49.
U l TRA'SONIC E V A 1 U A T I O N OF C O M P O S I T I O N I N HOGS ' S L A U G H T E R E D
A T 7 5 , 1 2 5 , 1 7 5 , 225, AND 275 POUNOS
R I C H A R D L.
H I W E R and J. W.
THORNTON
Early research by Warner, Ellis and Howe (1934) and Hankins and
Ellis (1934 j related both chemical determinations of ether-extract t o
physically separated f a t and carcass messuremnts of backfat thickness t o
t o t a l f a t i n the hog carcass.
During the l a s t f i f t e e n years there has been a concerted e f f o r t
made t o accurately determine t h e lean and f a t make-up of a l i v e hog. One
of t h e first attempts was that of i n j e c t i n g i n t o t h e blood stream a chemic a l , antipyrine. Fatness was then calculated from the water content as determined by t h e water delusion technique. Dr. H. F. B a y b i l l reported this
t o be an e f f e c t i v e and f a i r l y reliable rnethod for c a t t l e but not f o r hogs.
One of t h e troubles with hogs was that of being p o s i t i v e the s o l u t i o n was
i n j e c t e d i n t o t h e c i r c u l a t o r y syskm. Later D r . Louis F e i c s t e i n used s l e e p
t i m e as a method; a report of t h i s was given a t the Reciprocal Meat Conference i n 1955. He used the drugs Kkmithal and Thiopental.
The &as d i l u t i o n p r i n c i p l e has been reported by S i r i , i n which a
change i n concentration of helium permitted a body volume calculation.
Dr. A. Pearson has worked with the p r i n c i p l e of determining
volume i n a closed chamber.
The backfat probe reported by Hazel and Kline (1352) has beer,
used as an objective method of measuring f a t n e s s i n l i v e hogs a t market
weight. Hazel and Kline (1959) indicated that t h e probe technique was not
very e f f e c t i v e when used on pigs with less than 1 . 0 inch of backfat. This
lead t o t h e development of the l e a n m t e r a t Purdue.
Recently, u l t r a s o n i c equipment has provided another t o o l
t a i n i n g an Objective measure of baclcfatthicla?ess on the l i v e hog.
a c o u s t i c a l properties of aniroal t i s s u e have been studied by Lu6wig
S t o u f f e r (1959) and Price .e t a l . (1960). These i n v e s t i g a t o r s have
that the v e l o c i t y of ultl'gsonic aound through animal tissue v a r i e s
and l e a n t i s s u e .
-
f o r ob-
The
(1950),
indicated
for fat
Price et a l . (1960) reported a c o r r e l a t i o n of 0.74 between l i v e
estimated and a c t u a l eye muscle area. A c o r r e l a t i o n of 0.50 has been found
50.
between an average u l t r a s o n i c reading and average backfat thickness by Meat
Quality Laboratory personnel. These were hogs of market weight (225 pound
live-weight)
.
Missouri workers have indicated reliable estimates of backfat
thickness, eye muscle area and y i e l d of f a t and lean employing u l t r a s o n i c
equipment.
T h i s study was undertaken by the Meat Quality Laboratory i n cooperation with t h e Agricultural Engineering Division, ARS, USDA, t o evaluate
t h e usef'ulness of u l t r a s o n i c s i n detecting f a t and lean composition a t 75,
125, 175, 225 and 275 pounds.
A t o t a l of 97 crossbred pigs were used i n t h i s experiment. These
pigs were representative of "meat type" and f a t t e r and l e a n e r hogs. The
primary objective i n s e l e c t i n g these pigs was t o choose ones with a wide
range of fatness.
The experimental procedure was designed t o obtain u l t r a s o n i c
measures on a l l 97 pigs a t s p e c i f i c weight periods. A t each of 5 weight
periods a representative number of pigs were slaughtered. Pigs slaughtered
a t 275 pounds under t h i s system would have 5 recorded u l t r a s o n i c measures
while pigs slaughtered a t 75 pounds would have 1 u l t r a s o n i c measure.
The u l t r a s o n i c measure of f a t thickness was an average measure of
f a t depth a t t h e f i r s t r i b , f i r s t and last lumbar vertebrae. The a c t u a l
carcass backfat thickness a t these 3 points was a l s o recorded and averaged.
Lean depth was obtained a t a point 2" off the midline on the r i g h t s i d e of
t h e l o i n by f i r s t obtaining t h e measure of f a t and then measuring the distance t o the r i b a t t h i s point. I n t e r p r e t a t i o n o f both l e a n and f a t depth
requires some experience and t r a i n i n g i n reading t h e u l t r a s o n i c instrument.
A uniform c u t t i n g of the dressed c8rcasses by an appropriate
standard method was employed throughout t h e experiment. The method used
was described by Hiner (1949). Each of the primal c u t s was physically
separated i n t o lean, f a t , bone and s k i n . To obtain t o t a l lean, the weight
o f l e a n from each cut from the one animal were added. Total fat was obtained i n t h e same manner.
T'nese data were prepared f o r a n a l y s i s i n two ways. F i r s t , the
u l t r a s o n i c measure of f a t f o r each pig a t the f i r s t rib, first lumbar and
last lumbar vertebrae were recorded a t the time of slaughter and averaged.
Actual carcass backfat thickness a t these same points was a l s o recorded
after slaughter and averaged.
For these data, multiple regressions of composition on weight and
average of u l t r a s o n i c measures a t t h e f i r s t r i b , f i r s t lumbar and l a s t
lumbar f o r each weight group were determined. This involved only slaught e r e d animals from each weight group. Significant (PCO1) p a r t i a l regressions of composition on slaughter weight were used t o a d j u s t each
weight group t o its mean. P a r t i a l c o r r e l a t i o n s (slaughter weight held
constant) between composition and u l t r a s o n i c measures were then computed.
Using t h i s procedure, the usefulness of t h e u l t r a s o n i c instrument i n eva1.ua t i n g both a c t u a l carcass backfat thickness and composition a t each weight
group was determined.
51.
Next, f o r pigs slaughtered a t 175, 225, and 275 pounds there were
3, 4 and 5 sets of u l t r a s o n i c readings of f a t depth respectively. For t h e
225 pound group, four sets were formed by reading 1, reading 1 + 2, reading
1 + 2 + 3 and reading 1 + 2 + 3 + 4 a t t h e first r i b , a t the f i r s t lumbar
and a t the l a s t lumbar. This same procedure was used f o r each weight group.
For the 175, 225, and 275 pound groups, the sets of readings were used t o
determine i f ultrasonic readings a t an e a r l y weight were indicative of composition or a c t u a l backfat thickness a t time of slaughter. The described
sets evaluated the deposition of backfat thickness within pigs w i t h increasing weight.
The man6 and standard deviations of ultrasonic meausres, age,
slaughter and carcass weight are shown i n Table 1. The differences i n
standard deviations between slaughter and carcass weight is quite negligible
i n the l i g h t e r weight groups. As pigs become o l d e r evidently there i s
g r e a t e r d i f f e r e n t i a t i o n between viscera and carcass components. The preslaughter treatment b f a l l pigs was e s s e n t i a l l y the same. V a r i a b i l i t y i n
age increased as weight increased. Some of these pigs were from dams
selected f o r either high o r low f a t producing a b i l i t y and many account f o r
some of the wide variance i n time required t o reach prescribed weights i n
the heavier groups.
The u l t r a s o n i c measure of f a t thickness underestimated a c t u a l
carcass backfat thickness i n a l l weight groups. The v a r i a b i l i t y i n backfat
t h i c h e s s was g r e a t e s t i n t h e heavier weight groups. Lean thickness did
not show a consistent pattern.
The standard deviations of three of the carcass components i n
Table 2, t o t a l lean, f a t and skin, increased with increasing weight indicating more d i f f e r e n t i a t i o n i n these items a s pigs g e t heavier. Standard
deviations f o r t o t a l bone fluctuated from group t o group. Eye muscle area
was r e l a t i v e l y constant from 125 t o 275 pounds. Within weight groups, the
trend was toward more d i f f e r e n t i a t i o n between pigs i n t h e heavier groups.
weight.
Table 3 shows the increasing fat t o lean r a t i o w i t h increasing
It is apparent t h a t gains beyond 175 pounds a r e c h i e f l y f a t gains.
P a r t i a l correlations (slaughter weight held constant) betireen the
recorded and averaged u l t r a s o n i c measures of f a t depth a t t h e shoulder,
l o i n , and ham and composition and a c t u a l backfat thickness a t time of
slaughter are shown i n Table 4 . The u l t r a s o n i c measure of f a t depth was
not s i g n i f i c a n t l y related t o a c t u a l backfat thickness u n t i l pigs reached
the 2 2 5 pound weight group. Total lean was negatively related t o u l t r a sonic backfat thickness (increased backfat decreased lean) a t t h e 75, 225
and 275 pound weight groups. These f a c t s indicate t h a t both l e a n and f a t
between pigs can be detected a t either 225 o r 275 pounds when pigs are
heavy enough t o allow d i f f e r e n t i a t i o n i n theae components.
Table 5 shows t h e m l t i p l e correlations among u l t r a s o n i c measures of
fat depth a t t h e shoulder, l o i n and ham and composition i n pigs slaughtered
a t 175, 225, and 275 pounds. Actual carcass backfat t h i c h e s s a t these
weights can be predicted from u l t r a s o n i c measures taken at 75 poundson l i v e
pigs i n t h e 1 7 5 and 225 pound groups. For pigs slaughtered a t 275 pounds,
two u l t r a s o n i c measures were required, one a t 75 and one a t 1 2 5 pounds, t o
predict carcass backfat thickness a t 275 pounds.
52.
These 3 groups of pigs exhibited v a r i a t i o n s within pigs i n backThe 175-pound group was consistent i n depositing backfat
i n a l i n e a r fashion. For t h i s group, the most important s i n g l e point of
measurement was over the l o i n for a l l u l t r a s o n i c readings. The group
slaughtered a t 225 pounds was q u i t e variable i n age. They were a l s o q u i t e
variable i n length. I n f a c t , when these variables, age and carcass length
were included with t h e u l t r a s o n i c l o i n measure, t h e u l t r a s o n i c measure
taken a t 125, 1 7 5 and 225 pounds adjusted f o r v a r i a b i l i t y i n age and carcass
length was s t a t i s t i c a l l y s i g n i f i c a n t (R = .60, ,65 and .68 respectively).
f a t deposition.
Table 6 shows the most important points o f measurements f o r t h e
three groups of pigs f o r each recorded u l t r a s o n i c measure. As pigs increase i n f a t n e s s t h e shoulder measurement is more variable than measures
a t the o t h e r two points.
These data i n d i c a t e that the use of the u l t r a s o n i c instrument i n
hogs may be developed t o provide information on growth p a t t e r n s w i t h i n
pigs not f i l l y known a t the present time. This information would be very
usef'ul t o animal breeders i f carcass backfat thickness can be determined
i n young pigs of desired breeds of l i n e s . For hogs of market weight (225
pounds), t h e u l t r a s o n i c instrument appears t o be as e f f e c t i v e as t h e probe.
TAEZE 1
- MEANS AND STANDARD DEVIATIONS OF ULTRASONIC MEASURES, AGE AND WEIGHT BY WEIGFD GROUPS
aughter: Number:
eight : of :
roup
: pigs :
Age
(days)
: Slaughter:
: weight :
: (lbs.) :
92 ,* 10.9:
96.2:
-
78 97.4:
Carcass : Ultrasonic back-: Carcass back- : Ultrasonic l
weight : fat thickness a : fat thickness b:
thickness
(lbs.) :
(inches)
:
(inches)
:
(inches)
51 & 8.6:
.62
-12
:
.72 2 .17 :
1.00 2 .2
88
.89 2 .15
:
1.00 2 -17 :
1.26 *.15
:
1.36 2 -15 :
1.58 2 .1
1.38 2 .15
:
1.76 ,+ .30 :
1.75 2.18
1.62 f .20
:
2.12
1.71 f .1
75
:
18 :
125
:
19 : 120 2 9.2:
129
175
:
20 : 152
12.9:
178 +7.7:
129 2 9..8:
1.16
225
:
24 : 184
26.2:
227 f7.5:
173
10.3:
275
:
16 : 221 a 53.9:
274 +4.8:
213
7.6:
a
-
-
6.4:
f
* e09
* -33
:
An average ultrasonic measure of fat depth at the first rib, first lurribar and last lumbar.
An average ruler measure of carcass backfat thickness at the first rib, first lumbar and
last lumbar.
C
Ultrasonic measure of depth to bone minus ultrasonic measure of fat depth 2" off midline
on right side of l o i n .
TABLE
2
- MEANS AMI
m DEVIATIONS OF EYE MUSCLE AREA
S
AND CCMKISITION BY WEIGRI! GROUPS
: T o t a l sepsrable: T o t a l separable: Total separable: T o t a l separable: Carcass
: eye muscle:
lean
fat
bone
skin
: weight
: (sq. in.) :
(lbs.)
(lbs.)
:
(lbs.)
(lbs.)
(lbs.)
laughter: Area of
weight
p u p
75
: 2 ~ 5 2+ -58: 23.80 f 4.58
: 12.79t 2.28
: 10,322
1.42 :
4-02?
-55 : 51,
f .45: 39.25t 4.35
: 29.21f: 4.03
: 14.17+
2-39 :
6.26
-72
125
: 3.32
175
: 3.43 f .54:
53.56 $ 8.30
: 51.362 7.38
: 17,llf
1.82 :
7.04:
1.28
: 129
225
: 3.78
65.68
: 77.41+ 9.21
: 21.23
2.86 :
8.42 + 1.33
: 173
275
: 3.96
: 101.58+ 9.54
: 25.75
+-
77:
f 84;
75.40
+- 7.59
+- 8.25
-
+-
1.12 : 10.44
f
-
+-
1.47
8.6
: 88
6.4
'
9.8
+- '10.3
: 213 ? 7.6
TABU 3
- GAINS IN COMPONEWS OF COMPOSITION B E X "
laughter w e i g h t : Total
Period gains : lean
(lbs.)
: (lbs.)
SUCCESSIVE WEIGET PEEUODS
:
:
:
Total
fat
(lbs.)
:
:
:
Total
bone
(lbs.)
:
:
:
Fat t o lean
ratio
.
: Lean t o bone
ratio
: Fat to bone
0
=ti0
75 t o 125
: 15.45
:
16.42
:
3.85
:
LO6
4: 0 1
125 t o 175
: 14.31
:
22.15
:
2.94
:
1:55
4: 86
175 to 225
: 12.12
:
26.05
:
4.12
2:15
2 : 94
6:32
225 t o 275
:
9.72
:
24.17
:
4.52
2:15
5: 34
.
.
2;48
.
.
4: 26
7: 53
TABLE 4
- PARTIAL CORRELclTIONS E i W E E 3 J AVERAGE ULTRASONIC EWKFAT THICKNESS,
AM3 COMEUSITION
Slaughter : NuItiber of
weight
:
pigs
.
WUP
75
18
125
19
175
20
.
.
225
275
By WEIGW GROWS*
: Backfat
:
: thickness :
.
.
.
0
-38
038
.
0
0
10
Total
fat
14
:
:
Total
lean
.
:
: -*78*
031
: -a31
-61-
: -.09
24
:
.82#
:
068-
16
: -.E*
:
a 7 8 H
:
080*
: -.62*
.
.
.
Q
ACTUAL BACKFAT TmCKNES
Total
bone
:
:
- 031
- -17
.
.
Eye nruscle
area b
.600.24
w.36
-.e
-046
-e09
-048
-033
PCOl
a
b
S i g n i f i c a s t ( P C O ~ )weight gmup partial regessions of composition on slaue;hter weight
used to adjust composition for variability in sl;lughter weight for each @ x $ b
Au,
p u p s adjusted to means shown i n Table 1.
S-e
correlation between ultrasonic lean thickness and eye m u s c l e area.
TAl3LE 5
- M'LEXCpLE CORRECATIONS Ml!G SUCCE;ssIVE ULWSONIC READINGS QF BACKFAT TMCKMGSS AT 'EB S€K)W
IOIN AND HAM,
275 POUNDS
ACTUAL BACKFAT TKECKNESS AND COMPOSITION IN PIGS SLAUGHTERED AT 175, 225 AM)
Weight group
: Ultrasonic
: readings a
:
:
Total
lean
:
:
75
125
:
: 192
: 1 + 2 +3
.
:
-4.5
24
23
:
:
:
.88**
.82-
:
.
13
..66**
32
:
:
41
.44
.73*
78*
175 (slaughtered)
Weight group
75
125
175
225 (slaughtered)
Weight group
75
125
175
225
275 (slaughtered)
a
P<.01
1
1
0
: 1+ 2
: 1 + 2 + 3
:
:1 + 2 + 3 + 4 :
0
:
1
: 14- 2
: 1 + 2 + 3
:
:1 + 2 + 3 + 4 :
:b2+3+4+ 5
:
42
58
64
.46
e64
.72+*
.
:
:
:
:
:
Total
fat
:
: CarcassBackfat
: thickness
.62*
:
38
023
.a=
.35
.67
.87*
-89.92=
Total
bone
.
.18
23
041
.26
0
30
. .-36
.35
..31
30
.
.80*
66*
.63H
..
.
73*
048
.53
.57
0
..73=
045
96°C
.79*
.86-
1 = Fat depth a t shoulder, loin and ham recorded at 75 lbs.
2 = F a t depth at shoulder, loin and ham recorded a t 75 and 125 lbs.
3 = Fat depth a t shoulder, l o i n and ham recorded a t 75, 125, and 175 lbs.
4 = F a t depth a t shoulder, loin and ham recorded a t 75, 125, 175 and 225 lbs.
5 Fat depth a t shoulder, l o i n and ham recorded a t 75, 125, 175, 225 and 275 l b s .
.
An vera e r u l e r measure of carcass backfat a t the f i r s t r i b (shoulder), f i r s t lumbar
?loin$ and last lumbar (ham)
6
- lUK'IPLJ3
REx?rREsSIONS OF ACTUAL AVF3AGE CARCASS BACKFAT TBICKNESS ON ULTRASONIC BACKFAT
THICKNESS AT DDFZBENT WIGETS AND LOCATIONS
htered a t 175 lbs.
of Variation
d.f.
sion due t o ultrasonic shoulder measure.
onal reduction due t o loin over shoulder measure.
onal reduction due t o bam over s b u l d e r and l o i n
asure.
ual
:
htered at 225 lbs.
.
: d.f.
of Variation
sion due t o ultrasonic shoulder measure.
onal reduction due to loin over shoulder neasure.
onal reduction due t o ham over shoulder end loin
asure
ual
.
htered a t 275 lbs.
of Variation
sion due t o ultrasonic s b u l d e r measure.
onaJ. reduction due t o l o i n over shoulder measure.
onal reduction due t o ban over shoulder and l o i n
asure.
&
*
*
P<.01
P<.05
a Mean squares
1
: 1
:
: 1
: 17
:
:
:
: 75 lbs. : 125 lbs. : 175 l b s .
: M.SOa : M.S.
: M.S.
: 12.99
:
047
: 177.38w : 182.76*
: 25.55
: 129.66*
: 89.66*
: 9.11
:
9.82
: 15.88
: 7.84
: 14.34
: 75 IbS. : 125 lbs. : 175 IbS.: 225 l b s .
: M.S.
: M.S.
: M.S.
: M.S.
1 : 76.34
1 : 135.30
: 1 : 24l.81*
: l.3 : 30.81
: 5.92
: 185.15
: 24.24
: 210.20
: 52.64
: 222.37
: 3.01
: 50.76
: 8.05
: 47.03
: 5.16
: 44.14
: 75 lbs. : 125 l b s . : 175 lbs.: 225 lbs.:275
: dof. : M.S.
: M.S.
: M.S.
: M.S.
: M.S
: 1
: 1
:
: 1
: 12
: 168.47
:
.12
: 159.94: 96.61 : 622.72*:873.82
: 212.73w : 553.90H: 179.16 : 78
: 98.35
: 85.42
: 8ll.81M : 35.31
: 8.96
: 50.51
: 5.84
: 40.35
: 3
: 28
59.
DR. HIIJER: The next p a r t of our program, and one t h a t has given
me considerable concern, i s t h i s matter of f a t n e s s i n r e l a t i o n t o t h e
p a l a t a b i l i t y and t h e q u a l i t y of pork. We have a c e r t a i n amount of evidence
t h a t f a t n e s s i s one of t h e f a c t o r s t h a t must be kept i n ruind when developing
a lean or meat type hog.
To give us a report on t h a t D r . Saffle, a menber of t h i s Committ e e , has graciously consented t o be t h e leader f o r t h i s p a r t o f t h e program.
I believe he has had some experiences and a, head start on some of us. It i s
my understanding t h a t as a graduate student a t Michigan State he worked on
the problem of fatness. Dr. Saffle w i l l now report on t h e t h i r d p a r t of
our program "Effects of Finish on the P a l a t a b i l i t y of Pork." Dr.Saffle.