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Estimated requirements
of net energy, digestible protein
and NDF intake of young
Chianina bulls from 400 kg
liveweight to slaughter
Mauro Antongiovanni, Sara Minieri, Arianna Buccioni
Dipartimento di Scienze Zootecniche. Università di Firenze, Italy
Corresponding author: Prof. Mauro Antongiovanni. Dipartimento di Scienze Zootecniche. Università di Fi-
renze. Via delle Cascine 5, 50144 Firenze, Italy - Tel. +39 055 3288332 - Fax: +39 055 321216 - Email:
mauro.antongiovanni@unifi.it
Paper received September 6, 2007; accepted February 4, 2008
ABSTRACT
Three equations have been elaborated and proposed to predict the requirements of net energy and protein
digestible in the intestine and NDF voluntary intake of growing young Chianina bulls, starting from 400
kg live weight.
The animals examined in the present study were 100 young Chianina bulls starting from about 400 kg live
weight, at 10 months of age, up to the average slaughter weight of 800 kg at 20 months average age. The
diet was based on hay and concentrates.
The equation for the prediction of net energy ts quite perfectly to another experimental equation for-
merly proposed by Giorgetti and is characterised by a very high value of the correlation coefcient for the
regression comparison between observed and predicted gures (R
2
=0.90).
The statistical reliance degree
of the PDIN prediction equation is lower, but still very good (R
2
=0.75 between observed and predicted
values), but that of the estimate of NDF daily intake resulted very poor (R
2
=0.26 between observed
and predicted values), probably due to the non homogeneity of the intake capacity of the 100 examined
animals. The correlation between daily gains and the concentration of NDF in the diet DM results good
(R
2
=0.87), showing that young Chianina bulls take advantage of the diet bre.
Further useful indications on the nutritional and dietary requirements of young Chianina bulls are added
to the scarce information currently available.
Key words: Feed requirements, NDF intakes, young Chianina bulls.
RIASSUNTO
FABBISOGNI STIMATI DI ENERGIA NETTA, PROTEINE DIGERIBILI E CAPACITÀ DI IN-
GESTIONE DI NDF DEI VITELLONI CHIANINI A PARTIRE DA 400 KG DI PESO
Sono state elaborate e vengono qui proposte tre equazioni per la previsione dei fabbisogni giornalieri di
energia netta (espressa in UF carne) e proteine digeribili nell’intestino (espresse in g di PDIN) e per la stima
della capacità di ingestione di NDF, da parte di vitelloni Chianini a partire da 400 kg di peso corporeo.
Il materiale animale oggetto dello studio era costituito da 100 vitelloni Chianini a partire dal peso di circa
400 kg, a circa 10 mesi di età, portati al peso medio di macellazione di circa 800 kg, a 20 mesi di età
media. La dieta era basata su eno di prato stabile e concentrati.
Ital.J.anIm.ScI. vol. 7, 153-160, 2008 153
Ital.J.anIm.ScI. vol. 7, 153-160, 2008154
antongIovannI et al.
L’equazione di previsione dei fabbisogni di energia netta ricalca perfettamente un’altra equazione già pro-
posta da Giorgetti ed è caratterizzata da un elevato valore del coefciente di correlazione del confronto di
regressione fra i valori osservati e quelli previsti (R
2
=0,90). Il grado di afdabilità statistica dell’equazione
di previsione dei PDIN è risultato più basso, ma ancora molto buono (R
2
=0,75 fra valori osservati e valori
previsti), ma quello della previsione della capacità di ingestione giornaliera di NDF è risultato veramente
basso (R
2
=0,26 fra valori osservati e valori previsti), probabilmente a causa della non omogeneità delle
capacità di ingestione dei 100 animali studiati. La correlazione fra gli incrementi medi giornalieri e le con-
centrazioni di NDF riferite alla sostanza secca della dieta è risultata buona (R
2
=0,87), a dimostrazione del
fatto che i vitelloni Chianini utilizzano bene la bra della razione.
Ulteriori utili indicazioni sui fabbisogni nutritivi e dietetici dei vitelloni Chianini sono così andati ad aggiun-
gersi alle scarse informazioni disponibili no ad oggi.
Parole chiave:
Fabbisogni nutritivi, Capacità di ingestione, Vitelloni Chianini.
Introduction
Beef breeds other than the Italian Chi-
anina have been extensively studied in
France, Great Britain and North America
and requirements in terms of net energy
and proteins digestible in the intestine,
together with voluntary feed intake, have
been estimated (INRA, 1978; Verité et al.,
1987; Vermorel et al., 1987; NRC, 2001; Sau-
vant et al., 2002).
As far as we are aware, in the literature
only a few works have been published on the
subject (Antongiovanni et al., 1983, 1990;
Giorgetti et al., 1995). The first paper was
aimed at the estimation of energy require-
ments of Chianina bullocks between 300 and
600 kg live weight, but in the light of further
experimental data, the requirements were
overestimated. The paper by Giorgetti et al.
(1995) provides energy requirement figures
very close to those presented in the present
work. The comparison between the two sets
of data represents a kind of validation of
the energy requirement estimates proposed
herein. In addition, the present paper pro-
vides equations for the prediction of require-
ments of proteins digestible in the intestine
and of the voluntary intake of NDF.
The work is a further contribution to the
knowledge of requirements of growing Chi-
anina bullocks, between 400 kg and slaugh-
ter weight, which in some cases was more
than 900 kg at 21 months of age.
Material and methods
The examined animals were 100 young
Chianina bulls, live weight about 400 kg
(mean =416 kg, SD=112 kg) at the start of
the observation period, at the age of about
10 months (mean=10.3 months, SD=2.9
months), slaughtered very close to 800 kg
live weight (mean=774 kg, SD=75 kg), at the
average age of about 20 months (mean=19.7
months, SD=1.3 months). The observation
study was carried out for seven years, from
2000 through 2006, by the farm “Il Forteto”
located in in the Mugello region of Tuscany,
a few miles north of Florence. The animals
were usually calved in the open air, on pas-
tures, and kept with their mothers as long
as possible. At about 10 months of age they
were transferred to an indoor barn and kept
in pens with 10 bullocks per pen, where
they were observed for feed intake and in-
dividual weight gain. The observation pe-
riod lasted slightly longer than 9 months,
on average (mean=283 days, SD=89 days).
Recorded average daily gains were 1.250 kg,
SD=0.182 kg.
The diet was based on mixed hay and a
concentrate mixture (see Table 1 for chemi-
cal composition and nutritional traits and
Ital.J.anIm.ScI. vol. 7, 153-160, 2008 155
RequIRementS of young chIanIna bullS
Table 2 for the ingredient composition of
the mixture). The ration was programmed
in order to provide 1 kg concentrate per 100
kg live weight and hay free choice. Feed in-
take was controlled with the approximation
possible with pen group feeding. The mean
value of the forage/concentrate ratio was
53.0% hay (SD=4.2%).
Samples of hay and concentrate mixture
were analysed each year for dry matter,
crude protein, ether extract, ash, accord-
ing to A.O.A.C. (1990) and for fibre frac-
tions according to van Soest (Goering and
van Soest, 1970). The figures in Table 1 are
mean values of 3 samples per year. TDN and
metabolizable energy (ME) were calculated
by means of the equations presented by
NRC (2001) for dairy cows. The net energy
content, expressed as UFV, the French units
for beef cattle, were calculated starting from
ME, using the equations proposed by INRA
(Vermorel et al., 1987), at the animal pro-
duction level of 2.0. The amount of protein
digestible in the intestine (PDIN) was at-
tributed looking at table figures relative to
hays and concentrates as similar as possible
to our feeds. Only PDIN (the protein digest-
ible in the intestine, considering the amount
of microbial protein synthesizable from the
feed degradable protein) was considered, be-
cause it was assumed that energy was not
the limiting factor.
The equations proposed in the “results
and discussion“ section for net energy (UFV)
and protein (PDIN) requirements are actu-
ally correlation equations with body live
weight (LW) and average daily gain (ADG),
both in kg.
As the first step, the means of require-
ments relative to ADG’s only were estimat-
ed by the differences between the measured
intakes of UFV and PDIN corresponding to
different gains. As an example, for a body
weight of 450 kg and a gain of 1.4 kg/d, let
the recorded net energy intake be 7.7 UFV/d
and for another animal weighing the same
450 kg, but gaining 1.0 kg/d, let the intake
be 6.6 UFV/d. The difference 7.7 – 6.6=1.1
UFV/d was attributed to the higher weight
gain 1.4 – 1.0=0.4 kg/d. That is 1.1/0.4=2.75
Table 1. Chemical composition and nutritional traits of the diet ingredients (g
.
kg
–1
).
Hay Concentrate mixture
Dry matter 847.5 867.0
Crude protein 58.0 310.5
Ether extract
10.5 51.2
NDF 634.0 300.0
NDIP (crude protein of NDF) 40.0 11.0
ADF 57.5 102.0
ADIP (crude protein of ADF) 13.0 5.0
ADL
57.5 1.8
Ash 58.0 7.0
TDN
2x
498.4 796.4
Metabolizable energy Mcal
.
kg
–1
1.78 2.84
NE (French units) UFV
.
kg
–1
0.50 0.95
Ital.J.anIm.ScI. vol. 7, 153-160, 2008156
antongIovannI et al.
UFV/d per kg live weight gain in animals
weighing 450 kg. For 650 kg LW and 1.2
kg/d gain, let the intake be 9.4 UFV whilst
for another bull of the same weight, gain-
ing 1.0, let the intake be 8.7 UFV/d. The dif-
ference 9.4 – 8.7=0.7 UFV/d was attributed
to the difference of 0.2 kg of ADG, that is
0.7/0.2=3.5 UFV/d per kg live weight gain in
animals weighing 650 kg.
As the second step, the calculated mean
values of requirements of weight gains only
were correlated with LW’s. The equation was:
UFV
gain
/d=(0.004
.
LW + 0.6285) ADG
Then, for each animal the estimated gain
requirement was subtracted from the whole
net energy intake, in order to estimate the
hypothetical maintenance requirement, and
the maintenance values were correlated
with LW’s as well. The equation was:
UFV
m
/d=0.0075
.
LW + 0.8372
The total daily energy requirement is ob-
viously given by the sum of the two:
UFV/d=0.004
.
LW
.
ADG + 0.6285 x ADG
+ 0.0075
.
LW + 0.8372
That is, the proposed equation:
UFV/d=(0.004
.
ADG + 0.0075) LW +
0.6285
.
ADG + 0.8372.
Exactly the same procedure was adopt-
ed to calculate the prediction equation for
PDIN. For the prediction of NDF voluntary
intake, the procedure was simpler because
NDF intake is not sensibly affected by
ADG’s but only by the beef animal’s weight.
Results and discussion
As previously explained, the prediction
equations for NE (UFV) and PDIN require-
ments and for NDF voluntary intake were
calculated from the observed individual
intakes, considering the expected average
daily gains (ADG) and body live weights
(LW), both in kg. The proposed equations for
entire males are:
UFV/d=(0.004
.
ADG + 0.0075) LW +
0.6285
.
ADG + 0.8372 (1)
PDIN (g/d)=(-0.056
.
ADG + 0.681) LW +
328.98
.
ADG + 75 (2)
NDF (g/d)= 5.5093
.
LW + 1575.4 (3)
The next step was the validation of equa-
tion (1), proposed in the present paper for
young Chianina bulls, by comparing it with
the analogue, much more complex, equation
proposed by Giorgetti et al. (1995), calculat-
ed from direct measurements performed on
Chianina bulls more than ten years ago:
UFV/d=0.036
.
LW + 0.8526
.
ADG
(0.2771 +
0.6449 log ADG)
(4)
In order to do that, a regression equa-
Table 2. Ingredient composition of the concentrate mixture (kg
.
100 kg
–1
).
Maize meal 37
Barley meal 33
Commercial protein supplement
(*)
30
(*) composed of soybean meal, sunower meal, calcium salts of palm oil.
Ital.J.anIm.ScI. vol. 7, 153-160, 2008 157
RequIRementS of young chIanIna bullS
tion was calculated by comparing the NE
requirements predictable by our equation
(1) and the requirements predictable by the
one proposed by Giorgetti (4). The regres-
sion equation is:
y=1.0156 x – 0.1673 R
2
=0.9978 (5)
where y=daily NE requirements predictable
by equation (4) and x=daily NE requirements
predictable by the proposed equation (1).
The two equations are practically in-
terchangeable, but ours is much simpler.
In fact, R
2
is practically 1. Figure 1 is the
graphical representation of the regression.
As a further step, a second regression
equation was calculated between the actual
NE daily intakes and the predicted ones, by
using equation (1):
y=0.9472 x + 0.7299 R
2
=0.9009 (6)
where y=daily NE requirements predicta-
ble by equation (1) and x=actual NE intake.
The correlation coefficient is 0.9. Figure 2
presents the graphical aspect of this equation.
A third comparison was made between
actual PDIN daily intakes and predicted
ones, resulting in the equation:
y=0.6204 x + 303.22 R
2
=0.7489 (7)
where y=predicted PDIN (g/d) and
x=measured PDIN intake (g/d). The correla-
tion coefficient is not as good as the former
one, but still quite good (Figure 3).
The fourth step was the calculation of
another regression equation between the
actual NDF daily intake and the amounts
predictable by equation (3):
y=0.2635 x + 3578.4 R
2
=0.263 (8)
where y=predicted NDF (g/d) and
x=measured NDF intakes (g/d). The corre-
lation coefficient is lowest and predictions
definitely unreliable (Figure 4). This may
be due to the relative non homogeneity of
rumen capacity of Chianina cattle, not sub-
mitted to a serious selection for this trait. It
is our opinion that a selection in this direc-
tion could improve the growth performance
Figure 1. Regression between daily NE requirements predictable according to Gior-
getti et al. (1995) and requirements predictable by means of equation (1),
proposed in the present paper.
y = 1.0156x – 0.1673
R
2
= 0.9978
6
8
7
9
10
11
12
NE requirements , equation 4 (UFV/d)
NE requirements , equation 1 (UFV/d)
6 87 9 10 11 12
Ital.J.anIm.ScI. vol. 7, 153-160, 2008158
antongIovannI et al.
Figure 2. Regression between actual NE intake and predicted intake by equation (1).
y = 0.9472x + 0.7299
R
2
= 0.9009
NE daily intakes (UFV/d)
6
8
7
9
10
11
12
Predicted NE daily intakes (UFV/d)
6 87 9 10 11 12
Figure 3. Regression between actual PDIN intake and predicted intake by equation (2).
600
800
700
900
1000
1100
Predicted PDIN (g/d)
PDIN intakes (g/d)
600 800700 900 1000 1100 1200
y = 0.6204x + 303.22
R
2
= 0.7489
of young bulls. In fact, when measured ADG
(kg/d) were correlated with NDF concen-
tration in the diet (g/kg DM), the following
equation was obtained:
y=0104.49 x + 315.81 R
2
=0.8719 (9)
where y=NDF concentration in the diet
(g/kg DM) and x=ADG (kg/d). The R
2
value
is very promising. The higher the NDF was
in the diet, the higher the expected weight
gain (Figure 5). It confirmed the experience
of the breeders of Chianina bulls, who know
that their animals do not take advantage of
high amounts of concentrates.
Conclusions
Information about the energy and protein
requirements and voluntary feed intake
Ital.J.anIm.ScI. vol. 7, 153-160, 2008 159
RequIRementS of young chIanIna bullS
of young Chianina bulls has been actually
lacking to date.
Previous studies have been carried out in
conditions that could be defined as “laborato-
ry” conditions because the experimental proce-
dure was conducted on experimental premises.
On the contrary, the present work was carried
out on a farm, in real “farm” conditions and
over the rather long period of 7 years.
The only critical comment that can be
made on the experimental design is with
regard to the control of intake, which was
not individual, but a group measurement of
10 animals, although it was as homogeneous
and precise as possible.
Nevertheless, the proposed prediction
equations appear to be reliable tools to ade-
quately formulate the diet for the young bulls
of this particular breed in order to achieve
good performance. Particularly important is
Figure 4. Regression between actual NDF intake and predicted intake by equation (3).
y = 0.2635x + 3578.4
R
2
= 0.263
NDF intakes (g/d)
4000
4800
4400
5200
5600
6000
Predicted PDIN (g/d)
3000 40003500 4500 5000 5500 6000 6500 7000
Figure 5. Regression between actual average daily gains (ADG) and NDF concentra-
tion in the diet (g/kg DM).
ADG (kg/d)
0.9
380
400
420
440
460
480
500
1.9 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
y = 104.49x + 315.81
R
2
= 0.8719
NDF in the diet (g/kg DM)
Ital.J.anIm.ScI. vol. 7, 153-160, 2008160
antongIovannI et al.
the relationship between expected gains and
NDF concentration of the diet, resulting in
the recommendation to propose high fibre
diets (48-50% NDF on the DM basis).
The authors gratefully acknowledge the man-
agement of the farm “Il Forteto” and the Breed-
ers Association of the Province of Firenze (APA
of Firenze) for help in collecting the data.
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