Effect of StoverCal, corn silage, and corn stover in diets containing 60% distillers grains on performance and carcass characteristics of feedlot steers

Abstract Text:

The acidic nature of dried distillers grains with solubles (DDGS) is a key determinant in depressing DM digestibility in ruminants and consequently plays a primary role in decreased DMI and ADG when DDGS concentrations exceed 30% of the diet DM. The ability of alkali treatments, including calcium hydroxide (Ca(OH)₂) to increase rumen pH and enhance fiber digestibility of low quality roughages has been recognized for decades. Additional dietary forage also raises ruminal pH because of increased salivary buffering and may increase fiber digestibility and performance. Thus, 2 experiments were conducted to determine the effectiveness of StoverCal (Ca(OH)₂) and/or roughage on performance and carcass characteristics of steers fed 60% DDGS. Statistical analyses for both studies were conducted using the MIXED procedures of SAS. In experiment 1, 48 steers (353.5 ± 7.55 kg) were allotted to individual pens and fed 1 of 3 diets (DM basis) containing 60% DDGS, 20% corn silage, and 4% vitamin/mineral supplement with: 1) 14.5% corn and 1.5% limestone, 2) 14% corn and 2% StoverCal, and 3) 14.5% additional corn silage and 1.5% limestone. Steers fed StoverCal consumed the least (P = 0.03) and steers fed added corn silage consumed the most and had the lowest gain:feed (P = 0.02). Dressing percent was increased for steers fed StoverCal (P = 0.01). Gain and other carcass characteristics were not affected by treatment (P ≥ 0.48). In experiment 2, 112 steers (375.3 ± 19.25 kg) were allotted to group pens (4 pens/treatment; 7 steers/pen) in a 2x2 factorial and fed 1 of 4 diets (DM basis) containing 60% DDGS, 17% corn silage, and 4% vitamin/mineral supplement with: 1) 17.5% corn silage and 1.5% limestone, 2) 17% corn silage and 2% StoverCal, 3) 17.25% corn stover and 1.5% limestone, and 4) 17% corn stover and 2% StoverCal. Added stover decreased ADG compared to added corn silage (P = 0.04). StoverCal increased ADG when steers were fed stover, but not when steers were fed additional corn silage (P = 0.05; interaction). Forage source or StoverCal did not impact DMI, gain:feed, or carcass characteristics (P ≥ 0.10). In conclusion, added forage does not improve performance of cattle fed 60% DDGS. StoverCal may decrease intake and maintain performance when added to 60% DDGS, 34% corn silage diets and increases ADG when added to 60% DDGS diets where corn stover replaces a portion of the corn silage.

Keywords: cattle, calcium hydroxide, roughage