University of Nebraska Cooperative Extension MP 71

Summary

Finishing performance of yearling steers was used to assess eight treatments containing corn wet milling byproducts. Interactions were encountered for dry matter intake, average daily gain and feed efficiency as level of dietary steep liquor/distillers solubles increased and corn bran and(or) corn bran with solvent-extracted germ meal decreased. Average daily gain and feed efficiency increased as steep liquor/distillers solubles replaced corn bran or a combination of corn bran and solvent-extracted germ meal. Steep liquor with distillers solubles had higher feeding value than corn bran or solvent-extracted germ meal and solvent-extracted germ meal had 19.9 percent higher energy than corn bran.

Introduction

Corn wet milling allows for separation of corn grain into several components. Products of wet milling are further refined to yield ethanol and fructose from starch, oil from corn germ and gluten meal from corn protein. Whereas these products are destined to be marketed outside the cattle industry, corn bran, solvent-extracted germ meal, steep liquor and distillers solubles are byproducts of corn wet milling and are typically combined to produce corn gluten feed.

Replacing a portion of the corn in finishing diets with wet milling byproducts can enhance feed intake, average daily gain and feed efficiency of cattle. The benefit derived by feeding corn milling byproducts can be influenced by the ratio of byproducts to corn dry matter. Furthermore, individual byproducts may interact when blended, depending on the level of dietary inclusion, affecting intake, gain and feed handling characteristics (1998 Nebraska Beef Report, pp. 50-53). The objective of this experiment was to determine the effects of various blends of corn bran, solvent-extracted germ meal and steep liquor with distillers solubles on feed intake, ADG and feed efficiency in finishing yearling steers.

Procedure

Medium framed yearling steers (n=280, 782 lb) were fed for an average of 116 days to assess performance associated with either four blends of corn bran (BRAN) and steep liquor/distillers solubles (STEEP) or four blends of BRAN, STEEP and solvent-extracted germ meal (GERM). The finishing trial was initiated in mid-September when yearlings entered the feedlot following summer grazing. Steers were blocked by weight into one of four blocks and assigned randomly to treatment. Three blocks contained nine steers per pen, one block eight steers, for a total of 35 animals per treatment. Byproduct blends comprised 30 percent of dietary dry matter in each of the following eight treatments: 1) 24 percent BRAN, 6 percent STEEP; 2) 21 percent BRAN, 9 percent STEEP; 3) 18 percent BRAN, 12 percent STEEP; 4) 15 percent BRAN, 15 percent STEEP; 5) 12 percent BRAN, 12 percent GERM, 6 percent STEEP; 6) 10.5 percent BRAN, 10.5 percent GERM, 9 percent STEEP; 7) 9 percent BRAN, 9 percent GERM, 12 percent STEEP; and 8) 7.5 percent BRAN, 7.5 percent GERM, 15 percent STEEP (Table 1).

Table 1. Composition of finishing diets (percent of DM).

Finishing diets were formulated to contain a minimum of 12.5 percent CP, .7 percent Ca, .35 percent P and .7 percent K. Adaptation to high concentrate diets was accomplished over 21 days using diets containing 45, 35, 25 and 15 percent alfalfa hay (DM basis) and were fed for three, four, seven and seven days, respectively. Byproduct blends were maintained at 30 percent of dietary dry matter throughout the adaptation process. High-moisture corn and dry-rolled corn replaced alfalfa hay as steers were adapted to the 92.5 percent concentrate finishing diet which contained 25 g/ton Rumensin and 10 g/ton Tylan.

Before obtaining initial weights on two consecutive days, yearlings were fed a common 50 percent roughage diet at 2.0 percent of body weight for five days. Steers were implanted with Synovex® Plus^TM on day one, and fed once daily throughout the trial. Fat depth, quality grade and yield grade data were collected following a 24-hour chill. Hot carcass weight was divided by a common dressing percentage (62) to estimate final live weights.

Results

An interaction (P <.05) occurred for dry matter intake, ADG and feed to gain when STEEP replaced BRAN or BRAN/GERM. Dry matter intake exhibited a quadratic (P =.06) response when STEEP replaced BRAN and a linear response when STEEP replaced BRAN/GERM (P =.05) (Figure 1). Within the BRAN treatments, dry matter intake increased from 6 to 12 percent STEEP, but decreased at the 15 percent STEEP level. In the BRAN/GERM diets, dry matter intake was greatest at the ratio of 15 percent BRAN and GERM to 15 percent STEEP, but was similar for other treatments.

Figure 1. BRAN and BRAN/GERM by STEEP level interaction for dry matter intake.

A linear increase (P <.01) in ADG was demonstrated within the BRAN/GERM treatments as STEEP increased in the diet from 6 to 15 percent. (Figure 2). This treatment also exhibited a quadratic response (P =.03) for ADG due to the mean for 12 percent STEEP. Although the gain exhibited for this STEEP level appears lower than others within this three-way combination, it is unreasonable to conclude this depression is nutritionally based. We believe this mean was influenced by variation in gain potential of the yearlings, causing the noticeable departure from the linear nature of the response. Within the BRAN treatments, a quadratic response was observed for ADG (P =.01) with diets containing 9 and 12 percent STEEP exhibiting the highest daily gains.

Figure 2. BRAN and BRAN/GERM by STEEP level interaction for average daily gain.

A linear decrease (P <.05) in feed to gain was noted when BRAN or BRAN/GERM was replaced by STEEP. Within the BRAN/GERM treatments, the increased feed to gain associated with the 18 percent BRAN/GERM and 12 percent STEEP level (Table 2) is likely a function of the ADG for this treatment. A direct comparison of means for feed to gain between BRAN and BRAN/GERM treatments was not possible due to the significant interaction. However, linear regression analysis plotting feed efficiencies across STEEP levels (Figure 3) illustrated combining BRAN with GERM enhanced feed efficiency relative to BRAN alone.

Figure 3. BRAN and BRAN/GERM by STEEP level interaction for feed to gain ratio. Points define actual means, wheras lines represent estimates obtained through linear regression.

A BRAN and BRAN/GERM by STEEP level interaction was observed for hot carcass weight which reflected the ADG data. Means for fat depth, quality grade and yield grade did not indicate a similar interaction, nor did carcass measures differ due to treatment (Table 2).

Table 2. Performance data and carcass characteristics for yearling steers.