Histological and histochemical evaluation of the small intestine and caecal appendix of rabbits fed triticale-based diets with added xylanase

The inclusion of triticale in rabbit diets can negatively affect production parameters due to the presence of arabinoxylans that increase the viscosity of intestinal contents, making digestion and absorption of nutrients difficult. Therefore, the addition of the enzyme xylanase can improve intestinal morphology and the digestive process. This study aimed to conduct histological and histochemical evaluations of the small intestine and caecal appendix in growing-finishing rabbits fed diets containing 14% triticale supplemented with varying levels of xylanase. The rabbits had an initial average live weight of 822 g and reached a final weight of 2097 g. For this purpose, forty 35-d-old male rabbits crossbred New Zealand × California were used. Rabbits were housed in individual cages and randomly divided into four experimental treatments (xylanase at doses of 0, 4000, 8000 and 12 000 xylanase units (XU)/kg of dry matter). At the end of the experimental period, rabbits were slaughtered at seventy days of age and samples were taken from the duodenum, jejunum, ileum and caecal appendix. Samples were stained using the standard Haematoxylin-Eosin (HE) technique for the histological evaluation and Alcian Blue (PAS) for the histochemical evaluation. The addition of xylanase linearly increased the height of villi in the duodenum, jejunum and ileum, while villi width was linearly reduced in jejunum and increased in ileum. Crypt depth was linearly reduced by xylanase dose in duodenum, while the response was linear and quadratic in jejunum and ileum. The villi height to crypt depth ratio was linearly increased by the xylanase dose in the duodenum and jejunum, although the effect was quadratic in the ileum. The dome height of the caecal appendix increased linearly with the addition of xylanase. Epithelial mucus count was linearly reduced by xylanase dose in the base of the duodenum, jejunum and caecal appendix, although this linear reduction was only observed in the villi of the jejunum and in the caecal appendix. In conclusion, the addition of xylanase positively affected the histological and histochemical characteristics of the small intestine and caecal appendix, so its use could improve digestive and productive performance in rabbits.