Deleterious effects of pasture

a) Hypomagnesemic tetany

• Spring pastures have low concentrations of magnesium in the DM and invariably contain high concentrations of calcium and magnesium from the digestive tract.
• This predisposes lactating animals to grass staggers or hypomagnesemic tetany.

b) Bloat

• Soluble proteins in some legumes form stable foams preventing the escape of rumen gases.

c) Nitrate toxicity

• Rapidly growing immature pastures can accumulate nitrates, particularly on high-fertility soils during warm, wet conditions.
• Nitrate is reduced to nitrite in the rumen and this can oxidize hemoglobin, so toxic symptoms arising from a deficiency of oxygenint the tissues may occur.

d) Facial eczema

• Fungal spores accumulating in dead herbage during warm, humid weather conditions produce a toxic compound ( Sporidesmin) which causes liver damage and photosensitivity.