Digestibility, N retention,  growth and feed conversion were measured in growing goats (n=12) housed in individual pens and fed basal diets of fresh sweet cassava foliage or fresh water spinach supplemented or not with a  low level (5-6% of diet DM) of ensiled brewers’ grains. The design was a 2*2 factorial with 3 replications. The brewers’ grains were fed at between 5 and 6% of the DM of the diet. The forages were given ad libitum. There were major interactions between the effects of brewers’ grains supplementation and the nature of the basal diet. growing goats. In the absence of brewers' grains, growth, feed conversion, digestibility and N retention in performance were better when the  goats were fed water spinach; however, when brewers' grains were included in the  diets, performnance attributes all favored the diet of cassava foliage. Urine excretion of thiocyanate in the goats fed the cassava foliage diet was reduced by brewers’ grain supplementation; there was no thiocyanate in the urine of the goats fed water spinach. The results show that small amounts of brewers’ grains (5-6% of diet DM) confer major benefits on growth performance and health (expressed in the decreased urine excretion of thiocyanate) of goats fed cassava foliage as the sole diet.