WHITE AND WHOLEMEAL FLOURS FROM WHEATS OF LOW AND HIGHER APPARENT METABOLIZABLE ENERGY DIFFER IN THEIR NUTRITIONAL EFFECTS IN RATS

Wheats used for feeding poultry differ considerably in the ratio of so luble to insoluble non-starch polysaccharides (NSP) and apparent metab olizable energy (AME), We have examined effects of whole and white flo ur from a wheat of low (12.02 MJ/kg of dry matter) and high (14.52 MJ/ kg of dry matter) AME in rats fed a cholesterol-free diet. NSP concent rations were higher in whole flour from the low AME wheat but similar in both white flours. in contrast to chickens, food intake and body we ight gain of rats were unaffected by diet. Plasma cholesterol concentr ations were lower in rats fed whole wheat and low AME wheat. Cecal bil e acids and neutral sterol pools were larger in rats fed whole wheat b ut were unaffected by wheat type. Negative correlations were found bet ween digesta steroid pools and plasma cholesterol, consistent with gre ater fecal steroid excretion. Cecal digesta was greater in rats fed wh ole wheat and low AME wheat, Digesta pH was lower in rats fed whole wh eat, but there was a significant interaction between wheat and flour t ype with lower pH in rats fed low AME white flour. Total volatile fatt y acids (VFA) and acetate and butyrate pools were larger in rats fed w hole wheat than in those led white flour. Total and individual VFA poo ls were larger in rats fed low AME flours than in those fed high AME f lours, apparently due to greater cecal starch fermentation in the form er, Factors affecting wheat AME in chickens affect important metabolic variables in rats and may have similar actions in other species inclu ding humans.