Effect of substitution of distillers grains and glycerin for steam-flaked corn in finishing cattle diets on growth performance and carcass characteristics

Lay Summary Livestock producers have an opportunity to improve sustainably through the utilization of co-products of the bio-fuel industry through cattle feeding. Crude glycerin, although less commonly fed compared to distillers grains, provides an opportunity for cattle feeders to increase the versatility of feed ingredient sources without compromising performance. The present study examined the effect of substituting modified corn distillers grains and crude soy glycerin for steam-flaked corn in beef cattle finishing diets on cattle growth performance and carcass characteristics. Growth performance was not influenced by treatment suggesting that crude glycerin and modified corn distillers grains in finishing diets were effective substitutions for steam-flaked corn when market price permits. An experiment was conducted to determine the effect of substituting modified corn distillers grains with solubles (DGS) or crude soy glycerin (CG) for steam-flaked corn (SFC) in finishing diets on growth performance and carcass characteristics. Treatments were arranged as a 2 x 2 factorial with DGS (0% or 40%) and CG (0% or 10%) replacing dietary SFC in a basal diet. Growth performance and carcass traits were measured on 48 individually fed crossbred yearling cattle (21 steers and 27 heifers; 380 +/- 37 kg). Cattle were randomly allotted to 48 Calan gate bunks. After the first 28 days, nine animals were removed from the study for health reasons or observed confirmation of consumption of feed from unassigned Calan gate bunk (n = 39). After the feeding period, cattle were harvested in two groups on day-124 and day-173. No DGS x CG interactions were observed (P > 0.10) for any dependent growth performance or carcass characteristic variable tested. Cattle-fed DGS as 40% of diet dry matter (DM) had greater (P< 0.01) dry matter intake (DMI), while CG inclusion at 10% of diet DM did not affect DMI (P = 0.16). Carcass-adjusted average daily gain (ADG) was not affected by DGS (P = 0.73) or CG (P = 0.28). Decreased (P = 0.03) carcass-adjusted gain-to-feed (G:F) was observed as the main effect of DGS. Greater DMI resulting from feeding DGS as 40% of diet DM appears to have driven the tendency for reduced G:F. Hot carcass weight, longissimus muscle area, 12th rib fat depth, yield grade, and marbling score were not (P> 0.10) influenced by DGS or CG. However, kidney, pelvic, fat (KPH) was increased (P = 0.01) when cattle were fed DGS as 40% of diet DM. Based on the findings presented, it is concluded that CG can substitute up to 10% of SFC in the diet without negatively affecting cattle growth performance or carcass characteristics, regardless of DGS inclusion as 40% of the diet DM. Glycerin can be substituted for 10% of the steam-flaked corn without influencing growth performance or carcass characteristics in finishing cattle diets containing 0% or 40% modified corn distillers grains with solubles.