Hemp leaves, stems and flowers contain cannabinoids, psychoactive molecules that affect the central nervous system. Delta-9-tetrahydro-cannabinol (THC) is considered the most active psychoactive agent. Varieties grown for fibre and oil have much lower levels of THC (less than 0.2%) than varieties grown for drug production (Kahn, 2005; Terres Inovia, 2015). No pathological side effects have been reported for the by-products of industrial hemp. However, residues of ganja drug production consisting in dust, leaves, branches and burnt seed samples reduced feed intake and caused drowsiness, reduced activity and incoordinated movement in cattle, particularly when the residues were washed. Water treatment seems to have increased the concentration of psychoactive components, resulting in higher toxicity and lesser palatability (Jain et al., 1988).
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