Journal Article

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

Paul F. Cotter

in Poultry Science

Volume 94, issue 3, pages 512-517
Published in print March 2015 | ISSN: 0032-5791
Published online December 2014 | e-ISSN: 1525-3171 | DOI: http://dx.doi.org/10.3382/ps/peu009

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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.

Keywords: heterophil/lymphocyte ratio; stress; caged hen; welfare

Journal Article.  2915 words.  Illustrated.

Subjects: Zoology and Animal Sciences ; Animal Pathology and Diseases ; Animal Physiology ; Ornithology ; Veterinary Medicine

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