Mechanical injuries
Awned barley varieties may cause irritation and result in stomatitis in horses, cattle and poultry (Kahn, 2005; Göhl, 1982). The awns should be removed prior to feeding poultry (Göhl, 1982).
Mycotoxicosis
Barley grain is susceptible to scab (Fusarium head blight), a disease caused by Fusarium spp. in hot and humid conditions. Fusarium head blight results in the production of mycotoxins, notably in deoxynivalenol (DON, vomitoxin) (Burrows et al., 2008). Signs of toxicosis are weight loss, lower feed conversion, vomiting, bloody diarrhoea, severe dermatitis and death. It causes lower egg production in hens and abortion in mammals. Pigs are more susceptible to vomitoxin than cattle and poultry (Herrman, 2002). Harvested grain containing more than 5% infected kernels may contain enough toxin to be harmful to humans and animals (Buhariwalla et al., 2011). The USDA has set a limit for deoxynivalenol at 5-10 ppm in grains intended for animal feeding (Burrows et al., 2008).
Pentosans
Barley contains pentosans (ß-glucans) that cause sticky droppings in poultry, resulting in leg and breast damage and low-grade products. In laying hens, sticky droppings tend to adhere to the mesh and to mark the eggs as they roll away, reducing their market value (Chesson, 1991). ß-glucans also result in poor performance in monogastric animals. ß-glucanase supplementation may alleviate these problems (OECD, 2004; Göhl, 1982).