|HU, JIAYING - Purdue University|
|HESTER, PATRICIA - Purdue University|
|MAKAGON, MAJA - Purdue University|
|VEZZOLI, GIUSEPPE - Purdue University|
|GATES, RICHARD - University Of Illinois|
|XIONG, YIJIE - University Of Illinois|
|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2016
Publication Date: 8/2/2016
Citation: Hu, J., Hester, P.Y., Makagon, M.M., Vezzoli, G., Gates, R.S., Xiong, Y., Cheng, H. 2016. Cooled perch effects on performance and well-being traits in caged White Leghorn hens. Poultry Science. doi: 10.3382/ps/pew248.
Interpretive Summary: Heat stress is one of the most important environmental stressors facing the poultry industry. Various means of providing supplemental cooling to hens in facilities are available, including evaporative cooling from either pads, misting or fogging systems. Evaporative cooling efficiency can be seriously compromised by the challenge of providing cooled air to the hens when in cages and by the development of an axial building temperature gradient as heat loss by hens raises the air temperature. In addition, fogging and misting nozzles can generate too much moisture; and water can drip leading to wet manure with increased ammonia production and fly populations. Provision of perches, as an environmental enrichment for laying hens, has positive effects on skeletal health. The objective of this study was to determine if the provision of a thermally cooled perch improves hen performance and well-being traits during hot summer months. During acute heat stress, the onset of panting and wing spread was delayed for cooled perch hens, they perched more than perch hens and drank more than control hens. However, there were no treatment effects on the measured physiological and on production traits with the exception of nail length which was shorter for cooled perch hens than control hens but not air perch hens. These results indicated that the thermally cooled perch system used in this study effectively reduced hens’ thermoregulatory behaviors during acute heat stress, but did not affect their performance and physiological parameters. It may be that the natural ambient temperature of the 2013 summer in Indiana was not severe enough to evoke significant physical and physiological changes. Further studies are needed to evaluate the effectiveness of thermally cooled perches on hen health under higher ambient temperatures. These results can be used by the laying hen industries and scientists to develop management guidelines for improving laying hen welfare under hot weather.
Technical Abstract: We assessed the effects of chilled water cooling perches on hen performance, feather condition, foot health, and physiological and behavioral parameters during the 2013 summer with a 4-h acute heating episode. White Leghorn pullets at 16 wk of age were randomly assigned to 18 cages arranged into 3 banks. Each bank was assigned to 1 of the 3 treatments through 32 wk of age: 1) cooled perches, 2) perches, and 3) no perches. Chilled water (10° C) was circulated through the cooled perch loops when cage ambient temperature exceeded 25° C. At the age of 27.6 wk, hens were subjected to a 4-h acute heating episode of 33.3o C and plasma corticosterone was determined immediately after. Egg production was recorded daily. Feed intake, egg and shell quality were measured at 5 wk intervals. Feather condition, foot health, adrenal and liver weights, plasma corticosterone, and heat shock protein 70 mRNA were determined at 32 wk of age. The proportion of hens per cage perching, feeding, drinking, panting, and wing spreading was evaluated over 1 day every 5 wks and on the day of acute heat stress. There were no treatment effects on the measured physiological and production traits with the exception of nail length which was shorter for cooled perch hens than control hens (P = 0.002) but not perch hens. Panting and wing spread were only observed on the day of acute heat stress. The onset of both behaviors was delayed for cooled perch hens; and they perched more than perch hens following acute heat stress (P = 0.001) and at the age 21.4 wk (P = 0.023). Cooled perch hens drank less than control hens (P = 0.019) but not perch hens at the age 21.4 wk. These results indicate that thermally cooled perches reduced hens’ thermoregulatory behaviors during acute heat stress, but did not affect their performance and physiological parameters under the ambient temperature imposed during this study.