Abstract

This experiment was designed to investigate the effects of supplementation with phytase, either alone or in combination with an organic acid blend on growth performance, some internal organs measurements and tibia development, intestinal and cecal microbiology. One-day-old male Ross 308 strain broiler chickens (n=140) were allocated to 5 dietary treatments in a randomized complete block design. The treatments were as follows: (1) Positive control (PC); (2) Negative control (NC) that was the same as diet PC except that available phosphorus was reduced by 0.25 percentage units; (3) NC plus microbial phytase (MP) (NC + MP; 500 FTU/kg); (4) NC plus organic acid blend (OA) (NC + OA), and (5) NC + MP + OA. Body weight gain (BWG) was not improved by supplementation of OA to the NC diet. In contrast, BWG was increased by MP, and MP+OA interaction (P<0.001) compared to NC group. Tibia ash content was lowest (P<0.05) for birds fed the all NC diets compared to the PC and NC+P diet. The addition of phytase slightly increased tibia phosphorus according to NC+OA and NC+P+OA diets (P<0.05). NC diet resulted in increased weight of gizzard, heart, liver and bursa of Fabricious and length of duodenum, jejunum and ileum. In ileal digesta, lactic acid bacteria (LAB) counts were significantly increased for birds fed OA, whereas Escherichia coli were significantly decreased compared to PC group (P<0.001).

Key words: Broiler, phytase, organic acid, performance, bone development, intestinal measurements, intestinal microbiota.