Water availability and calcium propionate affect fungal population and aflatoxins production in broiler finisher feed during storage

Abstract

The aim of this study was to investigate the effects of calcium propionate, water activity (aw) and incubation time on the total fungal count and aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) production in the broiler finisher feed. The feed was added with calcium propionate (5 g kg–1), adjusted to 0.85, 0.90 and 0.95 aw and stored for 28 days at 25°C, analysing for mould growth and aflatoxins production every 7 days. Analysis of variance indicated that all the factors (preservative, aw and storage time) alone and in combination significantly (p < 0.001) affected the total fungal count and aflatoxins production in the feed. Minimum total fungal counts (1.99 × 102 CFU g–1) were observed in calcium propionate feed at 0.85 aw on day 1 and the highest (4.36 × 109 CFUs g–1) in control sample at 0.95 aw on day 28 of storage. During the storage period, AFB1 content in control samples increased from 11.35 to 73.44, from 11.58 to 81.81 and from 11.54 to 102.68 ng g–1, whereas in preserved feed the content of B1 increased from 11.47 to 37.83, from 11.54 to 49.07 and from 11.20 to 53.14 ng g–1 at 0.85, 0.90 and 0.95 aw, respectively. Similar patterns were noted for AFB2, AFG1 and AFG2 contents. All the aflatoxins readily increased over storage time; however, the increase was much slower in preserved feed that contained a lower amount of available water. This study reveals that calcium propionate addition to poultry litter along with water activity amelioration is an effective tool for controlling mould incidence and aflatoxin production in poultry feed.