Br.
J.
Nutr.
(198l),
46.
87
87
Utilization of free lysine
by
growing pigs
BY
E.
S.
BATTERHAM
AND
R.
D.
MURISON
NS W Department
of
Agriculture, Agricultural Research Centre, Wollongbar, New
South
Wales 2480, Australia
(Received
7
October 1980
-
Accepted 14 January 1981)
I.
The results of nine estimates of the efficiency
of
utilization of supplements of free lysine by growing pigs
fed
once
daily and reported by 13atterham (1974) and Batterham
&
O”eill(1978) were re-analysed using carcass
rather than live-weight values as the criteria of response.
2.
The efficiency of utilization of free lysine with once daily feeding relative to frequent feeding was
0.53
using
carcass gain as the criterion of r:sponse
(P
<
0401),
and
0.56
using food conversion efficiency on a carcass basis
(P
c
0401).
These estimates were lower than estimates
of
0.67 using live-weight gain
(P
c
0.01)
and 0.77 using
food conversion ratio on a liveweight basis
(P
<
0.05).
3.
The results indicate that current estimates of the lysine requirements
of
pigs that are based on responses to
supplements of
free
lysine undsr once daily feeding regimens may
be
10-30%
over-estimated, as a result
of
incomplete utilization of the free lysine.
Batterham
(1974)
reported that the efficiency of utilization of free lysine by growing pigs
fed once daily was only
0-43
of that of pigs given the same ration in six equal portions at
three-hourly intervals. It was suggested that the lower response with once daily feeding was
due to differential rates of absorption of free lysine and the protein-bound amino acids.
By feeding frequently,
a
more balanced supply of amino acids would arrive at the sites of
absorption and metabolism, thereby resulting in more efficient utilization. An additional
eight estimates of free lysine utilization were reported by Batterham
&
ONeill
(1978),
conducted over
a
range
or
basal diets and comparing wet and dry feeding systems. They
reported considerable variation in their estimates of lysine utilization, from 0.3
1-1
-01,
with
an over-all mean of
0.67.
No
relationship between type of diet or feeding system with lysine
utilization was established. They concluded that the variation in estimates may have been
due to ‘within experiment’ pig variation, as the estimates were sensitive to small changes
in
pig performance on any one treatment.
The estimates of Batterham
(1974)
and Batterham
&
O’Neill
(1978)
were based on
traditional measurements of live-weight gain and food conversion ratio as the indices
of
pig response. However, Balterham
et al.
(1979)
reported that with slope-ratio assays with
pigs, potency estimates based on carcass values appeared more reliable than those based
on live-weight values, as the potency estimates were sensitive to small changes in gut
contents. In the results
or
Batterham
(1974)
and Batterham
&
ONeill
(1978)
dressing
percentage was affected by a number of factors including interactions between frequency
of feeding and lysine response. Accordingly the results have been analysed on a carcass basis
to remove any effect variation in gut contents may have had on the original estimates of
free lysine utilization.
Lysine utilization was detmnined by Batterham
(1974)
and Batterham
&
O’Neill
(1978)
by comparing the response of pigs to supplements of
2
g L-lysine (as L-lysine monohydro-
chloride, anhydrous)/kg diet under once daily and frequent feeding regimens (six feeds/d
at
intervals of
3
h). The level of
2
g
L-lysine/kg was chosen to observe the response under
the two feeding regimens in conditions in which the full response to the added free lysine
EXPERIMENTAL
https://doi.org/10.1079/BJN19810011 Published online by Cambridge University Press
88
E.
S.
BATTERHAM
AND
R.
D.
MURISON
should
be
obtained. Batterham
(1974)
included an additional treatment of
4
g L-lysine/kg
diet to show that the diets supplemented with
2
g L-lysine/kg were in fact still lysine
deficient. This treatment was restricted to the frequent feeding regimen only by Batterham
&
O’Neill
(1978)
for five experiments, because it was anticipated that the responses to
4
g L-lysine/kg with frequent feeding would be equal or superior to that with once daily
feeding. In the sixth experiment of Batterham
&
O’Neill
(1978)
diets were supplemented
with
0,
I,
2,
3 and
4
g L-lysine/kg to allow a response curve to lysine supplementation to
be defined for both feeding regimens.
Carcass gain/d (kg cold carcass weight -(kg initial live weight
x
0.74)speriod (d) on
experiment) and food conversion efficiency (FCE) on a carcass basis (kg cold carcass
weight
-
(kg initial live weight
x
0.74)
+
kg food intake) were calculated using a factor of
0.74
for estimated initial dressing proportion at the commencement of the experiments. The
factor of
0.74
was determined with four piglets slaughtered at
20
kg live weight after they
had been trained in a similar manner to those used previously.
The experiments were analysed individually as well as a combined analysis on the nine
estimates from Batterham
(1974)
and Batterham
&
O’Neill
(1978).
For
the combined
analysis, wet
v.
dry feeding was confounded with experiments, except in Expts
5
and
6,
where
direct comparisons of wet and dry feeding were made. Accordingly only the results for Expts
5
and
6
were used for the wet
v.
dry feeding comparison in the combined analysis. The results
for
dressing proportion (cold carcass weight as a proportion of live weight) for the individual
experiments are also presented as these results were not presented previously.
RESULTS
For
the combined analysis, the mean response to
2
g L-lysine/kg diet with once daily feeding
was only 0-53
of
that with frequent feeding, using carcass gain as the criterion of response
(P
c
0.001;
Table
1)
and
0.56
using FCE on
a
carcass basis
(P
<
0.001;
Table 2). This
compares with responses of
0.67
using live-weight gain
(P
c
0.01
;
Table
1)
and
0.77
using
food conversion ratio
(P
c
0.05;
Table
2).
The individual estimates for lysine utilization were lower using carcass gain
(0.19-0.89)
and
FCE
on a carcass basis (0.28443) compared to live-weight gain (0.31-1.01) and food
conversion ratio
(0.28-1.27).
The statistical significances of the interaction between frequency
of
feeding and response to
2
g L-lysine/kg diet were greater in Expts
1,
6
for carcass gain
and Expts 1,
6, 7
for FCE on a carcass basis.
Dressing proportion was affected by frequency of feeding in Expts 3
(P
<
0.01),
5
(P
<
O.OS),
6(P
<
0.001),
7
(P
c
0.001),
lysine response (Expt
7,
P
c
0.05),
wet
1’.
dry
feeding (Expt
6,
P
<
0.001)
and interaction between frequency of feeding and lysine
response (Expts
I,
2,
P
<
0.05)
(Table
3).
The response of
4
g
v.
2
g L-lysine/kg diet ,with frequent feeding was significant for all
experiments except Expts
2,4,5
for carcass gain and Expts
4,5
for FCE on a carcass basis.
In Expt
7,
only the linear component of the lysine response was significant
(P
<
0.OOl).
It was the only component of the lysine response to vary significantly between the number
of
feeds/d
(P
<
0.01
for carcass gain/d;
P
-=
0.001
for FCE on a carcass basis).
DISCUSSION
The estimates of free lysine utilization based on carcass values are more applicable than
estimates based on live-weight values as the effects of variation in gut contents have been
removed and the interactions between frequency of feeding and lysine response are
statistically more significant. The over-all estimates
of
0.53
for carcass gain and
0.56
for
FCE on a carcass basis are considerably lower than estimates of
0-67
and
0.77
for gain and
food conversion ratio on a live-weight basis. Variation in individual estimates was also
https://doi.org/10.1079/BJN19810011 Published online by Cambridge University Press
Table
1.
Carcass gain
(g/d)
of
pigs during the
20-47
kg growth phase when given diets either once or
six
times daily, wet or dry, and
supplemented with L-lysine monohydrochloride
(Results of seven individual experiments)t
Expt no.
.
.
.
I
2 3 4 5 6 7
Mean
Frequency
of
feeding (F) L-lysine
(L)
Type of feeding
.
.
.
Wet Dry Dry Dry Dry Wet Dry Wet Wet
(no. of feeds/d) (g/kg)
No.
of pigs/treatment
. . .
8 8
8
8
8
8
8
8
4
68
I
0
350 355 279 291 337 343 331 325 333 327
1
346
2 362 399 354 321 362 369 358 355 364 360
a
-a7
e
G*
E
4 390 364
6
0
328 340 285 316 342 336 330 315 324 324
5’
I
343
z
2 392 412 369 367 392 402 387 385 390 388
3 407
4 423 431 408 368 392 384 395 429 414 405
“
A”,
2
m
SEM
7 7
10
7
11
9
11
4
Lysine utilization1
0.19
0.61 049 0.59
0.50
0.39 0.47 0.43 0.34 0.53
Statistical significance of treatment:
S‘
c
Wet and dry feeding (W/D)
NS
NS
NS
F
W/D
x
F
NS
NS NS
S‘
W/D
x
L
NS
NS
NS
00
W/D
x
F
x
L
NS
NS
NS
2.
Expt x
F
NS
2
* **
***
a
F
NS
NS
***
NS
L
FxL
***
NS
NS
NS
High lysine response.
**
NS
**
NS
NS
***
*** ***
***
***
***
***
***
**
***
**
***
***
3
Expt
x
L
Expt x F
x
L
NS
Previous estimate of lysine utilization
based on live-weight gain (Batterham,
1974;
Significance
of
F
x
L
on a live-weight-gain basis
NS NS
NS
NS
Batterham
&
ONeill,
1978) 0.43
1.01
0.90
0.72 0.52 0.47 0.52 0.58 0.31 0.67
*
**
**
~ ~ ~~ ~ ~~~
NS,
not significant
(P
>
0.05).
*
P
<
0.05,
**
P
<
0.01,
***
P
<
0.001.
t
Expt
1
is
from
Batterham
(1974);
Expts
2-7
were Expts
1-6
of
Batterham
&
ONeill(1978).
1
Response to lysine with once daily feeding expressed as a proportion
of
the response to frequent feeding.
https://doi.org/10.1079/BJN19810011 Published online by Cambridge University Press
Table
2.
Food conversion eficiency
of
pigs during the
22-47
kg
growth phase when given diets either once
or
six times daily, wet or
dry, and supplemented with L-lysine monohydrochloride
(Results of seven individual experiments)?
'
Expt
no.
. . .
1
2 3 4
5
6 7
Mean
Frequency of
feeding
(F)
L-lysine (L) Type of feeding
. .
.
Wet
Dry
Dry
Dry
Dry
Wet Dry Wet Wet
(no.
of
feeds/d) (g/kg)
No.
of pigs/treatment
8 8 8 8 8 8 8 8 4 68
6
1
0
1
2
3
4
0
I
2
3
4
SEM
Lysine utilization:
Statistical significance
of
treatment:
F
L
FxL
High lysine response
Wet and dry feeding (W/D)
WID x
F
W/D
x
L
W/DxFxL
Expt
x
F
Expt
x
L
Expt
x
F
x
L
Lysine utilization based
on
live-weight food conversion ratio basis
Significance of
F
x L
on
a
live-weight
food
conversion ratio basis
(Batterham,
1974;
Batterham
&
ONeill,
1978)
0.255
0-272
0.287
0.243
0.286
0.308
0.005
0.40
NS
0.0
**
**
0.67
NS
0-261 0.221 0.218 0-250 0.256 0.242 0.241 0.249
0.254
0.296 0.260 0.243 0.270 0.276 0.265 0.265 0.269
0.27
I
0.267
0.258 0.226 0.232 0.255 0.249 0.240 0.230 0-241
0.252
0.301 0.273 0.269 0.293 0.298 0.286 0.285 0-284
0,298
0.319 0.302 0,273 0.292 0.285 0.288 0.314 0.313
0.005
0@04
0~004
0~007
0.007
0-007
0-81 0.83 0.68 0.53 0.41
0.50
0.44
0.28
***
NS
*
NS NS
NS
*
***
***
***
***
NS
NS
NS
NS
NS
**
***
NS
1.27
0.84 0.97
0.58
0.54
0,
NS
NS
*
NS
***
**
*
NS
NS
NS
NS
2
0,
NS
**
***
***
***
6 0.28
**
0.243
0.269
0.241
0.286
0.299
0402
0.56
***
***
***
***
NS
NS
NS
NS
NS
NS
NS
0.77
*
NS,
not significant
(P
>
0.05).
*
P
<
0.05,
**
P
<
0.01,
***
P
<
0.001.
t
Expt
1
is
from Batterham
(1974);
Expts
2-7
were Expts
1-6
of
Batterham
&
ONeill
(1978).
#
Response to Iysine with once daily
feeding
expressed
as
a
proportion
of
the
response
to
frequent
feeding.
https://doi.org/10.1079/BJN19810011 Published online by Cambridge University Press
Table
3.
Dressing proportion?
of
pigs that were slaughtered at approximately
47
kg live weight after being given diets either once
or
six times daily; wet
or
dry, and supplemented with t-lysine monohydrochloride
(Results of seven individual experiments)$
~
Expt
no.
. . .
1
2 3 4
5
6 7
(no.
of
feeds/d) (g/kg) No. of pigsftreatment . . .
8 8 8 8 8
8
8 8 4
Frequency of
feeding
(F)
L-lysine
(L)
Type of feeding . . . Wet Dry Dry Dry Dry Wet Dry Wet Wet
1
i,
I
2
3
4
6
0
1
2
3
4
SEM
Statistical significance of treatment:
F
L
FxL
High lysine response
Wet and dry feeding (W/D)
WID
x
F
W/D
x
L
WfD
x
Fx L
6.7~
0.746
0.741
0.741
0.751
0.759
0.006
NS
NS
NS
0.149
0.727
0.738
0.746
0.744
0.006
SN
NS
NS
0.739
0.738
0.754
0.752
0.743
0.005
**
NS
NS
NS
0.732
0.720
0.728
0.724
0.725
0.006
NS
NS
NS
NS
0.745 0.741
0.744 0.736
0.132 0.726
0.731 0.730
0.735 0,719
0.007
NS
NS
NS
NS
NS
NS
NS
0.742 0.737
0.748 0.730
0.725 0.710
0.732 0.725
0.737 0.724
0.005
***
NS
NS
NS
NS
NS
NS
***
0.740
0.733
0.760
0.741
0.149
0.7 16
0.714
0.728
0.739
0.734
0.008
***
NS
NS
NS, not significant
(P
>
0.05).
P
<
0.05,
t
Cold carcass weight as a proportion
of
live weight before slaughter.
$
Expt
1
is from Batterham
(1974);
Expts
2-7
were Expts
14
of
Batterham
&
ONeill
(1978).
**
P
<
0.01,
***
P
<
0401.
https://doi.org/10.1079/BJN19810011 Published online by Cambridge University Press
92
E.
S.
BATTERHAM
AND
R.
D.
MURISON
reduced, particularly with the estimates based on
FCE
on a carcass basis. The treatment
effects on dressing proportion were inconsistent between experiments (Table
3).
The effect
of removing gut contents on the estimates of lysine utilization was not anticipated as the
experiments were balanced for the different treatment effects. Live-weight values were
normally used as the index for assessing pig response. It is apparent from the current studies
and the results with slope-ratio assays (Batterham
et
al.
1979)
that carcass values are more
applicable if the responses are sensitive to small changes in pig performance within any one
treatment
.
The approximate
0.50
wastage of free lysine with once daily feeding means that
it
is
essential when determining the pig’s response to supplements of free lysine to ensure that
the lysine is given under conditions that ensure its full utilization. This may not have been
achieved in many of the experiments that have been used to derive the current estimates
of the pig’s requirement for lysine. Up until now
it
has been assumed that supplements of
free amino acids are
fully
utilized under limited feeding systems.
As
a consequence, current
estimates for lysine requirements of growing pigs and sows could be
10-30%
over-estimated
(Batterham,
1980).
A
similar situation may also apply with current estimates for the other
essential amino acids, as it is most likely that differential rates of absorption between the
free and protein-bound forms occurs (Pion
et
al.
1972;
Rolls
et
al.
1972;
Rerat
et
al.
1976).
Until estimates of the efficiency of utilization of the other essential amino acids under limited
feeding regimens are reported it seems desirable to assume that they are utilized in a similar
manner to free lysine, i.e. approximately 0-SO’with once daily feeding.
REFERENCES
Batterham,
E.
S.
(1974).
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J.
Nutr.
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237.
Batterham,
E.
S.
(1980).
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-
1979,
p.
1
I
[W. Haresign
&
D.
Lewis, editors].
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E.
S.,
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D.
&
Lewis, C.
E.
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H.
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A,,
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[D.
J.
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https://doi.org/10.1079/BJN19810011 Published online by Cambridge University Press
