The effect of delayed corn silage harvest on performance of yearling steers fed 15 or 45% silage finishing diets

Abstract Text: Crossbred yearling steers (n=180; BW = 428 kg; SD = 39 kg) were used in a feedlot finishing trial to evaluate the effects of harvesting drier corn silage and replacing corn with corn silage in diets with 40% modified distillers grains with solubles.  Previous data suggests DM yield and starch (i. e., grain) content may be increased if silage harvest is delayed and silage is drier. Factors were harvested corn silage DM (37 or 43%) and inclusion of corn silage in the finishing diet (15 or 45 % of diet DM).  Steers were blocked by BW and assigned randomly within block to pen (n =20; 9 steers/pen).  Steers were fed for an average of 108 d before harvest.  On the day of harvest, HCW were recorded, and performance measures were calculated from HCW adjusted to a common dressing percentage (63%).  Marbling score, 12^th rib fat thickness, and LM area were recorded after a 48-h chill.  Data were analyzed using the GLIMMIX procedure of SAS as a randomized block design with pen as the experimental unit and block as a fixed effect.  There were no interactions between corn silage DM and corn silage inclusion (P ≥ 0.47) for feedlot performance or carcass characteristics. As corn silage inclusion increased from 15 to 45%, ADG decreased (P = 0.04) while DMI did not differ (P = 0.15), which decreased G:F (P < 0.01) for cattle fed 45% corn silage compared to 15%.  Carcass-adjusted final BW and HCW were lower (P ≤ 0.04) for steers fed 45% corn silage compared to 15%.  There were no differences (P ≥ 0.26) in LM area, 12^th rib fat, and marbling score as corn silage inclusion was increased.  As DM of corn silage was increased from 37 to 43%, no differences (P ≥ 0.30) in DMI, ADG, or G:F were observed.  Additionally, there were no differences (P ≥ 0.68) in carcass-adjusted final BW or HCW when drier corn silage was fed.  No differences (P ≥ 0.27) in 12^thrib fat or marbling scores were observed due to DM of corn silage.  While increasing corn silage inclusion from 15 to 45% in place of corn in finishing diets reduced ADG and G:F, feeding more corn silage than typical in finishing diets and or delaying corn harvest and ensiling drier corn silage to increase harvested tonnage could prove to be economical.

Keywords: Corn silage, Dry matter, Finishing cattle