The effect of wheat and maize meal on rumen fermentation and apparent nutrient digestibility in cattle

Abstract

Starch is the major energy component of grains. The variability of wheat and maize starch degradation in the rumen influences the fermentation process and nutrient digestibility in ruminants. We studied effects of feeding diets with different starch sources on fermentation in the rumen and apparent nutrient digestibility. The experiment was performed on four Black-Spotted bulls (mean live weight of 525 kg) fitted with rumen fistula. The basis of the diets was maize silage and alfalfa hay supplemented with wheat meal (W), or maize meal (M) in the diet. The ratio of starch to crude fibre (CF) was the 2.1:1 and the proportion of CF was maintained at 17% (DM) in both diets. Rumen fluid was collected prior to the morning feeding and 1, 2, 4 and 6 hours after feeding over three days. In the experimental period, two 96 h quantitative collections of faeces were done. Differences between treatments were evaluated by t-test using the Statgraphics, Version 5.0 software. Statistical significance of differences was declared at P ≤ 0.05 and P ≤ 0.01. Starch origin affected rumen fermentation significantly. Concentrations of propionic, butyric and lactic acid were higher with wheat than with maize meal. Large amounts of fermentable starch included in rations reduced rumen pH as a consequence of increased concentrations of propionic, butyric and lactic acid. Nutrient digestibility was influenced by different starch sources. The apparent digestibility of the 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 when experimental ration was supplemented with wheat meal.