Wheat middlings in roughage-based or limit-fed, high-concentrate diets for growing calves

A 101-day growing study was conducted to evaluate the growth performance of beef heifers fed wheat middlings in traditional fullfed, sorghum silage-based rations and in limit-fed, high-concentrate rations. Diets were formulated without wheat middlings or with wheat middlings replacing 33, 67, or 100% of rolled corn plus soybean meal. Daily gains decreased linearly (P<.01) with increasing levels of wheat middlings in the roughage-based diets because of lower feed intake (P<.10), but feed efficiency was not affected (P>.30). For the limit-fed diets, heifer daily gains decreased linearly (P<.01) as the proportion of wheat middlings in the diet increased, resulting in a linear reduction (P<.01) in feed efficiency. Wheat middlings can be utilized effectively as the predominant energy/protein source for growing cattle, though their nutritional and economic value, relative to corn and soybean meal, may be different for roughagebased and limit-fed diets.


Introduction
A 101-day growing study was conducted Previous research with wheat middlings to evaluate the growth performance of beef (WM) has focused primarily on its use as a heifers fed wheat middlings in traditional full-supplement for beef cows grazing poor fed, sorghum silage-based rations and in quality roughages, where forage utilization is limit-fed, high-concentrate rations. Diets an important consideration. Limited studies were formulated without wheat middlings or indicate that growing cattle respond very with wheat middlings replacing 33, 67, or favorably to WM as a replacement for grain 100% of rolled corn plus soybean meal. Daily and soybean meal in backgrounding rations. gains decreased linearly (P<.01) with increas- The objective of this study was to determine ing levels of wheat middlings in the the feeding value of WM relative to corn and roughage-based diets because of lower feed soybean meal in traditional high roughage intake (P<.10), but feed efficiency was not diets and in limit-fed growing cattle diets. affected (P>.30). For the limit-fed diets, This information about the substitution value heifer daily gains decreased linearly (P<.01) of WM in growing rations will enable beef as the proportion of wheat middlings in the producers to make more informed purchase diet increased, resulting in a linear reduction decisions. (P<.01) in feed efficiency. Wheat middlings can be utilized effectively as the predominant energy/protein source for growing cattle, though their nutritional and economic value, Two hundred and eighty-eight predomirelative to corn and soybean meal, may be nantly British crossbred heifers averaging different for roughage-based and limit-fed 442 lb were used in a randomized complete diets.
were obtained directly from a commercial 4. 40% sorghum silage plus wheat middlings flour mill. Cattle were fed their respective (SSMID100).
diets once daily at ad-libitum intake 5. Limit-fed diet containing dry-rolled corn (roughage-based) or at 2.4% of body weight as the primary energy source (limit-fed, DM basis), during the first 91 days (LFCRN100).
of the growing trial. The amount of feed 6. Limit-fed diet containing 2:1 mixture of offered to the limit-fed cattle was adjusted dry-rolled corn and wheat middlings every 14 days. During the final 10 days, all (LFCRN67).
heifers were fed their respective diet at 2.4% 7. Limit-fed diet containing 1:2 mixture of (DM basis) of body weight daily to equalize dry-rolled corn and wheat middlings ruminal fill differences between the roughage-(LFCRN33). and limit-fed diets. Feed consumption, weight 8. Limit-fed diet containing wheat middlings gain, and feed efficiency were monitored as the primary energy/protein source throughout the growing period. (LFMID100).

Upon arrival at the KSU Beef Teaching and Research Center, heifers were vaccinated
Heifer performance data were analyzed against common viral and clostridial diseases, by regression using percentage of WM in the treated for internal and external parasites with diet as a continuous variable, nested within a topically applied parasiticide, implanted diet type. Over the spectrum of WM evaluwith Synovex®-H, and fed a common re-ated in either the sorghum silage or limit-fed ceiving diet for approximately 2 weeks. At diets, a similar linear decline (P<.01) in daily the start of the study, all calves were weighed gain occurred as the proportion of WM was individually and blocked into three weight increased ( Figure 1). Heifer dry matter groups. On day 2, cattle in each weight block intake of the SSMID100 diet was approxiwere reweighed individually, stratified by mately 10% percent less (P<.10) than intakes weight, and randomly allotted within strata to of the other sorghum silage diets (Table 2). 48 pens containing six head each for a total On the silage diets, feed efficiency (feed of six replicate pens per dietary treatment. DM/gain) changed little (P>.30) as WM Cattle were pen weighed at about 30-day increased. However, in the limit-fed diets, intervals during the study and were weighed efficiency decreased (P<.01) as WM individually on the final 2 days of the experi-increased (Figure 2). ment.
Diets were formulated for approximately this study, WM had a feed value of 95% 2.0 lb daily gain. The roughage-based diets relative to corn and soybean meal when used contained 40% sorghum silage, 14.8% crude in full-fed sorghum silage-based rations but a protein and a Ca:P ratio of 2:1, and the limit-value of 83% when used in limit-fed diets. fed diets contained 15% chopped