Dietary available phosphorus and phytase levels can influence the pH of the upper intestine and histomorphological characteristics of the lower intestine in broilers
Three hundred eighty-four Ross 308 broilers were allocated to 6 dietary treatments for 22 d. Diets were a nutritionally adequate positive control (PC; adequate available phosphorus, aP) and negative control diet (NC; marginally deficient in aP and Ca, relative to PC) supplemented with 0, 500 or 1,500 FTU/kg phytase, in a 2 × 3 factorial arrangement. Following euthanasia by overdose of barbiturate, 2 birds per pen were used to measure indices of gut morphology. pH was taken in the duodenum (DUO), jejunum (JEJ), ileum (ILE), and cecum (CAE) and sections of DUO, JEJ, and ILE were collected for histomorphology. Data were analyzed using Genstat; significance was determined at P ≤ 0.05. Birds fed the PC diets tended to have an increase in DUO pH (P = 0.054). There was an aP × phytase interaction (P < 0.01) for JEJ pH, with phytase increasing pH in the PC (quadratic, P = 0.001) and NC (linear, P < 0.01). In the DUO, there was aP × phytase interaction (P < 0.05) on apparent villi surface area (SA); phytase increased SA in the NC (quadratic, P < 0.05), being greatest with 500 FTU, but requiring 1500 FTU in the PC. There was a quadratic increase in basal width as phytase increased (P < 0.05). In the JEJ, there was aP × phytase interaction (P < 0.05), with apical width increasing (linear, P < 0.01) in the NC with phytase but there was no effect of phytase in birds fed the PC. There was a tendency for aP × phytase interaction (P = 0.09) on crypt depth (Cd), whereas phytase increased Cd in the NC (quadratic, P = 0.09), but not the PC. There were interactive aP × phytase (P < 0.05) effects on ILE villi number and Cd; phytase in the PC increased villi numbers (quadratic, P < 0.05) and reduced Cd (linear, P < 0.05); however, these effects were not seen in the NC. Birds fed the PC had more crypts than birds fed the NC (P < 0.05). Phytase and aP appear to influence pH in the proximal intestine and intestinal morphology. This may be associated with phytate destruction and reduced endogenous cell sloughing in the proximal intestine and result in increased nutrient utilization, particularly in birds fed low aP diets.
Other Titles/Title of Conference
Symposium on Gut Health in Production of Food Animals, Kansas City, USA
Federation of Animal Science Societies
12 - 13