Aflatoxins
Like other peanut products, peanut crop residues can be contaminated by the fungi Aspergillus flavus and Aspergillus parasiticus, and may, therefore, contain potentially toxic concentrations of aflatoxins (see the Peanut meal datasheet for a more comprehensive discussion of aflatoxin contamination). There have been several reports of lethal aflatoxicosis occurring in cattle fed peanut hay. In Australia, 12 drought-stricken calves died after being fed peanut hay. Most of the aflatoxins were concentrated in the residual pods (McKenzie et al., 1981). In the USA, 125 adult cattle fed peanut hay died of an acute respiratory distress syndrome (Roberson et al., 1997). Though these incidents are uncommon, it is recommended to ensure that peanut haulms are well-preserved and free of mould, particularly if the hay was harvested after heavy rains and not dried sufficiently (Hill, 2002).
Fungicide residues
Fungicides used in peanut production may not be cleared for the feeding of peanut hay, making the feeding of peanut hay containing residues of those fungicides illegal in some countries, including the USA (Myer et al., 2010).
Scouring
Early literature, from when peanut was grown as a forage crop, raised the risk of scouring in cattle fed too large quantities of the forage containing pods (Göhl, 1982). This risk is minimal today since livestock are fed crop residues rather than whole mature plants.
Rumen compaction
Occasional cases of rumen compaction have occurred when beef cows consumed too much peanut hay in a short period of time (Hill, 2002).