Acidosis and enterotoxemia
Oats are rich in starch and may cause acidosis and enterotoxemia in ruminants, particularly young ones, that consume large amounts of them. Attempts to self-feed whole oats may result in scouring, bloat, and occasionally death (Boyles et al., 2006). However, due to their lower starch:fibre ratio, oats are safer than wheat, triticale and barley. High inclusion rates are possible when oats are introduced progressively in the diet in combination with hay (Lean et al., 2013; Walker, 2006). As with other grains, abscessed livers have been reported on high grain cattle diets with oats as the major concentrate source (Boyles et al., 2006).
Pentosans and ß-glucans
Oats are rich in pentosans (including ß-glucans), which are polymers of pentose sugars that increase diet viscosity. They can cause digestive problems in monogastric species and, in particular, sticky litter when fed to poultry (DAFS, 2012). Appropriate enzyme supplementation is required to avoid these adverse effects (Blair, 2008).
Mycotoxins
Though oats are less susceptible to fungal diseases than other small grain cereals, it was found that mycotoxin contamination of oats by T-2 and HT-2 trichothecenes and deoxynivalenol (DON) was higher than in other cereals, with a longer infection period. In Scandinavia, DON levels in oats reached 25000 µg/kg, with a T-2 and HT-2 contamination caused by Fusarium langsethiae that reached alarming levels (Bjornstad et al., 2008). In a 10-year survey in Scandinavia, DON levels in oats exceeded food regulatory levels in 28% of cases (Linblad et al., 2012). A 2005-2009 survey of European oat mills found mycotoxin levels in oats to be about 94 µg/kg. Processing (flakes, oat meal) reduced the T-2 and HT-2 levels by more than 80% and alkali treatments significantly reduced their toxicity (Pettersson et al., 2011). In 2013, the EFSA stated that exposures to T-2 and HT-2 mycotoxins were unlikely to be a health concern for ruminants, rabbits and farmed fish, and of low concern for pigs, poultry, dogs and horses (EFSA, 2013).