Location: Livestock Behavior ResearchTitle: Effect of cooled perches on physiological parameters of caged White Leghorn hens exposed to cyclic heat
|HU, JIAYING - Purdue University|
|HESTER, PATRICIA - Purdue University|
|MAKAGON, MAJA - University Of California, Davis|
|XIONG, YIJIE - University Of Illinois|
|GATES, RICHARD - University Of Illinois|
|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2019
Publication Date: 12/11/2019
Citation: Hu, J., Hester, P., Makagon, M.M., Xiong, Y., Gates, R., Cheng, H. 2019. Effect of cooled perches on physiological parameters of caged White Leghorn hens exposed to cyclic heat. Poultry Science. https://doi.org/10.3382/ps/pez012.
Interpretive Summary: Extreme temperature with heat waves occurs moore often with climate change and global warming, which is one of the most detrimental problems facing the commercial egg industry during hot summers. Each of the cooling methods currently applied in the egg industry has certain disadvantages. The objective of this study was to evaluate the physiological responses of laying hens given access to cooling perches during cyclic heating episodes (at 35 °C). In this study, the installation of the cooled perches ameliorated the negative response of hens to elevated environmental temperature as indicated by reduced rectal temperature, increased metabolism and lower stress response. These results indicate that the cooled perch device could be an alternative cooling method for caged laying hens to ameliorate the deleterious effects of high ambient temperature, thus improving hen health and welfare during hot weather.
Technical Abstract: We assessed the effects of water-chilled perches as a cooling device on the physiological parameters of caged laying hens exposed to 2 cyclic heating episodes. White Leghorns, 17 wk of age, were randomly assigned to 36 cages of 6 banks. Each bank was randomly assigned to 1 of 3 treatments: cooled perch (CP), air perch (AP), and no perch (CTRL) resulting in 2 replicate banks and 12 cages per treatment. Chilled water (10 °C ) circulated through the CP during heat periods when hens were 21 to 35 and 73 to 80 wk of age, respectively. During the heating episodes, hens were submitted to a daily cyclic temperature regimen of 35 °C (0600 to 1800 h) and 28 °C (1800 to 0600 h). Rectal temperature, packed cell volume (PCV), heterophil to lymphocyte (H/L) ratio, and plasma levels of triiodothyronine (T3), thyroxine (T4), interleukin (IL)-6, IL-10, immunoglobulin (Ig) Y, interferon (IFN)-gamma and heat shock protein (HSP) 70 were measured on the last day of the 2 heating episodes. At the end of the 1st heating episode, CP hens had lower rectal temperature (P = 0.02) than both AP and CTRL hens. The CP hens also had lower HSP 70 (P = 0.04) than CTRL hens but not AP hens. At the end of the 2nd heating episode, the CP hens had lower rectal temperature (P = 0.02) and circulating H/L ratio (P = 0.01) than both AP and CTRL hens. The CP hens also had higher levels of T3 (P = 0.002) and T3/T4 ratio (P = 0.0006) than CTRL hens but not AP hens, with a greater PCV than AP hens (P = 0.02) but not CTRL hens. Cytokines and IgY levels were similar among treatments. These results indicate that CP hens were able to cope with cyclic heat stress better than CTRL and sometimes AP hens as noted by the beneficial effects on rectal temperature, thyroid activity, HSP, and H/L ratio.