JAY, ARC RESEARCH REPORT WF79-3 APRIL, 1979
THE PRODUCTION OF LIGHTWEIGHT BEEF WITH STEERS S ON
COOL-SEASON ANNUAL PASTURES FOLLOWED BY HJ -
TWO PERIODS OF FEEDLOT FEEDING1 L
J. E. Bertrand, L. S. Dunavin, and R. L. West rV 1979
Cool-season annual pastures, consisting of a mixture erass, and
crimson clover, have produced good gains with lightweight (84 .
periods of feeding in the feedlot after removal of the steers from co
grazing have increased the carcass weight and improved the carcass quality of
this lightweight beef. Because lightweight beef heifers can be purchased
considerably cheaper (approximately $0.10/lb.) than comparable lightweight
beef steers in the fall in northwest Florida, the use of heifers for producing
lightweight beef needed to be evaluated.
The purpose of this study was to compare the performance, slaughter, carcass,
and economic data from growing beef heifers versus steers for the production of
lightweight beef after grazing cool-season annual pastures followed by two
periods (56 and 84 days) of feedlot feeding.
Thirty-two lightweight (average 413 lb.) feeder steers and heifers of
British breeding (Angus and Angus X Hereford crosses), grading U. S. Good or
better and each treated with a 36 mg ear implant of RALGRO (Zeranol a protein
anabolic agent), were weighed and allotted at random from breed and sex groups
to two experimental groups of eight steers and two experimental groups of eight
heifers each. The four experimental groups, utilizing two groups (replicates)
per treatment, were assigned to two treatments (steers versus heifers) on pasture-.
The pastures consisted of a mixture of 'Wrens abruzzi' rye, 'Gulf' ryegrass,
and 'Dixie' crimson clover. Each group of eight initial animals grazed four 1.25
acre plots in a rotational system.
The rye was planted in row widths of 7 inches with a grain drill at the
rate of 80 lb. per acre. The ryegrass and crimson clover were top-seeded over the
rye with a cultipacker-seeder at the rates of 11 and 9 lb. per acre, respectively.
All pastures were planted on October 17 and 18, 1977. A complete fertilizer
(8-24-24) was applied to all pastures at planting time at the rate of 250 lb.
per acre. Three applications of 100 lb. per acre each of ammonium nitrate were
made during the grazing season.
Grazing began on December 13, 1977, and was terminated when the forage was
essentially grazed out (May 25, 1978). Individual animal weights were taken after
an overnight shrink (fast from feed and water) at the beginning and end of the
trial period. Group weights were obtained on all groups every 28 days during the
trial. Additional grazer animals of the same type, sex, and size were added and
removed as needed to keep the forage uniformly grazed. Each experimental group of
steers or heifers was rotated between the four pasture plots assigned to it as
required for best utilization of good quality forage.
1/Presented at the 1979 Beef Cattle and Forage Field Day, Agricultural Research
Center, Jay, Florida.
2/Animal Scientist and Associate Agronomist, respectively, Agricultural Research
Center, Jay, and Associate Meat Scientist, Animal Science Department, Gainesville,
The proximate analysis of the pasture forage is listed in Table 1.
At the end of the pasture phase, the steers and heifers were assigned by
replicate groups (1 and 2) to two periods (56 and 84 days, respectively) of feedlot
feeding. The feedlot ration, composed of 50% corn silage, 45% ground corn, and 5%
concentrate supplement on an as-fed basis, was fed ad libitum twice daily.
Individual animal weights in the feedlot were taken after an overnight shrink
at the beginning and end of the trial periods. A mineral mixture (consisting of two
parts dicalcium/monocalcium phosphate and one part trace-mineralized salt), plain
salt, and clean drinking water were available to the animals at all times during
both the pasture and feedlot phases.
The composition and cost of the concentrate supplement fed during the feedlot
phase are listed in Table 2. The proximate analysis of the corn silage, ground corn,
and concentrate supplement are listed in Table 3.
The animals were slaughtered at the end of the feedlot trial periods at the
University of Florida Meats Laboratory, Gainesville. Slaughter and carcass data
were obtained by a federal grader and personnel at the Meats Laboratory.
Analyses of variance on performance, slaughter, and carcass parameters where
appropriate for the pasture and feedlot phases of the trial were conducted according
to the method of Snedecor (1946). The multiple range test of Duncan (1955) was
used to test significance between group means.
RESULTS AND DISCUSSION
Performance and economic data of growing beef steers and heifers grazing
cool-season annual pastures for a period of 163 days are presented in Table 4.
Steers gained (P<0.01) faster than heifers (1.95 versus 1.58 lb./head/day, respec-
tively). The animal gain per acre was 521 Ib. for steers and 425 lb. for heifers.
The stocking rate per acre was very similar. Therefore, because of the more rapid
daily gain, steers had a larger gain per acre per day than heifers (3.20 versus
2.61 lb., respectively).
The cost of gain was lower for steers on pasture than that of heifers ($19.58
versus $24.00/cwt, respectively) (Table 4). The off grazing cost per hundredweight
was $34.10 for steers compared with $31.38 for heifers. This narrowed the initial
difference in purchase cost ($45.20 versus $36.00/cwt, respectively) between steers
and heifers. The steers were estimated by the manager of the local auction market
to be worth $58.40/cwt and the heifers $52.40/cwt at the end of the pasture phase.
Performance, slaughter, and carcass data of beef steers and heifers for the
feedlot phases of feeding are presented in Table 5. Beef steers fed for 56 days
in the feedlot gained 1.57 lb. per head daily, followed by the daily gain (1.45
lb./head) of beef heifers fed for 84 days in the feedlot, the daily gain (1.39
lb./head) of beef steers fed for 84 days in the feedlot, and the daily gain (1.18
lb./head) of beef heifers fed for 56 days in the feedlot. Beef steers fed for 56
days in the feedlot gained (P<0.05) faster and were more efficient in converting
feed to gain than heifers fed for 56 days in the feedlot. For 84 days of feeding in
the feedlot, heifers gained faster than steers and were more efficient in convert-
ing feed to gain.
The performance data (gain, feed/gain, and feed consumption) for all groups in
the feedlot were not as good as obtained in previous studies. This was expected
since the corn silage and ground corn were of poor quality due to drought during
the growing season and plenty of rain prior to harvest resulting in a high
contamination with aflatoxin mold (approximately 500 ppb).
The carcass quality grades, marbling scores, and sizes of rib eye increased
for both steers and heifers as the length of feeding in the feedlot was increased
(Table 5). This was expected as a longer feeding period normally increases carcass
quality. The dressing percent and other carcass parameters did not differ to any
The economic data of beef steers and heifers for the feedlot phase are
presented in Table 6. The feed cost per hundredweight gain in the feedlot was
lowest ($47.04) for beef steers fed for 56 days and highest ($56.39) for beef
heifers fed for 56 days. The reverse was true for 84 days of feeding in the feedlot.
The feed cost per hundredweight gain was $48.91 for beef heifers and $54.21 for
beef steers. Considering all factors (off grazing cost, animal gain, feed/gain,
carcass quality grade, carcass yield grade, carcass weight, and dressing percent)
which contributed to the net return per head, the heifers fed for 84 days in the
feedlot were the most profitable ($87.98/head). In each comparison, heifers had a
higher net return per head than steers ($68.41 versus $55.90 for 56 days in the
feedlot, respectively, and $87.98 versus $67.20 for 84 days in the feedlot,
Proximate Analysis of the Pasture Forage (1977-78) ARC, Jay.
Item Pasture forage(a)
Moisture, % 83.00
Crude protein, % 4.51
Ash, % 1.60
Ether extract, % 0.97
Crude fiber, % 3.30
Nitrogen-free extract, % 6.62
(a) 'Wrens' abruzzi rye, 'Gulf' ryegrass, and 'Dixie' crim-
son clover mixture (average of five hand-plucked samples
collected at intervals during the trial).
Composition and Cost of the Concentrate Supplement (1978) ARC, Jay.
Ingredients % Lb./ton Cost(a)
Soybean meal (44% protein) 61.01 1220 $146.40
Urea 45% N 11.19 224 17.70
Dicalcium/monocalcium phosphate 7.46 149 18.25
Ground limestone 11.19 224 7.28
Salt (trace-mineralized) 8.96 179 8.86
Vitamin A supplement(b) + + 1.23
Zinc bacitracin supplement(c) 0.19 4 6.40
Total 100.00 2000 $218.12
(a) Based on the following prices: soybean meal (44% protein) =
$240.00/ton, urea 45% N = $158.00/ton, dicalcium/monocalcium
phosphate = $245.00/ton, ground limestone = $65.00/ton, salt
(trace-mineralized) = $99.00/ton, Rovimix A-650 (vitamin A supp-
lement containing 650,000 IU/g) = $6.00/lb., and Baciferm 40
(zinc bacitracin supplement containing 40 grams of the anti-
biotic per pound) = $1.60/lb.
(b) Rovimix A-650 (vitamin A supplement containing 650,000 IU/g) added
at the level of 60 million IU/ton or 30,000 IU/lb. of concen-
(c) Baciferm 40 (zinc bacitracin supplement containing 40 grams of
the antibiotic per pound) added at the level of 160 g/ton or 80
mg/lb. of concentrate supplement.
(d) Mixing, milling, overage, storage, etc.---$12.00/ton.
Proximate Analysis of the Corn Silage, Ground Corn, and
Concentrate Supplement (1978) ARC, Jay
Corn Ground Concentrate
Item silage(a) corn(a) supplement(a)
Moisture, % 62.94 11.51 9.74
Crude protein, % 4.79 9.93 50.07
Ash, % 2.18 1.78 29.89
Ether extract, % 1.50 3.59 3.23
Crude fiber, % 8.91 2.43 3.91
Nitrogen-free extract, % 19.68 70.76 3.16
(a) Average of three samples collected at intervals during the trial.
Performance and Economic Data of Growing Beef Steers and Heifers
Grazing Cool-Season Annual Pastures (1977-78) ARC, Jay(a).
Item Steers Heifers
Initial no. of animals 16(b) 16
Length of grazing, days 163 163
Avg initial wt, lb. 416 410
Avg final wt, lb. 734 667
Avg gain/animal, lb. 318 257
Avg daily gain, lb. 1.95** 1.58
Gain/acre, lb. 521 425
Animal days/acre 267 269
Stocking rate/acre(c) 1.64 1.65
Gain/acre/day, lb. 3.20 2.61
Pasture cost/cwt gain(d) $ 19.58 $ 24.00
Avg cost/head of feeder(e) $188.03 $147.60
Pasture cost/head of feeder $ 62.26 $ 61.68
Total cost/head of feeder(f) $250.29 $209M28
Off grazing cost/cwt(f) $ 34.10 $ 31.38
(a) Rotational grazing of a mixture of 'Wrens' abruzzi rye,
'Gulf' ryegrass, and 'Dixie' crimson clover.
(b) Initially, two groups of eight calves each.
(c) Additional grazer animals of the same type and size were
added and removed as needed to keep the forage uniformly
(d) Pasture cost = $102.00/acre.
(e) Steer calf cost = $45.20/cwt and heifer calf cost = $36.00/
cwt (includes cost of animals, hauling, veterinary costs,
(f) Does not include labor involved in caring for the animals.
**Significant at P<0.01.
Performance, Slaughter, and Carcass Data of Beef Steers and Heifers
Off Cool-Season Annual Pastures Followed by Various
Feedlot Feeding (1978) ARC, Jay.
Item Steers Heifers
No. of animals 8 8 8 8
Feedlot period, days 56 84 56 84
Avg initial wt, lb. 736 732 677 656
Avg final wt, lb. 824 849 743 778
Avg gain/animal, lb. 88 1i7 66 122
Avg daily gain, lb. 1.57a* 1.39ab 1.18b 1.45at
Feed/gain ratio 15.1 17.4 18.1 15.7
Feed/animal/day, lb. 23.8 24.4 21.4 22.8
Avg carcass quality grade(a) 12.3b** 14.4ab 14.lab 16.1a
Avg carcass yield grade(b) 2.7 2.7 3.0 2.9
Avg marbling score(c) 5.5b** 8.5ab 7.9ab 12.0a
Avg color of lean(d) 3.6 3.1 3.8 3.4
Avg color of fat(e) 2.8 2.6 2.4 2.5
Rib eye area, sq. in. 9.33ab* 10.03a 8.59b 10.01a
Avg hot carcass wt, lb. 496 509 447 472
Avg dressing percent (carcass yield) 60.2 60.0 60.2 60.7
(a) 12 = high standard, 13 = low good, 14 = average good, 15 = high good, 16 =
low choice, 17 = average choice, etc.
(b) Yield grades numbered 1 through 5, with yield grade 1 representing the high-
est yield of boneless, closely trimmed retail cuts (cutability) and yield
grade 5 the lowest.
(c) 5 = traces*, 6 = traces+, 7 = slight 8 = slight%, 9 = slight+, 10 = small-,
11 = small0, 12 = small+, etc.
(d) 3 = light cherry red, 4 cherry red, 5 = moderately dark red, etc.
(e) 1 = white, 2 = cream, 3 = slightly yellow, and 4 = very yellow.
*Means within rows followed by the same letter are not significantly different,
**Means within rows followed by the same letter are not significantly different,
Economic Data of Beef Steers and Heifers Off Cool-Season Annual Pastures
Followed by Various Periods of Feedlot Feeding (1978) ARC, Jay.
Item Steers Heifers
Feedlot period, days 56 84 56 84
Feed cost/cwt feedlot gain(a) $ 47.04 $ 54.21 $ 56.39 $ 48.91
Off grazing cost/head(b) $250.98 $249.61 $212.44 $205.85
Avg feed cost/head $ 41.40 $ 63.43 $ 37.22 $ 59.67
Total cost/head(b) $292.38 $313.04 $249.66 $265.52
Avg final value/head(c) $348.28 $380.24 $318.07 $353.50
Net return/head(b) $ 55.90 $ 67.20 $ 68.41 $ 87.98
Avg price/cwt on foot $ 42.27 $ 44.79 $ 42.81 $ 45.44
Avg price/cwt carcass $ 70.22 $ 74.70 $ 71.16 $ 74.89
(a) Corn silage cost = $20.00/ton, ground corn cost = $92.00/ton, and
concentrate supplement cost = $218.12/ton (Feedlot ration cost =
$62.31/ton on an as-fed basis).
(b) Does not include labor involved in feeding and caring for animals.
(c) Prices used for carcass value calculations: steers (Choice 1 and
2) 400 to 5CO lb. = $82.25/cwt and 500 to 600 lb. = $83.25/cwt:
steers (Choice 3) 400 to 500 lb. = $80.25/cwt and 500 to 600 lb. =
$81.25/cvt; steers (Good 1 and 2) 400 to 500 lb. = $71.25/cwt and
500 to 600 lb. = $74.375/cwt; steers (Good 3) 400 to 500 lb. -
$70.25/cwt and 500 to 600 lb. = $73.375/cwt; steers (Standard 1, 2,
and 3) 400 to 500 lb. = $69.25/cwt and 500 to 600 lb. = $70.375/cwt;
heifers (Prime 3) 400 to 500 lb. = $76.25/cwt and 500 to 600 lb. =
$78.25/cwt; heifers (Choice 1 and 2) 400 to 500 lb. = $78.25/cwt and
500 to 600 lb. = $80.25/cwt; heifers (Choice 3) 400 to 500 lb. =
$76.25/cwt and 500 to 600 lb. = $78.25/cwt; heifers (Good 1 and 2)
400 to 500 lb. = $71.00/cwt and 500 to 600 lb. = $73.00/cwt; heifers
(Good 3) 400 to 500 lb. = $70.00/cwt and 500 to 600 lb. = $72.00/cwt;
and heifers (Standard 1, 2, and 3) 400 to 500 lb. = $67.00/cwt and
500 to 600 lb. = $69.00/cwt.