Digestibility and nitrogen retention in pigs fed diets containing dried and undried field beans treated with propionic acid

Digestibility studies with pigs weighing 40 kg were used to determine the nutritive value of diets containing dried and undried field bean (Vicia faba L) nitrogen (N) in place of soya bean N and to examine the use of propionic acid as a means of storing beans in an undried state. An addition of 2% propionic acid satisfactorily preserved moist field beans and treatment with propionic acid prior to six months' storage did not alter the nutritive value of soya bean, dried field beans or undried field beans. The digestibility of N did not differ between soya bean and undried field bean diets but the digestibility of N in the dried bean diet was lower than that in the soya bean diet. Substitution of either dried or undried field bean N for soya bean N resulted in a reduction in N retention.