Neltuma ruscifolia extracts for poultry feed preservation

Abstract

Neltuma ruscifolia, also known as vinal, is an invasive tree that grows in the semi-arid andsubhumid regions of the South American Chaco. Its abundant leaves are a valuable source ofbioactive constituents, which are currently underutilized. This study examined the ethanolextract (ELE) and its alkaloid fraction (AF) from Neltuma ruscifolia leaves for their phytochemicalprofile and antioxidant activity. Their toxicological and antifungal properties were evaluated,both alone and in combination with potassium sorbate (PS). ELE, ELE+PS, or PS were also addedto a poultry feed to examine their protective impact against oxidative damage and antifungal andantiaflatoxigenic properties against A. flavus. ELE had a total content of phenolic compounds of132 mg of gallic acid equivalent/g, with a significant content of apigenin C-glycosides, mainlyisoschaftoside and schaftoside, and moderate antioxidant activity (IC₅₀ DPPH = 250 mg/L). AF,which was mainly composed of julifloridine, showed negligible antioxidant capacity. ELE and AFsuppressed the growth of Fusarium and Aspergillus strains at concentrations (750–1500 mg/Land 375–750 mg/L, respectively) lower or similar to that of PS (1500 mg/L). They also synergizedthe antifungal activity of PS. Toxicity evaluated by the brine shrimp lethality assay confirmedthat both ELE and its combination with PS are non-toxic (LC₅₀ > 1,000 mg/L). In applicationtrials in poultry feed artificially inoculated with A. flavus, ELE and ELE+PS, at minimuminhibitory concentrations, significantly reduced fungal viability, biomass, and aflatoxincontamination by 93–99%, 60–70%, and 90%, respectively, outperforming PS alone.Additionally, ELE showed a moderate protective effect against feed oxidative damage, lasting forat least one week. These findings suggest that ELE, alone or in combination with PS, is apromising phytogenic additive for poultry feeds, capable of controlling fungal and aflatoxincontamination, as well as oxidative spoilage.