SAFEGUARDING WELL-BEING OF FOOD PRODUCING ANIMALS
Location: Livestock Behavior Research
Title: Changes in the Heat Stress Response of Laying Hens Following Antioxidant Supplementation
Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: March 30, 2011
Publication Date: July 16, 2011
Citation: Felver-Gant, J.N., Eicher, S.D., Cheng, H. 2011. Changes in the Heat Stress Response of Laying Hens Following Antioxidant Supplementation. Poultry Science. (E-suppl.1)90:33.
Heat stress (HS) is a major contributor to mortality and other welfare issues in the poultry industry. The objective of this study was to determine the benefits of an antioxidant supplement during HS. One hundred and twenty White Leghorns at 32 wk of age were randomly transferred to two adjacent rooms. Hens were randomly pair-housed and assigned to a control feed (CF) or a feed including an antioxidant blend (ethoxyquin, propyl gallate, and propylene glycol; Agrado Ultra®) at 160 ppm (AF) and then raised for two wks at a control climate (C) (24°C, 15.6 % RH). Afterward, one room was subjected to a HS climate (H) (33°C, 23.7% RH) for 8 d. Physiological data were taken from 40 hens on d 1 and 8 respectively; and feed intake data were taken on d 1, 3, 6, and 8. Data were analyzed using a Proc Mixed model and slice adjustment. Compared to their controls, H-hens had higher core body temperatures (p < 0.01) on both d 1 and 8. Compared to their controls, H-CF hens but not H-AF hens had reduced liver wt on d 1 (p < 0.05; p > 0.05, respectively); and on d 8, liver wt was reduced in both H-CF and H-AF hens (p < 0.05). However, on d 8, H-AF hens liver wt was greater than the liver wt of H-CF hens (p < 0.05). The ratio of ileum weight and length was reduced in both H-CF and H-AF hens compared to their controls (p < 0.05) on d 1; while H-CF hens tended to be different on d 8 (p = 0.08). H-CF hens ate less than C-CF hens during d 1, 3, 6, and 8 (p < 0.01) while H-AF hens ate less than controls during d 3 and 6 only (p <0.01). Partial pressure CO2 (pCO2), HCO3¯, and total CO2 of cardiac blood of H-CF hens was lower than C-CF hens (p < 0.05) on d 8. However, only p CO2 was decreased in H-AF hens compared to controls (p < 0.05). Low pCO2, HCO3¯, and total CO2 are indicative of respiratory alkalosis or metabolic acidosis that can onset under HS through excess hyperventilation. These data suggest that hens exhibit a negative response under HS. Evidence is provided that hens fed AF have an improved coping capability to HS.