THE EFFECT OF MICROBIAL PHYTASE IN DIETS FOR PIGS ON APPARENT ILEAL AND FECAL DIGESTIBILITY, PH AND FLOW OF DIGESTA MEASUREMENTS IN GROWING PIGS FED A HIGH-FIBER DIET

The effect of Aspergillus niger phytase on digestibility of some nutrients, pH and flow of digesta in post valvular T-caecum (PVTC) cannulated growing pigs fed an oat (80.6%) diet was studied. Four barrows weighing on average 40 kg were assigned to four diets in a 4 x 4 Latin square design. Diet 1 contained 1.11% monocalcium phosphate (MCP); diet 2 had neither MCP nor phytase; diet 3 included phytase at a concentration of 487 phytase units kg(-1) feed; and diet 4 had 0.55% MCP and 320 phytase units kg(-l) feed. Ileal digestibility of phosphorus (P) increased by 19.4 and 26.8% in diets containing microbial phytase compared with the control diets 1 and 2, respectively. Corresponding increases in faecal digestibility values were 18.3 and 23.6%. Ileal digestibility of calcium (Ca) was significantly higher in diet 3 but there was no effect of diet on the faecal digestibility of Ca. There was no effect of microbial phytase on the digestibility of magnesium (Mg), dry matter (DM) or crude protein (CP). Ileal digestibility of crude fibre (CF) was not affected by diet, but faecal CF digestibility was lower (P < 0.05) in diets containing microbial phytase. There was no effect of phytase on excretion of Ca, Mg and N and Mg and N retention. There was a time-related response of pH of ileal digesta, with hourly pH measurements ranging between 7.1 and 5.9, irrespective of diet. Flow of digesta peaked 3-6 h after the morning feed and 1-2 hours after the evening feed.