Effects of Varying Inclusions of Corn Silage and Hybrid on Finishing Performance of Steers

The effect of corn silage hybrid and varying inclusion of silage in corn-based finishing diets were evaluated for impact on finishing performance and carcass characteristics. Steers (n = 288, 318 ± 3.0 kg) were blocked into two BW groups and assigned randomly to one of 36 pens (8 steers/pen). Two hybrids of corn silage were fed and included a traditional control corn silage (CON; hybrid TMF2H708) and a brown midrib hybrid (bm3; hybrid F27F627). Corn silage was included in the diet at three inclusions of 15%, 45%, and 75/15%. The 75/15% treatment was designed where silage was reduced to 15% after d70 to mimic the same silage usage as feeding 45% silage continuously. The treatment design was a 2×3 factorial with hybrid and inclusion as factors. Steers were ultrasounded on d70 and d126/127 to determine backfat deposition rate for a target endpoint of 1.4 cm. Data were analyzed using the MIXED procedure of SAS (SAS Inc., Cary, NC), with pen as experimental unit. Cattle on the 15% inclusion were slaughtered on d153 of the trial, and cattle fed the 45% inclusion and the treatment where 75/15% was fed followed by 15% inclusion of each corn silage hybrid were slaughtered on d181. Cattle were adapted to the 15% inclusion of silage over 24 d and four diets, and those fed 45% silage were adapted over a period of ten days and three diets. No interactions were observed between silage inclusion and hybrid (P > 0.10). Animals fed 45 and 75/15% silage inclusion had greater final BW due to greater days, but lower G:F (0.162) than cattle fed 15% silage (0.170; P < 0.01). Steers fed 45% and 75/15% inclusion had a lower ADG than 15% inclusion (P < 0.01). Carcass characteristics were affected by silage inclusion; those fed 45 and 75/15% had greater final HCW and LM area, and lower dressing percentage (P < 0.01) than 15%. Backfat thickness was greater for steers fed 45% (1.5 cm) over 15% (1.3 cm; P < 0.01), and 75/15% (1.4 cm) was intermediate between the two (P > 0.12). Dry matter intake was greater for cattle fed bm3 silage (P = 0.02), but did not translate to improved ADG or G:F (P > 0.18). Feeding corn silage at a consistent 45% inclusion throughout the feeding period resulted in similar performance to cattle fed 45% corn silage on average by feeding 75% then 15% inclusion.