JAY, ARC RESEARCH REPORT WF78-1 MAY, 1978
jf/7 4 THE PRODUCTION OF LIGHTWEIGHT BEEF ON WINTER AN AL 'A REL-/ IAf y
FOLLOWED BY VARIOUS PERICDS OF FEEDLOT FADING
4;OV 16 1797
J. E. Bertrand, L. S. Donavin, and R. L. est2/
IA.A.S 6 I
Winter annual pastures, consisting of a pure stand o r i@fiIa~-1u
as rye, wheat, oats, and triticale or a small grain crop in a mixture -
grass and crimson clover, have produced quality grazing and good gains with
unsupplemented and supplemented lightweight beef calves. Feeding on winter annual
pastures has been utilized as a system for finishing beef cattle. However, the
feeding of grain to beef calves grazing winter annual pastures has not always been
profitable. Therefore, a short period of feeding in the feedlot after removal of
the cattle from winter grazing may be a better system of utilizing expensive
concentrate feeds, such as grain, for increasing the carcass weight and improving
the carcass quality of lightweight beef.
The purpose of this study was to determine the effect of various periods of
feedlot feeding on the performance, slaughter, carcass, and economic data of
unsupplemented and supplemented lightweight beef steers after grazing winter
Sixty-four lightweight (average 456 lb.) feeder steers 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 groups to eight experimental groups
of eight steers each. The eight experimental groups, utilizing four groups
(replicates) per treatment, were assigned to two pasture treatments as follows:
1. Unsupplemented---rotational grazing of a 'Wrens abruzzi' rye, 'Gulf'
ryegrass, and 'Dixie' crimson clover mixture (four 1.25 acre plots for
each group initially containing eight steer calves).
2. Supplemented (11% protein high-energy ration at the level of 1% of body
weight daily)---same pasture mixture, land area, and number of calves
as 1 above.
The rye was planted in row widths of 7 inches with a grain drill at the rate
of 65 lb. per acre. The ryegrass and crimson clover were top-seeded over the rye
with a cultipacker-seeder at the rates of 15 and 8 lb. per acre, respectively. The
first and second rotational pastures for each treatment were planted on October 19
and 20, 1976; while the third and fourth rotational pastures for each treatment
were planted cn '7oovember 26 and 27, 1976. A commercial fertilizer (8-24-24) was
applied at the rate of 250 lb. per acre to all pastures at plant in time. Three
applicat.onc; of I00 lb. per acre each of ammonium nitrate were made during the
Grar.tng began on December 21, 1976, and was terminated when the forages were
essentially grazed out (May 19, 1977). The animals had to be removed from pastures
and f.':d corn silage in the feedlot for 23 days (January 26 February 18, 1977)
b.~.:. ,. of inclement weather and poor forage growth. Individual animal weights
l!/'esented at the 1978 Beef Cattle Short Course, May 3-5, University of Florida,
2/Animal Scienti st and Associate Agronomist, respectively, Agricultural Research
Center, Jay, and Neat Scientist, Animal Science Department, Gainesville, Florida.
were taken after an overnight shrink (fast from feed and water) at the beginning
and end of the trial period as well as at the beginning and end of the short corn
silage feeding period. Group weights were obtained on all groups every 28 days
during the trial. Additional grazer animals of the same type and weight were
added and removed as needed to keep the forage uniformly grazed. They were weighed
before entering the grazing plots and upon removal.
The pasture supplemental ration, where applicable, was fed once daily.
Supplemental feed consumed by grazer animals was appropriately accounted for. The
feed allowance for each group during each 28-day period was established by using
the previous 28-day weights to project average weights for the period. Each
experimental group of steers was rotated between the four pasture plots assigned
to it as required for best utilization of good quality forage.
At the end of the pasture phase, the unsupplemented and supplemented steers
were assigned by replicate groups (1, 2, 3, and 4) to various periods (0, 28, 56,
and 84 days, respectively) of feedlot feeding. The feedlot ration, composed of 50%
forage sorghum silage, 45% ground corn, and 5% concentrate supplement on an as-fed
basis (29, 64, and 7% on a dry matter basis, respectively), was fed twice daily in
an amount of feed that the steers in each respective group would clean-up between
Individual animal weights in the feedlot were also 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 the pasture and feedlot phases.
The composition and cost of the pasture supplemental ration and the
concentrate supplement are listed in Tables 1 and 5, respectively. The proximate
analyses of the feedstuffs consumed during the pasture and feedlot phases are
listed in Tables 2 and 6, respectively.
The animals were transported and 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
Analyses of variance on performance, slaughter, and carcass data where
appropriate for the pasture and feedlot phases of the trial were conducted accord-
ing to Snedecor (1946). The multiple range test of Duncan (1955) was used to test
significance between group means.
RESULTS AND DISCUSSION
Performance data of the steers during the pasture phase of the trial are
presented in Table 3. This period consisted of 126 days of pasture grazing plus
23 days of silage feeding for a 149-day total period. Steers fed the 11% protein
high-energy ration on pasture at the level of 1% of body weight daily gained
(P<0.01) faster than unsupplemented steers for both the 149-day total period
and the 126-day pasture period (2.18 versus 1.95 and 2.33 versus 2.08 lb./head/
day, respectively). The gains during the 23-day silage feeding period were not
significantly different. The animal gain per acre (513 lb.) was higher (P(O.01)
for steers receiving the supplemental feed on pasture than that (449 lb.) of
unsupplemented steers. The stocking rates per acre did not differ significantly.
However, because of a slightly higher stocking rate per acre and more rapid gain,
the supplemented steers had a larger (P(0.01) gain per acre per day than
unsupplemented steers (4.08 versus 3.56 lb., respectively).
Economic data of unsupplemented and supplemented steers are presented in
Table 4. The cost of gain was lower for the unsupplemented steers on pasture than
that of supplemented steers ($22.65 versus $32.74/cwt, respectively). Also,
unsupplemented steers finished the grazing phase of the trial with a lower cost
per hundredweight ($29.90 versus $33.77, respectively).
Performance, slaughter, and carcass data of beef steers for the feedlot
periods of feeding are presented in Table 7. Beef steers supplemented on pasture
and fed in the feedlot for 28 days gained (P(0.01) faster than the other groups
fed in the feedlot. They were also somewhat more efficient in converting feed to
gain than the other groups fed in the feedlot. Feed consumption for the groups
were very similar.
The carcass quality grades and marbling scores generally increased as the
length of feeding in the feedlot increased (Table 7). The carcass yield grades
increased as the length of feeding in the feedlot increased, indicating that leaner
carcasses were produced on the shorter periods of feeding. Average dressing percent
increased as the length of feeding in the feedlot increased and apparently were due
to proportionately smaller amounts of fill along with heavier and more highly
finished carcasses. The trend towards the progressive increase in carcass quality
grades, carcass yield grades, and dressing percent as the length of feeding in the
feedlot increased was more applicable for the steers unsupplemented during the
Economic data of beef steers for the feedlot phase are presented in Table 8.
The feed cost per hundredweight gain in the feedlot was lowest ($29.93) for steers
supplemented on pasture and fed for 28 days in the feedlot and highest ($52.71)
for steers unsupplemented on pasture and fed for 56 days in the feedlot. Considering
all factors (off grazing cost, feed cost, gain, feed conversion, carcass quality
grade, carcass yield grade, carcass weight, dressing percent, etc.) which contribut-
ed to the net return per head, the steers unsupplemented on pasture had a higher
net return in the feedlot. The steers with the highest net return per head ($42.49)
were those that were unsupplemented on pasture and fed for 84 days in the feedlot.
The steers with the lowest net return per head ($2.81) were those that were supple-
mented on pasture and fed for 84 days in the feedlot.
Under the conditions of this study the following statements appeared justified:
1. Beef steers supplemented on winter annual pastures with an 11% protein
high-energy ration at the level of 1% of body weight daily gained faster
(Pf0.01) than unsupplemented beef steers. However, considering the
economic situation existing at the time, the off grazing cost per
hundredweight was lower for unsupplemented beef steers.
2. In the feedlot phase, the fastest gaining and most efficient in converting
feed to gain was the group supplemented on pasture and fed for 28 days in
the feedlot. However, again considering the economic situation existing
at the time, they were not the most profitable group.
3. Considering all factors (off grazing cost, feed cost, gain, feed conver-
sion, carcass quality grade, carcass yield grade, carcass weight, dressing
percent, etc.) which contributed to the net return per head, it was not
profitable to supplement steers grazing winter annual pastures prior to
going into the feedlot for various periods of feeding. The highest net
return per head occurred with steers unsupplemented on pasture and fed in
the feedlot for 84 days.
Composition and Cost of the Pasture Supplemental Ration (1976-77) ARC, Jay.
Ingredients % ,Lb./ton Cost(a)
Corn (ground) 42.362 847 $ 40.23
Sorghum grain (ground) 54.600 1092 46.68
Salt (trace-mineralized) 0.500 10 0.43
Dicalcium/monocalcium phosphate 1.500 30 3.68
Urea 45% N 1.000 20 1.58
Zinc bacitracin supplement(b) 0.038 0.75 1.20
Vitamin A Supplement(c) + + 0.12
Subtotal $ 93.92
Total 100.000 1999.75 $105.92
(a) Based on the following prices: corn (ground) = $95.00/ton, sorghum grain
(ground) $85.50/ton, salt (trace-mineralized) = $85.00/ton, dicalcium/
monocalcium phosphate m $245.00/ton, urea ,45% N = $158.00/ton, Baciferm
40 (zinc bacitracin supplement containing 40 grams of the antibiotic per
pound) $1.60/lb., and Rovimix A-650 (vitamin A supplement containing
650,000 IU/gram) = $6.00/lb.
(b) Zinc bacitracin added at the level of 30 g/ton or 15 mg/lb. of pasture
(c) Vitamin A added at the level of 6 million IU/ton or 3000 IU/lb. of
pasture supplemental ration.
(d) Mixing, milling, overage, storage, etc.---$12.00/ton.
Proximate Analyses of the Pasture Forage, Corn Silage, and the Pasture Supplemental
Ration (1976-77) ARC, Jay.
Pasture Corn Pasture
Item forage(a) silage(b) supp. ration(c)
Moisture, % 83.05 58.50 13.01
Crude protein, % 4.44 3.41 11.03
Ash, % 1.70 1.30 2.85
Ether extract, % 0.90 1.21 2.45
Crude fiber, % 3.25 6.57 2.70
Nitrogen-free extract, % 6.66 29.01 67.96
(a) Pasture forage (mixture of rye, ryegrass, and crimson clover) (average of four
hand-plucked samples collected at intervals during the pasture phase).
(b) Corn silage (average of four samples collected at intervals during the pasture
(c) Pasture supplemental ration (average of four samples collected at intervals
during the pasture phase).
Performance Data of Unsupplemented and Supplemented Growing Beef Steers Grazing
Winter Annual Pasture (1976-7) ARC, Jay.
Item Unsupplemented Supplemented
Initial no. of animals 32(b) 32
Length of trial, days 149 149
Length of grazing, days 126 126
Length of silage feeding, days(c) 23 23
Avg initial wt, lb. 457 455
Avg final wt, lb. 747 780
Avg gain/animal, lb. 290 325
Avg daily gain for period, lb. 1.95 2.18**
Avg daily gain on pasture, lb. 2.08 2.33**
Avg daily gain on silage, lb. 1.20 1.40
Gain/acre, Ib. 449 513**
Animal days/acre 216 220
Stocking rate/acre(d) 1.71 1.75
Gain/acre/day, lb. 3.56 4.08**
Feed/cwt gain, lb.(e) ---- 273
Feed/animal/day, lb.(e) ---6.3
Silage/cwt gain, lb.(f) 2333 2000
Silage/animal/day, lb.(f) 28 28
(a) Rotational grazing of a rye, ryegrass, and crimson clover mixture (unsupp-
lemented and supplemented with an 11% crude protein high-energy ration at
the level of 1% of body weight daily).
(b) Initially, four groups of eight steer calves each.
(c) Animals had to be removed from pastures due to inclement weather and poor
forage growth (January 26 February 18, 1977).
(d) Additional grazer animals of the same type and weight were aaded and remov-
ed as needed to keep the forage uniformly grazed.
(e) Pasture supplemental ration in the 126-day period (does not include pasture).
(f) For the 23 days off of pasture (no other feed fed for that period).
** Significant at P40.01.
Economic Data of Unsupplemented and Supplemented Growing Beef Steers Grazing
Winter Annual Pasture (1976-77) ARC. Jar.
Item Unsupplemented Supplemented
Icost/cwt gain (b)
Pasture(c) $ 20.21 $ 17.62
Silage(d) $ 2.44 $ 2.18
Pasture supp. ration(e) ------ $ 12.94
Total(f) $ 22.65 $ 32.74
cost/head of feeder(g) $157.67 $156.98
feed cost/head of feeder $ 65.69 $106.41
Total cost/head of feeder(f) $223.36 $263.39
grazing cost/cwt(f) $ 29.90 $ 33.77
Treatments same as in Table 3.
For the 149-day period.
Pasture cost = $100.20/acre.
Corn silage cost = $22.00/ton.
Pasture supplemental ration cost = $105.92/ton.
Does not include labor involved in feeding and caring for the animals.
Calf cost = $34.50/cwt (includes cost of animals, hauling, veterinary costs, etc.)
Composition and Cost of the Concentrate Supplement (1977) ARC, Jay.
Ingredients % Lb./ton Cost(a)
Soybean meal (44% protein) 61.2 1224 $179.32
Urea 45% N 11.2 224 $ 17.70
Dicalcium/monocalcium phosphate 7.5 150 $ 18.37
Ground limestone 11.2 224 $ 7.28
Salt (trace-mineralized) 8.9 178 $ 8.81
Vitamin A supplement(b) + + $ 1.23
Markup(c) $ 12.00
Total 100.0 2000 $244.71
(a) Based on the following prices: soybean meal (44% protein) = $293.00/ton,
urea 45% N = $158.00/ton, dicalcium/monocalcium phosphate = $245.00/ton,
ground limestone = $65.00/ton, salt (trace-mineralized) = $99.00/ton, and
Rovimix A-650 (vitamin A supplement containing 650,000 IU/gram) = $6.00/lb.
(b) Rovimix A-650 (vitamin A supplement containing 650,000 IU/gram) added at
the level of 60 million IU/ton or 30,000 IU/lb. of concentrate supplement.
(c) Mixing, milling, overage, storage, etc.---$12.00/ton.
Proximate Analyses of the Sorghum Silage, Ground Corn, and
Cnncent-rat-a gpplmpent (1977) ARC, Jay.
Sorghum Ground Concentrate
Item silage(a) corn(a) supplement(a)
Moisture, % 63.34 11.69 9.12
Crude protein, % 2.30 8.87 46.58
Ash, % 1.62 1.64 29.27
Ether extract, % 0.81 3.96 0.75
Crude fiber, % 8.29 2.80 4.50
Nitrogen-free extract, %_ 23.64 71.04 9,78
(a) Average of three samples collected at intervals during the feedlot phase.
Performance, Slaughter, and Carcass Data of Beef Steers Off of Winter Annual Pastures Followed by Various Periods of
Feedlot Feeding (1977) ARC, Jay.
Item Unsupplemented on pasture Supplemented on pasture(a)
No. of animals 8 8 8 8 8 8 8 8
Feedlot period, days 0 28 56 84 0 28 56 84
Avg initial wt, lb. --- 742 756 746 --- 776 784 754
Avg final wt, lb. --- 795 854 922 -- 863 896 916
Avg gain/animal, lb. --- 53 98 176 --- 87 112 162
Avg daily gain, lb. --- 1.89b** 1.75b 2.10b --- 3.11a 2.00b 1.93b
Feed/cwt gain, Ib. -- 1548 1622 1377 --- 921 1455 1445
Feed/animal/day, Ib. -- 29.0 28.6 28.8 --- 28.6 29.1 27.8
Avg carcass quality grade(b) 13.8b* 13.3b 15.4ab 16.4a 14.3ab 14.6ab 16.6a 15.4ab
Avg carcass yield grade(c) 1.5c** 2.6b 2.7ab 3.2a 2.5b 2.8ab 2.8ab 2.9ab
Avg marbling scored) 7.6b** 7.3b 10.9ab 12.6a 7.9b 9.4ab 13.5a 10.3ab
Avg color of lean(e) 4.5ab** 3.6c 3.6c 4.0bc 4.8a 3.6c 3.9bc 3.9bc
Avg color of fat(f) 2.3bc** 2.4bc 2.3bc 2.3bc 2.8ab 3.1a 2.6ab 2.0e
Rib eye area, sq. inch 10.04abc* 8.90d 9.56bed 9.98abc 9.79abcd 9.37cd 10.60ab 10.75a
Avg slaughter wt, lb. 744 795 854 922 805 863 896 916
Avg hot carcass wt, lb. 422 460 513 560 474 505 548 555
Avg dressing percent 56.7d** 57.9cd 60.lab 60.7a 58.9bc 58.5bc 61.2a 60.6a
(a) Supplemented on pasture with an 11% crude protein high-energy ration at the level of 1% of body weight daily.
(b) 13 = low good, 14 = average good, 15 = high good, 16 = low choice, 17 = average choice, etc.
(c) Yield grades numbered 1 through 5, with yield grade 1 representing the highest yield of boneless, closely
trimmed retail cuts (cutability) and yield grade 5 the lowest.
(d) 5 = traces, 8 = slight, 11 = small, 14 = modest, etc.
(e) 3 = light cherry red, 4 = cherry red, 5 = moderately dark red, etc.
(f) 1 = white, 2 = cream, 3 = slightly yellow, and 4 = very yellow.
* Means within rows followed by the same letter are not significantly different, P(O.05.
** Means within rows followed by the same letter are not significantly different, P(<0.1.
Economic Data of Beef Steers Off of Winter Annual Pastures Followed by Various
Feedlot period, days
Feed cost/cwt feedlot gain(b)
Off grazing cost/head(c)
Avg feed cost/head
Avg final value/head(d)
Avg price/cwt on foot
Avg price/cwt carcass
------- $ 50.30
------- $ 26.66
$ 13.88 $ 11.03
$ 32.03 $ 32.65
$ 56.48 $ 56.42
$ 52.71 $ 44.75
$ 51.66 $ 78.76
$ 31.70 $ 42.49
$ 36.23 $ 37.34
$ 60.31 $ 61.48
Periods of Feedlot Feeding (1977) -
Supplemented on pasture(a)
0 28 56 84
------- $ 29.93 $ 47.28 $ 46.96
$271.85 $262.06 $264.76 $254.63
------- $ 26.04 $ 52.95 $ 76.08
$271.85 $288.10 $317.71 $330.71
$276.96 $297.12 $337.16 $333.52
$ 5.11 $ 9.02 $ 19.45 $ 2.81
$ 34.41 $ 34.43 $ 37.63 $ 36.41
$ 58.43 $ 58.84 $ 61.53 $ 60.09
(a) Same as Table 7.
(b) Forage sorghum silage cost = $20.00/ton, ground corn cost = $95.00/ton, and concentrate supplement cost =
$244.71/ton (Feedlot ration cost = $64.99/ton on an as-fed basis).
(c) Does not include labor involved in feeding and caring for animals.
(d) Prices used for carcass value calculations: Standard (400-500 lb.) = $54.25/cwt, Standard (500-600 lb.) =
$55.25/cwt, Good (400-500 lb.) = $56.25/cwt or $52.25/cwt for carcasses over Yield 3, Good (500-700 lb.) =
$58.25/cwt or $54.25/cwt for carcasses over Yield 3, Choice (400-500 Ib.) = $60.25/cwt or $56.25/cwt for
carcasses over Yield 3, Choice (500-700 Ib.) = $62.75/cwt or $58.00/cwt for carcasses over Yield 3, and
Prime (500-600 lb.) = $62.75/cwt.