Relative antifungal efficacies of phosphoric acid and other compounds on fungi isolated from poultry feed

Fusarium, Aspergillus and Penicillium spp. were isolated from poultry feed. Experiments were conducted to compare the efficacy of phosphoric acid (PPA) with other antifungal compounds at 1 g kg−1 and 5 g kg−1 levels. The order of antifungal efficacies varied with fungal strain. For example, the efficacies at 1 g kg−1 level of compound on a yellow-colored Aspergillus isolate were: sorbic acid (SA) = gentian violet (GV-11) = Na-benzoate (BA) ⩾ propionic acid (PA) > PPA = Na-pyrophosphate (PY) > Ca-propionate (CaPA), and on a greenish-yellow-colored Aspergillus isolate were: SA > GV-11 > PA > PPA > BA = CaPA. The antifungal efficacies for Penicillium isolates were: SA > PPA ⩾ PA > GV-11; while CaPA, BA, and PY did not exhibit any inhibitory effect. For a Fusarium isolate, the efficacy continuum was: SA = PA > BA = GV-11 > PPA; PY and CaPA did not inhibit the growth of this isolate. Results suggested that PPA may be an effective antifungal ingredient for poultry feed.