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THE ECONOMIC SIGNIFICANCE
OF
EXTRA RIBS m PIGS

THESIS FOR THE DEGREE OF M. S.
Verne A. Freeman
1934

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THE ECOI-IOMIC SIGNIFICISECE

OF

EXTRA RIBS IN PIGS

TIE ECONOMIC SIGNIFICANCE
OF

mm RIBS IN PIGS

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Verne A) fireman

THESIS

Submitted to the faculty of the Michigan State College
in partial fulfillment of the requirements for the

degree of Master of Science.

Department of Zoology
1934

ACKHOWLEDGEIEUTS

The writer wishes to express his appreciation
for the suggestions and constructive criticism
offered by Doctor Harrison R. Hunt, Head of the
Zoology Department, in planning the studies from
which the data was secured and in arranging it for
this thesis. r

To Professor George A. Brown, Head of the Animal
Husbandry Department, he is grateful for the timely
suggestions and advice given throughout the study.

Acknowledgement of indebtedness is made to
Professor Oren L. Snow, of the Physics Department
and to Luther Lyndrup for assistance in the X—ray

photography, and to Doctor Howard E. Johnson of the

Anatomy Department for special assistance and instruction.

at... t; r) r:

at «V « .°'JUL-

TABLE OF COI‘ITI‘I-ITS

Introduction
Changes in Type or Swine ............................................ 1
Reasons Advanced for Size ........................................... 1
variations in Number of Ribs and Vertebra Known to Exist in Pigs .... 3

Study of Vertebral variation in the Michigan State College Swine Herd and
on.M1chigan Farms ................................................... 5
Skeletons Examined by Dissection .................................... 5
Results - Table I ................................................... 6
Ezamination of Live Pigs by X-ray ................................... 7
Results - Table II .................................................. 8
Combined Data from.Dissection and Photography .......................7 -
Occurrence of Short Ribs ............................................ 9
Distribution of Variation- Table III ................................ 10
Percentage Distribution by Breads and Sexes - Table IV .............. ll
Graph I ............................................................. 12
Graph II ............................................................ 13
Plate Showing Pig with Twenty Vertebrae ............................. 14
Plate Showing Pig with Twenty-one Vertebrae ......................... 15
Plate Showing Pig with Twenty-two Vertebrae ......................... 16
Litters with Wide Variation ......................................... 17
Table V ............................................................ 18
Carcass Vertebra Counts at Rose-Vail Packing Company .............. 17 -
Comparison of Vertebra Number from College Hogs with those from Farms 19
Table VI ............................................................ 20

Feeding Exneriment ...................................................... 21

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Source of Pigs ..................................................... 21
Methods of Weighing ................................................. 22
Feeds and‘Management ................................................ 22
Method of Estimating Feed for Pigs Removed from the Experiment ...... 23
Table VII ........................................................... 25
Results ............................................................. 24
Table VIII .......................................................... 26
Slaughter Study ......................................................... 28
Weights and Yields of Hogs Slaughtered .............................. 28
Table IX ............................................................ 29
Errors in Observations from Photographs ............................. 30
Weight of Internal Organs ........................................... 30
Table X .......................................................... 31 -
VOlume of Internal Organs ........................................... 30
Table XI .......................................................... 33 -
Location of Diaphragm ............................................... 35
Table XII ........................................................... 36
Carcass Studies ......................................................... 38
Measurements Used ................................................... 58
Measurements of‘Carcasses from the Feeding Experiment ............... 39
Table XIII ........................................................ 4O -
Length of Individual Vertebra ....................................... 43
Table XIV ........................................................... 44
Measurements at Rose-Veil Packing Company ........................... 45
Table XV ............................................................ 46
Methods of Cutting and Weighing Carcasses ........................... 47

Weights and Cute of Carcasses from the Feeding Experiment ........... 47

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INTRODUCTION

The evolution of hog breeding in the United States has developed
several different types of hogs. The types have been changed, mainly for
economic reasons, although swine type may be moulded so rapidly that there
has been a tendency for some breeders to be guided by "whnms and fancies"
rather than.adequate reasons. The early packing industry or this country
demanded and paid a premium.for large well-finished hogs and the leading
breeders strove for great size. With the development of transportation
facilities and refrigeration, the demand swung to lighter carcasses of good
quality. The breeders emphasized early maturity and quality of flashing
with resulting marked deterioration of size and ruggedness. Reduced export
demand for lard and domestic use of lard substitutes next developed a demand
for hogs that would yield a higher per cent of lean meat cuts, and less lard.
The leading breeders swung back to the big type. A decade ago you would see
more advertisements of length.and height of hogs than any other character-
istics. While producers are still demanding size and length of body they are
also asking for depth and feeding qualities and insist upon a so called
hmediwm" or "meat type" hog and there has been a definite swing back away
from.the extreme large type.

The advantages claimed by breeders for’length of body and large
size in breeding hogs are enumerated by vaughn (p.410).

'1. In farm herds which produce market hogs there is
a tendency toward loss of size due to feeding corn too
exclusively and also due in some cases to lack of proper

08139 and management. coo-ooeoeeoeeeeoeeoeeeeooeeeoeoee

2. The cheapest gains are made during the growing

wriOd eoeeoeoeeoeeoecocosoeeeeoooeoooooeeooeeeeeecocoa

3. It is true of all kinds of farm animals that the
larger the breeding stock the longer the growing period

 

 

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of the off-spring will be, and the more rapid will

be the rate of increase in size during a given period.
The pig from large parents makes more growth daily and
monthly, and continues to grow for more months than
does the pig from smaller stock.

4. The growthy type of pig is, therefore, "younger"

at six months of age than the smaller type of pig.
This is true because at six months the former has more
days of growth ahead of him. As a rule the growthy
pig is also younger than the smaller type pig at the
same weight.

5. For these reasons the growthy pig makes his gains
at somewhat lower costs, because the cheapest gains
are made when animals are youngest.

6. If the breeding stock is of large size the pigs will
be growthy, will gain rapidly, and will attain market
weights in the shortest time.

7. Pigs marketed somewhat in advance of other pigs of

9.

the same age usually bring a better price than those
marketed later at times of largest receipts.

The shorter the feeding period the less the risk and
the less the labor cost of producing pork. The man who
raises pigs of growthy type has them.off to market while
hds neighbor who raises smaller hogs is still feeding
them and still running the risk of loss from disease and
other causes.

If the market slumps when hogs of the larger type are
ready for market, they may be held on feed and will con-
tinue to make more efficient use of feed and larger gains
than 11038 or smaller tmo ssssssssssssssssossssssosss'

Pork loins and pork bellies from choice butcher hogs are two of

the most popular cuts from the American hog and are exceeded in value only

by the ham. If the size of the ham can be maintained and the body lengthened

without loss of depth, and the other parts of the carcass held in balance,

the loin and belly would both be increased. Observations have shown that

pigs do vary in their number of ribs and that extra ribs usually mean extra

body vertebrae and are associated with longer bodied pigs.

A. M. Shaw (1929) reports the rib counts on a large number of

 

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hogs of the popular breeds in America and smaller numbers of hogs from other
countries. He found variation in the number of ribs in almost every breed.
With some breeds the smaller number of ribs seem to predominate while with
other breeds, particularly the bacon type breeds and those of longer and
growthier type, the larger number of ribs occur:more frequently. Wide
variation frequently occurs between pigs of the same litter and is common to
both sexes. The variations reported ranged from 13 to 17 pairs of ribs. He
found no variation in the cervical or sacral vertebrae. The number of pairs
of ribs varied With the number of thoracic vertebrae and occasionally there
was variation in the lumbar vertebrae. It appears that the combined count
of thoracic and lumbar vertebrae would be the factor determining the length
of the body if the length of the body is affected by the number of body
vertebrae.

A.method of determining the variations in the vertebral column of
the live pig by X-ray photograph was also described by Shaw (1930). He
showed radiographs of the skeletons of pigs that would enable one to make an
accurate record of the number of vertebrae in live pigs. Pictures of breed-
ing sows were shown, one sow having 17 pairs of ribs and the other sow 14
pairs. There was a noticable difference in the length of body and type of
the sows. He stated that through the use of radiographs quite large groups
of pigs possessing the different vertebral variations had been selected for
breeding purposes at the University of Saskatchewan farm, consisting mostly
of purebred Yorkshires with some Tamworths and Berkshires.

No other literature seems to be available on this subject. The
‘United States Department of.Agriculture at Beltsville, maryland Station, is
working on variations in body vertebrae of pigs and some other stations have
done some preliminary work on this subject. A communication from.Dean A.

M. Shaw suggested some evidence that the pigs with the larger number of

ribs and body vertebrae gain more rapidly and may make more economical use
of their feed, also that breeding hogs with 16 pairs of ribs seemed to

transmit more uniformity in number of ribs to their ofi'Spring than do the

breeding hogs with either 15 or 14 pairs of ribs.

STUDY OF VERTEBRAL'VARIATION IN THE MICHIGAN STATE COLLEGE SWINE HERD
AND ON MICHIGAN FARMS

The question raised by Shaw (1929) , ”How Many Ribs Has A Pig?”,
suggests a second question, "How Many Ribs Should A Pig Have?" Plans were
outlined to study the variation in the number of body vertebrae of the pigs
in the Michigan State College swine herd and any economic importance that
might be associated with the larger numbers. In the first part of the study
skeletons were examined by dissecting all of the pigs that were still-born
or that died soon after birth in the 1933 pig crop. The object was to
detennine the extent of variability found in the pigs of the five different
breeds in the College herd. Do the variations occur any more frequently
with one breed than with another, «- with one sex than with the other?

A record of the sex and the dam of each pig examined was kept.
The herd book also gives the sires. No observations were made cephalad to
the first rib or caudad to the sacral arch, but the ribs and thoracic verte-
brae were counted separately from the lumbar vertebrae. The examination was
made by Opening the pig laterally inthe back-bone and exposing the skeleton
sufficiently to identify the number of ribs and vertebrae. The thoracic
vertebrae combined with the lumbar vertebrae are hereinafter spoken of as
one group, at times, and called body vertebrae.

A total of l82 pigs were examined including 102 males and 80
females. The observations are sumnarized in Table I.

In the second part of the study examination of the live pig's
skeleton was attempted by X-ray photographs. There were three possible
objectives in this part of the study. The first one was to locate pigs of
known vertebral structure to use in a feeding test. The second was to add

to the information on variability of vertebral numbers in the College herd,

 

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Table I
VARIATIONS IN 801)! VERTEBRAE CE PIGS DISSETED

Ember of 80: Berkshire Chester Duroc Poland Yorkshire Total
Yertebree

13 Thoracic) Ii 1 1
and )
6 Dunbar ) l‘
14 Thoracic) M 8 16 3 81
and )
c Lumbar ) r l 13 1 s l?
14 Thoracic) M l 1 z
and )
7 lumber ) l' 1 1 8
15 Thoracic) I! l 8 8 13 80 M
and )
6 Imber ) l‘ 3 7 6 80 36
15 Thoracic) It 1 6' e 11
and )
7 Ember ) l' 1 l d l 'I
16 Thoracic) M i d
and )
s umber ) l' i e s
16 Thoracic) ll 3 1 8 1 9 16
and )
6 Imbar ) l‘ 1 8 1 8 18
16 Thoracic) H 1 1 1 3
and
7 Lumber ) r 1 1
Total 5 11 58 36 79 183

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and the third was to secure stock of known rib and vertebral count for
future breeding eXperiments. V .

Plans were made to use the X-ray nachine in the Physics Department.
Some repairs had to be made on it but this was arranged for by the Physics
Department in order to mks the equipment available for their laboratory
use. The Department of Zoology purchased films and some added equipment
essential for photographing the pigs and developing the films. Luther Lyndrup,
a graduate student in Physics operated the x-ray machine and developed the
films. The details of the photographic mrk, such as equipment used, hold-—
ing the pigs, identifying the pictures, and how the machine was Operated,
is given on pages 1'53 to :55 of his thesis on "Studies in the Technique of
X-ray Photography”, submitted to the Michigan State College in 1932.

The pigs were given individual identification marks by the
esrnotch system regularly used with the College herd, and were transferred
to the Physics laboratory for the X-ray. More than 200 animals were photo-
graphed although not the entire spring pig crop as had been planned, because
the X-ray mchine ceased functioning at the time that the pigs were at the
best ago. Many of the photographs were indistinct and had to be retaken.
Even then some of than were discarded and an attempt was made to make use of
only 172 for counting the vertebrae. When later results showed sane of these
observations to be inaccurate still more films that were not very distinct
were discarded and the results of the counts from 137 of these pigs are
shown in Table II.

These vertebra counts from the x-ray were combined with the
observations from the pigs that were dissected. The combination of 15
thoracic vertebrae and 6 lumbar vertebrae occurred most often in the Chester
Ihite, Poland China. and Yorkshire breeds. The small sample of Berkshires

showed a slightly larger number of pigs with 16 thoracic and s lumbar vertebrae

Table II

VARIATIONS IN BODY W 01' PIGS PHOTOGRAPHED BY X-RAY

lumber of Sex Berkshire

Vertebree

ll. Thoracicm
and )
s mar )P

14 Thoracicm
and )
7 mm W

15 Thoracic)!
and )
s III-bar )l‘

18 Thoracicm
end )
s lumber )r

18 thoracic)!
and )
7 mar )1

lo mmichl
and )
s mu: )1

lo Thoracic)!

and)
cameo)!

Tom

Chester

Duroo Poland ‘YOrkshire

Total

5

8 9
8

1 B
I

1

14 G7
16 36
1

4

3 5
1

d 13
3 8
‘8 137

and the Duroc Jerseys had a decidedly larger number of pigs with 14 thoracic
and 6 lumbar vertebrae.

The different combinations that made the same total numbers of
body vertebrae were grouped together from these studies. The occurrences of
19, 20, 21, 22 and 23 body vertebrae are shown for the different breeds and
sexes in Table III. The same is shown by percentage distribution in Table
IV} A.graph showing the distribution by breeds is shown in Figure I, and by
sexes in Figure 11.

These data show'e.merked contrast in the frequency of 20 and 22
body vertebrae between the Duroc and Yorkshire breeds represented in the
Ilohigan State College herd. One pig with 19 body vertebrae was found among
the Durocs, 40 with 20 body vertebrae, and only 8 with 22 body vertebrae.
no pigs of the Yorkshire breed were found with less than 20 body vertebrae
and there were only 7 of these. There were 29 Yorkshires with 22 body
vertebrae, and 2 with 23. While the Berkshire pigs showed the largest mean
the number observed was small. There were 76 Durocs and 121 Yorkshires
observed and the means of their number of body vertebrae show a significant
difference. The Yorkshire mean.was .66 larger than the Duroc with a
standard error for difference of .096. There was no significant difference
in the occurrence of the number of“vertebrae found in the Yorkshire, Poland,
and Chester pigs, nor between the two sexes.

Other variations that were observed showing intermediate condit-
ions snd suggesting a blending type of inheritance and probability of
multiple factors were as follows: 1 Poland China sow with 15 pairs of ribs
and thoracic vertebrae and 6 lumbar vertebrae had one short extra rib on her
right side only. One Yorkshire sow with 16 thoracic vertebrae and s lumbar
vertebrae had a similar small extra rib on the right side. One Yorkshire

male with 16 thoracic vertebrae and 5 lumbar vertebrae and also one Yorkshire

’Table III

DISTRIBUTION OF NUMBER OF BODY VERTEBRAE BY BREEDS
AND BY SEXES IN MICHIGAN STATE COLLEGE HERD"

-10..

 

Number of Total for Mean and probable
Log vertebrae: 19* 20 21 22 23 breed error
Berkshire 15 16 29 21.55 t .06
Chester 5 23 4 1 53 21.03 t .07
Duroc 1 4O 2? 8 76 20.55 «t .05
Poland 3 41 15. 1 so 21.23 1 .05
Yorkshire 7 83 29 2 121 21.21 t .03
Total 1 55 187 72 4 319 21.10 t .03
Isles 1 28 102 41 3 175 21.10 3 .04
Females 27 85 31 l 144 21.04 1 .04

*Data combined from pigs examined by dissection and by X-ray photograph.

 

3)..

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Table IV

memes DISTRIBUTION 01? NUMBER OF BODY VERTEBRAE BY

BREES AND BY SEES IN MICHIGAN STATE COLLEGE HERD

-11-

 

”her of
vertebra 13: 20 V 21 22 23

Berkshire 44.8 55.2

Chester 15.8 69.7 12.1 3.0
Duroc 1.5 62.6 36.5 10.5

Poland 5.0 68.3 25.0 1.7
Yorkshire 6.8 68.6 24.0 1.6
Isles .6 16.0 58.6 23.4 1.?
females 16.6 59.0 21.5 .7

e

a o e
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DIS‘I'BIBUTIW 0? NUMBER OZ! BODY VERTEBRL BY BREEDS

70

Ire queasy

5 percentage
e
H
e
H

body Vertebre

Figure I
IN MICHIGAN STATE COLLEGE SWINE. HERD

(t
k D
5
19 20 21 as
Berkshire — H Duroc Jersey .-
Chester White _- 6, Poland China ._

Yorkshire _. E

 

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D

12—

Frequency

60

50

4O

30

’A

percentage

‘
Number of 19
bOdY vertebrae

,
LI"
.

Figure II
DISTRIBUTION OF NLRBER OF BODY Va‘RTEJBRA BY 81:13.33
IN MICHIGAN STATE COILEGE SHINE .nRD

 

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x/ \.
I/ l\.‘ ,
2O 21 22 23

Females —.. fl

Males .1. I?)

-13-

-14..

 

 

 

Poland barrow No.26 has fourteen thoracic vertebrae and six
lumbar vertebrae.

-15-

 

 

 

Poland barrow No.56 is a litter mate to Poland barrow No.26
and has fifteen thoracic vertebrae and six lumber vertebrae.

-16-

 

 

 

Poland barrow No.2 has fifteen thoracic vertebrae and seven
lumbar vertebrae.

 

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n ”7.!

 

 

-17-

male with 16 thoracic and 6 lumbar vertebrae each had a short last rib on

the right side and a normal full length rib on the left side. Four Yorkshire
pigs, including two males and two females, and one Poland male had a last
pair of ribs shorter than usual estimated at about one-half the average
length, both ribs being about equal. One Yorkshire male pig had a last pair
of ribs that were estimated at about three-fourths the usual length. No
attempt was made to measure these ribs because the pigs varied in size from
very slightly over one pound at birth to nearly four pounds at the time they
were examined.

Marked variation was shown by pigs within the same litter as
shown in Table V. The three litters represent the wider variations found and
are one each of purebred Duroc Jersey, Poland China, and Chester White. L
heterozygous condition of the parents of these litters is indicated, especially
in the parents of the litter from Chester sow number 33.

A third part of the study of variations was made by counting the
vertebrae in pork carcasses at the Rose-Vail Packing Company, located at
Dewitt. Practically all of these hogs were purchased from farmers within
30 miles of the plant and excluding those counted which came from the College
herd, it is believed that they represent a good random sample of the hogs
that are being produced on central Michigan farms.

The object was to determine the extent of variation and to locate,
if possible, some carcasses that would be suitable for measuring and making
cutting records to supplement the data from the feeding and slaughtering
studies. The plant was visited on the days that they made their larger kills,
or the following day,so theta considerable number of carcasses could be
observed in a few trips.

Counts were made on a total of 342 carcasses, including 10'?

coming from the Michigan State College herd. No attempt was made to classify

Table V
VARIATION IN VERTEBRAE OF PIGS FROM SALE LITTER

Rmnber of Sex Litter of Duroc Litter of Poland Litter of Chester
Vertebrae sow No.1 sow No. 5 sow No. 33
14 Thoracic) M 5 2
and )
6 lumbar ) F 4 1 1
14 Thoracic) M
and )
7 Lumbar ) F 1
15 Thoracic) ll 8 5 2
and )
6 Lmbar ) F 2 l
15 Thoracic) M 1 2 l
and )
'l Limbar ) I" 1
l6 Thoracic) M 2 2
and )
6 Lumbar ) I 1
1? Thoracic) M 1
and )
'1 Lumbar ) F

Total 14 12 11

- 19 -

these carcasses by sex or breed, and only the total number of body
vertebrae were counted. The results of the counts are shown in Table VI.
Only carcasses showing 20, 21, or 22 body vertebrae were found.
There was a significant difference in the number of carcasses with 20 and
22 body vertebrae found among the carcasses from farms and those from the
College herd. Thirty-four per cent of the farmer's hog carcasses had 20
body vertebrae as compared with only 7-3.; per cent of the carcasses from the
Michimn State College. Less than nine per cent of the farm carcasses had
22 body vertebrae as compared with 27 per cent of the College carcasses.
There was a significant difference of .445 in the mean number of vertebrae
of the two groups with a standard error of difference of only .066. Ex-
pressed in toms of probable error the difference in the means is .445 f
.045. The difference is nearly 10 times its probable error and the mathe-
matical odds that a real difference exists are almost 65,000,000,000 to 1.
No attempt had been made to select breeding stock in the College
hard with a larger number of body vertebrae, as there were no records of the
number of vertebrae in the breeding herd. However, it appears that the
College herd may have been more carefully selected for the present day
approved type and that the selection for relatively long growthy hogs had
resulted in a line of breeding showing a tendency toward the larger number of
body vertebrae. Some evidence that the form is modified by the number of
body vertebrae is shown by the pictures on pages 14 to 16 . These pictures
were taken a few days before slaughter. The vertebrae were counted in their

carcasses.

 

“In“.

 

 

1.4)“)rlill'II-II2-Elfl a V.
. . a

Table VI

-20..

BODY VERTEBRLE IN CARCASSES EXKIINED AT DBWITT

 

Ember of body vertebrae 20 21 22 Total Mean and probable
We , error
carcasses from farms 80 154 21 255 20.749 i .027
Percentage distribution 54.04 57.02 8.24
carcasses from Michigan 8 70 29 107 21.196 1 .036
State College
Percentage distribution 7.48 65.42 27.1

Difference of means

.447 i .045

FEDING ECPERIIZEIT

The object of the feeding experiment was to determine whether
longem'bodied pigs or pigs with extra ribs and body vertebrae would grow
faster or more economically than ordinary pigs. The pigs used in the feed-
ing test could be dressed at uniform weights and used for a carcass study.

Two lots were selected so that they wauld represent as much
variation in.number of ribs and number of body vertebrae as it was possible
Ito secure from the pigs photographed by X-ray. These pigs were selected by
pairs with both pigs of the pair having similar breeding, but one of the
pair having one or more body vertebrae more than the other. The pairs of
pigs were selected as near equal as possible for thrift. There were three
males and five females in Lot 1 and four of each sex in Lot 2. The pigs
starting Lot 1 averaged 76 days old compared with 71 days for Lot 2. The
Lot 1 pigs averaged 42.6 pounds at the start compared with 44.4 for Lot 2.

A good ration similar to what the pigs had been receiving was
fed both lots. Self-feeders were used so as to give the pigs every oppor-
tunity to feed heavily and gain at their full capacity.

The pigs were selected from.a total of 172 with fairly good Xpray
photographs. They were produced in the breeding hard at the Michigan State
College. Every effort was made to raise them under sanitary conditions so
that treatment for round-worms would be unnecessary. They were immunized
from.Hog Cholera by double treatment while they were still nursing their
mothers. They appeared healthy and thrifty at the beginning of the exper-
iment. Eight pairs were selected for the two lots. Ten of the pigs were
started on feed June 7, and two other pairs were started June 21, soon
after weaning. The youngest pair started July 5. One of the later pigs

became unthrifty and died July 50. The pig that was paired against him was

-22-

taken out of the experiment August 2, which was the next weigh-day for the
lot. d.third pig became unthrifty and was removed from Lot 1 September 15.
The remaining 15 pigs were carried through the feeding test.

The animals were weighed individually three days in succession
at the beginning of the experiment and the average of these was taken as the
initial weight. The pigs were started on feed the second day they were
weighed. They were weighed as a lot at intervals of 14 days. Individual
weights were taken every 28 days. When they approached 200 pounds they were
weighed individually for three days in succession and the average was used
as the final weight.. They were taken out of the lot the second day of their
final weight, but were kept on the same ration thus giving them a unifonm
”fill” as compared with the other days. weights were taken about the middle
of the forenoon.

The pigs were given a uniform daily allowance of buttermilk. The
other feeds used were weighed when placed in the feeder and a record kept
of all feed added. An estimate of the feed left in the feeder was made
each.28 days and any time that a pig was removed from.a lot the feed was
weighed back to give a basis for estimating the feed consumed by the pig
taken out. At the close of the experiment the feed left in the feeder was
weighed out. The feed consumed by each lot was computed for any desired
period between weighing dates by deducting the feed left at the end of the
period from.the total amount added and in the feeder at the beginning.

Both lots were fed in adjacent rape pastures. Artifical shade
was provided and the pigs had a portable cot to sleep in when they chose.
Tater'was provided in self-waterers and both lots were fed at the same
type of self-feeders. A.minera1 mixture of equal parts of steamed-feeding
bone meal, fine ground limestone, and salt was kept before both lots. The

amounts of mineral consumed by either lot was so small that it could not

-23-

be accurately weighed. more of the mineral was thrown out from becomming
wet and.dirty than was consumed by the pigs. Shelled corn and tankage were
fed in.separate compartments throughout the expertment. A.small amount of
ground.wheat was fed in a separate compartment at the beginning. The wheat
was used to avoid a violent change in the ration.because the pigs had been
receiving wheat in their feed mixture before weaning. Buttermilk was trough-
fed atrthe rate of'8 pounds per pig daily.

It was necessary to estimate the feed that had been consumed by
pigs taken out of’the experiment so as to deduct it from.the total feed
consumed by each lot. The same.method was used that theIMichigan Experhment
Station has been using in recent years for estimating the feed consumed by
pig: removed from.an experiment. The total feed consumed by the lot for the
period, which had included the pig, was divided by the number of pigs and
40 per cent of this amount deducted for the maintenance of the pig. The
total.amounts of‘feed consumed by the lot were then divided by the number
of pounds of gain made by the whole lot during the period. Sixty per cent
of this amount was considered the amount of feed more than the estimated
maintenance used for each pound of gain. In the case of a pig which had
'weighed more at the last individual weighing than he did at the time he was
removed from.the experiment, the feed required for gain was based on the
heaviest weight that was recorded for him» These estimates of feed for the
maintenance and gain for any pig removed from.the experiment are added to-
gether and deducted from the total feed charged to the entire lot.

The method is illustrated by the corn deducted for Chester barrow
12 removed from Lot 2. During the period which he was fed with the lot of
8 pigs they consumed 560 pounds of corn and gained 321.7 pounds. Chester

barrow 12 gained only 21.7 poundso

- 24 -

560 divided by 8 equals 70 pounds (an average pig'sShare).

7O multiplied by 40 per cent equals 28 pounds (corn estimated
for maintenance of one pig)

560 pounds divided by 321.7 equals 1.74 pounds (average corn
consumed per pound of gain)

1.74 multiplied by 60 per cent equals 1.046 pounds (estimated
corn above maintenance for each pound of gain)

1.046 multiplied by 21.7 (gain of 0.8.12) equals 22.7 pounds
(estimated corn consumed by C.B.12 for gain)

28 plus 22.? equals 50.7 pounds (total corn estimated that
C.B.12 consumed).

When a lot of pigs are fed together there is no method by which
the exact amount of feed consumed by any one pig may be accurately estimat-
ed. In some cases where lirited rations have been fed in comparison with
full feeding at the Michigan Experiment Station, it appeared that approx-

hnately 40 per cent of the full fed ration was used for maintenance. While
vthe accuracy of this method is cpen to question it is:more nearly correct
than to deduct an average pig's share of the total feed if the pig removed
has been unthrifty and failed to gain long enough to justify his removal
from.the experiment. The feed deducted for the pigs taken out of the ex-
periment is shown in Table VII.

The results of the feeding experiment are given in Table VIII.
The pigs with 20 body vertebrae of Lot 1 made an average daily gain of 1.29
pounds as canpared with 1.35 pounds for Lot 2, the pigs with the larger
number of body vertebrae. While this difference of .06 of a pound was in
favor of the pigs with the extra vertebrae, the difference is too small and
the number of pigs not large enough to indicate any significant superiority
for the pigs with extra vertebrae.

There was no indication from.the feed consumed per hundredweight

FEED DEDUCTED FOR P

13. B. 13

Maintenance

(July 5,1932
to

Sept. 13,1932)

Grain of 30 lbs.

0. S. 22

Maintenance
(Tune 21,1932
to
Aug. 2,1932)

Corn

86.1

47.2

27.0

Grain 0! 32.7 lbs. 54.7

Total for Lot I

0.13.12

Maintenance
(June 21,1932
to
July 30,1932)

195.0

Grain of 21.7 lbs. 22.7

Total for Lot II

50.7

Table VII

IGS RRZOVED FROM FEEDING TEST

Lot

Wheat

2.0

1.3

6.6

7.9

17.8

Lot

6.4

5.1

11.5

I

II

Tanlcage Buttermilk

.8 224.0
.4 125.1
.3 131.2
.4 ’ 165.t

1.9 645.8
02 131.5
.2 98.4
04 220.0

The method of estimating the above feed is given on page 23.

Table VIII
RESULTS OF FEEDINGWTEST

Twenty Body‘Vertebrae vs Twenty-One
(Julie 7, 1932 to Novenber 28, 1932)

lot 1* Lot II”
War of pigs 6 7
Total pig days 746 822
Average initial weight 42.55 «.63
Average final weight 203.8 203.26
Average daily gain 1.29 1.35
Total feed consumed:
Shelled corn 8470. 2940.
Ground wheat 133. 135.
Tango 380 280
Buttermilk 6101. 6552.
Average daily ration:
Shelled corn 3.31 3.58
Ground wheat .18 016
Tame. .043 .0“
Bllttermllk 8.18 7097
lead consumed per cwt. gain:
Shelled corn 255.8 264.5
mm 'hmt 13.8 1201
Tankage 3.3 2.5
Buttermilk H by 7) 90.3 64.2
Total 363.2 363.3

* Lot 1 included: four pigs with 20 body vertebrae,
one pig with 21 body vertebrae,
one pig with 22 body vertebrae,

** Lot 2 included: four pigs with 21 body vertebrae,
three pigs with 22 body vertebrae.

-27-

gain that either lot was more efficient. On account of the pigs taken out
of the experiment and the consequent deduction of feed, there was a slight
difference in the proportion of buttermilk fed the two lots. If instead of
adding in the total amount of milk, the pounds of milk fed each lot is
divided by 7 to reduce it to the probable equivalent of concentrates that it
Inight.replace, the total feed consumed would amount to 363.2 pounds for Lot
1, and 363.3 for Lot 2. The pigs in Lot 2 ate a slightly larger average
daily ration and gained slightly faster but it is not probable that two check
lots on the some ration would have been closer together in feeding results
obtained. These results are in accord with the findings of Carroll (p.364)
that:”type in swine is not a controlling factor in either rate or economy of

gain.”

~28-

SLKUGHTER STUDY

The object of the slaughter test was to determine, if possible,
any difference in the size of the vital organs or the yield of the wholesale
cuts of pork attributable to the difference in the number of ribs and body
vertebrae. These slaughter tests gave an Opportunity to check the accuracy
of the observations of the number of ribs and body vertebrae made through
the X-ray photographs. Some of these photographs were not very distinct,
but were believed to be reasonably accurate. Six of the observations did not
prove to be correct.

As fast as the individuals of either lot in the feeding exper-
iment reached an approximate weight of 200 pounds they were removed from the
experiment and slaughtered in groups of one to three. The hogs were given
their usual feed up until 5:30 of the night previous to slaughtering. They
were killed the following forenoon. and weighed before bleeding, after bleed-
ing, and after scraping. Also the hot dressed carcasses and the cold
dressed carcasses were weighed. These weights are shown in Table IX.

{An attempt was made to note any possible difference in the anatomy
between the two lots, such as the location of the diaphragm. Each internal
organ was weighed to the nearest gram. The stomach, small intestine, and
large intestine were weighed both before and after cleaning. The volume of
oach.organ was measured by water displacement through the use of a ten
gallon can having an outlet so that the surplus water could be caught and
measured. The can was filled to the outlet before immersing the organ and
the water that ran off after immersion was measured to give the volume.

weights and measurements of organs were taken for all 13 of the
hogs slaughtered. After finding there were only five pairs in the two lots

that actually had a difference within the pair for number of'vertebrae,

IPig:

Idontif 1'.-

cation

11.8.41
13.8.17
D.8.11
13.3. 4
P.8.18
3.8.22

IVOM

13.3.16
9.8.57
3.8.56
3.3. 7
1.8. 5
5.8.12
5.8. 5

Average

Table IX
SLEUGHTERxdeL

(pounds)

not I
Live weight weight Hot Cold
weight after after dressed dressed

bleedc scraping weight* weight*
ins

197 190 187.5 154 148
197.5 191 189 158 154.5
197 189.5 187.5 159 155.5
194 187 185.5 152 147
196 189 185.5 155 148
194 187 185 155 146
195.9 149.8

Lat 11
198 192 190 159.5 152
184 177 175 147 144
202 195 193 165 156
197 191 188.5 157 151
191 184 .181.5 156.5 151
196.5 189 167 157.5 152.5
195.5 188.5 187 156 155
195.1 151.4

I“Dressed shipper style but leaf fat and kidney removed.

Dressing

percentage

(cold)

75.13
78.23
78.93
75.77
75.51
75.26

76.48

76.77
78.“
77.25
76. 65
79.06
76.85
78.86
77.56

-30..

only the data from these five for each lot are included in the tables. The
data from the pigs out of Lot 1 included four Durocs having 20 vertebrae
each.and one Poland with 21. From Lot 2 it included four Durocs with 21
‘body vertebrae each and.one Poland with 22.

The weights of the organs are shown in Table X and the volume
in Table II. Great variation was observed between individuals of'the same
Lot compared with the small difference between the averages of the two lots.
ZFor instance, in Lot 2 the liver from D.B.7 weighed only 1344 grams compared
‘with.l734 grams for D.B.l6. In Lot 1 Duroc barrow number 4 had the smallest
heart, weighing only 292 grams, but he also had the largest lungs, weighing
1027 grams. Duroc sow’number 41 had next to the largest heart in this lot
weighing 327 grams, but the smallest lungs, weighing only'514-grams, or
Just half as much.as the lungs from.Duroc barrow number 4. Whether the
larger heart was due to the small lungs, and the necessity for it to produce
greater blood pressure that the smaller lungs might do their work can only
be guessed. iMost of the internal organs were smaller in the hogs of Lot 2,
both.in weight and volume as measured by the water displacement, but the
differences in the means were not large. Due to the small number of animals
in the slaughter study no conclusions.could be drawn from.the results.

l.further reason for formulating no conclusions from these
results was the small difference in the number of ribs and body vertebrae
between the two lots. This was due to incorrect observations from the X-
ray photographs when selecting the pigs for the feeding experiment. One of
the pigs in Lot 1, Berkshire sow number 22, was supposed to have 16 thoracic
vertebrae and 5 lumbar vertebrae, but proved to have 6 lumbar vertebrae.
Either one of‘the Berkshires in Lot 2 could have been paired against her.
Berkshire sow number 12 was supposed to have 16 thoracic vertebrae and 7

lumbar. She proved to have the 7 lumbar vertebrae, but had only 15 thoracic

-31..

Table I
mm 6! mom

(areas)
not I - Teenty and Twenty-one Vertebrae

0.8.41 0.8.17 0.8.11 0.8. 4 P.S.12 "‘ Total Mean

m 327 310 580 200 300 1000 321.8
rans- 014 070 789 1027 000 0000 739.8
Liver 1400 1648 1823 0002 1572 8590 1718
Pancreas 170 186 150 146 153 735 146.0
310M kidney 124 150 130 120 110 668 132.4
left kits-v 100 144 181 110 126 700 141
”men 1080 840 707 080 070 4007 001.4
(before cleaning) '
atoms]: 070 000 700 004 070 5348 000.0
(after cleaning)
mu inteetinee 0000 1040 1701’ 2.000 1070 10000 0000.4
(before eleening)
sun intestinee 14s: 1410 1278 1216 1000 0004 1278.8
(after cleaning)
hrs. intestines 4007 2842 2022 3148 0007 10180 0307.:
(before cleaning)
hrs- intutinu 1047 1711 1500 1000 1200 7852 1570.4
(after cleaning)
8710011 150 153 120 117 100 718 140.0
Tongue s00 :04 as: 001 250 1274 254.8
Ieeentery end 0052 1407 1044 1000 1000 0002 1004.4

intestinal fat
9:11 bladder 48 71 85 broken 18 222 55.5

* Bad twantyone vertebrae.

Table I Continued
mm or 0886118

(ere-e)
not 11 - twenty—one end Iventy-teo Vertebree

2.282 2.021. 2:51....“ 2.0.1 2......8 7* “Tom

M9 509 389 368 896 876 1668
Luna 668 818 713 966 608 3769
Liver 1786 1367 1666 1366 1669 7560
Puereee 813 116 190 177 168 866
mm mm 136 167 188 180 119 666
Left 116801 139 177 116 118 113 661
M0]: 867 893 868 888 668 6090
(before 018811123)
808100011 074 586 598 087 . 000 0000
(efter cleaning)
~11 inteetinee 8095 1681 1777 1576 1768 8891
(before cleaning)
M11 intestine. 1508 1279 1888 1867 1137 6667
(after cleaning)
large int eetinee 5718 8866 8913 8090 8766 16811
(before cleaning)
large intestine 1778 1688 1686 1601 1608 7769
(after 0108111113)
Spleen 113 167 183 813 158 768
Tongue 863 181 186 898 886 1166
lleuntery 6.116 1506 1086 1686 1811 1010 6776
intentinel fet
M1 bladder 68 76 out 56 87 219

‘Hnd tIenty-two vertebrae.

-32-

M“
w

769.8

1518

178.8
188.8
138.8
818

601. 2

1778.8

1893.6

8968.8

1569.8

153.6
838.8

1388

Int 1’ - henty and treaty-one Vertebrac

lbart

Inna.

Liver
P6868868
Bight kidney
Lett‘kidnly

M
(before cleaning)

Stow]:
(after cleaning)

Inall inteetinee
(before cleaning)

hall inteatinee
(after cleaning)

Large intentinee
(before cleaning)

Large intentinee
(after cleaning)

8.1608
m
0811 bhufl'

Table XI

70mm: 01' INTERNAL ORMS’

2.8.2

510

1888

1880

176

188

1696

8650

1856

6695

1596

167

8.8.17

895
1600

1565
160
150
156

1866
670

1590

6558

1690

1810

6165

1560

616

8787

1165

5979

1666

678

1006

5755

12.16

169

17

11759
6187
80780
7706

700

815

INola-e Ice neaenred in cubic centi-etere by water dieplacelncnt.

9 Had I8|lenty--one vertebrae.

11.22
505.8
1569.8
1575
168
188.6
1855.6
661.8
8351.8
1885.6

6160.8

1561.8

866.6
55.8

Table XI Continued

‘7onuur<0r INTERNAL ORG‘NS‘

not 11 - Twenty-one and Twenty-two Vertebrae

Heart
Lung.
14:0:
Pancrea-
middle!

1.9883168.)

M
(before cleaning)

ate-eel
(after cleaning)

~11 intentilee
(beta-e cleaning)

lull intentinee
(after eleaning)

Large inteetinee
(before cleaning)

Large intentinee’
(after cleaning)

88100!
Tongue
Gall bladder

03h”

896
1660
1565

81.1

151

185
1598

8768

1655

1760

8

8.8,57

808
1856
1896

168
157

1780

1860

5150

1690

(out)

869
1556
1867

E555
§E

18m

6175

801

P

.8. 5

III-unil—
858

1600
1570
178

*
a:

116.

1078

6056

1557

855
87

i.

1566
7655
7056

875

615

8919

10668

656

19707

7686

717
1117
”7

l7701mm 'ae neaenred in cubic centimetere by rater displacement.

1mad tlenty-tvo vertebrae.

-34-

I?

875.8
1691
1611.8

175

182.6

188.6
1786.8

8098 .6

1866.8

5961.6

1586.8

165.6
885.6
51.8

- 35 -

vertebrae. Berkshire sow number 3 was supposed to have 16 thoracic vertebrae
and 7 lumbar, she had the 16 thoracic vertebrae, but only 6 lumbar. Poland
sow number 3 of Lot 2 was supposed to have 16 thoracic vertebrae and 7

lumbar vertebrae but proved to have only 6 lumbar vertebrae. Duroc barrow
number 16 was supposed to have 16 thoracic vertebrae and 6 lumbar, but
proved to have 15 thoracic vertebrae. Duroc sow number 36 was supposed to
have 15 thoracic vertebrae and 7 lumbar, but proved to have only 14 thoracic
vertebrae. This left only 7 pigs on which no errors had been made, but

left 5 pairs with.a difference of one vertebra between the 2 pigs of each
pair.

A second examination of the X—ray films was made to see if it
were possible to determine why these errors were made. One of them was due
to an indistinct film. Another was due, apparently, to the pig having moved
during the Xkray exposure. The others were due to photographing too late
for getting the whole pig on one film, and attempting to picture part of
the body at a time. In these cases the vertebraewere counted from.the front
rib to the last rib on one film, and from the last rib to the last lumbar
vertebra on another. Senetimes the outlines of the ribs were indistinct and
there was danger of the last rib not showing on the film for the caudal
part of the body. In this case the last thoracic vertebra was accidentally
counted.with the lumbar vertebrae. The best results were obtained when the
pigs were two to three weeks old.

In measuring the length of the thoracic cavity as shown by the
dorsal and ventral attachments of the diaphragm, it was observed that the
attachment at the breast was always adjacent to the ventral and of the
sixth rib. The dorsal attachment varied slightly with the pigs of different
numbers of ribs. In the case of the pigs with 14 pairs of ribs the dia-

phragm was attached at the base of the last rib. In pigs with 15 and 16

..D-" .‘._ n4_-._.‘ _ _

9 fl'l“

Table III

WHERE'S 0F LBDGVIINAL CAVITIES

(millimeters)

Let I - Twenty and Twenty-one Vertebrae

b.8341

‘Length of thoracic

vertebra 616
Length of’lumbar

vertebra 264
I..ength:""I

at back 615

at breast 205
Length:¥‘

at back 338

at breast 573

Lot II - Twenty-one and Twenty-two Vertebrae

D.B.lc
‘Length of thoracic
vertebra 469
‘Length of lumbar
vertebra 236
Length?”
at back 612

at breast 210

M113!"

*8

8*
8*

at back 388

at breast 626

Had twenty-one vertebrae.

D=S.17

668

260

627

210

615

625

D.B.37

656

220

622

210

550

D.B.ll

662

239

630

220

565

597

D.B. 7

670

256

626

222

583

585

D.B. 6

625

230

606

208

358

552

D.8.36

623

269

606

217

580
585

sees.”

603

260

587

216

372

565

P.8. 5

666

222

590

220

581

590

- 35 -

Eben

626

260.6

613

211.6

369.6

578.6

Eben

656.6

256.2

610.8

215.8

576.6

586.8

Measurement was taken from the anterior edge of first rib to the anterior

side of’the end of the diaphragm.

Ileasurenent was taken from.the aitch bone to anterior side of the end of
the diaphragm. The aitch bone is the ischio-pubic symphysis.

sac twenty-two vertebrae.

pairs of ribs it was sometimes attached between the 14th and 15th ribs and
sometimes at the level of the base of the 15th rib. But in no case with
any of this group was it attached caudad t3 the 15th.rib. The measurements
for these cavities are shown in Table XII. The length of the thoracic
cavities as measured from the anterior margin of the first rib to either
dorsal or ventral attachment of the diaphragm was strikingly similar in the
two lots. The same was true of their abdominal cavities. There was less
variation between the two lotsin these respects than in the length of the

thoracic and lumbar vertebral columns.

CARCASS STUDIES

The object of the carcass studies was to determine Whether there

was any difference in the value of carcasses of pigs with varying numbers of

body vertebrae as shown by'a system of carcass measurements, or by actual

cutting record of the carcasses into wholesale cuts. The carcass measurements

used were worked out by the United States Department of Agriculture, Bureau

of Anhmal Industry, and published on.a mimeographed sheet entitle “Method

For Measuring

flN’Oel "

No.2 -

No.3 -

110.4 -

No.5 "

No.6 "

11°07 “

11009 -

Reg Carcasses". The directions are as follows:-

Length of head - from thc.snout (between nostrils) to
the tip of the Atlas Joint (occipito-atloid articulation)
(Use calipers).

Length of neck - from the base of the Atlas Joint to

 

the anterior aspect of the first thoracic vertebra.

Length of carcass - from the anterior edge of the
first rib to the lowest point (as the carcass hangs
on the book) of the aitch bone.

Length of leg_- from the lowest point of aitch bone
to the coronary band of the hind foot.

At the seventh thoracic vertebra measure the thickness
of the back fat (exclusive of the skin).

At the seventh thoracic vertebra measure the distance
from.the lower margin of the back fat to the upper
edge of the spinal canal.

At the seventh thoracic vertebra measure the distance
from the upper edge of the spinal canal to the lower
edge of the split breast bone.

2.1199282 213.8265 28!. 1650161163.: skinl
At the first thoracic vertebra.
Count from the last lumbar vertebra to a point 7 vertebra
lower as the carcass hangs (include last lumbar vertebra

in count). At this point measure the thickness of back
fat.

No.10 - Count from last lumbar vertebra to a point 5%
vertebra lower as the carcass hangs (include last
lumbar vertebra in count). At this point measure
the thickness of back fat.

No.11 - At the last lumbar vertebra measure the thickness
of back fat.

No.12 - Measure the circumference of the right front leg at
the point of least circumference between knee and
pastern joints.

No.15 - Width through shoulders. From.inside of carcass
at first thoracic vertebra to outside of shoulder
on a line parallel with the floor. ‘measure both
sides of carcass. (Use calipers).

No.14 - Width through hams. From.the top point of the aitch
bone to the outside of the ham on a line parallel to
the floor. Measure both sides of carcass. (Use
calipers).

No.15 - Measure from the lowest point of the aitch bone to
the center of the inside of the hock joint. The
point of the hook joint to which this measurement
should be taken is at a bony projection which may be
felt under the skin of the leg.

No.16 Plumpness of ham. Using one-half of measurement No.

15 locate 3 or 6 points on ham equidistant from plane

through center of hock joint. It is best to mark

these points with sharp skewers. ‘Measure circumference
of ham, encircling with steel tape immediately below

skewers e

 

All measurements are taken in millimeters and with carcass hang-
ing from hook in normal position. "

The measurements for the 15 carcasses frmm the feeding experiment
are grouped according to the number of body vertebrae and are shown in Table
IXIII. The means for each measurement were computed for each group, but
standard deviation and probable error were not computed on account of the
xnnnbers being so small. IMost of the measurements are very similar for the

different groups. The length of the carcass did show an increase for the

 

Twenty Body Vertebrae Carcasses

Measurement

Length of head
(NOcl)

Length of neck
(N002)

Length Of body
(No.5)

. Length d: leg
“70.4)

Depth of body
(Total of Nos.5,6, and 7)

Thickness of fat
("0 Of N05. 5,8,9’10 and
11)

Circumference of leg
(No.12)

Width through shoulders
(“0013)

Width through hams
(NO 014)

iitch bone to hook
(No.15)

Plumpness of ham
(NOeM)

Total length of body
vertebrae

l’Carcasses from hogs in feeding experiment.

Table XIII
CARCASS NEASU'RHIEIYPS"

D.S.61

278

160

756

558

520

158

162

166

560

665

652

D.S.17

272

170

805

587

511

59

166

156

571

688

0.8.11

280

175

698

585

295

168

157

162

561

670

678

D.B. 6

289

166

755

567

57

167

150

161

570

662

Mean

279.8

167.5

752.5

576.5

508.5

57.5

166.5

155.5

160.5

565.5

655.8

666.5

Measurements in millimeters.

Twenty-one Body Vertebrae Carcassee

Measurement

Length of head
(N091)

Length of neck
(NOsZ)

Length of body
(No.3)

length of leg
(N005)

Depth of body
(Tatu Of N0305,6,
and 7)

Thickness of fat
(Av. of Nos.5,8,9,
10 and 11)

Circumference of leg
(No.12)

516th through
shoulders (No .15)

Width through hams
(No.14)

Litch m to hook
(NOelS)

Plumpncss of ham
(No.16)

Total length of body
vertebrae

Table XIII Continued
CARCASS WWEMS"

P.S.12

282

156

762

565

551

51

158

157

169

565

502

662

D.B.16

279

182

805

576

508

61

161

155

125

555

622

709

D.B.57

265

171

760

566

506

55

166

155

158

552

655

682

W... from hogs in feeding experiment.

13.8.56

252

161

777

559

552

65

155

161

161

551

679

687

D.B. 7

500

161

801

596

518

56

165

158

157

576

665

715

-41-

Mean

271.2

165.8

777.

571.2

519

57.2

160.2

156.8

157.6

559.8

660. 2

690.6

Measurements in millimeters.

Table XIII Continued
CARCASS Mmm fill-TBS”

Twenty-two Body Vertebrae Carcasses

Measurement P.S.3 B.S.22 8.8.12 B.S.3 Mean
Length of head 297 256 265 265 270.5
(No.1) '
Length of neck 167 162 155 157 160.3
(No.2)
Length of body 782 785 801 787 788.5
(NOeS)
Length of leg 575 526 534 530 541.3
(No.6)
Depth of body 309 309 298 308 306
(Total of Nos.5,6 and 7)
Thickness of fat 38 32 32 34 34
(Av.cf Nos.5,8,9,10 and
11)
Circumference of leg 146 144 145 158 148.3
(Nbelz)
Width through shoulders 139 144 136 142 140.3
(No.13)
Width through hams 144 140 140 141 141.3
(No.14)
Aitch bone to hook 360 345 356 338 549.8
(No.15)
Plumpness of has 676 662 671 673 470.
(Nbcls)
Total length of body 697 705 717 692 702.8
vertebrae

'Carcasscs from hogs in feeding experiment. Measurements in millimeters.

-43..

group with the larger number of vertebrae. The 20 vertebrae carcasses
averaged 752.5 millimeters, the 21 vertebrae group averaged 777 millimeters,
and the 22 group averaged 788.3.millimeters. Between the first and third
groups an increase of ten per cent in body vertebra increased the length of
body less than five per cent. The length of the leg was noticeably shorter
for the 22 vertebrae group. This can probably be explained by the fact that
three of the pigs with 22 body vertebrae were Berkshires, and there were no
pigs of the same breed in the other groups. The Berkshire pigs in the
College herd are noticeably shorter legged in proportion to the length of
body than the other breeds. measurements 5, 6, and 7 were added together to
give the depth of the body. The three lots showed no consistent difference
with reapect to depth of body. IMeasurements 5, 8, 9, 10 and 11 were averaged
because all were measurements of depth of back fat at different points. Here
again the fact that the 22 body vertebrae group have a slightly smaller thick-
ness of fat back may be due to breed. Imeasurement number 16 for the plumpness
of ham, shows a slightly higher average for the 22 body vertebrae group but
is of questionable accuracy. This measurement varied greatly with slight
change of its location.

The vertebrae were measured individually for each one of the
above carcasses. The total lengths of the body vertebrae were included at
the end of the table of carcass measurements. This measurement shows a de-
cided tendency toward the increased length of body with the increased number
of vertebrae. The 20 vertebrae pigs averaged 666.5 millimeters, the 21
vertebrae pigs averaged 690.6 millimeters, and the 22 vertebrae pigs averag-
ed 702.8 millimeters. This difference is as much as one short vertebra
between the first two groups, but less than half a vertebra between the 21
and 22 vertebrae groups. The individual vertebraw of the 21 group averaged

1.2 per cent shorter and the 22 group 4.2 per cent shorter than the vertebrae

- Table XIV
LENGTH OF INDIVIDUAL VERTEBRAE

(Average of 15 carcasses from feeding experiment)

Vertebra“ Thoracic Lumbar

(m.m. ) (m.m.)

1 26.5 57.5

2 28.2 58.5

5 28.5 58.8

6 28.5 59.6

5 28. 5 59 . 1

6 28.7 57.1

7 29.2 56.5
8 29.8
9 50.5
10 51.2
11 51.6
12 52.5
15 55.2
16 56.7
15 35.1
16 55.0

*Vertebrae were numbered from the anterior.

- 45 -

of the 20 vertebrae pigs.

From the individual.measurements of vertebrae the average length
of the thoracic and lumbar vertebrae are shown in Table XIV. There is a
gradual increase in the length of each vertebra from.the anterior toward the
posterior until the fourth lumbar vertebra is reached, after which there is
a slight reduction in the length. The lumbar vertebrae were distinctly
longer than the thoracic.

Seven pairs of carcasses were selected at the Rose-veil Packing
Dompany on which carcass measurements were made. Not all of the United
States Department of Agriculture measurements could be applied because the
carcasses were dressed "packer style" with the bones of the head removed.

No attempt was made to measure the length of the heads or necks. IMeasurements
number 15 and 16 were omitted because they seemed hard to obtain with any

high degree of accuracy. It was attempted to select carcasses that would

show about the same degree of finish and approximately the same weight. In
order to find enough that would have a difference of two body vertebrae it

was necessary to use carcasses ranging in weight frmm 155 to 174 pounds.
Hewever, they were selected by pairs so that when a light carcass or a heavy
carcass was included in one group a.similar carcass was selected for the

other group.

The means of the measurements for the seven carcasses in each
pair are given in Table XV. The average weight was also given. The carcasses
with 22 body vertebrae were 45.? millimeters longer. An increase of ten per
cent in body vertebrae increased the length of body less than six per cent.
The length of leg and depth of body was also slightly longer. The average
depth of back fat was five millimeters less than in the shorter bodied hogs
and indicates a possibility that the longer bodied group were not quite so

well finished, which would naturally result in their being somewhat longer

-46..

Table XV
CARCASSIMEASUREHENTS*

measurement 20 Body Vertebrae 22 Body Vertebrae Difference
Length of body 745.6 787.5 45.7
(No.3)
hmh of 106 550.6 542.6 120
(NOO‘)
Depth of body 545.6 351.9 8.5
(total of 5,6 and 7)
Thickness of fat 39.2 5309 a 5.3
(Av.of 5,8,9,10 and 11)
Width through shoulders 159.9 140.9 - 1.0
(No.15)
Width.through hams 156.1 141. - 5.1
(1°44)
Average weight of 155. (pounds) 158.1 (pounds) - .9
carcasses

I'Average of seven pairs measured at Dewitt. Measurements in millimeters.

- 47 -

and deeper for the same weight of carcass. However, this difference in
finish probably would not account for the difference in length. The standard
deviation and probable error was not computed because of the small numbers.

The thirteen carcasses from the pigs in the feeding eXperiment
were cut into wholesale cuts and weighed to the nearest gram. The hams were
cut off one-half way between the aitch bone and the last lumbar vertebra and
through the middle of the fourth sacral vertebra. The head was severed with
a square out just cauiad of the occipital bone. The shoulder was cut from
the back and side between the second and third thoracic vertebrae and between
the distal ends of the first and second ribs. (The loin was cut from the side
at the lower edge of the tender loin on the rear end and squarely below the
edge of the backbone at the front end. The ribs were not separated from the
side nor the loin from.the fat back. Error, due to variation in the amount
of meat taken with either of these cuts in the separation, was thus avoided.
Comparison was also made of the percentage which each cut constituted of the
total weight of the carcass. The results are shown by grouping the carcasses
according to the number of body vertebrae in Table XVI.

The number is, of course, too small to justify any conclusions.
The mean weight of loin and fat back is slightly higher for the 21 and 22
body vertebrae groups than for the 20. The difference was only .82 per cent
between the 20 and 21 body vertebrae groups and practically the smne for the
21 and 22 groups. Although the percentage of side for the 21 body group was
.5 per cent larger, it was even lower in the 22 body vertebrae group than in
the 20.

The seven pairs of carcasses that were measured and five addition-
al pairs, were selected for cutting records at the Rose-Vail.Packing Company.
The system of cutting was exactly the same as used on the carcasses from the

feeding eXperiment. The two cutting records could not be combined because

Pig Identi-
ficaticn

D.

D.

D.

D.

8. 11
Height
Percentage
S. 41
Weight
Percentage
B. 4
weight
Percentage
S. 17
weight
Percentage

Average

P.

D.

D.

D.

D.

Weight
Percentage

S. 12
Weight
Percentage
B. 57
weight
Percentage
S. 56
Height
Percentage
B. 7
Height
Percentage
B. 16
leight
Percentage

Average

P.

B.

B.

Weight
Percentage

3. 5
weight
Percentage
3. 13
weight
Percentage
S. 22
Height
Percentage
3. 5
weight
Percentage

£70388.

weight
Percentage

Head

6118
8.89

5784
8.65

6590
9.55

5980
8.66

6068
8.92

Table XVI
WEIGHTS AND EERCENTAGES 0F WHOLESALE CUTS
(Carcasses of pigs in feeding experiment)

Shoulder

17909
26.01

16722
24.94

17091
25.49

17918
25.95

17410
25.60

TwentygBodygvertebrae

Loin and fat

back
16520
25.70

18057
26.90

17419
25.98

17960
26.02

17454
25.64

Twentyecne BodyfVertebrae

5882
8.27

5284
8.27

6215
8.78

6058
8.81

6516
9.20

5947
8.67

16762
25.55

16705 ,
26.15

17144
24.22

17872
26.07

16655
24.24

17025
24.84

17040
25.95

16495
25.81

19647
27.75

17805
25.97

19778
28.82

18155
26.46

Twenty-two Bodl‘Vertebrae

6212
9.08

5954
8.54

5494
8.28

5994
8.65

5908
8.64

17154
25.05

17185
24.75

17578
26.49

17059
24.62

17259
25.22

18225
26.64

18768
27.01

17180
25.89

18745
27.06

18229
26.65

Side

12064
17.52

11801
17.60

11515
16.87

11819

17.12

11749
17.28

14875
20.90

9989
15.65

12570
17.47

11827
17.25

12282
17.90

12269
17.85

11081
16.20

12015
17.29

12029
18.15

11977
17.29

11776
17.25

Ham

16445
25.88

14699
21.92

14842
22.15

15558
22.25

15556
22.55

16605
25.55

15446
24.16

15415
21.77

15015
21.90

15611
19.84

15217
22.20

15759
25.04

15581
22.42

14084
21.22

15502
22.58

15252
22.26

WEIGHTS AND PERCENTAGES 0F WHOLESALE:CUTS

head

Shoulder

Loin and fat back
Side

Inns

Leaf lard

Table XVII

(Average of 14 pairs of carcasses)

Carcass with 22
jbcdy vertebra

55404
207207
220804
162118
192190

26122

carcass
5.97
24.61
26.25
19.26
22.85

5.10

Carcass with 20

-49-

Bit ference Standard

 

body vertebra of mans
carcass

56852 4.28 .55
30254: 23.56 1.01
216297 26.16 1.17
174571 20.51 1.08
201551 85.42 .62
28010 5.26 .16

(Weight Percent of Weight Percent of

error of
difference

.05
.49
.69
.80
.48

.29

the carcasses at the packing plant were dressed "packer style" with the head
bones removed. The average weights and percentages of the wholesale cuts are
shown in Table XVII.

The mean percentage of loin and fat back is slightly larger for
the carcasses with 22 body vertebrae, but the difference in the mean percent-
ages is only 1.17 and is less than twice its standard error of difference of
.69. This would not usually be considered a significant difference but the
odds that a difference exists in favor of the longer carcasses are 20 to 1.
The difference in percentage of shoulder is also close to the point usually
considered significant, being 1.01 t .55. The odds that a difference in favor
of the 22 group are 22 to 1. A mathematically significant difference is shown
between the two groups in the percentage of head. This could not be consider-
ed reliable as there was considerable variation in these cuts due to the

removal of the head bones with varying amounts of flesh.

- 51 -

EKEHDHFY

The vertebrae of 519 pigs from the Michigan State College herd
were counted. variation ranged from 19 body vertebrae consisting of 15
thoracic and 6 lumbar to 25 comprising 16 thoracic and 7 lumbars. The
variation and the mean number of body vertebrae was practically the same for
both.males and females. or the five breeds examined the Yorkshire, Chester
White, and Poland China were about equal with a mean number of body vertebrae
ranging from 21.05 to 21.25. The Berkshires had slightly higher counts but
the numbers examined were too small to justify definite conclusions. The
Durocs were distinctly lower in number of vertebrae, their mean being 20.55.

The vertebrae of carcasses from the Michigan State College swine
herd outenumbered the vertebrae of carcasses from.central'Michigan farms.

The mean difference was .445 with a standard error of difference of .066
which is statistically significant. This difference appears to be due to

more careful and rigorous selections practiced in the College herd toward

the present approved type.

X-ray photography proved unsatisfactory as a method of determin-
ing the number of vertebrae in live pigs in a large percentage of cases
under the handicaps encountered. Errors made in their use were not discovered
until the pigs were slaughtered.

There was only a slight and insignificant advantage for the hogs
with the larger number of vertebrae as shown by the rate of gain in the feed-
ing test. There was no difference in the economy of the gain.

The slaughter data involves too small a number of pigs for any
conclusion on the size of vital organs. The diaphragm did not move caudad
to the full extent of the increased length of the thoracic column by increas-

ing numbers of ribs and thoracic vertebrae. It was always attached at the

level of the sixth pair of ribs at the breast. With 14 pairs of ribs the
attachment at the back was even with the 14th rib, and was between the 14th
and 15th or even with the 15th in carcasses with 15 or 16 pairs or ribs.
Extra vertebrae seemed to lengthen the abdominal.more than the chest cavity.

The larger number of vertebrae were associated with longer
carcasses, and longer thoracic and lumbar vertebral columns. In.some cases
the extra number was offset by shorter individual vertebrae.

No significant differences were found in the yield of wholesale
cuts of higher value from the carcasses with 20 and 22 body vertebrae
studied.

In this feeding eXperiment from which carcasses were secured for
the measuring and cutting records, it was unfortunate that pigs with greater
variation were not used. Larger numbers would also have been advisable.
Access to a large number of pigs with known vertebral variations is needed
to initiate Such an eXperiment. It would have been better it all of the
pigs could have been of the same breed.

A better source and supply of pigs should have been available
for the cutting records. These records should give the most valuable infor-

mation regarding the economic value of extra ribs and vertebrae.

Carroll,

- 55 -

LITERATURE CITED

Tie E0, Bull, Se, Rice, Jo Be, Laible, R051. and 811111711, Re A0,

1929. Swine type studies. University of Illinois Agricultural

EXperiment Station Bulletin No.521.

Shaw, A. M}, 1929. Variations in the skeletal structure of the pig.

Scientific Agriculture Volume X, No.1: 25 - 27.

Shaw, A. M., 1950. A method of determining the variations in the vertebral

vaughan,

column of the live pig. Scientific Agriculture Volume X, No.10:

690 - 695.

H. W., 1950. Types and.market classes of livestock. R. G. Adams

and Company.

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