Digestibility of nutrients in growing-finishing pigs is affected by Aspergillus niger phytase, phytate and lactic acid levels 1.: Apparent ileal digestibility of amino acids

In growing-finishing pigs, the effects of microbial phytase, lactic acid and phytate levels in a maize-soybean meal diet on the apparent ileal digestibility (AID) of N and amino acids were studied. The experimental design was a 2 x 2 x 2 factorial arrangement plus a positive control treatment. Six crossbred castrates of 37 kg initial BW, fitted with steered ileo-caecal valve cannulas, were used during six collection periods. The dietary treatments consisted of Aspergillus niger phytase (Natuphos(R); 0 or 900 FTU kg(-1)), Na phytate (0 or 1.5 g P kg(-1)) and tactic acid (0 or 30 g kg(-1)). The positive control diet was supplemented with 1.0 g P kg(-1) from monocalcium phosphate monohydrate (MCP). Ileal digestible amino acids were supplied at 80% of the Dutch recommended allowances for a 60-kg growing pig. The feeding level was 2.3 times the maintenance requirement for energy (418 kJ ME BW-0.75). Estimates of AID were calculated using Cr2O3 as a marker. Results showed that for almost all amino acids there was a significant interaction between Na phytate and phytase. Supplementing Na phytate to the diets without phytase increased the AID of N and amino acids. In general, phytase alone stimulated the AID of N and amino acids in the diets without Na phytate. Supplementing both Na phytate and phytase slightly decreased AID compared with the diets with only one supplement. Lactic acid stimulated the AID of N and amino acids, bur a synergistic effect between phytase and lactic acid was not detected. Adding MCP had no effect on the AID of N and amino acids, it was concluded that when diets are supplemented with either phytase or lactic acid, AID of amino acids is improved. However, supplementing both did not result in a further increase in AID. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.