Antioxidant and antimicrobial capacity of three agroindustrial residues as animal feeds

Abstract

Currently, different countries’ policies prohibit the use of synthetic antibiotics in animal production. As a consequence, researchers have been looking for sources of these molecules in plants, vegetables, and agro-industrial waste in order to inhibit pathogenic microorganisms, such as Escherichia coli, Salmonella and Listeria and control livestock health. Hydro-alcoholic extracts of the leaves of three different plants- Avocado (Persea americana Mill) Hass variety, guava (Psidium guajava L.) Calvillo variety, and cherry plum (Prunus cerasifera Ehrh) Pissardii variety, at three different ethanol:water ratios (20:80, 50:50, and 80:20 volume/volume) were analyzed. Total phenols in the extracts were quantified by the Folin-Ciocalteu Method and the inhibitory spectrum test against Gram+: Listeria monocytogenes ATCC 19115, Bacillus subtilis ATCC 662, Enterococcus sp., Staphylococcus sp. and Gram−: Escherichia coli ATCC 25922, Salmonella enterica serotipo Enteriditis ATCC 13076, Klebsiella sp. and Pseudomonas sp. using the agar well-diffusion method. The highest phenol content and antioxidant capacity were found in the guava leaf extract at 50:50 (111.7 ± 8.8 EAG mg/mL dry matter, 450 ± 3 μM TE/g dry matter), and this was the only extract that showed total inhibitory spectrum activity for all the microorganisms evaluated among the extracts tested, with a range of 0.62–1.25 mg/mL minimal inhibitory capacity (MIC). A hydroalcoholic extract of guava leaves had strong antimicrobial activity against different pathogenic microorganisms and could be considered as a potential alternative to synthetic antibiotics for use in animal production.