Effects of Corn Processing Method and Protein Concentration in Finishing Diets Containing Wet Corn Gluten Feed on Cattle Performance1

Professional Animal Scientist, Feb 2006 by Macken, C N, Erickson, G E, Klopfenstein, T J, Stock, R A

Abstract

Three hundred twenty crossbred steer calves (308 kg) were used to determine the effects of corn processing and addition of urea on performance with diets containing wet corn gluten feed (WCGF). The treatment design was a 5 � 2 factorial with factors of corn processing (dry-rolled, DRC; fine-ground, FGC; rolled high-moisture, RHMC; ground high-moisture, GHMC; or steam-flaked corn, SFC) and CP concentration (14 or 15%) with 4 pens per treatment and 8 steers per pen. The final diet contained 60% corn, 25% WCGF, 10% com silage, and 5% supplement (DM basis). No significant protein � grain processing interactions occurred for feedlot performance or carcass variables. Steers fed DRC and FGC had similar DMI, but greater (P

Key words: corn gluten feed, finishing cattle, grain processing, protein

Introduction

Using products such as wet corn gluten feed (WCGF) to replace a portion of the corn in finishing diets has been shown to improve feed intake and daily BW gain while maintaining or improving feed efficiency (Stock et al., 2000). This improvement in cattle performance is thought to be due to acidosis control, as WCGF can reduce acidosis challenges (Krehbiel et al., 199Sb). Most of this research has been done with dry-rolled corn (DRC)-based diets, although more intensively processed corn has been shown to improve feed efficiency when WCGF is included in finishing diets (Scott et al., 2003). Ruminai starch digestion is increased when corn is processed more intensively than DRC (Huntington, 1997; Cooper et al, 2002b), resulting in greater degradable intake protein (DIP) requirements (Cooper et al., 2002a). The dietary DIP requirement for DRC-based diets has been reported to be in the range of 6.3 to 6.7% of dietary DM (Milton et al., 1997; Shain et al., 1998; Cooper et al., 2002a). Processing the corn as early harvested, high-moisture (HMC) or steam-flaked (SFC) increased DIP requirements in the range of 10.1 to 10.2% and 7.1 to 9.5% of dietary DM, respectively (Cooper et al., 2002a). Relieving acidosis challenges with WCGF increased ruminai pH (Krehbiel et al, 1995b) and increased microbial synthesis efficiency in the rumen (Russell et al, 1992). Feeding WCGF with intensively processed corn may potentially increase dietary DIP requirements. Therefore, the objectives of this study were 1) to determine effects of corn processing methods on cattle performance, 2) to determine the dietary energy derived from corn processed by various methods, and 3) to evaluate protein requirements of finishing cattle fed diets containing WCGF.

Materials and Methods

Animals and Diets. Three hundred twenty crossbred (British � Continental) steer calves (308 kg) were stratified by BW and assigned randomly to 1 of 40 open lot pens (8 steers per pen). Pens were assigned randomly to 1 of 10 dietary treatments (4 pens per treatment). Treatments were assigned based on a 2 � 5 factorial arrangement of treatments with factors of CP concentration and grain processing method. Crude protein concentrations were formulated to be 13 or 14% (DM basis) with the additional CP supplementation from urea. However, actual average CP analyses were 13.9 and 14.9% (Table 1). Grain processing methods were DRC, fine-ground (FGC), early harvested high-moisture rolled (RHMC), early harvested high-moisture ground (GHMC), and SFC. Visual presentation of these corns can be found in Figure 1.

Dry-rolled corn was processed through a single-roll roller mill. Fine-ground corn was processed through a hammermill to pass through a 0.95-cm screen. All early harvested HMC was harvested in 1 d at approximately 30% moisture. Corn was either processed through the same roller mill (RHMC) as DRC or a tub grinder fitted with a 0.95-cm screen (GHMC) and stored 70 d before the initiation and throughout the trial in oxygen-limiting silo bags. Steamflaked corn was processed to a flake density of 0.34 kg/L (26 Ib/bu) at a commercial feedlot (Mead Cattle Company, Mead, NE) and delivered twice weekly. Corn was transported to minimize breakdown of flakes. During storage, no spoilage was observed during the winter and spring feeding trial. All corn, except SFC, was grown at the University of Nebraska-Lincoln Agricultural Research and Development Center to minimize variation in sources. However, current hybrids produced in eastern Nebraska were also used and were similar in nutrient content.

Diets contained 25% (DM basis) Sweet Bran brand (Cargill Incorporated, Blair, NE) WCGF. All diets fed contained 10% (DM basis) corn silage. Steers were adapted to finishing diets in 21 d using the respective treatment of corn to replace alfalfa hay (35% alfalfa hay for 3 d, 25% for 4 d, 15% for 7 d, and 5% for 7 d, DM basis). Feed ingredients were sampled weekly, and DM analyses were conducted to ensure accurate composition of diets. Supplements were fed in 2 phases based on NRC (1996) protein requirements to supply undegradable intake protein (UIP) early in the finishing stage when calves are deficient in metabolizable protein. During phase 1, UIP was supplemented to calves using feather meal and blood meal (50:50) at 1% of dietary DM. In phase 2, UIP was replaced with urea when cattle were estimated to weigh 398 kg. This occurred on d 40 of the feeding period. Finishing diets (Table 1) were formulated (DM basis) to contain a minimum of 0.70% calcium, 0.65% potassium, 34 mg of monensin (Elanco Animal Health, Indianapolis, IN)/kg, and 11 mg of tylosin (Elanco Animal Health)/kg.