-Department of Animal Science F or1' .rm-
Q', Mimeograph Series No. AN71-5 E e M
'' June, 1971 G inesville, o
USE OF BLIGHT INFECTED CORN IN SWINE DIET JUL 20 1971
G. E. Combs and H D. Wallace !/ IA Un
I.F.A.S. Univ. of Florida
Southern corn leaf blight (Helminthosporium maydis) was a serious ise
on the 1970 corn crop. This fungus produces a toxin which damages the corn plant
but is not necessarily injurious to animals. Because the nutritional value of
corn from blight infected fields may have been altered and there existed the
possibility of toxicity to swine two experiments were conducted.
The blight corn was grown in the Lake City area and came from fields that
produced about 10 bushels per acre. Although the kernels irere small only 10%
or less were discolored and shriveled. No evidence of mold growth was present
at the time of purchase and none developed during storage. Periodic checks for
Aflatoxins also proved negative;
The regular corn was purchased for U.S. No. 2 from a firm in Illinois. It
too was free from molds and Aflatoxins during the experimental period.
Experiment 1: Eighteen pigs averaging 245 lb. were allotted to 2 treatment
groups. Each treatment consisted of 3 replicated pens of 3 pigs each. The
experiment was terminated after a 24 day period.
Experiment 2: Twenty-eight pigs weaned at 4 weeks of age were allotted to
2 replicated pens of 7 pigs each. The duration of the feeding period was 84 days.
In both experiments the pigs were housed in concrete-floored pens equipped
with self-feeders and automatic waterers.
The differences in chemical composition of regular and blight corn were not
considered in formulating the treatment diets. The composition of diets used is
presented in table 1.
The comparative chemical composition of blighted and normal corn is presented
in table 2. The dry matter content was similar for both samples. Blighted-corn
contained slightly less energy than regular corn and this reduction was reflected
by a reduction in fat and starch content.
Table 3 shows the nitrogenous constituents of blighted and regular corn.
Blighted corn contained 1.3 percentage units more "otal protein than regular corn.
This total protein figure was composed of nitrogen-originating from nitrates and
nitrites, ammonia and amlno acids. The nitrogen from these three sources was
convertedd by the 6.25 factor to percentage protein and for blighted corn accounted
!or 94% of the total protein and about 90% for normal corn. The percentage of
,rotein coming from nitrate and nitrite was equal for both corn samples. Protein
crom ammonical nitrogen which is usually considered unavailable to the pig was
highest in the blight corn. Amino acid nitrogen which came from 15 amino acids
was also higher with the blight corn.
1/ Combs and Wallace, Animal Nutritionists, Department of Animal Science.
- 2 -
The essential and non-essential amino acid content of several corn samples
is shown in Table 3. The blight corn and regular corn (Fall '70) represents that
used in the feeding trial; the regular corn in the Fall of 1970 undoubtedly
contained Emall amounts of blighted corn whereas the regular corn in the Spring
of 1970 was harvested prior to the blight outbreak.
With 12 of the 15 amino acids the highest values -were with the blight corn
The 3 exceptions were with methionine and tyrosirc (regular Fall '70) and phenyla-
lanine (Spring '70). In general a small increase in essential and non-essential
amino acids was associated with the blighted corn but this increase was not
sufficient to be of major nutritional significance.
The mineral content of blight and regular corn is compared in Table 4. The
regular corn is not that used in this experiment but represents that found in the
most recent National Research Council's publication on nutrient requirements of
swine. The blighted corn values represent an average of six different samples ob-
tained from six locations in Florida. Blighted corn contains slightly more ash than
regular corn. The content of phosphorus, calcium and copper were comparable for the
two samples. Magnesium was highest in the regular corn whereas iron, copper and
manganese were highest with the blighted corn. With the possible exception of iron
and copper these differences would probably be of minor nutritional significance.
The results of the experiment with finishing swine are shown in Table 5.
The similarity in rate and efficiency of gain for the 2 groups indicates that
consumption of blighted corn did not adversely Influence pig performance.
Table 6 summarizes the results of experiment 2. This study with young pigs
should provide a more critical evaluation of the nutritional and possible toxic
factors than the previous experiment with older pigs.
The daily gain, feed consumption, and feed efficiency figures for the groups
fed regular or blighted corn show that performance was comparable for the two treat-
These data indicate that blighted corn, free from molds, can be satisfactorily
fed to young and finishing swine. However, if mold is present, It is recommended
that the infected corn not be fed to breeding stock nor to pigs weighing less than
75 pounds. Also, if possible dilute the moldy corn (about 20% moldy corn is satis-
factory) with sound corn to alleviate the decreased palatability of moldy corn and
diminish the concentration of possible toxins.
Blight damaged corn free from molds and containing less than 10% discolored
and shriveled kernels was fed to young and to finishing pigs. The feeding value
as measured by rate and efficiency of gain was equivalent to regular corn.
A chemical analysis for starch, fat, gross energy; nitrate, ammonical and
amino acid nitrogen; phosphorus, calcium, magnesium, iron, zinc, copper and
manganese showed minor differences between blight and normal corn.' It is not
recommended that these differences be considered in diet formulation.
Table 1. Composition cf Diets, lb.
Ingredient 'Experiment 1 Experiment 2
Corn, regular or blighted 82.30 75.70
Soybean meal (50%) 15.10 21.00
Defluorinated phosphate 1.00 2.50
Ground limestone 0.50
Salt 3.50 3.50
Trace minerals/ 0 :5 0.10
Vitamin supplement./ 0.05 0.10
Baciferm '25" 0.10 0.10
'/ Supplied the following in ppm: Mn, 57; Fe, 73;
Cu, 4.3, C:, 1.5 and Zn, 100 when added at the
level of .10 lb. per 110 lb.
2/ At the .10 lb. level the following were supplied
per lb. of diet: vitamin A, 2500 I.U.; vitamin D
403 I.U., riboflavin, 6 mg., niacin, 20 mg.,
pantothenic acid, 6 mg ; choline chloride, 40 mg.;
vitamin B12 5 mcg.
Table 2. Comparative Chemi -al Composition
Of Blighted and Regular Corn i'
Dry Matter Gross Energy Fat Starch
Corn % Kcal/gm % %
Blight 35.7 4.4 3.5 60.7
Regular 35.3 4.6 4.4 66.3
1/ Expressed on dry matter basis.
Table 3. Nitrogenous Constituents Of Blighted and
Corn Total Nitrate Ammonical Amin'
Protein and Nitrogen Acid
% Nitrite % Nitrogen
% Protein %
Blight 12.2 1.1 1.7 9.7
Regular 10.9 0.1 1.0 3.6
Acid Content Of Blighted and Regular Corn
% of dry matter
Blight Regular Regular
FaFall '70 Fall '70 Spring '70
0.40* 0.39 0.35
0.10 0.13* 0.33
0.31* 0.23 0.25
1.17* 1.07 0.83
0.43* 0:35 0.33
0.42* 0.41 0.29
0.52* 0.48 0.41
ine 0.02 0.04 0.35*
:id 0.71* 0.57 0.62
0.50* 0.49 0.43
:id 2.17* 2.04 1.93
0.44* 0.39 0.39
0.31* 0.75 0.75
0.97* 0.06 3.02
0.31 0.02* 0.01
of the 3 corn values.
Table 4. Mineral Content Of Blighted And Normal Corn
Ash P Ca Mg Fe Zn Cu Mn
Corn % % % % PPM PPM PPM PPM
Blighted 1.6 0.33 0.05 0.13 63 25 5 8
Regular 1.2 0.35 0,02 0.20 20 12 5
Table 5. Comparison Of Blighted and Normal
Corn For Finishing Swine
Av. initial weight, lb. 244.2 245.50
Av. final weight, lb. 293.80 297.00
Av. daily gain, lb. 2.27 2.18
Av. daily feed, lb. 9.58 8.97
Av. feed/gain, lb. 4.22 4.11
Days on test 24 24
Table 6. Performance Of Young Pigs Fed Diets
Containing Blighted Corn
Av. initial weight, lb. 16.30 16.19
Av. final weight, lb. 131.49 127.01
Av. daily gain, lb. 1.36 1.32
Av. daily feed, lb. 3.12 3.23
Av. feed/gain, lb. 2.29 2.45