Everglades Station Mimeo 62-12 January 1962
Feeding value of corn silage with and without zinc-bacitracin as a preservative
H. L. Chapman, Jr., C. E. Haines and V. E. Green, Jr.
The purposes of the experiment in this report were to obtain preliminary
information concerning the feeding value of Everglades-produced corn silage and
to determine if zinc bacitracin (Silotracin) altered the feeding value.
/ Experimental Procedure
Forty grade Angus and Hereford steers, having an average initial low-stan-
dard slaughter grade, were divided into two equal groups, on the basis of weight,
grade, breed and previous treatment. They were then allotted, at random to the
experimental treatments. The experimental design was as follows:
1 Corn silage, with no preservative
2 Corn silage, with 5 gm. of zinc
bacitracin per ton of fresh material,
as a preservative.
All experimental animals received a full feed of the silage. The corn
ensiled was Corneli 54 field corn grown at the Everglades Station. It was
harvested in the soft-dough stage and had an estimated yield of 82.8 bushels
per acre of ear corn containing 15.5 percent moisture. The zinc-bacitracin
was broadcast on the fresh material as it was distributed in the bunker-type
silo, at the rate of 5 grams per ton of fresh material. The silos were lined
on the sides and covered over the top with plastic sheeting and kept as air-
tight as possible. Data was kept to determine the cost of the edible ensilage.
In addition the steers received an average of 10 pounds of concentrate
feed per animal, daily. This feed was comprised of 65.75 percent ground
snapped corn, 33.0 percent 41% cottonseed meal and 1.25 percent of a complete
mineral mixture, and had a mixed cost of $3.26 per hundred weight pounds.
An initial slaughter grade was placed on each animal by a grading com-
mittee. The initial value per animal was based on the price of cattle of
similar quality at the Belle Glade auction market. The final value was the
actual selling value of each animal. The grades shown in Table 2 are coded
6, 7, 8 for low, medium and high standard and 9, 10 and 11 for low, medium
and high good grades of cattle.
1/ Acknowledgement is made to L. V. Morris, Tom Swager, J. V. McLeod and
who assisted in the conduction of this experiment.
2/ This study was supported in part by a grant in aid furnished by Co ial
Solvents, Inc., Terre Haute, Indiana. i-t
3/ Associate Animal Nutritionist, Assistant Animal Husbandman and Associs
Agronomist, respectively, Everglades Experiment Station.
At the completion of the feeding period the cattle were shipped to Miami
for slaughter and shipping and carcass data obtained. Calculations for this
information were made, as follows:
Final weight Miami weight
a. Intransit shrink Final weight x 100
Warm carcass weight
b. Unadjusted dressing percent Miami weight x 100
Warm carcass weight cold carcass weight
c. Cooler shrink Warm carcass weight x 100
The costs of producing the corn ensilage are presented in Table 1. These
are representative of the cost per acre annually experienced in the production
of field corn at the Everglades Station. They vary only slightly from year to
year. Based on these values the edible corn silage cost $9.90 per ton.
The overall rate of gain of the 40 steers was 2.00 lb. per day, requiring
an average of 10 pounds of concentrate feed and 41.2 pounds of corn silage
daily. When the two silages were compared there was an average daily gain of
1.87 lbs. for the steers receiving the silage with no preservative as compared
to 2.12 for those receiving the zinc-bacitracin silage. The difference in
rate of gain due to treatment was highly significant. There was no statis-
tically significant effect of treatment upon intransit shrink, increase in
slaughter grade, dressing percent or cooler shrink. The return above steer
and feed cost was $3.17 per steer for the animals receiving the corn silage
with no added preservative and $9.14 per steer for those eating the Zinc
Bacitracin treated ensilage.
Table 1. Summary of production costs for field corn silage.
I. Corn production, per acre
a. Plowing $ 5.00
b. Discing (3 times @1.50) 4.50
c. Planting of seed/ 1.50
d. Seed cost (15 lbs. @0.272) 4.08
e. Fertilizer costs?/ 12.05
f. Scratch cultivation (2 times @1.00) 2.00
g. Lay-by and deepen middles 1.00
h. Bird patrol (60 man hrs. for 80 acres) 0.64
i. Wire worm and bud worm controlJ/ 6.66
Total costs per acre $37.43
12.5 acres of corn @$37.43 $467.88
II. Cost of ensiling corn
a. Machinery and labor charges/hour
1. Wheel tractor and driver at chopper $ 2.50
2. Wheel tractor and driver hauling 2.50
3. Crawler tractor in stack 2.00
4. Two men in stack 2.00
Total/hr. $ 9.00
Total of 20 hours per silo @$9.00 $180.00
Total cost for two silos $360.00
III. Ccat of plastic per silo $15.00
Cost of plastic for two silos $ 30.00
Total production cost $857.88
IV. Total green material ensiled 155.73 tons.
Total silage fed 86.67 tons.
2J 500 Ibs. per acre of 0-8-24 with 1.0 CuO, applied broadcast.
SWireworm control 4 pound aldrin/acre in fertilizer.
Budworm control 1 pt. of 2 lb. heptachlor/acre.
Summary of average weight changes, carcass data and cost data per
animal for steers on corn silage study, on test 105 days.
Number of animals
Final weight (Ibs.)
Initial weight (Ibs.)
Total gain (Ibs.)l/
Daily gain (lbs.)
Initial slaughter grade
Final slaughter grade
Increase in slaughter grade (1/3)
Intransit shrink (%)
Unadjusted dressing percent (%)
48-hr. cooler shrink (%)
Daily feed consumption
Concentrate feed (lbs.)
Corn silage (lbs.)
Final animal value ($)
Initial animal value($)
Total feed costs
Return over steer and feed-costs ($)
plus 5 lbs.
1/ Differences in gain are significant at 1% level of probability.