ARS | Publication request: Effects of chronic and repeated repeated coritcosterone administration in rearing chickens on physiology, the onset of lay and egg production in hens.

Submitted to: Physiology and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 16, 2009
Publication Date: August 4, 2009
Citation: Shaniko, S., Agim, S., Huff, G.R., Kaiser, P. 2009. Effects of chronic and repeated coritcosterone administration in rearing chickens on physiology, the onset of lay and egg production in hens. Physiology and Behavior. 98(1-2):73-77.

Interpretive Summary: A stress hormone, corticosterone (CORT), was used to study the effects of repeated stress during the rearing phase on physiology and performance of hens in the subsequent laying period. Two hundred and seventy Hy-line laying birds were reared in environmentally controlled battery cages. At 7, 11, and 15 wk of age birds were exposed for 1 wk to the following treatments in drinking water: CORT dissolved in ethanol, ethanol, or untreated water. One wk following each treatment, and at 35 wks of age a number of physiological tests were conducted. Body weight was measured throughout the study, and egg production was recorded daily throughout the laying period. The levels of CORT and the ratio of immune cells in blood that are know to change during stress (H/L ratio) were increased after each CORT delivery, showing the effectiveness of the treatment. When CORT delivery was interrupted, plasma CORT and H/L ratio were significantly reduced. Exposing birds to repeated and long-term CORT treatment significantly affected body weight and relative organ weights. CORT delivery also resulted in increased blood levels of glucose , cholesterol , and triglyceride. Administration of CORT during the rearing phase delayed the laying cycle and decreased egg production at 35 wks of age. These results demonstrate that oral CORT treatment affects hen physiology, reduces performance, and may model the effects of production stressors.

Technical Abstract: A corticosterone (CORT) model was used to study the effects of repeated stress during rearing phase on physiology and performance of hens’ in subsequent laying period. Two hundred and seventy Hy-line laying birds were reared in environmentally controlled battery cages. At 7, 11, and 15 wk of age birds were exposed for 1 wk to the following treatments in drinking water: CORT dissolved in ethanol, ethanol, or untreated water. One wk following each treatment, and at 35 wks of age endocrine, metabolic and haematological tests were conducted. Body weight was measured throughout the study, and egg production was recorded daily throughout the laying period. Plasma CORT levels and heterophil to lymphocyte (H/L) ratio were increased after each CORT delivery, showing the effectiveness of the treatment. When CORT delivery was interrupted, plasma CORT and H/L ratio were significantly reduced. Exposing birds to repeated and long-term CORT treatment significantly affected BW (P<0.01), and relative organ weights (P<0.01). CORT delivery also resulted in increased blood levels of glucose (GLU), cholesterol (CHOL), and triglyceride (TRG). Administration of CORT during the rearing phase delayed the laying cycle and decreased egg production at 35 wks of age. These results demonstrate that oral CORT treatment affects hen physiology, reduces performance, and may model the effects of production stressors.