Model of physiological stress in chickens 5. Quantitative evaluation.

Physiological stress was studied in broilers using a new model employing continuous release of adrenocorticotropin (ACTH). A total of 42 adaptive response parameters were evaluated. A treatment response ratio, P-value transformation, and stress score were determined for each parameter. The treatment response ratio was calculated by dividing the maximum response of the ACTH-treated birds for each parameter by the average response of control (CON) birds in all cases in which maximum response of ACTH-treated birds exceeded the average response of CON. This treatment response ratio is designated hereafter as ACTH/CON ratio. In those cases in which average response of CON exceeded maximum response of ACTH-treated birds, the reciprocal equation was employed (i.e., CON/ACTH ratio). Probability value transformations were determined by transforming P-values as follows: NS P-values or those exhibiting significance at values less than probability of 5% were expressed as P<0.05 = 1, P-values exhibiting significance between 0.05 and 0.02 were expressed as P at 0.05 to 0.02 = 2, and P-values exhibiting significance at probabilities of 1% or less were P<0.01 = 4. Each stress score was calculated as treatment response ratio times P-value transformation. The 42 response parameters were assigned to one of four adaptive categories, and these were morphologic, endocrine, and blood metabolites; digestion and metabolism; and reticuloendothelial responses. The endocrine and blood metabolites category had the highest average of the four stress response categories, and five of the top ten parameters were found in this category.