Evaluation of Buffy Coat Smears Prepared by Different Methods in Chicken Blood

Abstract

Hematological assessment of poultry is often hindered by delays in the field, which affect the quality of smears. Therefore, this study optimized a protocol for preparing buffy coat smears from chicken blood by comparing two centrifugation protocols and three fixation methods (air-drying, methanol, and ethanol) after storage at 4°C for 0, 24, and 48 hours. The quality of the slides was assessed using a degradation scale ranging from 0 to 5. The findings highlight the importance of timing: centrifugation must happen before storage to maintain sample integrity. Smears processed immediately consistently outperformed those where centrifugation was delayed, with the 48-hour delay causing the most noticeable degradation. When it came to fixation, air-drying proved the most reliable, followed closely by methanol (when used with immediate centrifugation). Ethanol fixation, however, struggled after 48-hour delays, especially if centrifugation had been postponed. Immediate centrifugation was clearly superior, better preserving nuclear and cytoplasmic clarity along with the integrity of white blood cells, red blood cells, and thrombocytes. Although we observed expected signs of cell lysis and degeneration, cellular aggregation was never an issue. Ultimately, these results demonstrate that accurate differential leukocyte counting remains possible even with delayed processing, provided our standardized protocol is followed. For the best morphology, we recommend performing PCV before storage and opting for air-drying or methanol fixation. Ethanol remains a viable secondary choice but is less ideal for extended storage. This approach offers a practical way to ensure reliable field-based hematological evaluations when instant processing isn't an option.