The effect of formalin on rumen surface area in red deer

Previously published studies have related the surface area of rumen wall to diet. The validity of studies that utilize preserved material depends upon the predictability of any change in rumen dimension brought about by preservation. Changes in the surface are of different sections of the rumen wall of red deer (Cervus elaphus) were monitored after immersion in 10% formal saline solution at room temperature for 2, 7 and 14 days. There was a high degree of variability (0-39.5%) in wall-area reduction. Ignoring such changes when calculating the factor of increase in surface area (FISA), a composite of papillary surface area and density, can result in errors of up to 39.5%. This study questions the validity of using FISA calculations when formalin-preserved specimens are used in studies of rumen response to diet. Rumen papillary dimensions were not significantly changed by preservation in formalin.