Influence of
energy
and
protein
levels
ongrowth
rate,
feed
efficiency,
carcaseand
meat
quality
of steers
M.G. KEANE F.J. HARTE
The
Agricultural
Institute,Grange, Dunsany,
Co.Meath,
Ireland.Abstract
The
growth pattern
of full fed Friesian steers was one of initialincreasing
rate ofgain
followed
by
adeclining
rate ofgain
withincreasing
bodyweight.
Differences in ration energylevel which had a
significant
effect onperformance
had little influence onefficiency
orcar-case
composition
oflarge
breed type steers. In a serialslaughter
experiment
with Friesiansteers, the carcases of animals grown on a grass
silage/barley
diet had more fat and less meat than those grown on aconcentrates/chopped
straw diet eventhough
both diets were similar in energy content andsupported
similar levels ofperformance.
There was an inter-action between the effects of diet andslaughter weight.
At low carcaseweights
there was no effect of diet oncomposition
but withincreasing
carcaseweight,
the diet effectemerged.
A restriction of 20 per cent in feed intake reducedperformance,
efficiency
and carcase fatcontent.
Résumé
Influence
du niveau
des
apports
énergétiques
etazotés
surla
vite.ssede
croissance,
l’efficacité
alimentaire,
la
qualité
des
carca.s,ses etdes viandes de
boeufs
La forme de la courbe de croissance de bouvillons Frisons alimentés intensivement à
volonté,
comporte unephase
initiale de croissance accélérée suivie d’unephase
où la vitessede croissance diminue avec l’accroissement du
poids
vif. Des variations dans le niveau desapports
énergétiques
des rations ont eu un effetsignificatif
sur lacroissance,
mais ont peumodifié l’efficacité alimentaire ou la
composition
des carcasses des bœufs de races degrand
format. Dans uneexpérience
comportant desabattages
successifs de boeufsFrisons,
les car-casses des animaux alimentés avec une rationd’ensilage
d’herbe !- orge contenaientplus
de
graisse
et moins de viande que celles d’animaux ayant reçu une ration de concentrés asso-ciés à de lapaille
hachée,
bien que ces deux rations aient eu la même concentrationéner-gétique
etpermis
les mêmes vitesses de croissance. On a observé une interaction entre les effets de l’alimentation et dupoids d’abattage.
Eneffet,
l’influence de l’alimentation sur lacomposition
des carcasses n’est pas apparue pour les faiblespoids
de carcasse mais s’est manifestéelorsque
lespoids
de carcasse ontaugmenté.
Une réduction du niveau alimentaire de 20 p. 100 a réduit lacroissance,
l’efficacité alimentaire et la teneur engraisse
desIntroduction
Beef
production
in Ireland is based
ongrazed
grass and grass conserved
assilage
orhay. Gradually, ensiling
is
replacing hay
making
asthe
chief
method
of conservation and this
permits
the
production
of
ahigher quality
feed. Protein
content
of
both grass and
silage
is
generally adequate
for beef
production.
There-fore,
research
onthe effects of different
protein
levels has
received
less attention
than other
aspects
of cattle nutrition and the
subject
is
notdiscussed
in this paper.
The influence of energy
levels,
mainly
in the
contextof
silage quality
and
concen-trate
supplementation
of
silage,
is
important
and has been
widely
researched. There
is also
agrowing
awarenessof the need for
moreinformation
onthe
composition
of
ourbeef
carcases(which
arepredominantly
Friesian)
and the factors which
affect
it,
with
aview
toproducing
carcasesin
termsof both
weight
and
composition
suitable for
awide range of markets.
Review of literature
Differences in
plane
of nutrition in
early
life have little
effect
on carcasecomposition
when animals which
wereearlier restricted
areallowed
anadequate
compensatory
period
of unrestricted recovery before
slaughter
(WINCHESTER
and
How
E
,
1955 ;
LAWRENCE and
P
EARCE
,
1964 ; D
RENNAN
,
1979).
There
is less
agreement
onthe effects of
plane
of nutrition in the immediate
pre-slaughter
period
on carcasecomposition.
When animals
finished
ondifferent
nutritional
levels
areslaughtered
atthe
sametime,
differences in
carcaseweight
could
accountfor
part
orall
of the
compositional
differences noted. Even
at constant carcaseweights,
however,
there
arereports
showing
noeffects of
pre-slaughter plane
of
nutrition
on carcasecomposition
(K
AY
et
al.,
1970 ;
L
EVY
et
al.,
1976).
On the
other
hand,
someworkers
have observed
carcasedifferences
due
tolevel of
feeding
before
slaughter.
In the data of SWAN and
LAMMING(1967)
percentage
carcasebone
waspositively
related and
percentages
of
kidney
and
carcasefats
werenegatively
related
toration
roughage
content.The main
carcaseeffect of
decrea-sing
the level of energy in the diet
was adecrease in fat
deposition
without any
major change
in muscle
orbone
development.
Similar conclusions
canbe drawn
from other
publications
(H
ENRICKSON
etal.,
1965 ; B
ROADBENT
,
1977 ;
SMITH
et
al.,
1977).
A
study
onthe effects of
nutritional
level
on carcasecomposition
of
Holstein
steers
serially slaughtered
(W
A
r.
DMAN
etal.,
1971)
showed that up
to227
kg
liveweight, composition
was notinfluenced
by
nutrition but
thereafter
ahigh
energy
ration
produced
greater
amountsof
carcasefat
than
amoderate energy
ration. This
indicates
that there
areinteractions
between
the effects of
energy
level and
slaughter weight
on carcasecomposition.
Interactions between
the effects
of breed
type
and
plane
of
nutrition
on carcasecomposition
arealso
likely.
The
greater
capacity
of the
large
breeds for
proteino-genesis
suggests
that
they
could
use morefeed
energy for this function than
small breeds. PRIOR
etal.
(1977)
have demonstrated
aninteraction between breed
type
and
feeding
level. An increase in ration energy
concentration
increased fat
gain only
in
steersof small breed
types
and
therefore affected
carcasecomposition,
with the result
that overall
carcasecomposition
remained
unchanged.
However,
S
MITH
et
al
(1977)
found
nointeractions between
breed
type
and ration energy
content.
Both
large
and small breed
types
showed increased fatness
independent
of
carcaseweight
as aresult of
increasing
the ration energy
content.Experimental
resultsPatterns
of
growtl2
and
efficiency
The
general
patterns
of
performance
and
efficiency
of Friesian
steersthrough-out
life
werereported by
H
ARTE
(1968a, b)
when the effects of
aperiod
of feed
restriction in
early
life
wereinvestigated.
Twin Friesian
steersindividually
fed from
birth
toslaughter
at450
kg liveweight
wereused in
the
experiment.
For the first
84
days
all animals
werefed
the
samebut from then
to200
days
onemember
of each
pair
of twins
wasfed
arestricted level of
concentrateswhereas the other
had unrestricted
access to concentrates.From 200
days
toslaughter
all animals
had
unrestricted
access to concentrates.Hay
wasavailable
ad
libitum
throughout.
The
performance
of
the
full
fed
cattle increased
gradually
to apeak
of 1 100
g/d
at
200
days
of age and then declined
to alow of 400
g/d
before
slaughter.
Efficiency
of utilisation of metabolisable
energy
(ME)
for
liveweight gain (MJ/kg)
decreased
throughout
life from 40 in
calfhood
to500
atslaughter.
Feed restriction from 84
to200
days
did reduce
performance during
this
period
but did
notaffect average
daily
lifetime
performance,
carcaseweight
atslaughter
or carcasecomposition
(Table 1).
It
did, however,
lead
to asignificant
but small
improvement
in
efficiency
of
carcaseand lean
meatproduction.
From
200
days
toslaughter
average
daily
feed and energy intakes
weresimilar for
both
treatments sothe
superior
performance
of ¡he
previously
restricted cattle
resulted in
greater
efficiency during
this
period.
In
subsequent
experiments
(D
REN
-NAN
,
1979)
there
was nocompensation
in
animals restricted earlier
than
200
days
of age, but
aperiod
of restriction after this
wasfollowed
by
full
compensation
Effects of different
energylevels
K
EANE
(1978)
compared
the effects
of 80 :
20
and 50 :
50 ratios
of maize
grain
tomaize
silage
onperformance,
efficiency
and
carcasecomposition
of
Charolais
and Simmenthal sired
steersgrown from 208
kg
toslaughter
at550
kg
liveweight.
Estimated ME
contentsof the
high
and
medium maize diets
were12.9 and11.7
MJ/kg
dry
matter(DM)
respectively.
Carcase
assessment wasbased
on
separation
of the round
(including rump)
into
fat,
lean
and
bone. Data
onfeed
intake,
performance
and
efficiency
areshown in Table 2.
Calculated
daily
ME intakes
were98 and 91 MJ for the
high
and medium
maize
diets
respectively.
The decrease
in the energy
contentof the
ration,
due
toincreasing
the
silage
level
from 20 per
cent to50
per cent,
resulted in
asmall
increase in DM intake but this did
notmaintain energy
intake. The
daily
ME
intake
onthe medium
grain
ration
wasonly
93
per
centof that
onthe
high grain
ration and this resulted in
asignificant
reduction
in
performance
of
9
per
cent.However,
asthe reduction in
performance
wasof
comparable
magnitude
tothe
reduction
in energy
intake,
there
waslittle difference between the
tworations in
efficiency
of energy utilisation.
Composition
of the
round is shown in
Table
3.
There
was nosignificant
effect
of ration energy level
onany of the traits. The lack of
anenergy level
effect may have been due
tothe breed
types
involved and
to useof
growth
Effects of
diet
type
and level
of
feeding
A number
of
studies
(M
C
C
ARRICK
,
1966 ; F
LYNN
,
1978)
have shown
that
type
of diet
(i.e.
dry
matter contentof conserved
forage)
canaffect
carcasecomposition.
However,
the
differences
observed in
some casescould have been
partly
due
toother factors such
aslevel of
feeding,
rateof
gain
or carcaseweight
at
slaughter.
In
order
to assessthe relative
influence
of diet and
slaughter
weight
on carcasecomposition
the
following experiment
wasundertaken
using
54 Friesian
steersof 315
kg
initial
liveweight.
Three
dietary
treatmentswere
imposed
ongroups of 18 animals
(1)
66 per
centgrass
silage plus
34 per
centbarley,
(2)
75 per
cent concentratesplus
25 per
centchopped
straw,
(3)
66 per
centgrass
silage plus
34 per
centbarley
restricted
to80 per
centof the
intake
onTreatment 1. The ratio of
concentrates to strawin Treatment 2
wasvaried
slightly
from time
totime in order
tomaintain the animals
onthe
samegrowth
curve asthose
onTreatment 1. On average the energy concentration of
the
twodiets
wassimilar
at11
MJ/kg
DM.
Groups
of 6 animals each
wereslaughtered
at260,
300 and 340
kg
carcaseweight
and the
right
side from each
carcase was
separated
into fat
trim,
meatand bone. Initial
carcaseweight
and
composition
werecalculated
using
data from another
experiment.
The main
objective
was toascertain if diet
type
(Tr
1
vTr
2)
orlevel of
feeding
(Tr
1
vTr
3)
had
aninfluence
on carcasecomposition
and
werethere
interactions with
slaughter weight. Daily
feed DM and ME
intakes
for the 3
slaughter
intervals
are
shown in Table 4.
Daily
DM
and ME
intakes
increased with
increasing weight
but declined
as a
function of
liveweight.
Daily
intakes of the
twofull fed
groups
weresimilar
so
type
of diet did
notaffect intake. The
daily
intake of the restricted cattle
which
waslower than that for the animals full fed the
samediet
ranged
from
79.2 per
centof the latter in the first
slaughter
interval
to83.1 per
centin the
third
slaughter
interval.
Daily liveweight gains
for
each
slaughter
interval
areshown in Table 5.
There
was nosignificant
difference in
performance
between the animals full fed
the
silage/barley
ration and those fed the
concentrates/straw
ration. As intended
those
restricted fed
had
alower
overall
growth
rate.Performance
onall three
treatments
declined
with
time,
but this
decline
wasless in
the restricted
than in
the full fed groups.
Therefore,
restriction of feed intake
did
nothave
a constanteffect
onperformance
overtime. Over
the first
slaughter
interval,
arestriction
of 20 per
centin
feed intake reduced
performance
to67 per
centof that for
the animals full fed the
samediet,
while
overthe final
slaughter
interval the
performance
of the restricted animals
was91
per
centof that of the full fed group.
The
probable
explanation
for this is that
atthe time the
experiment
commenced
the animals had
acapacity
for
somecompensatory
growth
and
early
in the
experimental period
this
wasexploited
morefully
onad
libitum
feeding
than
onrestricted
feeding.
Carcase
gains
overthe
three
slaughter
intervals
areshown in Table 6. The
main effects of feed and
slaughter weight together
with the interaction
werehighly significant.
On average,
carcasegains
constituted
64
per
centof
liveweight
gains.
Efficiencies of energy utilisation
(MJ
ME/kg
carcasegain)
areshown
in
Table
7. Over
the first
110
kg
carcasegain,
the full fed cattle
produced
onekg
carcase
per
150
MJ ME
consumed,
while
the restricted fed cattle
required
170
MJ
ME per
kg
carcasegain.
Therefore,
arestriction of 20 per
centin energy
intake reduced
carcasegain by
30 per
centand
efficiency
by
14 per
cent overthe
first
slaughter
interval. Over the
carcaseweight
interval
260 - 300
kg
neither
type
of diet
norlevel
of
feeding
had
alarge
influence
onefficiency
which
wasmuch
inferior
tothat
for
the
earlier
period,
while
overthe final 40
kg
interval
of
carcasegain,
efficiency
wasbetter for the restricted cattle than for those full
fed the
samediet.
Average
overthe entire
experimental period efficiency
of energy
utilisation for
carcasegain
wassimilar for
the
twofull fed groups
atapproxima-tely
220 MJ
ME/kg
carcaseand
slightly
inferior for the
restricted animals
atCarcase
weights
and
percentage
composition
for the
main
effects of diet
and
slaughter weight
areshown in Table 8. There
was nosignificant
difference
in
carcaseweight
between
the
comparisons
of interest
(Tr
1
vTr 2
and Tr 1
vTr
3).
There
were,of
course,highly
significant
differences
between
slaughter weights.
There
weresignificant
differences in
percentage
carcasecomposition
between
the diets. Cattle fed the
silage/barley
diet had
alower
meatpercentage
and
ahigher
fat
percentage
than those
fed the
concentrates/straw
diet.
Bone
percentage
was
similar for both
treatments.Restricted
feeding
increased bone
percentage,
because the animals
wereolder
atslaughter,
and reduced fat
percentage.
Increases
in
slaughter weight
decreased
meatand bone
percentages
and increased fat
per-centage.
Animals full fed the
silage/barley
diet had
morekidney
and
channel fat
than those
onthe other
two treatmentsand also
there
wereincreases in
kidney
and channel fat
weights
with
increasing
slaughter weight.
The
interaction
between diets and
slaughter weight
onpercentages
of
meatand fat in the
carcase areshown in Table 9. At
260,
300
and
340
kg
carcaseweights,
average
meatpercentages
were68.6,
64.5 and 63.5
respectively,
while
corresponding
values
for fat
were12.4,
17.2 and 19.6
respectively.
At 260
kg
carcaseweight
there
was noeffect
of
diet
on carcasecomposition.
At 300
kg
carcase
weight
there
was asmall
difference,
while
at340
kg
the
carcasesof
animals full fed
silage/barley
had
significantly
less
meatand
morefat than either
of the other
twogroups.
Therefore,
up
to260
kg
carcaseweight
neither the
type
of diet
northe level of
feeding
had any effect
on carcasecomposition,
but
athigher
carcaseweights
there
wereeffects
which
became
morepronounced
asslaughter weight
increased.
Since
mostof
the
carcasetissue
(260
kg)
wasdeposited
before
dietary
treat-mentsstarted
to exert aninfluence
oncomposition
of
the
gain,
the final
composition
is
not a truereflection
of
the
influence of
treatments overthe
period
260 - 340
kg.
Therefore,
the
composition
of the
gain prior
to260
kg
is
compared
with that
for the interval 260 - 340
kg
carcaseweight
(Table 10).
From the
startof the
experiment
to260
kg
carcaseweight,
carcasegain
consisted of
63
per
cent meatand
22
per
centfat
in
the
twofull fed groups and
62 per
cent meatand 19 per
centfat
in the
restricted
group. From
260
to340
kg
carcase,
the
carcasegain
of cattle full
fed the
silage/barley
diet had
only
39
per
cent meat
compared
with 51 per
centand
53
per
centfor
the
concentrates/straw
and restricted
fed
treatmentsrespectively. Percentages
of
fat
in
the
gains
wereDiscussion
The
decline in
performance
of Friesian
steerswith
increasing weight
has
been
observed
in
anumber
of
experiments
and appears
morethan
canbe accounted
for
by
increased maintenance
requirements
and increased energy
contentof the
gain.
It is necessary
toestablish the
reasonsfor this reduction in
performance
and ascertain if
anything
canbe
done
to avertit.
More
precise
information is needed
onthe effects and interactions of
geno-type,
sex,plane
of nutrition and
slaughter weight
on carcasecomposition.
This
will
require large
research
resourcesin
termsof
animals, feed,
labour and
carcaseassessment cost.
Complete
carcaseanalysis
is
expensive
but there
appears
tobe
no
alternative
method of
obtaining
the data
that
arerequired
todefine
clearly
all the
interacting
factors
which influence the
development
of
a carcase toits
final
composition.
The
finding
that diets of similar energy
contentand which
support
similar
ratesof
gain produce
carcaseswhich differ in
composition
has
interesting
nutri-tional
implications.
It
canbe
argued
that
atsimilar
ratesof
gain
increased fat
growth
(and
reduced muscle
growth)
on onediet
compared
with another is
indica-tive of amino acid
deficiency
attissue level. The crude
protein
contentof the
silage/
/
barley
diet
wasadequate by
normal standards and in
ourexperiments
there
has
generally
been
noworthwhile
response
tofeeding
supplementary protein
with
a
view
toincreasing
the
amountpassing undegraded
from the
rumen tothe small
intestine. The animals fed the
silage/barley
diet retained
moreof their feed energy
and
the
challenge
is
tofind how
the
surplus
fat energy
might
be
diverted
toprotein deposition
with
aconsequent
increase in
meatyield
and
efficiency.
References
Bxonna E rr
T
P.J.,
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RENNAN
M.J.,
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A.V.,
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ARTE
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ARTE
F.J.,
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AY
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EANE
M.G.,
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G.M.,
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H.,
LAMMING G.E., 1967. Studies on the nutrition of ruminants. II The effect of level of crude fibre in maize based rations on the carcasscomposition
of Friesian steers.Anim. Prod.
9,
203-208. WALDMAN
R.C.,
TYLERW.J.,
BRUNGARDT V.H., 1971.Changes
in the carcasscomposition
of Holstein steers associated with ration energy levels and
growth.
J. Anim. Sci.32,
611-619.WINCHESTER
C.F.,
HowEP.E.,
1955. Relative effects of continuous andinterrupted growth
on beef steers. USDept. Agric.
Bull. 1108.Discussion
Chair :
D. LANARI(Italy)
T. GRIFFITHS(Ireland).
- I would like toput a
question
to Dr.!obié
concerning
his data on
nitrogen
retention. I did not look at all the data but some of it seemed to bea bit difficult to
interpret.
I wonder if he would care to comment on it. Oneoccasionally
finds data onnitrogen
retention ingrowing
animals,
which is ratherconfusing.
T.
!
O
BI
é
(Yugoslavia).
- In the firstexperiment,
with the mixeddiet,
we have gotsome data which is not easy to
explain.
Forinstance,
youprobably
saw thatnitrogen
balance in the first group was 3.7 g and the last group was 4.5 g. Itjust happened
and weregistered
it,
but we cannotexplain
it. We used this apparentdigestibility
ofprotein
data in order tocalculate this
relationship
between crudeprotein
anddigestible protein.
T. GRIFFITHS. - For bulls
growing
at thisrate, did it have any effect at all on
carcase lean or carcase
protein deposition ?
T. CoBic. - We did not
investigate
that. Weonly
went up toslaughter
and weregis-tered the
dressing
percentage andnothing
more. We did not go further.J.M. FORBES
(UK).
- I have aquestion
for Dr.Boucqu6
about his conclusions
regar-ding
effets ofdietary
energy concentration on food intake. First of all in the rat ; it lookedto me, in the slide that he showed of
Baumgardt’s
work with rats, that intake did notkeep
rising
withincreasing digestible
energyconcentration,
it did reach aplateau. Secondly,
his conclusion that some of his cattlekept
oneating
moredigestible
energy, even withincreasing
energy
concentration,
is rather doubtful. The energy contents of the feeds areexpressed
asstarch
equivalents, presumably
derived from tables. I want to ask whether the energy value of the feed was measured orsimply
calculated from the tables ?Ch. V. BOUCQUE
(Belgium).
- Weonly
used these diets where thedigestibility
wasdetermined,
as I mentioned in the introduction. We had otherexperiments
too, but we didnot use them for these purposes. We used
digestibility
coefficients obtained at maintenance level with thesheep,
of the diet we calculated here.J.M. FORBES. - So
you think that this is a real effect - that there is a
positive
relationship
between the energy concentration of the diet and foodintake,
in your animalsat
least,
even atfairly
high
concentrations ofenergy ?
Ch. V. BOUCQUE. -
Yes,
I believe that. There are several other authors in the UKwho agree. It has been
proved
that withincreasing
energydensity,
intake ishigher
andgain
is
higher
- and feedefficiency
is not worse.J. L’ESTRANGE
(Ireland).
- I would liketo ask Dr.
Boucqu6
if he found any diffe-rence between the sources of energy, inparticular
between beetpulp
andcereal,
since the starchequivalents
for beetpulp
and cereals wereprobably
very similar. Did you find anydifference between intake and
performance ?
Ch. V.
Bood
Q
u
E
.
- I didnot compare it because we use very little
cereal ;
they
aretoo
expensive
compared
to sugar beetpulp.
Even in the concentrate with which wesupple-ment
roughage
diets,
we do not use very muchcereal,
it ismostly
beetpulp.
Therefore,
I cannotgive
you an exact answer.However,
we have someexperiments
in which we substituted beetpulp
forbarley
(this
hasalready
beenpublished)
where we obtained a substitution value based onfeeding
trials and ondigestibility
trials. The value of beetpulp
reached about 90 per cent - 95 per cent of the energy value ofbarley.
Itdepends
on the type ofbarley
that isused ;
it wasbarley
with about 4 per cent crude fibre. You can also havebarley
with 7 per cent - 8 per cent crudefibre ;
when you use that asreference,
you obtain another relative value for your beetpulp.
Wespecified
thequality
of thebarley
which wasused.
J. L’ESTRANGE. - Is it dried beet
Ch. V. BoucQuE. - It is not molassed beet
pulp.
Sugar
content was not more than6 per cent on
dry
matterbasis,
indicating
no molasses had been added.H. BICKEL
(Switzerland).
-May
I make ageneral
comment. We have heard severalresults from
experiments concerning
different intakes inprotein
and energy. I think we should make an effort tobring
these differentfeeding experiments,
and manyothers,
together.
By
bringing
themtogether
I mean we should have a model. We have 4 factorsaffecting
daily liveweight gain
and energy conversion ratio. Thequestion
is,
how to put themtoge-ther ? We have the factor of the gross energy intake. We have the
requirement
ofmetabo-lisable energy for
maintenance,
the energy value ofgain
and thepartial efficiency
ofgain.
In myopinion
there are no other factors.Everything
that we aredoing
can be included in these four factors.Take as an
example
theexperiment
on differentproteins
by
Dr.!obié.
Perhaps
there is apossibility
that if the animal can put onprotein,
the&dquo;kg&dquo;
will go down. Or there isthe
experiment
of Dr. Keanewhere,
in his Table5,
he made thehypothesis
thatperhaps
the metabolisable energy
requirement
for maintenance isgoing
down. That was ahypothesis,
but there is some
explanation
in Table 9 which willexplain
Table 5. You mustanalyse
onething
after another and put themtogether
in a model.Again,
regarding
theexperiments
ofDr. Keane, if you have a restriction
period
and a compensatorygrowth
somewhere - ifyou do not have a
growth
curve which is normal in most intensive beefproduction
systems-you will
always
find that it ispossible
that energy conversion rate, amount ofME/kg
live-weight gain,
may be lower with the restrictionperiod
than with thegrowth
rate of thenormal,
the control group. It is very difficult tointerpret
because you do not seeany-thing
on the carcase and you are not sure what the energy value ofgain
is.As a final
point
I would like to say that it would be a greathelp
if the dimensions couldalways
be shown on the Tables -MJ/kg, g/kg,
etc.R. DAENICKE
(Federal Republic of Germnny).
- Dr.Boucqu6,
don’t you think that the levels you
give
for yourGroup
3 would causeproblems
inpractice ?
In our country, if we fed such animals with more than 700 starchunits/kg
dry
matter, we would have conside-rableproblems
of fat content in the carcase.Ch. V. BOUCQUE. - In
Group
3they
areWhite-red,
intensively
fed animals. Theaverage fat content in the carcase was between 20 and 22 per cent which is
quite
normal for that breed. It is nearer the Friesian than our White-blue breed. With theWhite-blue,
becausethey
have aliveweight higher
by
about 100kg,
fatness atslaughter
isonly
between 18 and 20 per cent. However inBelgium
this system ofbaby
beef bulls is nolonger
applied.
They
are grown on toliveweights
of 550kg.
As for my conclusion for the White-blue
animals,
in alarge
number ofexperiments
there is nonegative
effect offeeding
higher
intensities to that breed onefficiency
offeeding,
and on carcase
quality.
I do not think this conclusion is valid for Friesians or for someother
early maturing
breeds. There is a distinction between loose-housed animals andtied-up
animals.
Recently
wepublished
anexperiment
where wecompared
eight
diets in the samebuilding,
with the sameanimals,
with the same initialweight,
from the sameorigin,
in both tiedhouses,
individually
fed,
and in loose houses, with strawbedding.
It was not theprimary
purpose to compare
them,
but wealready
hadthem,
we got the same differences with alarge
number of animals -not with the sames
diets,
but with the sameintensity
of diets, thesame concentrations.
A.
N
EIh
tnNrr-StbRerrserr
(Denmark). - Dr. Bickelsays that we should
always
tryto find a
principle
in the manyexperiments
that we make. I would like to comment on Dr. Keane’s paper where he discusses the influence of the type of diet on carcasecomposition.
I am inclined to think that what you find here is not the diet itself. It is a reflection of thedifferences in
growth
which you have between these three diets.Therefore,
the fatdeposition
stage is different in one from the other. It is the same for the straw group because with the
straw
animals,
although they
received the same metabolisable energy,they
did not grow as fast.Maybe
your system overestimates the value of straw. Ireally
believethis,
because you have got lowergrowth.
I see this as aprinciple
of that and not as a diet influence on carcasecomposition.
I would now like to ask Dr.
!obié
if the difference in theprotein effect,
the differencewhen it is used in a concentrate and a non-concentrate
diet,
might
be that thesehigher
proteins
also have an effect on thepH
of the rumen, which may be more favourable to the animal when you have ahigh
concentrate diet. It could be a reflection of that.T.
!
OBl
é.
- I do not think that this is the case. Thegeneral
situation is that if wefeed
plenty
ofmaize,
there is adanger
ofgetting
sub-clinical lactic acid acidosis. In that case we have an unfavourable condition in the rumen. I do think that this is the case ;maybe
some other factors are involved.J. ROBELIN
(France).
- I would like to come back to Professor Bickel’s comments.It is necessary to know about the different factors which can affect the
relationship
between gross energy intake and energydeposited
in thegain.
At the same time I would like tooffer an
explanation
to Dr. Keane on his lastexperiment.
He said that the effect of the level of energy was lower f’or the firstslaughter
weight
than for the lastslaughter
weight.
This is true, but I would like to make asimple
comment on the parameters we use for these measurements. When we measure the effect of level of energy on carcase orbody
composition,
we have a very poor parameter. It is not a sensitive parameter. Dr. Keane has shownclearly
in hisgraphs
that a difference of 10 per cent or 5 per cent in thecompo-sition of the carcase, or in the
composition
of thebody
at the end of theexperimental period,
means that the difference in terms oflipid
deposition
wasprobably
three or four timesgreater. I do not agree that when there is a small difference in the fat percentage in the
carcase, you can conclude there is no difference.
Statistically,
I agreecompletely,
but theproblem
is to know what ispractical
and what is statistical. You must take into account themagnitude
of the treatment that you haveimposed
on your animals. In myopinion
there is no halt in the effect of level of energy intake oncomposition
ofdaily gain.
I think it is reasonable to say that it is a continuous process. If you see no difference sometimes it isprobably
due to the difference in the animals at thebeginning
of theexperiment
or someother factors.
I have looked at the data from a number of
experiments
recorded in the literature andI have come to the conclusion that the
explanation
of the different effects of level offeeding
at different ages is that at different ages you have animals which are at different levels of
maturity,
in the same way that animals of different ages can haveapproximately
the sameweight,
and therefore the effect onlipid deposition
is different.G. ALDERMAN. — I have a comment, followed
by
aquestion.
It relates to Dr.!obié’s
paper and his comments about the fact that he was
finding
crudeprotein
levels in diets which seemedto be
higher
than recommendedby digestible
crudeprotein
standards. Ithought
itmight
be usefulto remind you what the ARC
protein
system would have said about the type of diets he wasusing.
It follows from therelationship
that RDP ! 7.8 ME, that the crudeprotein
content of yourdiet,
ing
l
’kg,
will be7.8 D
(where
D
is the energy
concentration of adiet),
dividedby
thedegrad-D D m
ability.
If you do that for his firstexperiment,
the i
5
appears to be 11.6MJ/kg
and thedegradability
I have estimated to be about. 73. The result is that the crudeprotein
content of the dietwould be 123
g;kg.
Dr.!obic
wassuggesting
128gjkg.
If you go into his second
experiment,
which had ahigher
energydiet,
I estimated the energy content of that to be 12.5MJ/kg
and thedegradability, again,
is about 0,7. That would suggest that we should want 139g/kg
of crudeprotein
in thedry
matter of the diet.He was
suggesting
132g/kg.
I was
just
making
thepoint
that the ARC system issuggesting
a strictrelationship
between energy concentration of diets and crudeprotein
at any onedegradability.
I havedone what I can with the little information that we have about
degradabilities
ofthings
like maizesilage
and maize and sugar beetpulp,
to suggest that I am notsurprised
that he hascome up with these conclusions in relation to the crude
protein
content of thesediets,
it isonly
in the context of thedegradability
of the diets that heactually
used.Moving
on toother
diets,
like thosebeing
usedby
Dr.Keane,
what was your estimated metabolisableenergy of your
silage ?
M.G. KEANE
(Irelanc!.
-We gave it an ME value based on the conventional
relation-ship
between ME andDOMD,
asgiven
in Bulletin 33. G. ALDERMAN. - Iam hoist with my own
petard
there.M.G. KEANE. - To
answer your
question,
it was either 9.6 or 9.7MJ/kg.
It wasquite
agood
quality silage.
G. ALDERMAN. - We have many estimations from the Rowett Feed Evaluation
Unit,
and from our own unit,suggesting
that theappropriate
value for asilage
of thequality
you wereusing
would be 11 MJ. So your basicsupposition
that you werecomparing
iscenergetic
diets,
is not true. I would suggest to you that thereality
is that there was between 8 - 12 MJextra metabolisable energy in your treatment 1. In the context of the paper I
presented
yester-day,
if these animals werealready
depositing
all theprotein they
could manage - which I suspect would have been the case - theonly thing
they
could do was to put down morefat. In the model that I was
suggesting yesterday,
this is most insensitive in terms oflive-weight gain.
Youwould,
infact,
pick
upexactly
what youfound,
which was a muchhigher
fat content, with no effect on the rate of
gain.
K. ROHR
(Federal Republic of
Germany).
- I would also like to make a shortcom-ment on the work of Dr. Cobic.
My
interpretation
would differ somewhat from that of Mr.Alderman.
These
findings
confirm manyexperiments
done with younggrowing
bulls,
which show that theprotein supply
is crucial below aliveweight
of 270kg.
Toput
itsimply,
below this we need a crudeprotein
content in the ration of about 16 per cent. When you get abovethis
liveweight
range there is noproblem
withprotein
supply
in these animals. At thisearly
stage I do not think you will come up with the
right figures using
your system.G. ALDERMAN. -
Perhaps
I should say that the calculations which I gave wereonly
on the middle
period
- the 300kg liveweight
middleperiod.
The ARC system wouldsug-gest a need for
undegraded
protein
at the lowerliveweight animal,
but whether it would have gone critical at thepoint
you aresuggesting
needs further discussion.A. GiousEL.rnrrNts
(Greece).
- I have twoquestions
for Dr.Boucqu6. Firstly,
how much is the intake from energy in the rations with ensiledpressed
beetpulp
ascompared
todried beet
pulp ?
How much is the energy intake or thekg
intakeduring
thefattening
period ? Secondly,
what do you think about the molassesincreasing
ordecreasing
the energyvalue of dried beet
pulp ?
Ch. V. BOUCQUE. -
Concerning
your first
question, pressed
ensiled beetpulp.
Wecompared
it with dried beetpulp, giving
it to the same animals for two consecutive years.The intake of
dry
matter from this kind of ensiledpulp
was not lower than with the dried beetpulp.
We did the samecomparison
about 15 years ago with beetpulp ranging
from9 per cent - 14
per cent
dry
matter,compared
with dried beetpulp.
Then we had a lower dried matter intake of 0.3kg
dry
matter per 100kg
LW. That was due to the mechanical fill of ruminants -mechanically they
stopped
eating.
We weresurprised
at thehigh
intakewe obtained with the
pressed
beetpulp.
I do not have thefigures
for theproportion
of beetpulp
to concentrates, but the concentrate levelapplied
was 0.7 - 0.75kg
per 100kg
LW. That means that it is a maximum of one third of the totaldry
matter intake of concentrates.Intake of beet
pulp
increases from abeginning liveweight
of 260kg
to about 600kg
at the end. A maximum of about 28kg
perday
of the ensiledproduct
was eaten.Your second