Research PaperA new ventilation system to reduce temperature fluctuations in laying hen housing in continental climate
Introduction
Modern confined laying hen houses in continental climates are typically equipped with tunnel ventilation and wet-pad evaporative cooling (TV) system. In summer, the most common ventilation practice is to run the TV system, in which cooling pads are installed on the gable wall or/and both sidewalls in one end of the building, while fans are installed in the other end (Hui et al., 2016). However, several studies have been carried out and concluded that laying hen houses equipped with TV systems have the drawbacks of cold or heat stress, large diurnal temperature variations and non-uniform airflow distribution under continental climate conditions (Cao et al., 2014, Olgun et al., 2007, Ruzal et al., 2011). Temperature is commonly assumed to be the most important environmental factor influencing poultry health, behaviour and production (Webster & Czarick, 2000), also the feed intake of hens which could affect egg size (Wang, Zheng, Qin, & Li, 2018). Continental climates are characterised by large temperature differences between daytime and night time, large differences between wet and dry bulb temperatures and hot and dry weather in the summer (Olgun et al., 2007). During the daytime in continental climates, the TV system helps to lower the indoor temperature to the required set-point but can cause big temperature variations and non-uniformity of air distribution in the poultry houses, resulting in cold stress for the birds near the pads or heat stress for the birds near the fans (Cao et al., 2014, Webster and Czarick, 2000). During the night, the baffle inlets in side walls are operated instead of the cooling pads to minimise the temperature gradation.
The TV system could cause a great range of amplitude variations in air temperature and humidity between the two ends of poultry houses in continental climates. In one study, when the indoor temperature reached the required set-point in day time, the ventilation rate would greatly decrease or the water pump would be shut off, which caused a considerable air temperature variation between the two ends of the poultry house (Teitel et al., 2008). When the outdoor air temperature fell rapidly at night time, the ventilation rate was dramatically reduced, which could also cause big temperature differences between the inlet and exhaust ends of the poultry houses. Evidentially, the layer hens in such a TV system could suffer from cold-stress near the cooling pads and heat-stress near the fans.
Large temperature variations and non-uniform air distribution usually negatively affect the birds' health and their production performance, resulting in different levels of feed intake, feed consumption, layer mass, and egg mass which are not acceptable on the market (Abbas et al., 2011, Czarick and Lacy, 1993, Dawkins et al., 2004, Kocaman et al., 2006, Webster and Czarick, 2000, Yahav et al., 2000). In extreme conditions, large temperature variations may also lead to excessive mortality of layers, consequently, reducing the farmer's profits (Feizil et al., 2012, İsmail and Kamanlı, 2015). Abbas et al. (2011) carried out experiments to observe the effects of fluctuating ambient temperature and humidity on the performance of layers, and revealed that birds located at the center of the house, where the temperature ranged 14–28 °C and relative humidity 22%–90%, exhibited better performance than in the other two locations, where temperature ranges were 18–30 °C and 20–32 °C, respectively, and relative humidity of 30%–80% and 34%–84%, respectively. As conclusion, the large fluctuations of air temperature inside the confined poultry houses would affect the performance of laying hens. Heat stress has negative effects on feed consumption, feed efficiency and egg production of layers (Kocaman et al., 2006). Hens consume more feed to maintain their body heat when they suffered cold stress (Wang, Zheng, Shi, & Li, 2018). Webster and Czarick (2000) reported that excessive variations of temperature in different places within the closed layers house would lead to marked variation in feed consumption, and layers would consume lesser or greater amounts of nutrients than required, and resulting in large variations in egg sizes. Also, the great fluctuations temperature during cold weather may lead to poor feed conversion ratio and to health problems (Czarick & Lacy, 1993). The uniformity of hygro–thermal parameters was one of the key factors affecting poultry health and increasing the bird mortality (Webster & Czarick, 2000).
Numerous studies about alternative cooling methods of laying hens had been conducted to mitigate heat stress, such as use of intermittent partial surface sprinkling, misting or fogging (Chepete & Xin, 2000). Intermittent partial surface sprinkling had the following merits: lower body temperature rise, higher lethal heat load threshold, longer survival time, and reduced mortality (Ikeguchi, 2001). But Timmons, Baughman, and Murray (1983) suggested that misting systems should be designed to promote the wetting of the bird occupied zones instead of attempting to mist the air of the entire house. The use of misting and sprinkling systems has the problem of wet litter, equipment, and feed. Therefore, an ideal ventilation system is desired for the continental climate to mitigate the large air temperature variations and provide an uniform indoor environment for laying hens.
The objectives of this study were to design a new ventilation (NV) system based on the limited sticking jet principle (Kostel, 1995) and to evaluate its effects on reducing heat stress, mitigating the air temperature differences of laying hen houses during the summer of a continental climate.
Section snippets
Design of the new ventilation system
A better ventilation control method is required to ensure a more comfortable and uniform thermal environment. The environment control provided by the ventilation system should be determined by the ambient environment desired for poultry health. Kocaman et al. (2006) reported poultry had better egg production and feed conversion ratios under suitable environmental conditions and gave recommended temperature and relative humidity values of 18–28 °C and 60%–70% for cage layer houses. Effective
Experimental poultry houses
Two adjacent commercial layer houses (A and B) separated by a distance of 20 m from each other and located at Fukang city, Xinjiang, Northwest of China were used for the experiment. The house (Fig. 2) orientated in a North-South direction. The two poultry houses were each 96 × 11.5 m (length × width), with a side-wall height of 3 m and maximum distance from the floor to the roof of 4.35 m. Each house contained four rows of cages with three stair-step tiers. At the beginning of the experiments,
Outdoor air temperature and relative humidity
Figure 4 shows the variation of outdoor air temperature and relative humidity for 34 consecutive days (from 11th August, 2016 to 13th September, 2016). It appears that the outdoor air temperature and relative humidity varies between 28.7 and 37.8 °C, 40.4% and 51.5%, respectively. Figure 5 presents variations of the outdoor air temperature and relative humidity on the selected extreme condition day (24th August, 2016). The air temperature and relative humidity ranged from 20.8 to 41.2 °C and
Conclusion
In this study carried out over one summer month in a zone with a continental climate, characterised by hot dry summers and sudden temperature changes between day time and night time, the NV system was much more effective than the TV system. It could provide uniform cooling air distribution and mitigate the large air temperature variations compared to the TV system. In this study, the air temperature variations in the NV system were reduced compared to the TV system, and the maximum fluctuation
Acknowledgments
The authors would like to thank Prof Brian He of the University of Idaho for providing a useful revision of the article. The Staff of the laying hen farm are appreciated for their assistance with data collection. The author would also like to thank Fu Kang Yuan Poultry Co. Ltd., Urumqi, Xinjiang, China. The funding of this work was supported by the National Key R&D Program of China (2018YFD0500700) and the China Agricultural Research System (CARS-40).
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2021, Thermal Science and Engineering ProgressCitation Excerpt :Petek, Dikmen [35] reported that with a cooling system designed in two stages, a temperature decrease of 5.6 °C could be achieved in Bursa climate conditions. Wang, Zheng [36] reported that the ambient temperature varied between 26.7 and 33.4 °C in a house cooled by conventional FPES where the outdoor temperature was 20.8–41.2 °C and the relative humidity was 18.2–57.7%. Kaydar and Yıldız [37] stated in their study on the cooling of a broiler house with the fan-pad system in the Çukurova Region that when the air flow rate from the pad was 1.41 m s−1, the cooling efficiency was 71.25%, the temperature decrease was 4.99 °C and the saturation level was 85.95%.
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