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Impact of Grinding on Digestibility & Energy Content of Corn for Pigs, Summaries of Nutrition

A research article that investigates the effect of grinding corn on its digestibility and metabolizable energy content when consumed by pigs. The study was conducted by W.P. Gakkigus and H.H. Mitchell at the Illinois Agricultural Experiment Station. The researchers found that grinding corn improved its digestibility, particularly for protein and nitrogen-free extract, but the increase in metabolizable energy was minimal. The study also highlighted the importance of measuring the digestibility of corn to determine its nutritive value and economic feasibility of grinding.

What you will learn

  • What is the effect of grinding on the digestibility of corn for pigs?
  • What are the advantages and disadvantages of grinding corn for pigs in terms of nutritive value?
  • How does grinding affect the metabolizable energy content of corn for pigs?

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THE
EFFECT
OF
GRINDING
ON
THE
DIGESTIBILITY
OF
CORN
BY
PIGS
AND
ON
ITS
CONTENT
OF
METAB-
OLIZABLE
ENERGY
1
By
W.
P.
GAKKIGUS,
graduate
student^
and
H.
H.
MITCHELL,
chief
in
animal
nutrition,
Department
of
Animal
Husbandry,
Illinois
Agricultural
Experiment
Station
INTRODUCTION
The
effect
of
grinding
on
the
value
of
corn
{Zea
mays)
as
a
feed
for
pigs
has
been
studied
mainly
in
feeding
experiments,
the
results
being
measured
by
the
rapidity
and
feed
economy
of
the
gains
secured.
In
the
United
States
it
has
in
general
been
found,
according
to
Morrison,^
that
for
young
pigs
ground
corn
is
not
appreciably
superior
to
whole
corn,
but
for
older
pigs,
variable
percentage
advantages
in
economy
of
gains
may
result
from
the
feeding
of
ground
corn.
How-
ever,
a
more
recent
summary
by
Crampton
^
indicates
no
advantage
due
to
grinding
at
any
weight
of
pig.
In
sharp
contrast
to
the
American
experiments
are
the
results
of
Hansson
^
in
Sweden,
who
calculated
from
his
own
feeding
experiments
on
pigs
that
the
produc-
tive
value
of
maize
was
increased
by
fine
grinding
by
as
much
as
15
to
18
percent.
Such
findings
as
are
obtained
in
feeding
experiments
are
the
resultants
of
a
number
of
factors,
including
effects
of
grinding
on
the
digestibility
of
the
corn,
on
its
palatability,
and,
as
Crampton
points
out,
on
its
wastage
at
the
feed
trough:
^*Shelled
corn
lost
from
the
feederds
salvaged
by
the
hogs
but
ground
feed
is
not
*
*
*
Feed
rooted*out
of
the
trough
and
lost
to
the
pig
is,
of
course,
still
charged
to
the
gains
made.^'
A
complete
understanding
of
the
problem,
therefore,
demands
a
consideration
of
each
of
these
factors.
PREVIOUS
INVESTIGATIONS
The
factor
most
amenable
to
quantitative
study,
and
perhaps
the
most
fundamental
factor
of
all,
is
the
effect
of
grinding
corn
on
its
digestibility.
However,
very
little
study
seems
to
have
been
made
on
this
point.
A
summary
of
such
work
as
has
been
found
in
the
literature
is
embodied
in
table
1.
The
corn
in
Jordan's
experiment
^
was
a
flint
variety.
The
experi-
mental
pig
weighed
about
50
pounds
and
received
in
each
of
the
two
digestion
trials
787
g
of
corn
daily.
The
collection
period
was
of
5
days
duration.
1
Received
for
publication
Feb.
18,1935;
issued
July
1935.
2
HENRY,
W.
A.,
and
MORRISON,
F.
B.
FEEDS
AND
FEEDING;
A
HANDBOOK
FOR
STUDENT
AND
STOCK-
MAN.
Ed.
18,
770
pp.,
illus.
Madison,
Wis.
1923.
3
CRAMPTON,
E.
W.
THE
COMPARATIVE
FEEDING
VALUES
FOR
LIVESTOCK
OF
BARLEY,
OATS,
WHEAT,
RYE,
AND
CORN,
A
REVIEW
AND
ANALYSIS
OF
PUBLISHED
DATA
*
*
*
107
pp.,
illus.
Ottawa.
1933.
(Canada
Honorary
Advisory
Council
Sei.
and
Indus.
Research
Rept.
28.)
*
HANSSON,
N.
EINFLUSS
DER
VERSCHIEDENEN
BEREITUNGSWEISEN
AUF
DER
VERDAULICHKEIT
UND
DEN
FUTTERWERT
DER
GETREIDEARTEN.
Biedermann's
Zentbl.
Agr.
u.
Rationellen
Landwirtschaftsbet
rieb,
Abt.
B.
Tierernährung,
Ztschr.
Gesamt.
Fütterungslehre
u.
Futtermittelkunde
3:
243-274.
1931.
«
JORDAN,
W.
H.
DIGESTIBILITY
OF
MAIZE
KERNEL
(CORN)
IN
VARIOUS
FORMS.
Maine
Agr.
Expt.
Sta.
Ann.
Rept.
1885-86:
59-64.
1886.
Journal
of
Agricultural
Research,
Vol.
60,
no.
9
Washington,
D.
C.
May
1,
1935
Key
no.
I11.-59
(731)
pf3
pf4
pf5

Partial preview of the text

Download Impact of Grinding on Digestibility & Energy Content of Corn for Pigs and more Summaries Nutrition in PDF only on Docsity!

THE EFFECT OF GRINDING ON THE DIGESTIBILITY

OF CORN BY PIGS AND ON ITS CONTENT OF METAB-

OLIZABLE ENERGY 1

By W. P. GAKKIGUS, graduate student^ and H. H. MITCHELL, chief in animal nutrition, Department of Animal Husbandry, Illinois Agricultural Experiment Station INTRODUCTION

The effect of grinding on the value of corn {Zea mays) as a feed for pigs has been studied mainly in feeding experiments, the results being measured by the rapidity and feed economy of the gains secured. In the United States it has in general been found, according to Morrison,^ that for young pigs ground corn is not appreciably superior to whole corn, but for older pigs, variable percentage advantages in economy of gains may result from the feeding of ground corn. How- ever, a more recent summary by Crampton ^ indicates no advantage due to grinding at any weight of pig. In sharp contrast to the American experiments are the results of Hansson ^ in Sweden, who calculated from his own feeding experiments on pigs that the produc- tive value of maize was increased by fine grinding by as much as 15 to 18 percent. Such findings as are obtained in feeding experiments are the resultants of a number of factors, including effects of grinding on the digestibility of the corn, on its palatability, and, as Crampton points out, on its wastage at the feed trough: ^Shelled corn lost from the feederds salvaged by the hogs but ground feed is not * * * Feed rootedout of the trough and lost to the pig is, of course, still charged to the gains made.^' A complete understanding of the problem, therefore, demands a consideration of each of these factors.

PREVIOUS INVESTIGATIONS

The factor most amenable to quantitative study, and perhaps the most fundamental factor of all, is the effect of grinding corn on its digestibility. However, very little study seems to have been made on this point. A summary of such work as has been found in the literature is embodied in table 1. The corn in Jordan's experiment ^ was a flint variety. The experi- mental pig weighed about 50 pounds and received in each of the two digestion trials 787 g of corn daily. The collection period was of 5 days duration.

1 Received for publication Feb. 18,1935; issued July 1935. 2 HENRY, W. A., and MORRISON, F. B. FEEDS AND FEEDING; A HANDBOOK FOR STUDENT AND STOCK- MAN. Ed. 18, 770 pp., illus. Madison, Wis. 1923. 3 CRAMPTON, E. W. THE COMPARATIVE FEEDING VALUES FOR LIVESTOCK OF BARLEY, OATS, WHEAT, RYE, AND CORN, A REVIEW AND ANALYSIS OF PUBLISHED DATA * * * 107 pp., illus. Ottawa. 1933. (Canada Honorary Advisory Council Sei. and Indus. Research Rept. 28.) * HANSSON, N. EINFLUSS DER VERSCHIEDENEN BEREITUNGSWEISEN AUF DER VERDAULICHKEIT UND DEN FUTTERWERT DER GETREIDEARTEN. Biedermann's Zentbl. Agr. u. Rationellen Landwirtschaftsbet rieb, Abt. B. Tierernährung, Ztschr. Gesamt. Fütterungslehre u. Futtermittelkunde 3: 243-274. 1931. « JORDAN, W. H. DIGESTIBILITY OF MAIZE KERNEL (CORN) IN VARIOUS FORMS. Maine Agr. Expt. Sta. Ann. Rept. 1885-86: 59-64. 1886.

Journal of Agricultural Research, Vol. 60, no. 9 Washington, D. C. May 1, 1935 Key no. I11.- (731)

732 Journal of Agricultural Research Vol. 50, no. 9

In Haberhauffe's experiment,^ the degrees of fineness of the ground corn studied can be roughly characterized by the percentages passing through a 1-mm round-hole sieve, i. e., 42, 63, and 98. The two pigs weighed initially 87.5 kg. They received daily 4 kg of the corn mixed with water, except that the whole corn was fed mixed with the coarsely ground corn in even proportions. The digestibiUty of the whole corn was then computed indirectly. Apparently the pigs were not fed or confined separately during the collection period of 7 days.

TABLE 1.-— Previous investigations of the effects of grinding on the digestibility of corn when consumed by swine

Condition of corn

Num- ber of pigs

Digestion of coefficients obtained Authority and Organic reference matter

Crude protein

Crude fat Crude fiber

N-free extract

Whole kernels^ ___ _-. 1 1 2 2 2 2

1Jordan. 1 1

Finely ground _ _ _ _. _ _ Whole kernels Coarsely ground Medium ground Finely ground. _

Haberhaufl:e.

1 See footnote 5. 2 See footnote 6.

The experiment of Jordan ^ in particular indicates a marked mi- provement in the digestibility of corn by grinding it to a fine meal, possibly because a flint variety of corn was used. In Jordan's study, grinding improved the digestibility of the organic matter 9.4 percent, that of protein 25.3 percent, and that of nitrogen-free extract 6. percent. The results obtained by Haberhauffe indicate less improve- ment for the finely ground meal, i. e., 5.9 percent in the digestibility of the organic matter, 10.9 percent in the digestibility of the protein, and 3.0 percent in the digestibility of the nitrogen-free extract. The meals of intermediate fineness show an intermediate but graded improvement. It appears from these two experiments, constituting the only published work on the problem, that the effect of grinding on the digestibility of corn has not yet been precisely measured. Since the nutritive advantages of the grinding of corn must be balanced against the cost of grinding in deciding whether and when this method of preparing corn is economical, the need of more work of this character seems evident. The experiment reported below is a further contri- bution to this problem.

PLAN OF EXPERIMENT

The subjects of the experiment were 5 Chester White barrows and 1 Hampshire barrow (pig 4), weighing initially from 135 to 196 pounds. Each of the pigs received daily either 1,300 g or 1,500 g of corn, depending upon appetite, with no other feed. The digesti- bility and metabolizable energy content of the whole corn and of the same corn after grinding was determined with 5 of the 6 pigs, 1

6 HABERHAUFFE, W. üBER DEN EINFLUSS DER ZUBEREITUNG AUF DIE VERDAULICHKEIT DER FUTTER- MITTEL. Jour. Landw. 74: [191]-230. 1926. 7 JORDAN, W, H. See footnote 5.

734 Journal qf Agricultural Research Vol. 50, no. 9

TABLE 3.— Results of the digestion and the metabolism trials with whole and ground corn when consumed by swine

Daily intake in food Coefficients of digestion Metabolizableenergy

Body Condition

Nitro- Pig (^) Per kilo-

gen bal- no. weight of corn Corn Dry mat- ter

Gross en- ergy

Nitro- gen

Dry mat- ter

Per-

Gross en- ergy

Nitro- gen Crude fiber Total^

gram of dry mat- ter con- sumed

ance day

Kilo- Calo- Per- Per- Per- Calo- grams Grams Grams ries Grams cent cent cent cent ries Calories Grams 1 / 83.5I 78.9 Whole-Ground _^ 1,5001,500^ 1,3421,335^ 6,0376,049^ 25.0525.05^ 85.187.4^ 82.585.9^ 65.077.2^ 68.570.5^ 4,8475,010^ 3,6123,753^ -f3.19+4. {"78:5" 2 Whole- Ground. 1,500 1,335 6,049 25.05 89.2 88.0 83.2 73.6 5,153 3,860 -f5. 3 f 62.1t 63.5 Whole-Ground-^ 1,3001,300^ 1,1531,156^ 5,1575,219^ 21.7121.71^ 86.087.6^ 83.686.3^ 63.080.0^ 77.072.9^ 4,1744,367^ 3,6203,778^ --3.32--3. 4 f 67.1\ 64.4 Whole-Ground-^ 1,3001,300 1,1631,157^ 5,2325,243^ 21.7121.71^ 88.488.8^ 87.286.6^ 73.178.2^ 7a 073.1^ 4,4074,422^ 3,7893,822^ --4.01--4. 5 f 83.9I 86.2 Whole-Ground-^ 1,5001,500 1,3311,333^ 5,9506,022^ 25.0525.05^ 91.490.4^ 89.689.0^ 80.085.1^ 75.7 (0^ 5,1245,125^ 3,8503,845 --4.31--4. 6 f 89.4I 90.7 Whole-Ground-^ 1,5001,500^ 1,3311,333^ 5,9506,022^ 25.0525.05 82.087.9 86.180.0^ 71.078.2^ 46.570.9^ 4,5755,008^ 3,4373,757^ --2.76-f4.

1 This sample of feces was accidentally thrown out before the crude fiber determination was made.

The most significant results of the digestion and metabolism trials are assembled in table 3. It is evident from the coeflicients of digest- ibility that, except for protein (nitrogen), the constituents of the ground corn were not digested to a markedly greater extent than the constituents of the unground corn. Omitting the incomplete results for pig 2, the average coefficients of digestibility of the whole corn and ground corn were, respectively, 86.6 and 88.4 for dry matter, 84. and 86.9 for gross energy, and 70.4 and 79.7 for protein. The per- centage improvement in the digestibilities were 2.1 for dry matter, 2. for gross energy, and 13.2 for protein. For the four pigs for which the coefficient of digestibility of crude fiber was determined, the averages were 65.5 for the whole corn and 71.8 for the ground corn, but if the atypical results of pig 6 are omitted, the averages are very nearly the same, i. e., 71.8 and 72.2. It is especially noteworthy that pig 6, which appeared to be passing unbroken and undigested more than a third of all whole corn kernels consumed, digested the whole com fairly well, except for the crude fiber. While grinding improved the digestibility of corn for this pig somewhat more than for the other pigs, the relative improvement was far less than would be expected from the physical examination of the feces for unbroken kernels, proving the latter method to be quite unreliable as a criterion of completeness of digestion. The apparently unbroken kernels must have been very largely denuded of their digestible contents by the digestive enzymes. Since corn is preeminently an energy food, the metabolizable energy values of whole and ground corn are of great practical significance. But here also the improvement brought about by grinding is slight, except for pig 6. In fact, for one pig (no. 5) no improvement at all resulted. For all five pigs upon which complete data were obtained, the metabolizable energy per kilogram of dry matter averaged 3, calories for the whole corn and 3,791 calories for the ground corn, representing an improvement of only 3.5 percent.

May 1,1935 Efsct oj Grinding on Digestibility of Corn by Pigs 735

The pigs were in positive nitrogen balance in all periods. The consistently greater digestibility of the protein of the ground corn did not, however, promote consistently higher nitrogen balances, since without exception the urine from pigs on the ground corn ration con- tained more nitrogen than that from the same pigs on the whole corn ration. In one pig (no. 5) the lesser wastage of nitrogen in digestion on the ground corn ration was more than offset by the greater wast- age in metabolism, while for another pig (no. 3) these two tendencies just balanced each other. Thus, the 13-percent improvement in the digestion of the nitrogen of the corn brought about by grinding was largely lost in metabolism, a result suggesting that the digestible nitro- gen escaping digestion in the whole corn represents a fraction of the corn protein that is of low value biologically.

SUMMARY AND CONCLUSIONS

The relative digestibility of whole and ground corn and their con- tent of metabolizable energy were determined on five pigs weighing from 135 to 196 pounds. Grinding corn to a medium degree of fineness (29 percent passing a 40-mesh sieve, 58 percent a 20-mesh sieve, and 95 percent a 12-mesh sieve) increased the digestibility of the protein by 13 percent, but the digestibility of the gross energy of the corn was raised only 2.8 percent. The metabolizable energy was also only slightly improved; i. e., 3. percent. Furthermore, the appreciable advantage in protein di- gestibility occasioned by the grinding of corn was largely lost by greater losses of nitrogen incurred in metabolism, so that the net effect on the nitrogen balance of an animal receiving an exclusive ration of corn was slight and inconstant. The net effect of grinding upon the nutritive value of corn for pigs of the weights used in this test is to increase its value as a source of energy by 3.5 percent. Its value as a source of protein was not appreciably altered.