Abstract
The major changes in the composition of field beans (Vicia faba L.) caused by micronising were as follows: the moisture content was reduced from 16.5 to 13.2%, the trypsin inhibitor activity reduced from 2.49 to 0.21 trypsin inhibitor units/mg dry matter and the available carbohydrate content raised from 40.6 to 50.2%. Growth and food consumption of broiler chicks from 1 to 2 weeks of age were not affected significantly when micronised beans replaced raw beans in their diets at a level of 300 g/kg. However, food conversion efficiency, apparent dry matter digestibility and nitrogen retention were significantly improved and pancreas size significantly reduced when the birds were fed the diet containing the micronised beans. The nitrogenβcorrected metabolisable energy (m.e.) of the diet containing 500 g of micronised beans/kg (10.88 MJ/kg) was significantly higher than that of a diet containing 500 g of raw beans/kg (10.33 MJ/kg). It was calculated that the m.e. of the beans had been raised from 10.59 to 11.67 MJ/kg dry matter by micronisation. The improvement in nutritive value is attributed partly to the destruction of the trypsin inhibitor and partly to the increased availability of the carbohydrate fraction of the beans.