Evaluation of Lactic Acid Bacteria for the Control of Aflatoxin Contamination in Silage

Abstract

: This study evaluated the effect of lactic acid bacteria (LAB) on fermentation and aflatoxin concentrations of napier grass, whole crop green maize and whole crop dry maize plant silages, infested with aflatoxigenic mold Aspergillus flavus. The forage was chopped into 10kg portions in duplicates and inoculated with 100 ml of 10 6-7 CFU/ml, B2 27 Lb. plantarum/pentosus/paraplantarum (LAB1); B410 Lb. plantarum/pentosus/paraplantarum (LAB 2); LAB 1 + 100 ml of cultured spores (100 cfu/ml) of mold; LAB 2 + 100 ml of cultured spores (100 cfu/ml) of mold ; control 1-no addition; control 2 – mold only; control 3 – LAB 1 only; control 4 – LAB 2 only. The inoculated silage bags were sealed for 90 days and sampling done monthly to evaluate LAB, fungal counts and aflatoxin B1. Dry matter (DM), pH, crude protein (CP), neutral detergent fiber (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) were determined using AOAC methods. Mold population decreased in month one but increased thereafter. Silage type determined LAB ( p = 6.2e-08) and mold ( p = 3.9e-08) proliferation. Dry maize and napier grass silages favoured LAB and mold growth, respectively. LAB inhibited mold growth and aflatoxin production ( p = 2.2e-04). Silage pH in the third month ranged between 4.55 – 5.67 with no smell of butyric acid. Though napier and dry maize plants showed higher nutritional qualities, they favoured mold growth and aflatoxin proliferation. Aflatoxin-inhibiting LAB starters are useful in controlling aflatoxin risk in silage.