heat stress reduces feed intake in layers (Mignon-Grasteau  et al., 2015) and broilers (Liu et al., 2020). Elevated temperatures induce physiological and metabolic adjustments, including increased water consumption and reduced feed intake, as birds attempt to minimize metabolic heat production and maintain thermal balance (Brugaletta et al., 2022).
       
Whereas during winter season, moderate temperature in association with higher relative humidity of 55 to 70 per cent supported better feed intake. Relative humidity acting as a secondary modifying factor, have improve feed intake.
 
Water intake (ml)
 
In contrast to feed intake, the water intake was comparatively higher by 21 to 102 per centage during summer season and seasons had a highly significant effect.
       
The mean relative humidity inside the poultry house was also lesser (38.8%) in addition to elevation in temperature during summer season. The maximum water intake was noted during the week when the temperature inside the poultry house crossed 36°C, irrespective of the relative humidity. 

As the birds’ pant to dissipate heat, water was lost and needs to be replaced in order to maintain body water balance.  As temperature increases, the water consumed per kg of feed consumed also increased (Lawal et al., 2024).
       
The water: feed intake ratio during the experimental period was recorded to be 1.6 to 2.6 during winter season and 2.9 to 3.6 during summer season. Similar results were documented by Orakpoghenor  et al. (2021).
 
Live body weight and weight gain
 
During the winter season the live body weight of the birds was comparatively higher and the mean cumulative body weight increased from 148.10±2.62 g at one week to 2005.00±18.90 g at five weeks. During summer it increased from 135.00±2.23 g to 1868.10±19.81 g, respectively and was found to be statistically significant at P<0.05. There was 6.0 per cent reduction in body weight during summer season against winter season (Table 3).  The difference in body weight between the seasons widened with age and this effect was likely due metabolic heat production.

Table 3: Effect of winter and summer seasons on cumulative body weight of broilers (g).


       
The cumulative body weight was consistently higher during winter than during summer at all ages. Season had a significant effect on cumulative body weight (P<0.05).
       
The lower feed intake and higher water intake during summer has contributed to the reduced body weight. Whereas, favourable environmental conditions during winter season have attributed to efficient feed utilization resulting in higher body weight.
       
The higher temperature during summer season resulted in reduction in feed intake and inturn, the body weight (Aswathi et al., 2019; Teyssier et al., 2022).  Even though, during the summer season the feed as well as water intake were higher; the reason for lesser weight gain might be the loss of energy by the bird for dissipation of excess heat (Ogunlowo et al., 2024). Gogoi et al., 2021 depicted that heat stress depresses the body weight generally by loss of energy for neutralizing high temperature stress.
       
It would also be noted that the relative humidity inside the poultry house was between 40 to 70 percent during the winter season while it was 33 to 49 percent for summer season. 50-70 per cent being the ideal RH for broiler production (Oloyo and Ojerinde, 2019), lower RH leads to dehydration and respiratory problems, which in turn adversely affect the growth performance of the birds.
 
FCR
 
The average FCR was found to be 1.45±0.022 and 1.51±0.022 in winter and summer seasons, respectively. FCR was significantly higher in summer than in winter (except during the first week) (Table 4).

Table 4: Effect of winter and summer season on feed Conversion ratio (FCR) of broilers.


       
High ambient temperature and relative humidity were the major environmental stressors that influence performance of broilers by reducing feed intake, feed efficiency by increasing water intake and finally increasing feed conversion ratio (Nejib El Melki  et al., 2024 and Apalowo  et al., 2024). Similarly, Akyuz (2009) observed similar relationship between FCR and poultry house temperature in winter and summer seasons.
 
Body temperature and THI on livability of broiler
 
The THI was found to be between 73.9 to 78.6 inside and between 73.6 to 77.5 outside the poultry house during the winter season. Whereas, it was 75.1 to 80.4 inside and 77.9 to 81.5 outside the poultry house during summer season. This clearly shows that the birds have experienced mild to moderate stress during winter season and moderate to severe stress during the summer season. The higher THI recorded during summer, particularly outside the poultry house, indicates a greater thermal load on broilers. The comparison of THI inside and outside the poultry house highlights the importance of appropriate housing in moderating the thermal environment, particularly during the summer season.
       
Livability of the birds was found to be 100 per cent with THI of 73.6 to 78.6 inside the poultry house during winter season. However, during summer season, livability of birds was 99, 98, 98, 97 and 97 per cent from first to fifth week of age, respectively where the THI inside the poultry house was 75.1 to 80.4. The mortality of the birds has coincided with the higher THI values indicating that stress might be the factor influencing the mortality (Fig 4).

Fig 4: Effect of THI (inside poultry house and outside poultry house) on livability of broilers.


       
During the afternoon time (at 2.30 pm), the body temperature in winter season was <42°C whereas in summer season it was >42°C, while the optimum body temperature range was reported to be within 40.6-41.7°C (Skomorucha and Sosnówka-Czajka, 2017). Body temperature increased by 1.9°C between 7:00 am and 2:30 pm during summer. At 2:30 pm, body temperature was 1.1°C higher in summer than in winter.
       
When the ambient temperature is higher, the heat lost or dissipated by the birds was lesser than the heat gain or internal heat produced by the birds and hence the body temperature rises (Ruuskanen et al., 2021).

CONCLUSION

This study examined the interaction between broiler birds kept in a poultry house and temperature and RH on the homeostasis of the birds. The optimum feed consumption, higher live body weight, best FCR and 100 per cent livability were observed during winter season. In contrast, summer conditions heat stress and inturn the higher THI, is reflected in reduced feed intake, increased water intake, higher body temperature, elevated FCR, lower weight gain and mortality.

ACKNOWLEDGEMENT

Authors acknowledge the technical support from Department of Science and technology, Ministry of science and technology, GOI (DST/CCP/NMSKCC/CoE/237/2024).
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures for experiments were approved by the Committee of Experimental Animal care and handling techniques were approved by the University of Animal Care.

CONFLICT OF INTEREST

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

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    ABSTRACT

    Background: The weather parameters influence the thermal comfort and productivity of commercial ‘Cobb 400’ broilers.  Hence, this study was conducted to evaluate the effect of seasonal weather on the growth, feed and water intake, FCR, body temperature and livability of broiler chickens.

    Methods: The experiment was conducted for five weeks each during winter and summer on 200 number of broiler chicks. Environmental parameters (temperature and relative humidity) were recorded inside and outside the poultry house and the key physiological responses like feed intake, water intake, FCR and livability of the birds were observed and compared among summer and winter seasons.

    Result: Results revealed winter season (mean maximum temperature of 30.4°C, relative humidity between 40-70 per cent) was found to be optimal for broiler performance, with, higher feed consumption, greater live body weight (2005 g vs. 1868 g), improved feed conversion ratio (1.80 vs. 1.90) and 100 per cent livability. In contrast, summer season (mean maximum 36.6°C and reduced relative humidity 33-49 per cent) increased the Temperature Humidity Index (THI), leading to reduced feed intake, higher water intake, poorer FCR and increased mortality during summer season. This shows winter season to be suitable for broiler growth, ensuring better production efficiency compared to summer season.

    INTRODUCTION

    Among the animal protein industry, broiler chicken production is one of the most rapidly growing sectors. India is the fifth largest producer of broiler producing countries of the world, with monthly over 400 million broiler chicks, contributing about 65.3 per cent to the total poultry industry output (Ghosal, 2020). This growth is attributed to the integration of improved genetic lines, specialized feed, better housing and management practices that have significantly reduced the age of market-ready birds to just 40 days, with an average live body weight of 2 kg (Cicek and Tandogan, 2016).
           
    Despite of all the advancements, attaining the potential production of these homoeothermic birds is highly weather dependent, especially during the post brooding phase. Temperature and Relative Humidity (RH) within the poultry house are the critical parameters that influence the physiological responses, growth and feed efficiency of broilers. At higher temperatures, birds exhibit reduced feed intake, increased water consumption as well as respiratory rates, which can negatively impact growth and feed conversion efficiency (Vandana et al., 2021). High temperatures and low RH increases energy expenditure for thermoregulation, through increased respiration and heat dissipation. Furthermore, the simultaneous occurrence of high temperature and high humidity impairs heat dissipation, worsening the stress response (Krishnan et al., 2023).
           
    Several THIs have been developed to quantify the thermal comfort and heat stress experienced by livestock and poultry by combining environmental variables such as dry-bulb temperature, wet-bulb temperature, relative humidity, air velocity and solar radiation (Moraes et al., 2008; Purswell et al., 2012; Omomowo, 2021; Narmilan et al., 2021; Kumar et al., 2025). The interpretation of THI values generally ranges from conditions of thermal comfort to mild, moderate and severe heat stress, although the specific thresholds vary depending on the index used. In broilers, increasing THI beyond the thermoneutral range is associated with reduced feed intake, impaired weight gain, poorer feed conversion, increased water consumption and, under severe heat stress, increased mortality (Lallo et al., 2018). Thus, THI provides a practical means of linking environmental conditions with physiological and productive responses.
           
    Although there are several studies, there exist limited studies specifically about the seasonal impacts on broiler productivity under standard management conditions in South Indian tropical environments. Hence, the present study aims to assess the seasonal influence on broiler production by evaluating physiological indicators, performance indicators and THI.

    MATERIALS AND METHODS

    The experiment was conducted during the winter (November to December 2023) and summer (March to April 2024) seasons in Tamil Nadu Agricultural University, Coimbatore, TamilNadu. The experimental period lasted for five weeks in each season.
     
    Experimental birds and design
     
    The experiment was laid out in completely randomized design (CRD) with four replications, using pens (each measuring 4.2 m x 1.8 m) as experimental units. The long axis of the poultry house was oriented in an east-to-west direction and naturally ventilated.
           
    For this study, 200 number of ‘Cobb 400’ strain broiler chicks were purchased from a private commercial hatchery and reared as experimental birds under standard management practices. All the chicks were weighted using digital electronic balance and raised in a deep litter system of management, with rice husks as the litter material for the entire duration of the experiment under standard management practices. The birds were fed with a pre-starter diet (0-7 days), a starter diet (8-21 days) and finisher diet (22-35 days) as per BIS (2007) guidelines was purchased from the private feed mill. The diets were tested for proximate analysis as per AOAC (2016) guidelines and results are tabulated (Table 1).

    Table 1: Nutrient composition of broiler diet.


           
    Ambient temperature inside and outside the broiler house was continuously measured, except during the brooding period (0-14 days of age), when standard spot-heating was provided using hover brooders. No thermal mitigation strategies were employed during the experimental period. Broiler chicks were vaccinated against Newcastle disease (LaSota strain) on day 5 and infectious bursal disease (MB/intermediate-plus strain) on day 14 of age.
     
    Environmental data
     
    Weather parameters of the poultry house were collected by fixing maximum, minimum, wet bulb and dry bulb thermometers inside and outside the poultry house. Data were recorded daily at 7.00, 14.30 and 16.30 hours. Inside the poultry house, the parameters were recorded at three heights viz., at bird’s level, middle of the house and roof level by using standard methods.
     
    Physiological data
     
    The growth parameters, like feed intake, water intake, body temperature and livability were measured. Feed conversion ratio (FCR), average weight gain and THI were calculated from the observed parameters.
     
    Feed intake per bird
     
    At weekly intervals average feed intake per bird was measured in grams. The feed intake was calculated by using the following formula.
      
     
      
    Water intake per bird
     
    The observation on water intake was measured in millilitres per bird on daily basis by using the following formula:
      
      
     
    Average weekly weight gain (g)
     
    The average weekly weight gain of broiler was calculated by subtracting subsequent week body weight from the previous week body weight in grams. 
     
    Feed conversion ratio 
     
    The FCR of broiler was calculated by using the following formula.
     
      
     
    Livability
     
    Livability is an expression used to describe the number of survivors in a flock and was expressed as percentage (per cent). 
     
     
      
    Body temperature
     
    The body temperature of broilers was measured at 07:30 and 14:30 hours by using cleaned and disinfected clinical thermometer by measuring the cloacal temperature and expressed in °C.
     
    Temperature humidity index (THI)
     
    (Moraes et al., 2008).
    Tdb = Temperature of Dry bulb in oC.
    RH= Relative humidity.
     

     
    Statistical analysis
     
    Data were analysed using IBM SPSS Statistics, with ANOVA used to compare means and variances at P<0.05.

    RESULTS AND DISCUSSION

    Temperature
     
    During the winter season, maximum temperature inside the poultry house ranged between 28.3 to 31.6°C (Fig 1). The difference between the maximum temperature inside the poultry house and the outside condition was about 0.3 to 0.8°C. Whereas the minimum temperature inside the poultry house (24.0 to 25.8°C) was higher by 2.1 to 5.4°C compared with outside minimum air temperature. This increase in minimum temperature was because of the combined effects of structural buffering and continuous metabolic heat accumulation within the house during night time.

    Fig 1: Temperature inside and outside poultry house (°C).


           
    During the summer season, the maximum temperature inside the poultry house (35.7 to 37.0°C) was higher than that of the ambient maximum temperature (by 0.2 to 1.2°C). Similarly, in winter season, the minimum temperature inside the poultry house (18.8 to 23.7°C) was higher compared with ambient minimum temperature (by 1.9 to 2.5).
           
    The diurnal temperature was found to be lower (winter 3.1 to 6.3°C and summer 0.7 to 2.3°C) inside the poultry house when compared outside. The temperature variation inside the poultry house was quite stable, with a daily variation of 9.6°C to 12°C. This suggests effective temperature control inside the broiler house. The daily variation outside was slightly higher, reflecting the more fluctuating and unpredictable nature of outdoor summer temperatures.
           
    The higher minimum temperature inside the poultry house during both the seasons might be due to the trapping of the terrestrial radiation by increase in ammonia, CO2, carbon monoxide, nitrous oxide and methane gases inside the poultry house. The reduction in maximum temperature during the summer season inside the house might be because of the tree canopies surrounding the poultry house, acts as a micro climate modifier (Zaerpour et al., 2025). The smoothening of temperature was due to the presence of large green trees surrounding the poultry house (Bounoua  et al., 2000).
     
    Relative humidity
     
    During winter season, the average relative humidity inside and outside the poultry house was 60.2 and 70.4 per cent, respectively. There was a noticeable drop in humidity inside, as the age of the broilers increases, with the lowest humidity recorded during 4th week of age. Relative humidity outside follows a different trend. The relative humidity outside ranged from 63.4 per cent to 77.4 per cent.
           
    During summer season the RH outside the poultry house ranged between 61.1 to 67.1 per cent and the RH inside ranged between 33 to 49 per cent.
           
    This shows that during both the seasons, the outside relative humidity (RH) was higher than inside (Table 2). However, the variation was more pronounced in summer than in winter. The lower RH inside the poultry house, compared to outside, might be attributed to bird activity, metabolic heat production and ventilation. This difference was also influenced by the larger difference between maximum and minimum temperatures during summer.

    Table 2: Relative humidity during summer and winter season in broiler house.


     
    Vertical temperature distribution
     
    The temperature was higher by 4.5°C, 6.2°C and 6.3°C at the roof level during morning, afternoon and evening time, respectively during the summer season when compared to the winter season. Similarly, compared to winter season, the temperature at the middle of the house was higher by 3.5°C, 6.4°C and 5.7°C during morning, afternoon and evening time, respectively during the summer season. It could be noticed that the temperature at the bird level was only higher by 2°C, 5.3°C and 5°C, respectively at the morning, afternoon and evening time during the summer season (Fig 2).

    Fig 2: Temperature inside the poultry house at different heights and time.


           
    Temperature fluctuations were clearly observed between seasons in the broiler poultry house. Roof temperature during both the seasons was lowest during early morning (7:00 am) and highest in the afternoon and evening, indicating rapid heating due to solar radiation and cooling at night. The asbestos roof material contributed to higher heat gain (Akinwemoye et al., 2025), as material properties influence radiation absorption (Fiorelli et al., 2010).
           
    A buffering effect was noticed in the middle of the house, where wired mesh ventilation and surrounding vegetation helped reduce temperature by directing and filtering wind flow (Rojano et al., 2016).
           
    At ground level, higher temperatures resulted from heat exchange between birds and the surrounding air. Proper airflow minimizes heat build-up and reduces inside-to-outside temperature differentials (Aengwanich, 2017).
     
    Feed intake (g) 
     
    During winter, the mean feed intake increased from 157.00±1.70 at one week to 1346.00±7.80 at five weeks, whereas during summer it increased from 140.00±1.18 to 1249.00±13.17, respectively (Fig 3).

    Fig 3: Feed and water intake during summer and winter seasons.


           
    The feed intake was relatively higher in winter season when compared with the summer season by 3 to 16 percentage. The higher reduction in feed intake during first week of growth (11%) indicates the sensitive of the young chicks to the thermal stress.
           
    While in the subsequent weeks the comparative reduction in feed intake was lesser (3 to 4%) during summer season, indicating the ability of the birds to partially adapt to the environmental conditions. Analysis of variance revealed a significant effect of season on feed intake (P<0.05). A significant age vs. season interaction was also observed (P<0.05), indicating that the influence of season on feed intake varied with the age of the broilers.
           
    The present findings agree with previous reports that heat stress reduces feed intake in layers (Mignon-Grasteau  et al., 2015) and broilers (Liu et al., 2020). Elevated temperatures induce physiological and metabolic adjustments, including increased water consumption and reduced feed intake, as birds attempt to minimize metabolic heat production and maintain thermal balance (Brugaletta et al., 2022).
           
    Whereas during winter season, moderate temperature in association with higher relative humidity of 55 to 70 per cent supported better feed intake. Relative humidity acting as a secondary modifying factor, have improve feed intake.
     
    Water intake (ml)
     
    In contrast to feed intake, the water intake was comparatively higher by 21 to 102 per centage during summer season and seasons had a highly significant effect.
           
    The mean relative humidity inside the poultry house was also lesser (38.8%) in addition to elevation in temperature during summer season. The maximum water intake was noted during the week when the temperature inside the poultry house crossed 36°C, irrespective of the relative humidity. 

    As the birds’ pant to dissipate heat, water was lost and needs to be replaced in order to maintain body water balance.  As temperature increases, the water consumed per kg of feed consumed also increased (Lawal et al., 2024).
           
    The water: feed intake ratio during the experimental period was recorded to be 1.6 to 2.6 during winter season and 2.9 to 3.6 during summer season. Similar results were documented by Orakpoghenor  et al. (2021).
     
    Live body weight and weight gain
     
    During the winter season the live body weight of the birds was comparatively higher and the mean cumulative body weight increased from 148.10±2.62 g at one week to 2005.00±18.90 g at five weeks. During summer it increased from 135.00±2.23 g to 1868.10±19.81 g, respectively and was found to be statistically significant at P<0.05. There was 6.0 per cent reduction in body weight during summer season against winter season (Table 3).  The difference in body weight between the seasons widened with age and this effect was likely due metabolic heat production.

    Table 3: Effect of winter and summer seasons on cumulative body weight of broilers (g).


           
    The cumulative body weight was consistently higher during winter than during summer at all ages. Season had a significant effect on cumulative body weight (P<0.05).
           
    The lower feed intake and higher water intake during summer has contributed to the reduced body weight. Whereas, favourable environmental conditions during winter season have attributed to efficient feed utilization resulting in higher body weight.
           
    The higher temperature during summer season resulted in reduction in feed intake and inturn, the body weight (Aswathi et al., 2019; Teyssier et al., 2022).  Even though, during the summer season the feed as well as water intake were higher; the reason for lesser weight gain might be the loss of energy by the bird for dissipation of excess heat (Ogunlowo et al., 2024). Gogoi et al., 2021 depicted that heat stress depresses the body weight generally by loss of energy for neutralizing high temperature stress.
           
    It would also be noted that the relative humidity inside the poultry house was between 40 to 70 percent during the winter season while it was 33 to 49 percent for summer season. 50-70 per cent being the ideal RH for broiler production (Oloyo and Ojerinde, 2019), lower RH leads to dehydration and respiratory problems, which in turn adversely affect the growth performance of the birds.
     
    FCR
     
    The average FCR was found to be 1.45±0.022 and 1.51±0.022 in winter and summer seasons, respectively. FCR was significantly higher in summer than in winter (except during the first week) (Table 4).

    Table 4: Effect of winter and summer season on feed Conversion ratio (FCR) of broilers.


           
    High ambient temperature and relative humidity were the major environmental stressors that influence performance of broilers by reducing feed intake, feed efficiency by increasing water intake and finally increasing feed conversion ratio (Nejib El Melki  et al., 2024 and Apalowo  et al., 2024). Similarly, Akyuz (2009) observed similar relationship between FCR and poultry house temperature in winter and summer seasons.
     
    Body temperature and THI on livability of broiler
     
    The THI was found to be between 73.9 to 78.6 inside and between 73.6 to 77.5 outside the poultry house during the winter season. Whereas, it was 75.1 to 80.4 inside and 77.9 to 81.5 outside the poultry house during summer season. This clearly shows that the birds have experienced mild to moderate stress during winter season and moderate to severe stress during the summer season. The higher THI recorded during summer, particularly outside the poultry house, indicates a greater thermal load on broilers. The comparison of THI inside and outside the poultry house highlights the importance of appropriate housing in moderating the thermal environment, particularly during the summer season.
           
    Livability of the birds was found to be 100 per cent with THI of 73.6 to 78.6 inside the poultry house during winter season. However, during summer season, livability of birds was 99, 98, 98, 97 and 97 per cent from first to fifth week of age, respectively where the THI inside the poultry house was 75.1 to 80.4. The mortality of the birds has coincided with the higher THI values indicating that stress might be the factor influencing the mortality (Fig 4).

    Fig 4: Effect of THI (inside poultry house and outside poultry house) on livability of broilers.


           
    During the afternoon time (at 2.30 pm), the body temperature in winter season was <42°C whereas in summer season it was >42°C, while the optimum body temperature range was reported to be within 40.6-41.7°C (Skomorucha and Sosnówka-Czajka, 2017). Body temperature increased by 1.9°C between 7:00 am and 2:30 pm during summer. At 2:30 pm, body temperature was 1.1°C higher in summer than in winter.
           
    When the ambient temperature is higher, the heat lost or dissipated by the birds was lesser than the heat gain or internal heat produced by the birds and hence the body temperature rises (Ruuskanen et al., 2021).

    CONCLUSION

    This study examined the interaction between broiler birds kept in a poultry house and temperature and RH on the homeostasis of the birds. The optimum feed consumption, higher live body weight, best FCR and 100 per cent livability were observed during winter season. In contrast, summer conditions heat stress and inturn the higher THI, is reflected in reduced feed intake, increased water intake, higher body temperature, elevated FCR, lower weight gain and mortality.

    ACKNOWLEDGEMENT

    Authors acknowledge the technical support from Department of Science and technology, Ministry of science and technology, GOI (DST/CCP/NMSKCC/CoE/237/2024).
     
    Disclaimers
     
    The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
     
    Informed consent
     
    All animal procedures for experiments were approved by the Committee of Experimental Animal care and handling techniques were approved by the University of Animal Care.

    CONFLICT OF INTEREST

    The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

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