An examination of the utility of heterophil-lymphocyte ratios in assessing stress of caged hens

Abstract

To measure stress in caged hens, differential counts of their wing vein blood were used to determine heterophil/lymphocyte (H/L) ratios and total white blood cell counts (TWBC). The H/L values of 18-wk samples from conventionally caged hens (CC) were not statistically different from hens raised in aviaries (AV) when calculated by either of 2 methods (H/L 1 and H/L 2). However, there was a high degree of variation among samples within each cage type. The TWBC data and hematology indicated leukocytosis, leukemoid reactions, and a high frequency of atypia. Reactive lymphocytes, large plasmacytoid lymphocytes, cyanophils, coccinocytes, and atypical heterophils were common. Analysis of 77-wk data indicated significant differences among 3 cage types. The H/L 1 of enriched caged (EN) hens was twice (0.91) that of either AV (0.33) or CC (0.44) hens (P < 0.01); the H/L 2 values were also highest for EN (0.46) versus AV (0.29) and CC (0.34; P <0.01). As was the case with 18-wk samples, TWBC distributions and hematological data indicated leukocytosis, leukemoid reactions, and a high frequency of atypia. Among the likely reasons for the hematological observations was the occurrence of polymicrobial bacteremia and fungemia, both of which could account for high TWBC and atypical cells. Collectively, these observations challenge the general application of the H/L ratio method when applied alone as an indicator of stress and welfare of hens caged in modern systems.

Feeding dihydroquercetin and vitamin E to broiler chickens reared at standard and high ambient temperatures

“…Heat stress alters homeostasis by affecting the adrenal-corticoid axis and the resulting changes in hormone levels may change the numbers of lymphocyte and heterophil, thus changing the H/L. This method has however been criticised for not providing an adequate indication of stress alone (Müller et al, 2011;Cotter, 2015;Lentfer et al, 2015), which agrees with our results.…”

Effects of vaccination on acute-phase protein response in broiler chicken

“…Changes in H/L ratios, as a parameter of stress in poultry, reflect the innate immune response but not exactly the consequence of specific humoral response. Agonistic (stimulation) or antagonistic (suppression) cross-regulation between stress/APR and adaptive immunity might be related to the type of vaccine and the state of inflammation [14]. In our experiment, a positive correlation between SAA concentration and HI titer is indicative of agonistic cross regulation.…”

“…However, when comparing both Lasota and Vitapest, there are minor differences in antibody production. It has been also anticipated that birds with high H/L ratios produce lesser antibody due to stress-induced suppression [14]. This is likely correct in cases of chronic inflammatory states.…”

Virus-induced immunosuppression in turkeys (<i>Meleagris gallopavo</i>): A review

“…Evaluation of cellular immune competency is used in vitro as well as in vivo (Fadly et al, 1982). Hematological investigations may provide heterophil:lymphocyte ration, as significant indicator of stress (Huff et al, 2005;Cotter, 2015) and immunocompetency (Hocking et al, 2002). In vitro lymphocyte proliferation response to mitogen is widely used to evaluate the integrity of cell-mediated immunity.…”