Phytase Activity in the Digesta from Different Parts of the Digestive Tract and Ileal Digestibility of Nutrients in Broilers Fed with Buckwheat Diets

摘要

In the present study, the effects of dietary buckwheat on phytase activity in the digesta from different parts of the digestive tract, and ileal digestibility of nutrients were determined in broilers fed with buckwheat diets. Eighty male broilers (29-d-old) were divided into four groups (20 birds each), and were fed one of the following diets until they were 36-d-old: positive control (PC) diet formulated based on the NRC recommendations, negative control (NC) diet containing 0.15% lower non-phytate phosphorus (P) than that in the PC diet, and two other diets formulated by replacing corn in NC diet with either 20% non-germinated (BU) or germinated (GBU) buckwheat. At the age of 36 d, broilers were sacrificed to collect digesta from the crop, gizzard, duodenum, jejunum, ileum, and cecum. The activity of phytase was low in the PC and NC diets, which increased in the BU diet and increased further in the GBU diet. A similar trend was observed in the crop digesta; however, the phytase activity in the crop digesta of BU and GBU diets was marginally lower when compared with that in each diet. These values decreased sharply when the digesta moved to the gizzard, and then decreased gradually. The ileal digesta exhibited significantly low activity with negligible effect of dietary treatment. The result of two-way analysis of variance with germination and digestive tract parts as main factors showed that the effect of digestive tract parts and interaction between factors was significant on the phytase activity in digesta. The dietary BU and GBU did not affect the ileal crude protein digestibility; however, it increased the ileal phytate P digestibility. These results suggest that in broilers, the crop might be the primary site of phytate degradation by buckwheat phytase, and the buckwheat might have negligible adverse effect on ileal digestibility of nutrients.