Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol87.Issue3-4.Oct2000:
Animal Feed Science and Technology
87 (2000) 203±213
Nutritional evaluation of cardoon
(Cynara cardunculus) seed for ruminants
C. Cajarville1, J. GonzaÂlez*, J.L. Repetto1,
M.R. Alvir, C.A. RodrõÂguez
Departamento de ProduccioÂn Animal, Escuela TeÂcnica Superior de Ingenieros AgroÂnomos,
Universidad PoliteÂcnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain
Received 9 September 1999; received in revised form 8 June 2000; accepted 3 August 2000
Abstract
Chemical composition, rumen degradability, and digestibility coef®cients of whole cardoon
(Cynara cardunculus L.) seed were studied on two different samples. Ruminal degradability of
whole seed was determined by using the nylon bag technique in three rumen ®stulated wethers.
Four wethers were used to perform digestibility studies on a basal diet (0.5 hay and 0.5 concentrate)
and three diets more where cardoon seed was included at rates of 0.1, 0.2, and 0.3 at the expense of
the basal diet in a 4 4 Latin-square design. Additionally, the effects of three substitution rates (0,
0.1, and 0.25) on rumen fermentation patterns and ®brolytic activity, measured by the in sacco
degradation of the lucerne hay included in the diets, were established using a 3 3 Latin-square
design with three rumen ®stulated wethers. Crude protein (CP), ether extract (EE) and neutral
detergent ®bre (NDF) contents of whole cardoon seed were 225, 250, and 338 g kgÿ1 DM,
respectively, the last being highly ligni®ed (acid detergent lignin ADF 104 g kgÿ1 DM) as
consequence of its high hull proportion (45%). Rumen DM degradability of whole seed was 56.8%,
while CP degradability was 82.9%. Diet digestibility coef®cients were maximum for 0.1
substitution rate, except for EE, that showed a linear and quadratic increase through all diets. The
estimates of seed digestibility obtained by the substitution and extrapolation methods were only
similar for the 0.3 substitution rate. Digestibility coef®cients (%) obtained by substitution at this
level were 83.8 for CP, 82.8 for EE, 20.3 for NDF, 56.1 for OM, and 59.2 for energy. Seed inclusion
in diets up to a 25% had not effect on rumen fermentation patterns or on ruminal ®brolytic activity,
in spite of the high content of fat rich in unsaturated fatty acids (85.5% of total fatty acids) of this
seed. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Cynara cardunculus; Whole seed; Nutritive value; Rumen degradability
*
Corresponding author. Tel.: 34-91-5493069; fax: 34-91-5499763.
E-mail address: [email protected] (J. GonzaÂlez).
1
Departamento de NutricioÂn Animal, Facultad de Veterinaria, Universidad de la RepuÂblica Oriental del
Uruguay, Lasplaces 1550, 11600 Montevideo, Uruguay.
0377-8401/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 0 0 ) 0 0 1 9 8 - X
204
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
1. Introduction
The cardoon (Cynara cardunculus L.) is a kind of thistle that belongs to the asteraceae
family. This perennial herbaceous species grows naturally in Mediterranean countries,
where the petioles of its lowest leaves have been traditionally used as human food. The
vegetative cycle of this plant, that can persist during 8 years, includes the development of
leaves in autumn and winter, the elongation of the stalk in spring, and, in early summer,
the formation of the capitules that contain the seeds. During summer the aerial part of the
plant becomes dry, leaving underground buds in a latent state. Because of its strong root
system, this plant is well adapted to semiarid conditions with high biomass production per
ha, which includes 2±3 t haÿ1 of seeds with high protein and lipid contents (FernaÂndez
and Manzanares, 1990). As a consequence, different industrial possibilities for this crop
are in study, as the use of the biomass for energy production or for pulp paper
manufacture, and the oil extraction from its seeds (FernaÂndez and Manzanares, 1990;
FernaÂndez et al., 1996). In addition, it is interesting to consider the potential of the
different foods derived from this crop for animal nutrition. Although there is some
information about the nutritive value of green forage and crop by-products of cardoon
(FernaÂndez and Manzanares, 1990; Romero et al., 1997; Cajarville et al., 1999), the data
concerning the nutritive value of cardoon seed is limited to some data of chemical
composition (FernaÂndez and Manzanares, 1990). Therefore, the aim of the present work
was to evaluate its potential use for feeding ruminants, studying its chemical composition,
its rumen degradability and its digestibility.
2. Material and methods
2.1. Trial feeds
The cardoon seeds were harvested respectively in 1994 (S1) and 1995 (S2). Sample S1
was used for chemical composition determinations (including amino acids and fatty acids
analysis) and for rumen degradability studies. A portion of this sample was manually
dehulled to establish the proportion of hull and kernel fractions, which were also analysed
for chemical composition. Sample S2 was employed in feeding trials to assess the
apparent digestibility and the effects of increasing the dietary inclusion of this seed on the
ruminal ®brolytic capacity. The chemical composition of both seeds is given in Table 1.
2.2. Ruminal degradability
Three wethers (2±3-year old) provided with a rumen cannula were used in the
experiment. The wethers were fed a mixed (2:1 on DM) forage to concentrate diet
containing 121 g CP kgÿ1 DM and 354 g NDF kgÿ1 DM. The diet was distributed at an
intake level of 40 g DM kgÿ1 BW0.75, in two equal-weight meals at 9.00 and 17.00 h.
The nylon bag technique was used to measure rumen degradability of DM and CP. The
nylon-bags (Blutex nylon 120T, pore size 46 mm, Tissages Tissues Techniques, Paris,
France) were made by heat-sealing and measured 6.5 cm 10:5 cm (inner dimensions).
205
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
Table 1
Chemical composition (g kgÿ1 DM) of Cynara cardunculus seed and of basal diet ingredientsa
Item
Cynara cardunculus seed
ÿ1
DM (g kg )
OM
CP
EE
NDF
ADF
ADL
GE (MJ kgÿ1 DM)
NDIN (g kgÿ1 N)
ADIN (g kgÿ1 N)
Basal diet
S1
Hullb
Kernelb
S2
Hay
Concentrate
948
959
213
250
388
306
102
943
969
54.9
41.3c
812
667
220c
955
951
317
418
45.5
14.7
7.2
922
953
237
250
388
304
106
23.25
883
891
177
25.8
448
348
81.9
17.96
892
956
165
31.7
311
104
31.8
18.55
137
100
872
835
26.6
10.6
a
DM: dry matter; OM: organic matter; CP: crude protein; EE: ether extract; NDF: neutral detergent ®bre;
ADF: acid detergent ®bre; ADL: acid detergent lignin; NDIN: neutral detergent insoluble nitrogen; ADIN: acid
detergent insoluble nitrogen.
b
Fractions obtained from S1 sample.
c
Indirect estimation from kernel and hull proportions and chemical composition of whole seed and kernel.
The sample S1 was ground to pass through a 2 mm sieve and approximately 3 g (air dry
basis) was incubated in the rumen of each animal for intervals of 2, 4, 8, 16, 24, 48 and
72 h. Two series of incubation were conducted in different days in order to have two bags
per animal and per incubation time. All bags of each incubation series were inserted
simultaneously at the morning feeding time. After removing from the rumen, the bags
were washed thoroughly under tap water and frozen (ÿ208C). Once defrosted for
analysis, the bags were washed three times for 5 min in a turbine washing machine, dried
at 808C for 48 h and analysed for DM and N. Three additional bags were reserved for
zero incubation that involved the washing procedure without prior rumen incubation. The
percentages of DM and N disappearance from the nylon bags at each incubation time
were calculated from their respective amounts remaining after incubation in the rumen.
Microbial contamination of the bags was not estimated. Disappearance data of DM and
CP were ®tted for each sheep to the exponential model of érskov and McDonald (1979),
and effective degradability (ED) values were estimated from the respective kinetic
parameters and the rumen particulate out¯ow rate (kp) of this seed.
Values of kp were determined by supplying to the animals, immediately before the ®rst
daily meal, a pulse dose (40 g) of 2 mm ground seed S1 previously washed with a
commercial detergent in an automatic washing machine to eliminate the soluble
components, and labelled with ytterbium. Labelling was done by the immersion method,
as described by GonzaÂlez et al. (1998), at a rate of 5 mg Yb per g DM. Then, a total of 19
faecal grab samples were collected from the rectum of each animal, the ®rst before
supplying the marker and the rest at intervals of 4, 6, 8 and 12 h in the periods of 16±36,
36±60, 60±84 and 84±144 h postdosage, respectively. The samples were dried, ground
and analysed for Yb. The pattern of Yb concentrations in faeces with time was described
by ®tting the model proposed by Dhanoa et al. (1985), and the rate constants derived from
the decreasing phase of concentrations were used as kp values.
206
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
2.3. Feeding trials
Two trials were carried out by substituting a basal diet with ground seed S2 at increased
substitution rates. As basal diet was employed a mixed diet (1:1 on DM) of chopped
lucerne hay and concentrate meal (0.65 barley grain, 0.2 wheat bran, and 0.15 sun¯ower
meal). The chemical composition of the basal diet ingredients is given in Table 1. All
diets (basal and substituted) were offered in both trials at a restricted level of
70 g DM kgÿ1 BW0.75 in two equal-weight meals at 9 and 17 h. In addition, animals had
free access to a mineral block.
In trial 1, four wethers (59:3 4:15 kg BW) were used in a 4 4 Latin-square design
to determine the apparent digestibility of four experimental diets with substitution
rates of 0, 0.1, 0.2, and 0.3. After a 15 days adaptation period to each diet,
digestibility coef®cients of organic matter (OM), crude protein (CP N 6:25), ether
extract (EE), neutral detergent ®bre (NDF), acid detergent ®bre (ADF), and energy
were determined by collection of faeces through 7 days. The respective digestibility
coef®cients for cardoon seed were determined from the digestible components of each
diet by the substitution method and by extrapolation for the components which showed
a linear ®tting.
In trial 2, the ruminal degradation of the lucerne hay of basal diet was determined to
establish the effects of seed substitution rate on the rumen ®brolytic capacity. In this trial
three substitution rates (0, 0.1, and 0.25) were studied, using a 3 3 Latin-square design
and three rumen cannulated wethers. Each experimental period of this trial consisted in a
15 days adaptation period followed by the determination of the ruminal degradation
kinetics of DM and NDF of the lucerne hay, using the in sacco methodology above
described. Degradation kinetics were also described by the model of érskov and
McDonald (1979). Nevertheless, the soluble fraction (a) for NDF was assumed to be zero,
as zero incubation results do not show any bag disappearance. Finally, samples of rumen
¯uid were collected hourly in the interval between meals to determine rumen pH and
ammonia and volatile fatty acids (VFA) concentrations.
2.4. Analytical methods
Samples of feeds and faeces were ground to pass through a 1 mm sieve before analysis.
DM, ash, EE and CP were determined following the AOAC (1990) methods. The contents
of NDF, ADF, and ADL were determined as described by Robertson and Van Soest
(1981). Insoluble N in neutral detergent (NDIN) and in acid detergent (ADIN) solutions
was determined by Kjeldahl analysis of the NDF and ADF residues, respectively. Gross
energy and digestible energy contents were obtained measuring heat production from the
offered feeds and faeces in an adiabatic calorimeter bomb. Proportions of fatty acids in
seed were determined in a Perkin-Elmer 8500 gas chromatograph (Perkin-Elmer Co.,
Beacons®eld, UK), provided with a ¯ame ionisation detector. Amino acids were
determined for the whole seed by high pressure liquid chromatography in reverse phase
after previous derivatization, following the technique of Jones et al. (1981), but using a
¯uorescence detector only. Proline, cystine and tryptophan were not determined due to
technical limitations.
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
207
Samples of faeces collected for transit studies were incinerated at 5508C and then
digested by boiling with a solution of 1.5 M nitric acid and potassium chloride
(3.81 g lÿ1). The resultant solutions were analysed for Yb by atomic absorption
spectrometry (Smith-Hieftje 22. Thermo Jarrell Ash, MA, USA), using predosed samples
of faeces to prepare common matrix standards.
Ammonia in rumen ¯uid was analysed by distillation with a solution of sodium
tetraborate (2.5% w/v), collected on boric acid solution (1% w/v) and titrated with
hydrochloric acid (0.02 M). Rumen ¯uid VFA concentration was determined in a
Hewlett-Packard 5710 A (Hewlett-Packard, Palo Alto, CA, USA) gas chromatograph
with a ¯ame ionisation detector.
2.5. Statistical analysis
The transit and degradation kinetics were ®tted by non-linear regression. The
differences between DM and N degradation values were compared by the paired t-test.
Data of feeding trials were examined by analysis of variance, and linear and quadratic
effects of diet were established in trial 1 by orthogonal polynomials. When linear effects
at P < 0:05 were observed for the content of digestible components, response curves
were ®tted to estimate seed digestibility by extrapolation. Standard errors of the
substitution and the extrapolation values of cardoon seed digestibility were determined as
indicated by Villamide (1996). All statistical analyses were performed with the Statistical
Analysis System for windows software, version 6.12 (SAS, 1990).
3. Results
3.1. Chemical composition of cardoon seed
The proportions of hull in whole cardoon seed was 45% (sample S1). This seed
presents high contents in EE and CP (concentrated in the kernel), but also high levels of
®bre and lignin (mainly located in the hull, which concentrates also the main part of the
®bre bound nitrogen) (Table 1). Proportions of lipid fatty acids in the whole seed were
56.8% polyunsaturated (C18:2 56:7%; C18:3 0:11%), 28.7% monounsaturated
( C 1 6 : 1 0:11%; C 1 8 : 1 28:4%; C 2 0 : 1 0:13%) a n d 1 4 . 5 % s a t u r a t e d
(C16:0 10:6%; C18:0 3:56%; C20:0 0:37%). The amino acid content
(g kgÿ1 DM) in the whole seed were: 11.7 arginine, 3.2 histidine, 6.1 isoleucine, 10.2
leucine, 6.1 lysine, 1.2 methionine, 8.3 phenylalanine, 6.4 threonine, 7.8 valine, 8.0
alanine, 16.9 aspartic acid, 30.7 glutamic acid, 8.9 glycine, 11.8 serine, and 5.9 tyrosine.
Essential amino acids represent 46.9% of total analysed amino acids.
3.2. Ruminal cardoon seed degradability
Degradation extent (a b) and fractional degradation rate for seed S1 were much
higher for CP than for DM, though the difference for degradation rate was not signi®cant,
as consequence of the high variability observed (Table 2). Mean value of the rumen
208
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
Table 2
Rumen degradation kinetics and effective degradability of dry matter (DM) and crude protein (CP) of whole
Cynara cardunculus seed
Item
DM
CP
S.E.D.b
Pc
Soluble fraction (a, %)
Potentially degradable fraction (b, %)
Undegradable fractiona (u, %)
Fractional degradation rate (kd, % hÿ1)
Effective degradability (ED, %)
33.3
27.4
39.3
20.6
56.8
49.5
36.3
14.2
50.8
82.9
0.33
1.04
1.10
14.3
0.54
87 (2000) 203±213
Nutritional evaluation of cardoon
(Cynara cardunculus) seed for ruminants
C. Cajarville1, J. GonzaÂlez*, J.L. Repetto1,
M.R. Alvir, C.A. RodrõÂguez
Departamento de ProduccioÂn Animal, Escuela TeÂcnica Superior de Ingenieros AgroÂnomos,
Universidad PoliteÂcnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain
Received 9 September 1999; received in revised form 8 June 2000; accepted 3 August 2000
Abstract
Chemical composition, rumen degradability, and digestibility coef®cients of whole cardoon
(Cynara cardunculus L.) seed were studied on two different samples. Ruminal degradability of
whole seed was determined by using the nylon bag technique in three rumen ®stulated wethers.
Four wethers were used to perform digestibility studies on a basal diet (0.5 hay and 0.5 concentrate)
and three diets more where cardoon seed was included at rates of 0.1, 0.2, and 0.3 at the expense of
the basal diet in a 4 4 Latin-square design. Additionally, the effects of three substitution rates (0,
0.1, and 0.25) on rumen fermentation patterns and ®brolytic activity, measured by the in sacco
degradation of the lucerne hay included in the diets, were established using a 3 3 Latin-square
design with three rumen ®stulated wethers. Crude protein (CP), ether extract (EE) and neutral
detergent ®bre (NDF) contents of whole cardoon seed were 225, 250, and 338 g kgÿ1 DM,
respectively, the last being highly ligni®ed (acid detergent lignin ADF 104 g kgÿ1 DM) as
consequence of its high hull proportion (45%). Rumen DM degradability of whole seed was 56.8%,
while CP degradability was 82.9%. Diet digestibility coef®cients were maximum for 0.1
substitution rate, except for EE, that showed a linear and quadratic increase through all diets. The
estimates of seed digestibility obtained by the substitution and extrapolation methods were only
similar for the 0.3 substitution rate. Digestibility coef®cients (%) obtained by substitution at this
level were 83.8 for CP, 82.8 for EE, 20.3 for NDF, 56.1 for OM, and 59.2 for energy. Seed inclusion
in diets up to a 25% had not effect on rumen fermentation patterns or on ruminal ®brolytic activity,
in spite of the high content of fat rich in unsaturated fatty acids (85.5% of total fatty acids) of this
seed. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Cynara cardunculus; Whole seed; Nutritive value; Rumen degradability
*
Corresponding author. Tel.: 34-91-5493069; fax: 34-91-5499763.
E-mail address: [email protected] (J. GonzaÂlez).
1
Departamento de NutricioÂn Animal, Facultad de Veterinaria, Universidad de la RepuÂblica Oriental del
Uruguay, Lasplaces 1550, 11600 Montevideo, Uruguay.
0377-8401/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 0 0 ) 0 0 1 9 8 - X
204
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
1. Introduction
The cardoon (Cynara cardunculus L.) is a kind of thistle that belongs to the asteraceae
family. This perennial herbaceous species grows naturally in Mediterranean countries,
where the petioles of its lowest leaves have been traditionally used as human food. The
vegetative cycle of this plant, that can persist during 8 years, includes the development of
leaves in autumn and winter, the elongation of the stalk in spring, and, in early summer,
the formation of the capitules that contain the seeds. During summer the aerial part of the
plant becomes dry, leaving underground buds in a latent state. Because of its strong root
system, this plant is well adapted to semiarid conditions with high biomass production per
ha, which includes 2±3 t haÿ1 of seeds with high protein and lipid contents (FernaÂndez
and Manzanares, 1990). As a consequence, different industrial possibilities for this crop
are in study, as the use of the biomass for energy production or for pulp paper
manufacture, and the oil extraction from its seeds (FernaÂndez and Manzanares, 1990;
FernaÂndez et al., 1996). In addition, it is interesting to consider the potential of the
different foods derived from this crop for animal nutrition. Although there is some
information about the nutritive value of green forage and crop by-products of cardoon
(FernaÂndez and Manzanares, 1990; Romero et al., 1997; Cajarville et al., 1999), the data
concerning the nutritive value of cardoon seed is limited to some data of chemical
composition (FernaÂndez and Manzanares, 1990). Therefore, the aim of the present work
was to evaluate its potential use for feeding ruminants, studying its chemical composition,
its rumen degradability and its digestibility.
2. Material and methods
2.1. Trial feeds
The cardoon seeds were harvested respectively in 1994 (S1) and 1995 (S2). Sample S1
was used for chemical composition determinations (including amino acids and fatty acids
analysis) and for rumen degradability studies. A portion of this sample was manually
dehulled to establish the proportion of hull and kernel fractions, which were also analysed
for chemical composition. Sample S2 was employed in feeding trials to assess the
apparent digestibility and the effects of increasing the dietary inclusion of this seed on the
ruminal ®brolytic capacity. The chemical composition of both seeds is given in Table 1.
2.2. Ruminal degradability
Three wethers (2±3-year old) provided with a rumen cannula were used in the
experiment. The wethers were fed a mixed (2:1 on DM) forage to concentrate diet
containing 121 g CP kgÿ1 DM and 354 g NDF kgÿ1 DM. The diet was distributed at an
intake level of 40 g DM kgÿ1 BW0.75, in two equal-weight meals at 9.00 and 17.00 h.
The nylon bag technique was used to measure rumen degradability of DM and CP. The
nylon-bags (Blutex nylon 120T, pore size 46 mm, Tissages Tissues Techniques, Paris,
France) were made by heat-sealing and measured 6.5 cm 10:5 cm (inner dimensions).
205
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
Table 1
Chemical composition (g kgÿ1 DM) of Cynara cardunculus seed and of basal diet ingredientsa
Item
Cynara cardunculus seed
ÿ1
DM (g kg )
OM
CP
EE
NDF
ADF
ADL
GE (MJ kgÿ1 DM)
NDIN (g kgÿ1 N)
ADIN (g kgÿ1 N)
Basal diet
S1
Hullb
Kernelb
S2
Hay
Concentrate
948
959
213
250
388
306
102
943
969
54.9
41.3c
812
667
220c
955
951
317
418
45.5
14.7
7.2
922
953
237
250
388
304
106
23.25
883
891
177
25.8
448
348
81.9
17.96
892
956
165
31.7
311
104
31.8
18.55
137
100
872
835
26.6
10.6
a
DM: dry matter; OM: organic matter; CP: crude protein; EE: ether extract; NDF: neutral detergent ®bre;
ADF: acid detergent ®bre; ADL: acid detergent lignin; NDIN: neutral detergent insoluble nitrogen; ADIN: acid
detergent insoluble nitrogen.
b
Fractions obtained from S1 sample.
c
Indirect estimation from kernel and hull proportions and chemical composition of whole seed and kernel.
The sample S1 was ground to pass through a 2 mm sieve and approximately 3 g (air dry
basis) was incubated in the rumen of each animal for intervals of 2, 4, 8, 16, 24, 48 and
72 h. Two series of incubation were conducted in different days in order to have two bags
per animal and per incubation time. All bags of each incubation series were inserted
simultaneously at the morning feeding time. After removing from the rumen, the bags
were washed thoroughly under tap water and frozen (ÿ208C). Once defrosted for
analysis, the bags were washed three times for 5 min in a turbine washing machine, dried
at 808C for 48 h and analysed for DM and N. Three additional bags were reserved for
zero incubation that involved the washing procedure without prior rumen incubation. The
percentages of DM and N disappearance from the nylon bags at each incubation time
were calculated from their respective amounts remaining after incubation in the rumen.
Microbial contamination of the bags was not estimated. Disappearance data of DM and
CP were ®tted for each sheep to the exponential model of érskov and McDonald (1979),
and effective degradability (ED) values were estimated from the respective kinetic
parameters and the rumen particulate out¯ow rate (kp) of this seed.
Values of kp were determined by supplying to the animals, immediately before the ®rst
daily meal, a pulse dose (40 g) of 2 mm ground seed S1 previously washed with a
commercial detergent in an automatic washing machine to eliminate the soluble
components, and labelled with ytterbium. Labelling was done by the immersion method,
as described by GonzaÂlez et al. (1998), at a rate of 5 mg Yb per g DM. Then, a total of 19
faecal grab samples were collected from the rectum of each animal, the ®rst before
supplying the marker and the rest at intervals of 4, 6, 8 and 12 h in the periods of 16±36,
36±60, 60±84 and 84±144 h postdosage, respectively. The samples were dried, ground
and analysed for Yb. The pattern of Yb concentrations in faeces with time was described
by ®tting the model proposed by Dhanoa et al. (1985), and the rate constants derived from
the decreasing phase of concentrations were used as kp values.
206
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
2.3. Feeding trials
Two trials were carried out by substituting a basal diet with ground seed S2 at increased
substitution rates. As basal diet was employed a mixed diet (1:1 on DM) of chopped
lucerne hay and concentrate meal (0.65 barley grain, 0.2 wheat bran, and 0.15 sun¯ower
meal). The chemical composition of the basal diet ingredients is given in Table 1. All
diets (basal and substituted) were offered in both trials at a restricted level of
70 g DM kgÿ1 BW0.75 in two equal-weight meals at 9 and 17 h. In addition, animals had
free access to a mineral block.
In trial 1, four wethers (59:3 4:15 kg BW) were used in a 4 4 Latin-square design
to determine the apparent digestibility of four experimental diets with substitution
rates of 0, 0.1, 0.2, and 0.3. After a 15 days adaptation period to each diet,
digestibility coef®cients of organic matter (OM), crude protein (CP N 6:25), ether
extract (EE), neutral detergent ®bre (NDF), acid detergent ®bre (ADF), and energy
were determined by collection of faeces through 7 days. The respective digestibility
coef®cients for cardoon seed were determined from the digestible components of each
diet by the substitution method and by extrapolation for the components which showed
a linear ®tting.
In trial 2, the ruminal degradation of the lucerne hay of basal diet was determined to
establish the effects of seed substitution rate on the rumen ®brolytic capacity. In this trial
three substitution rates (0, 0.1, and 0.25) were studied, using a 3 3 Latin-square design
and three rumen cannulated wethers. Each experimental period of this trial consisted in a
15 days adaptation period followed by the determination of the ruminal degradation
kinetics of DM and NDF of the lucerne hay, using the in sacco methodology above
described. Degradation kinetics were also described by the model of érskov and
McDonald (1979). Nevertheless, the soluble fraction (a) for NDF was assumed to be zero,
as zero incubation results do not show any bag disappearance. Finally, samples of rumen
¯uid were collected hourly in the interval between meals to determine rumen pH and
ammonia and volatile fatty acids (VFA) concentrations.
2.4. Analytical methods
Samples of feeds and faeces were ground to pass through a 1 mm sieve before analysis.
DM, ash, EE and CP were determined following the AOAC (1990) methods. The contents
of NDF, ADF, and ADL were determined as described by Robertson and Van Soest
(1981). Insoluble N in neutral detergent (NDIN) and in acid detergent (ADIN) solutions
was determined by Kjeldahl analysis of the NDF and ADF residues, respectively. Gross
energy and digestible energy contents were obtained measuring heat production from the
offered feeds and faeces in an adiabatic calorimeter bomb. Proportions of fatty acids in
seed were determined in a Perkin-Elmer 8500 gas chromatograph (Perkin-Elmer Co.,
Beacons®eld, UK), provided with a ¯ame ionisation detector. Amino acids were
determined for the whole seed by high pressure liquid chromatography in reverse phase
after previous derivatization, following the technique of Jones et al. (1981), but using a
¯uorescence detector only. Proline, cystine and tryptophan were not determined due to
technical limitations.
C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
207
Samples of faeces collected for transit studies were incinerated at 5508C and then
digested by boiling with a solution of 1.5 M nitric acid and potassium chloride
(3.81 g lÿ1). The resultant solutions were analysed for Yb by atomic absorption
spectrometry (Smith-Hieftje 22. Thermo Jarrell Ash, MA, USA), using predosed samples
of faeces to prepare common matrix standards.
Ammonia in rumen ¯uid was analysed by distillation with a solution of sodium
tetraborate (2.5% w/v), collected on boric acid solution (1% w/v) and titrated with
hydrochloric acid (0.02 M). Rumen ¯uid VFA concentration was determined in a
Hewlett-Packard 5710 A (Hewlett-Packard, Palo Alto, CA, USA) gas chromatograph
with a ¯ame ionisation detector.
2.5. Statistical analysis
The transit and degradation kinetics were ®tted by non-linear regression. The
differences between DM and N degradation values were compared by the paired t-test.
Data of feeding trials were examined by analysis of variance, and linear and quadratic
effects of diet were established in trial 1 by orthogonal polynomials. When linear effects
at P < 0:05 were observed for the content of digestible components, response curves
were ®tted to estimate seed digestibility by extrapolation. Standard errors of the
substitution and the extrapolation values of cardoon seed digestibility were determined as
indicated by Villamide (1996). All statistical analyses were performed with the Statistical
Analysis System for windows software, version 6.12 (SAS, 1990).
3. Results
3.1. Chemical composition of cardoon seed
The proportions of hull in whole cardoon seed was 45% (sample S1). This seed
presents high contents in EE and CP (concentrated in the kernel), but also high levels of
®bre and lignin (mainly located in the hull, which concentrates also the main part of the
®bre bound nitrogen) (Table 1). Proportions of lipid fatty acids in the whole seed were
56.8% polyunsaturated (C18:2 56:7%; C18:3 0:11%), 28.7% monounsaturated
( C 1 6 : 1 0:11%; C 1 8 : 1 28:4%; C 2 0 : 1 0:13%) a n d 1 4 . 5 % s a t u r a t e d
(C16:0 10:6%; C18:0 3:56%; C20:0 0:37%). The amino acid content
(g kgÿ1 DM) in the whole seed were: 11.7 arginine, 3.2 histidine, 6.1 isoleucine, 10.2
leucine, 6.1 lysine, 1.2 methionine, 8.3 phenylalanine, 6.4 threonine, 7.8 valine, 8.0
alanine, 16.9 aspartic acid, 30.7 glutamic acid, 8.9 glycine, 11.8 serine, and 5.9 tyrosine.
Essential amino acids represent 46.9% of total analysed amino acids.
3.2. Ruminal cardoon seed degradability
Degradation extent (a b) and fractional degradation rate for seed S1 were much
higher for CP than for DM, though the difference for degradation rate was not signi®cant,
as consequence of the high variability observed (Table 2). Mean value of the rumen
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C. Cajarville et al. / Animal Feed Science and Technology 87 (2000) 203±213
Table 2
Rumen degradation kinetics and effective degradability of dry matter (DM) and crude protein (CP) of whole
Cynara cardunculus seed
Item
DM
CP
S.E.D.b
Pc
Soluble fraction (a, %)
Potentially degradable fraction (b, %)
Undegradable fractiona (u, %)
Fractional degradation rate (kd, % hÿ1)
Effective degradability (ED, %)
33.3
27.4
39.3
20.6
56.8
49.5
36.3
14.2
50.8
82.9
0.33
1.04
1.10
14.3
0.54