Abstract
Incorporation of carrot or pumpkin at 0, 20 or 40% dry matter (DM-basis) with crop maize, with or without a silage inoculant was evaluated after 70 days ensiling for microbial community diversity, nutrient composition, and aerobic stability. Inclusion of carrots or pumpkin had a strong effect on the silage bacterial community structure but not the fungal community. Bacterial microbial richness was also reduced (P = 0.01) by increasing vegetable proportion. Inverse Simpson’s diversity increased (P = 0.04) by 18.3% with carrot maize silage as opposed to pumpkin maize silage at 20 or 40% DM. After 70 d ensiling, silage bacterial microbiota was dominated by Lactobacillus spp. and the fungal microbiota by Candida tropicalis, Kazachstania humilis and Fusarium denticulatum. After 14 d aerobic exposure, fungal diversity was not influenced (P ≥ 0.13) by vegetable type or proportion of inclusion in the silage. Inoculation of vegetable silage lowered silage surface temperatures on day-7 (P = 0.03) and day-14 (P ≤ 0.01) of aerobic stability analysis. Our findings suggest that ensiling unsalable vegetables with crop maize can successfully replace forage at 20 or 40% DM to produce a high-quality livestock feed.
Highlights
Despite heightening concerns over food security, up to 1.6 Gt of food is wasted globally each year[1,2]
The chemical composition of maize at harvest, in addition to carrot and pumpkin are presented in Supplementary Table 1
The dry matter (DM) content of 100% ensiled maize was greater (P = 0.02) than with the addition of 40% of either vegetable, or 20% pumpkin, but was similar to 20% carrot inclusion
Summary
Despite heightening concerns over food security, up to 1.6 Gt of food is wasted globally each year[1,2]. Within Australia, ~40% of vegetables are rejected by commercial grading standards due to cosmetic defects, regardless of their nutritional quality or suitability for consumption This amounts to 1.3 billion tonnes of food waste and is estimated to cost Australia $8.4 billion annually[3,4]. Previous literature suggests the use of vegetable residues, with or without a lactic acid-bacteria (LAB) inoculant, in a crop silage can produce a highly digestible feed that positively affects the profile of acetic and propionic acids[5,13]. The objectives of this study were to determine whether unsalable vegetables at varying proportions could be successfully ensiled with crop maize to produce a silage of high nutritional value, which maintains aerobic stability, and quality through in vitro fermentation, and to characterise the bacterial and fungal microbiota of the resulting silage. Unsalable vegetables ensiled with crop maize would produce a silage with greater acetic and propionic acid concentrations, increase the overall microbial diversity at higher vegetable levels, and improve aerobic stability with the introduction of a second-generation microbial inoculant in the vegetable silage
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