Influence of Hull-less Oats on Feedlot Performance and Carcass Characteristics in Beef Steers

Dan Schimek, Marc Bauer, Joel Caton, Vern Anderson, Dan Dhuyvetter, and Paul Berg

Animal and Range Sciences Department

North Dakota State University, Fargo

SUMMARY

One hundred and forty-four crossbred beef steers were used to evaluate hull-less oats (Paul) when substituted for corn in feedlot finishing diets. Five diets were fed using the following ratios of corn to hull-less oats: 0:100, 25:75, 50:50, 75:25, and 100:0. Steers were allotted to treatment on October 30, 1996 at 622 ± 1.71 pounds and were slaughtered in May of 1997 at 1200 ± 31 pounds. Steers fed diets containing hull-less oats had lower dry matter intakes, and lower average daily gains. There was also a linear decrease in hot carcass weight, marbling, ribeye area, and back fat in steers fed hull-less oats when compared with controls.

INTRODUCTION

Hull-less oats are a new crop with considerable potential as a livestock feed. Preliminary data suggests that its high energy level could result in hull-less oats being competitive with corn (Johnson et al., 1995). Moreover, North Dakota growing conditions and production costs are well suited for expanded production of naked oats. With construction of potato and corn processing plants, conditions support expanding the cattle feeding industry. Hull-less oats could potentially be a competitive feed source for this developing industry in the Northern Great Plains Region.

Few studies found in the literature address both nutritional and economic potential of hull-less oats as a feed source and its influence on subsequent meat quality characteristics in beef cattle. This novel grain is characterized by a relatively high lipid (7 to 10%) and crude protein (16 to 19%). The added expense of supplemental protein in beef cattle diets can contribute significantly to total feed costs. The high concentration of protein in hull-less oats could help minimize these supplemental protein costs. The high lipid content not only increases energy density in hull-less oats compared to other feed grains, but the distinctive fatty acid composition, characterized by a higher proportion of unsaturated fatty acids may assist in addressing human health concerns related to meat quality. Evaluation of hull-less oats as a feed source because of its unique protein and lipid qualities is a prerequisite for developing a market for this grain in the beef cattle feeding industry. The objectives of this study was to determine a relative feed value of hull-less oats compared to corn, so that economic comparisons to other feed grains can be made.

PROCEDURE

One hundred and forty-four crossbred beef steers were (622 ± 1.71 lb) were allotted randomly to one of five treatments. Initially there was a 21 day acclimation period during which steers received diets containing 45% roughage for 3 days, 35% roughage for 4 days, 25% roughage for 7 days, and 15% roughage for 7 days. Final diets consisted of 7.5% roughage and 92.5% concentrate. The roughage portion of the final diet contained 50% alfalfa hay and 50% corn silage (50% percent grain) on a dry matter basis. The concentrate portion consisted of 5.2% supplement and 84.8% dry rolled corn or hull-less oats. Hull-less oats replaced 0, 25, 50, 75, and 100 percent of the corn (Table 1). Grains were dry-rolled using a roller grinder (Roskamp Champion, model K) equipped with two pairs of rollers and 1.5:1 speed reduction. Final diets were formulated to contain .7% Ca, .7% K, .32% P, 25 g/ton Rumensin, and 10 g/ton Tylan; also, trace minerals and vitamins were added to meet or exceed NRC recommendations.. Steers were implanted with Ralgro on day 1 and again on day 84 with Revalor-S. After day 84, hull-less oats fed in the 100% hull-less oats treatment were left whole. Rolled oats were processed too fine and were depressing intake severely in the 100% hull-less oats treatment.

Table 1. Diet and Nutrient Composition
Percentage of Hull-less Oats in Grain Portion of Diet
Item 0% 25% 50% 75% 100%
Diet Composition
Hull-less Oats, % 0.0 21.2 42.4 63.6 84.8
Corn, % 84.8 63.6 42.4 21.2 0.0
Corn Silage, % 5.0 5.0 5.0 5.0 5.0
Alfalfa, % 5.0 5.0 5.0 5.0 5.0
Supplement, %a 5.2 5.2 5.2 5.2 5.2
Nutrient Composition
Crude Protein, % 12.3 14.4 16.4 18.5 20.5
NDF, % 14.6 14.9 15.2 15.5 15.8
NEm Mcal/cwtb 94.4 94.1 95.9 100.7 94.7
NEg Mcal/cwtb 64.3 63.8 65.5 69.3 64.1
a Contained 14.4% urea, 37.2% sunflower meal, minerals, vitamins, and feed additives.

b Calculated net energy values were based on steer performance; hull-less oats NEg = 70.9 Mcal/cwt , corn NEg = 73.2 Mcal/cwt.



Initial weights were an average of two-day weights taken before feeding following a 3-day feeding period of a 50% alfalfa hay and 50% corn silage (DM basis) diet. Intake during this time was limited to 1.75% (DM) of body weight. Steers were weighed every 28 days after initial weights were taken. Final weights were based on hot carcass weights at a 62% dress. Average daily gain, dry matter intake, and feed to gain ratio were calculated. Carcass measurements included hot carcass weight, liver score, ribeye area, back fat thickness, marbling, kidney pelvic and heart fat, and yield grade.

RESULTS

Steers were shipped to IBP (Luverne, MN) on April 30 and May 19 (182 and 202 days on feed, respectively). Dry matter intake declined linearly (P < .10) throughout the trial (Table 2) with increasing levels of hull-less oats. There was also a linear decrease (P < .10) in ADG from day 0 to day 84 and throughout the trial. On day 84, the decision was made to discontinue rolling the hull-less oats for the 100% hull-less oats diet, this was done because the rolled oats were too fine and thought to have been reducing intakes. From day 84 to the end of the trial ADG was not affected (P > .10) by treatment. No difference on FG was observed with the addition of hull-less oats to the diet (Table 2).

Table 2. Effect of Hull-less Oats on Steer Performance
Percentage of Hull-less Oats in Grain Portion of Diet
Item 0% 25% 50% 75% 100% RMSEe
Weight, lb
Initial 621 621 622 624 620 3.3
Day 84abc 903 889 875 879 813 21.1
Slaughter ad 1262 1230 1199 1183 1132 60.5
DMI, lb/day
Day 0 to 84a 18.55 17.58 15.72 15.40 12.82 0.943
Day 84 to Slaughtera 21.74 21.27 20.29 19.13 19.62 1.457
Day 0 to Slaughtera 20.35 19.64 18.28 17.50 16.80 1.091
ADG, lb/day
Day 0 to 84abc 3.31 3.15 2.97 3.00 2.26 0.238
Day 84 to Slaughter 3.30 3.10 2.98 2.75 2.88 0.521
Day 0 to Slaughtera 3.30 3.13 2.98 2.87 2.62 0.318
Feed/Gainf
Day 0 to 84 5.62 5.54 5.28 5.07 5.62 0.016
Day 84 to Slaughter 6.57 6.78 6.80 6.90 6.81 0.031
Day 0 to Slaughter 6.19 6.23 6.14 6.05 6.36 0.021
a Linear effect of hull-less oats (P < .10).

b Quadratic effect of hull-less oats (P < .10).

c Cubic effect of hull-less oats (P < .10).

d Calculated from hot carcass weights at a 62% dress.

e Root Mean Square Error. Standard Error = RMSE/n; n=4 for 0% hull-less oats and 5 for remainder.

f Feed/gain was analyzed as gain/feed. Feed/gain is the reciprocal of gain/feed.

Addition of hull-less oats linearly (P < .10) decreased ribeye area, lowered carcass weight, decreased back fat thickness and lowered marbling (Table 3). Yield grade and liver score were not effected by the addition of hull-less oats.

Results from this trial show that hull-less oats decreased gains, lowered dry matter intakes, decreased ribeye area, lowered back fat thickness, lowered carcass weights, and decreased marbling scores. However hull-less oats did not significantly affect feed efficiency, liver score, or yield grade.

Rapid fermentation of the hull-less oats within the rumen may have led to acidosis and depressed feed intake in steers receiving hull-less oats. Depressed intakes could account for many of the other effects of hull-less oats seen in the experiment. Feed to gain ratio was not significantly effected by the addition of hull-less oats to the diets, so decrease in average daily gain could be a direct affect of decreased intake; furthermore, dietary NEg was not different (P = .83) among treatments. Based on steer performance, NEg for hull-less oats (.709 Mcal/lb) was 97% of corn (.732 Mcal/lb). Decreased average daily gain led to a lighter final weight on the same number of days on feed. Lighter final weights can lead to the other effects on carcass characteristics such as smaller ribeyes, less backfat, and decreased marbling scores. It seems too fine of processing contributed to poor intakes by steers fed hull-less oats. It also appears intakes improved after switching from rolled to whole hull-less oats on day 84 in the 100% hull-less oats treatment. More research is planned to determine the effects hull-less oats and particle size on ruminal acidosis.

Table 3. Effect of Hull-less Oats on Carcass Characteristics
Percentage of Hull-less Oats in Grain Portion of Diet
Item 0% 25% 50% 75% 100% RMSEd
Carcass Weight, lba 782 763 743 733 702 47.7
Liver Scorec 0.08 0.14 0.08 0.16 0.08 0.140
Marbling Scoreab 414 377 392 357 350 34.1
Yield Grade 2.3 2.2 2.3 2.2 2.0 0.27
Ribeye Area, in2a 14.2 13.9 13.6 13.3 13.4 0.64
Fat Thickness, ina 0.36 0.32 0.33 0.29 0.28 0.054
a Linear effect of Hull-less oats (P < .10).

b Slight=300-399; Small= 400-499.

c Liver score 0= healthy, 1= small abscesses, 2= medium abscesses, 3= large abscesses, 4= liver adhered to diaphragm.

d Root Mean Square Error. Standard Error = RMSE/n; n=4 for 0% hull-less oat and 5 for remainder.



Literature Cited

Johnson,J., D.Dhyuvetter,B. Kreft, and K.Ringwall.A comparison of naked oats to barley when fed in a grower diet to beef calves. Dickinson Research and Extension Center 43rd annual Research Roundup. p. 83-88.