Beet pulp as an alternative roughage source for feedlot steers fed feedlot diets based on dry-rolled corn containing 30% modified distillers grains with solubles*

Abstract

Objectives: These studies evaluated the effects of roughage source when fed in combination with modi- fied distillers grains with solubles on digestion, ruminal fermentation, and pH, as well as growth performance of steers. Materials and Methods: Three ruminally and duode- nally cannulated steers were used the digestibility experi- ment. A total of 165 steer calves were randomly assigned to feedlot pens (n = 5 per treatment) and used for the feedlot experiment. Treatments were based on roughage source and consisted of (1) 20% DM inclusion of corn si- lage (CS), (2) 20% DM inclusion of beet pulp (BP), or (3) 10% DM inclusion of grass hay (GH). In the feedlot study 3% wheat straw was added to BP following observations of acidosis. Results and Discussion: Intake (percentage of BW basis) was less for steers fed either CS or GH compared with steers fed BP (P ≤ 0.02). Total-tract digestibility of NDF was greatest for BP and least for CS, with steers fed GH being intermediate (P < 0.05). Ruminal pH and VFA composition were not affected by treatment (P ≥ 0.34). Hot carcass weight was greater for steers fed either GH or CS (P ≤ 0.01) compared with BP. Backfat was greater for steers fed CS when compared with those fed BP (P = 0.02), with steers fed GH being intermediate and similar to both BP- and CS-fed steers (P ≥ 0.16). Implications and Applications: The decreased carcass weight and backfat reported in the feedlot study may indicate that beet pulp, when include at a 1:1 substitu- tion for corn silage, may not support similar animal per- formance to more traditional roughage sources. Research evaluating starch digestibility and physically effective fi- ber of beet pulp may also prove beneficial when fed in combination with modified distillers grains with solubles.