Caecal abnormality in a layer hen (Gallus gallus forma domestica) without deficits in digestive performance or egg productivity.

We report a case of a layer hen (Gallus gallus forma domestica) with deviation in the morphology of the caecum, and unique opportunity to investigate the digestive performance of the animal compared with normal hens. In a study investigating digestive and reproductive performance, an atypical caecal arrangement was found in a hen that was unremarkable in regards to body mass, digestive performance and egg productivity in comparison to other hens fed a similar diet. Examination of the gastrointestinal tract revealed a singular tubular outgrowth from the ileo-caecal junction, rather than the typical paired outgrowths. The single caecal duct bifurcated into two separate blind-ended sacs. Similar caecal deviations have been described in adult and juveniles, but no indications of animal performance were reported in these cases. We conclude that if the presence of an abnormal caecal arrangement reduces digestive abilities they were not obvious, and some compensatory mechanism/s may exist. Alternatively, the abnormal caecal arrangement of our hen might function adequately, such that no compensation in feed intakes or reduced egg productivity was required or observed.