Heterophil to lymphocyte ratio and tonic immobility reactions to preslaughter handling in broiler chickens treated with ascorbic acid

Stress and fear responses were evaluated in broiler chicks that were pretre ated for 24 h with 0 ppm (control) or 1,200 ppm of L-ascorbic acid (AA) in their drinking water. The birds were subsequently subjected to either uprig ht handling (UH) or inverted (IH) handling for about 45 s. Heterophil (H) c ounts, lymphocyte (L) counts, and H/L ratios (H/L) ratios were determined i mmediately (T-0) and at 20 h (T-20) following the handling treatment. The H /L ratios were similar for both groups at T-0, whereas 20 h after the handl ing treatment, AA-supplemented birds had lower ratios than controls, result ing in a significant water treatment x time of blood sampling interaction. Inverted handling had negligible effect on H/L ratios but augmented tonic i mmobility (TI) durations as compared with UH. Irrespective of handing proce dure, supplemental AA reduced underlying fearfulness, as measured by TI rea ction. Neither water treatment nor handling method had significant effect o n number of attempts to induce TI.