IMPLICATIONS FOR DAIRY PRACTICE

Cassava residues should be incorporated into farm-level mycotoxin management plans with (i) specification-based procurement (moisture limits, visible mold rejection, storage conditions), (ii) periodic screening (rapid tests for aflatoxins where relevant; Liquid chromatography-tandem mass spectrometrywhen diagnosing complex issues), and (iii) documented storage and stabilization methods that minimize aerobic spoilage and fungal growth.

MICROBIOLOGICAL HAZARDS IN ENSILED/FERMENTED FORMS: CLOSTRIDIA, LISTERIA, AND HYGIENE FAILURES

When cassava pulp is stabilized via ensiling, the hazard profile shifts from rapid aerobic spoilage toward risks associated with suboptimal fermentation and pathogen persistence, particularly if packing density is poor, DM is too low, or oxygen ingress occurs during storage and feed-out. A recent review on silage pathogens and biological control agents highlights that silage fermentation can be compromised by undesirable microorganisms, including yeasts, molds, Clostridia, and Listeria spp., with consequences for animal performance and feed hygiene [118]. Dairy-relevant evidence indicates that poor-quality silage is a major risk factor for Listeria monocytogenes on farms, and that Listeria can persist in farm environments even with good hygiene, emphasizing the centrality of silage quality and feed-out management [119]. A mechanistic review of LAB performance in silage production further clarifies why fermentation success is not guaranteed: silage outcomes depend on substrate composition, epiphytic microbiota, moisture, compaction, and additive choice, variables that are especially volatile in non-forage residues like wet cassava pulp [120].

In dairy practice, if cassava pulp is ensiled, safety constraints should include minimum DM targets, rapid sealing, sufficient packing density, and management of aerobic stability at feed-out. Inoculant selection should be justified by expected substrate limitations (e.g., sugar availability, buffering capacity) and the specific goal (preservation, improved aerobic stability, or detoxification support) [120].

INORGANIC AND CHEMICAL CONTAMINANTS: SOIL/ASH, HEAVY METALS, AND PESTICIDE RESIDUES

Beyond biological hazards, cassava residues can carry inorganic contaminants introduced via soil adhesion, drying on bare ground, or processing environments. Elevated ash, particularly insoluble ash, reduces energy density and can indicate contamination that may co-occur with trace metals depending on local soil conditions. Recent research on tuber crops reports widespread attention to heavy metal contamination (e.g., Pb, Cd, As, Hg) at a population-sample level, suggesting a plausible risk pathway for cassava-derived materials in contaminated environments [121]. While many heavy metal studies focus on food, the same agronomic drivers apply to feed chains, and a precautionary approach is warranted when residues are sourced from regions with known industrial or mining activity in soils.

Chemical residues (e.g., pesticides) are another emerging consideration, not because cassava is uniquely pesticide-intensive, but because feed chains increasingly detect diverse residues across plant-based feedstuffs. A 2019–2023 monitoring study using gas chromatography-tandem mass spectrometry found pesticide residues in a high proportion of feed samples (region-specific), illustrating that multi-residue contamination is common in modern feed systems and can shift over time [122]. Regulatory frameworks (e.g., EU coordinated control programs for pesticide residues in food/feed commodities) reinforce that residue monitoring is a continuing policy priority and that feed and food chains are analytically linked [123].

In dairy practice, chemical and inorganic hazards should be managed through supplier qualification (source-area risk screening), ash/insoluble ash as a routine indicator for soil contamination, and targeted testing when sourcing from high-risk regions or when unexplained performance/health issues occur.