Investigating ruminant digestive characteristics of finishing beef steers fed sorghum wet distillers grains treated with calcium hydroxide1

Abstract

Alkali treatment has been used to increase the digestibility of low-quality, fibrous crop residues. However, alkali treatment of the fiber fraction in distillers grains has only briefly been explored. Six ruminally cannulated steers (444 ± 4.0 kg of BW) were used to evaluate the effects of treating sorghum wet distillers grains plus solubles (SWDGS) with calcium hydroxide (CH) in finishing diets. Treatment diets were based on steam-flaked corn and included (1) 30% corn wet distillers grains plus solubles (CDG), (2) 30% SWDGS (SDG), or (3) 30% SWDGS treated with 2.27% CH (SDG-CH). Data were analyzed as a replicated Latin square with 3 dietary treatments and 3 periods using the MIXED procedure of SAS with animal within square as the experimental unit. No differences (P = 0.47) in DMI were observed. Steers consuming CDG had the greatest (P < 0.01) total ruminal VFA concentration, followed by SDG-CH, with SDG having the least. Steers consuming SDG had the greatest (P < 0.01) ruminal pH, followed by SDG-CH and then by CDG. Steers consuming SDG had the greatest (P < 0.01) ruminal acetate:propionate ratio, followed by SDG-CH, with CDG having the least. Steers consuming SDG-CH tended (P = 0.07) to have a greater apparent total-tract digestibility of NDF. No differences (P ≥ 0.15) were observed in apparent total-tract digestibility of DM, OM, ADF, starch, or N. Treating SWDGS with CH increased the digestibility of fiber compared with untreated SWDGS in finishing diets.