## 4 Results and Discussion
Moreover, there remains a widening gap between the values of sensible and latent heat production per bird. Once this gap gets shrieked under any abnormal condition of ambient temperature, there comes an end to the welfare of poultry birds. Figure 12 represents the variations in heat production against the weight of poultry birds at different temperatures. Figure 12a shows an increase in total HP by poultry birds since they gain weight at 18 \({}^{\circ}\)C. At an early stage, sensible HP increases comparatively higher than that of latent HP. This trend continues to grow. It is seen that, at 3 kg weight of poultry bird, sensible HP (i.e., 14.8 W/kg) is roughly double the value of latent HP (i.e., 7.5 W/kg). Similarly, Figure 12b-d shows the trend of total HP by poultry birds of different live weights at 30 \({}^{\circ}\)C, 40 \({}^{\circ}\)C, and 45 \({}^{\circ}\)C, respectively. Sensible (13.7 W/kg) and latent (7.7 W/kg) HP is observed at 30 \({}^{\circ}\)C. Sensible and latent HP of 6.9 W/kg and 8.1 W/kg as well as 3.4 W/kg and 4.5 W/kg at 40 \({}^{\circ}\)C and 45 \({}^{\circ}\)C, respectively. Additionally, Figure 12d indicates a higher latent HP compared to sensible HP indicating that the bird is suffocating due to an increase in the humidity ratio in the surrounding air. Moreover, at 40 \({}^{\circ}\)C, the difference between sensible and latent HP is at the lowest, which indicates that the bird is about to expire due to heat stress and suffocation. With increasing THI, poultry birds start losing their strength to fight against heat stress. Impact of \(T_{db}\) and \(T_{wb}\) on _THI_ is further explored in Appendix A, as given by Figure A1. Figure 13 shows yearly THI analysis of ambient air under DEC, IEC, and MEC systems. Permissible limit of THI denotes 30 \({}^{\circ}\)C \(T_{db}\) and 50% RH. THI of ambient air from November to March (winter) is within the permissible limit, which indicates no need of AC for poultry birds. Figure 14 shows a psychometric representation of performance variation of EC systems from April to October for the climatic conditions of Multan against thermal comfort zones of poultry birds of different ages. Figure 11: The numerical values of THI corresponding to various temperature and relative humidity levels. The green color presents relatively better THI whereas a red color reflects the worst scenario of THI. The detailed psychometric representation of the EC systems performance for the months of April to October is provided in Appendix A, as given by Figure A2a-g, respectively. Results indicate that MEC, DEC, and IEC systems somewhat achieve required thermal comfort conditions of different ages of the poultry for some of the months (April to October). Moreover, applicability of the EC systems for poultry AC and ventilation from the viewpoint of THI is summarized in Table 1.  
Figure 12: The sensible and latent heat production per poultry bird for (**a**) 18 \({}^{\circ}\)C, (**b**) 30 \({}^{\circ}\)C, (**c**) 40 \({}^{\circ}\)C, and (**d**) 45 \({}^{\circ}\)C.  
Figure 6.0 Annual profile of THI resulting from the EC systems for climatic conditions of Multan. The red dotted line shows the optimum level of THI i.e., 30.