P. F. Cotter

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

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.

Are peripheral Mott cells an indication of stress or inefficient immunity

Atypical plasmacytes having distinctive cytoplasmic vacuoles (Mott cells) were detected in 77/1,000 (7.7%) of commercial hens housed conventionally, in aviaries, or in enriched environments. The earliest Mott positive peripheral blood samples were at placement (18 wk) from 2 consecutive commercial flocks. Additional samples obtained at 32, 48, 56, and 77 wk were positive. Most Mott cells came from hens with high total white blood cell counts as a component of leukocytosis. However, Mott cells were found in hens with low total white blood cell counts, and low heterophil/lymphocyte ratios. Phagocytosis of bacteria by some Mott cells was a remarkable feature. Many of the Mott positive hens had polymicrobial bacteremia and a few had fungemia likely accounting for the leukocytosis. In other cases, free-swimming bacteria were located near to a Mott cell. These atypical cells were in the peripheral blood samples from other poultry; a tom at slaughter (17 wk), experimental toms (10 wk), and experimental ducklings. Examples are included.As descriptions of avian Mott cells are few, the purpose of describing these cells is their contribution to hematology, immunology, and cytology. Mott cells like other atypia are sentinels, frank cytological indicators of an unusual hemogram, and consequently infer stress. Therefore, they bear directly on welfare issues.

Identification of Salmonella enteritidis from Experimentally Infected Hens Using a Colorimetric DNA Hybridization Method

Identification of Salmonella enteritidis from cloacally challenged commercial laying hens was studied by comparing bacterial isolations using conventional methods with detection by the use of the GENE-TRAK colorimetric DNA probe assay. More positive test results were obtained using the latter on days 14, 28, and 42 postchallenge, but the difference between the two methods was not statistically significant. Over the duration of the experiment, positive cloacal samples were statistically more frequent from a commercial strain of white leghorn hens when compared with a commercial brown egg-producing strain (28/60 vs. 9/57; chi-square 1 df = 12.9, P < 0.001). Eggs having various shell defects were produced by the infected hens only after Salmonella challenge. These defects included, in order of frequency, elongated shape, thin shells, off-white color (tints), small size, wrinkles, and pimples. No Salmonella could be recovered from 193 defective eggs, nor were positive isolates made from additional tests performed on 50 normal eggs. Proteus sp. was isolated from 10 eggs, however. Our observations demonstrate that the GENE-TRAK colorimetric method is comparable with conventional bacteriology for the identification of Salmonella in cloacal samples taken from laying hens. Moreover, the two methods demonstrate the existence of breed differences in susceptibility to S. enteritidis challenge.

A comparison of Mott cell morphology of three avian species. II. - Bad behavior by plasmacytes?

&NA; Mott cells are atypical plasmacytes recognized microscopically by endoplasmic reticulum (ER) distensions (Russell bodies) a result of retained secretory product (antibody). Originally associated with parasitism, they are observed in a broad spectrum of immunopathology, sometimes involving hypergammaglobulinemia. Few descriptions of Mott cells appear in avian literature. The purpose of the manuscript is to provide examples identified by light microscopy in three poultry species. Transmission electron micrographs (TEM) of plasmacytes from the turkey oviduct mucosa are included for comparison with Mott cell light microscopic images. Wrights stained blood and bone marrow from commercial and specific pathogen free (SPF) chickens, ducks, and turkeys are the sources. Mott cell positive samples commonly occurred with leukocytosis or leukemoid reactions, polymicrobial bacteremia, and fungemia. Atypical granulocytes and leukocytes regularly accompanied Mott cells. It is proposed that circulating Mott cells are “sentinels” indicative of stress, dyscrasia, and pathology. Moreover, Mott cells, like other atypia, complicate the interpretation of simple heterophil/lymphocyte (H/L) ratios. As Mott cells are defective plasmacytes these observations address hematology, immunology, pathology, and welfare issues.