Wheat middlings in high concentrate finishing rations: cattle performance

One hundred twenty medium-framed steers were fed one of six high (90%) concentrate rations: control (0), 5, 10, or 15% pelleted wheat middlings (WM) replacing the concentrate (dry rolled corn) and 5 or 10% pelleted WM replacing the roughage (chopped alfalfa hay). Increasing WM replacement of the concentrate increased both dry matter (DM) intake and feed/gain ratio linearly, without influencing daily gain or final weight. WM replacement of the roughage decreased DM intake linearly, but it ha d no effect on daily gain, final weight, or feed efficiency . The data indicate that WM could replace only 5% of the concentrate without reducing cattle performance, but complete (100%) or partial (50%) replacement of the roughage with WM had no adverse effect on cattle performance.

The pelleted wheat middlings were provided by ADM Milling Co., Shawnee Mission, Kansas. 1 Former graduate student, current address: Grant County Feeders, Ulysses, Kansas.

Summary
One hundred tw enty medium-framed steers were fed one of six high (90%) concentrate rations: control (0), 5, 10, or 15% pelleted wheat middlings (WM) replacing the concentrate (dry rolled corn) and 5 or 10% pelleted WM replacing the roughage (chopped alfalfa hay).Increasing WM replacement of the concentrate increased both dry matter (DM) intake and feed/gain ratio linearly, without influencing daily gain or final weight.WM replacemen t of the roughage decreased DM intake linearly, but it ha d no effect on daily gain, final weight, or feed efficiency .The data indicate that WM could replace only 5% of the concentrat e without reducing cattle performance, but complete (100%) or partial (50%) replacemen t of the roughage with WM had no adverse effect on cattle performance.

Introduction
In 1991, 11.0% of the flour milled in the United State s was produced in Kansas, yielding about 700,000 tons of mill feeds.Wheat middlings (WM) are bypro ducts of flour milling comprising a m i xture of small particles of bran, germ, and the aleurone layer of the wheat kernel.Al though WM are used commonly as a feed source for livestock, very little information is available concerning their nutritive value when added to high conce ntrate, feedlot rations.In an earlier trial, we found that pelleted WM could replace about 10% of the corn without reducing the rate and efficiency of gain of finishing stee rs (KAES Report of Progress 497, page 21).We know of no publis h ed studies that have determined the potential value of WM as a roughage source in beef cattle finishing rations.
Our objectives were to determin e the effects on cattle performance of WM fed as a replacemen t for either the concentrate or roughag e components in finishing rations for feedlot steers.

Experimental Procedures
One hundred twen t y medium-framed steers averagin g 805 lb were blocked by weight and rando mly allocated from each block to one of six treatment groups of 20 steers (four replicates of five steers per pen).The treatment s consisted of the following high concentrat e rations (81.5% dry-rolled corn, 10% chopped alfalfa, 6% suppl e ment, and 2.5% molasses on a DM basis): control ; 5, 10, or 15% pelleted (.25 inch) WM replacing the concentrate; and 5 or 10% pelleted WM replacing either 50 or 100% of roughage.Daily NE g intakes were estimated from the NRC NE g values of the dietary ingred i ents.After a 12-day adaptatio n to the rations, the steers were weighed on 2 consecuti ve days, and the average was used as the initial weight.Final weights were determined in the same manner.At the terminatio n of the trial (112 days), steers were slaughtere d at Iowa Beef Packing, Emporia, Kansas , and standard carcass measurements were made at 24 h ours postslaughter by Kansas State University personnel.
Data were analyzed using the SAS GLM procedure.The feedlot performance and carcas s data were analyzed as a Randomized Complete Block design using orthogonal contrasts (linear, quadratic, and cubic) for specific treatment comparisons.Terms in the fixed effects mo del included the main effects of block (steer weight) and level of WM as a concentrate or roughage replacement.
The effect of replacing the concentrate componen t with WM on performance and carcas s characteristics in the feedlot steers is presented in Table 1.Both DM intake (P<.01) and feed/gain ratio (P<.05) increased linearly with increasing level s of WM in the ration.DM intake increased 9.2% and feed/gain ratio increased 1 0.1% for steers fed the 15% level of WM compared to controls.Daily gains and final weights were not influenced by WM replacin g corn.Estimated daily NE intake ing creased (P<.01) in a linear manner as WM replaced concentrate .The 10 and 15% replacements increased NE intake by 9.4 and 7.1%, g respectively, compared to the control ration.In Figure 1  The effect of replacing the roughage component w ith WM is also presented in Table 1.Intakes of both D M and NE were decreased g (P<.05) in a linear manner wit h increasing levels of WM.This reduct i on in energy intake did not affect ADG because of the linear increase in nutrient digestibilities observed with increasing replacemen t of the roughage component with WM (se e page 22 of this report).Final weight, ADG, and feed/gain were not affected by replacing the roughage with 5 or 10% WM.No liver abscesses were observed.
In summary, wheat mi ddlings could replace only 5% of the concentrate in the finishing rations without reducing cat t le performance, but complete (100%) or partial (50%) replacement of the roughage in finishin g rations with wheat middlings did n ot affect growth performance of steers in this study.

Figure 1 .
Figure 1.Effect of Replacing the Concentrate Component of Finishing Rations with WM on Observed ADG ( n ) and ADG Predicted from Daily NE g Intake are the observed daily gains and those predicted from the daily NE intakes:

Table 1 . Effects of Replacing either the Concentrate or Roughage Components with Pelleted WM on Performance and Carcass Characteristics in the Feedlot Steers a
a Values are least square means, and SE is the pooled standard error of the mean.