RESPONSE OF CHICKENS FED ON HULL-LESS BARLEY TO DIETARY BETA-GLUCANASE AT DIFFERENT AGES

A high viscosity hull-less barley with or without beta-glucanase supplementation was compared to wheat in diets given to broiler or Single Comb White Leghorn (SCWL) cockerels. Both genotypes fed on the unsupplemented hull-less barley had poorer gain and feed conversion, higher digesta viscosity, slower rate of food passage and lower fat digestibility than chicks given the enzyme-supplemented hull-less barley or wheat diets. These effects were largely confined to the early growth period (0-4 weeks) and, with the exception of higher digesta viscosity, disappeared with ageing. Streptococcus faecium colonization of the upper small intestine also declined with ageing in all treatments, but chicks given unsupplemented hull-less barley tended to have higher counts than those given the enzyme-supplemented hull-less barley or the wheat diet. Older chickens were apparently better able to cope with higher viscosity induced by feeding barley. Despite the slower growth and reduced nutrient requirements of SCWL chicks, they responded in a parallel fashion to broiler stock.