Influence of Wheat and Maize Starch on Fermentation in the Rumen, Duodenal Nutrient Flow and Nutrient Digestibility

Abstract

We investigated the effects of feeding diets with different starch sources on fermentation in the rumen, duodenal nutrient flow and nutrient digestibility. The basis of the diets was maize silage and alfalfa hay supplemented with wheat meal in diet W, or maize meal in diet M. The experiment was performed on four Black-Spotted bulls with mean live weight of 525 kg, which were fed twice daily at 06.30 and 18.30 h. Experimental animals were fitted with ruminal fistulae and duodenal T-shaped cannulae. Cr2O3was used as a marker of nutrient flow to the duodenum. Rations were formulated so that the ratio of starch to crude fibre (CF) was 2.1:1 and the percentage of CF was maintained at 17% (DM). Duodenal chymus was collected at 2-h time intervals. Starch origin significantly affected ruminal fermentation. Concentration of propionic, butyric and lactic acid was higher with wheat than with maize meal. When the maize meal was the source of starch there was a significantly higher flow of fat, CF, nitrogen-free extract, and starch into duodenum. Differences in duodenal flow of crude protein were not significant across the starch sources. Intake of wheat meal or maize meal increased duodenal flow relative to intake by 33% or 42 % respectively. The apparent digestibility of dry matter (76 ± 2%), crude protein (67 ± 0.9%), CF (64 ± 1.9%), nitrogen-free extract (82 ± 1.5%) and organic matter (76 ± 1.3%) was significantly higher by offering wheat meal.