The effects of starch or neutral detergent soluble fiber associated with two dietary levels of NDF on performance of finishing feedlot beef steers were evaluated in this trial. Twenty-four crossbred ½ Angus x ½ Nellore steers averaging 18 months of age and 329 ± 24 kg of body weight at the beginning of the trial were used. All four diets were balanced to supply the crude protein requirements for a daily weight gain of approximately 1.4 kg. Diets were composed (dry matter basis) by 40% of corn silage and 60% of concentrate containing corn grain, citrus pulp, soybean hulls, salt, and urea. Animals fed the diet containing high soluble fiber and low NDF content had the lowest dry matter intake (DMI), which compromised weight gain and feed conversion. This decrease in DMI can be explained by the greater level of citrus pulp (45%) compared to the other three diets. Between diets with higher NDF levels, that with soluble fiber resulted in greater daily weight gain (1.435 vs. 1.262 kg) and better feed conversion ratio (7.494 vs. 8.651) than the diet with starch. However, no significant difference was observed between the diet with high NDF and soluble fiber compared to that with low NDF and starch for these same variables. In conclusion, animal performance can be improved by changing the source and content of dietary soluble carbohydrates.
neutral detergent fiber; neutral detergent soluble fiber; weight gain
