Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol84.Issue3-4.May2000:
Animal Feed Science and Technology
84 (2000) 279±294
Interactions between dietary fat type and enzyme
supplementation in broiler diets with high pentosan
contents: effects on precaecal and total tract
digestibility of fatty acids, metabolizability
of gross energy, digesta viscosity
and weights of small intestine
S. DaÈnickea,*, H. Jerocha, W. BoÈttchera, O. Simonb
a
Institut fuÈr TierernaÈhrung und Vorratshaltung, Landwirtschaftliche FakultaÈt, Martin-Luther-UniversitaÈt
Halle-Wittenberg, Emil-Abderhalden-Straûe 26, 06108 Halle (Saale) Wittenberg, Germany
b
Institut fuÈr TierernaÈhrung, Freie UniversitaÈt Berlin, BruÈmmerstraûe 34, 14195 Berlin, Germany
Received 15 June 1999; received in revised form 19 October 1999; accepted 10 January 2000
Abstract
One hundred grams fat, based on blends of beef tallow and soya oil (0:100, 20:80, 40:60, 60:40,
80:20 and 100:0) which corresponded to dietary ratios of unsaturated to saturated fatty acids (U:S
ratio) of 5.47, 3.23, 2.11, 1.45, 1.00 and 0.69, respectively, was incorporated into a rye-based broiler
diet (610 g kgÿ1). All diets were tested without or with supplementation of a xylanase-containing
enzyme preparation in a combined growth test and balance study. Increasing the proportion of
dietary tallow resulted in depression in live-weight gain and increased feed conversion ratio,
exponential increase in jejunal supernatant viscosity, increased empty weight of small intestine and
reduced digestibility of fat and fatty acids and metabolizability of gross energy. The bene®cial
effect of addition of xylanase was greatest at higher tallow concentrations.
In diets which were not supplemented with enzyme, it was shown that small incremental
increases in U:S ratio up to 1.5 resulted in distinct incremental increases in digestibility, whereas
ratios exceeding this value had virtually no further bene®t. Such effects were less pronounced in
enzyme supplemented groups.
*
Corresponding author. Present address: Institute of Animal Nutrition, Federal Agricultural Research Centre,
Braunschweig (FAL), Bundesallee 50, D-38 116 Braunschweig, Germany; Tel.: 49-531-596-436; fax: 49531-596-376.
E-mail address: [email protected] (S. DaÈnicke)
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 1 6 - 4
280
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
In conclusion, addition of an exogenous xylanase to a rye-based broiler diet containing 100 g
added fat/kg gives results which very much depend on the U:S ratio. As the ratio increases up to
maximum of 1.5 U:S, which corresponds to 40 g soya oil and 60 g tallow/kg, the enzyme effects are
greatly pronounced in terms of growth performance, fat and fatty acid digestibility and
metabolizability of energy. Beyond this U:S ratio effects of xylanase are more limited. # 2000
Elsevier Science B.V. All rights reserved.
Keywords: Broiler; Tallow; Soya oil; Xylanase; Fat digestibility
1. Introduction
Several investigators have shown that the effect of exogenously supplied xylanases is
dependent on the dietary fat type when diets with high concentrations of soluble
pentosans are fed to broilers. It was demonstrated that enzyme effects were much more
pronounced in diets containing animal fat compared with plant oil (Smulikowska
and Mieczkowska, 1996; DaÈnicke et al., 1997a; Langhout et al., 1997). Intestinal
viscosity was found to interfere with digestibility of saturated fatty acids more
dramatically than with digestibility of unsaturated fatty acids in rye-based diets (DaÈnicke
et al., 1997b) which partially explained the greater effectiveness of xylanase addition in
such diets. Furthermore, fatty acid utilization from saturated fat sources, such as beef
tallow, can be improved by the addition of small amounts of an unsaturated fat, such as
plant-derived oils (Garrett and Young, 1975; Leeson and Summers, 1976; Sibbald, 1978;
Sibbald and Kramer, 1978; Muztar et al., 1981; Wiseman and Lessire, 1987). Moreover,
the ratio of unsaturated-to-saturated fatty acids (U:S ratio) in the diet in¯uences
digestibility of fat and metabolizable energy (ME)-contents of fats or fat blends (Ketels
and De Groote, 1989; Wiseman et al., 1991). This relationship was described by nonlinear regression models characterized by saturation kinetics. Such models considered
that, at low ratios (more saturated fats), fat digestibility and ME responded more
dramatically to addition of unsaturated fats than at higher ratios (mainly unsaturated fats).
The physiological basis of this synergistic effect between unsaturated and saturated
fatty acids is most likely due to the greater emulsifying capacities of the former and
the dependence of long chain saturated fatty acids on such emulsifying agents for
effective digestion and absorption. However, it is not known how dietary fat blends,
which differ markedly in their U:S ratios, interact with intestinal viscosity and
effectiveness of xylanase addition. This is of particular importance from a practical
point of view, since fat blends are commonly used in broiler diets rather than pure plant
oils or fats of animal origin.
The aim of the current study was to investigate the effects of increasing U:S ratios by
blending soya oil with beef tallow under conditions of high intestinal viscosity, as
mediated by dietary rye inclusion, on the performance of male broilers, precaecal and
total tract digestibility of fat and fatty acids and ME-values of experimental diets. A
further aim was to study the ef®cacy of xylanase addition under the various conditions on
the same parameters.
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
281
2. Material and methods
2.1. Experimental design
A rye-based diet (610 g kgÿ1) varying in dietary proportions of beef tallow and soya oil
(beef tallow:soya oil, g kgÿ10:100, 20:80, 40:60, 60:40, 80:20 and 100:0, respectively)
was tested in an intestinal milieu differing largely in viscosity which, in turn, was markedly
altered through absence or presence of a xylanase-containing enzyme preparation (Avizyme
1300, Finnfeeds, Marlborough, UK). Hence, each diet was tested without (ÿ) or with ()
xylanase supplementation. The xylanase preparation was obtained from Trichoderma
longibrachiatum and contained 3000 IU/g, measured at pH 6.0 on the basis of formation
of reducing substances. û-Glucanase and cellulase activities measured under the same
conditions were very low, 40 and 14 IU/g, respectively. The inclusion rate of the enzyme
preparation was 1 g kgÿ1 of the diet. The composition of the experimental diets is given in
Table 1 and fatty acid pro®le of beef tallow and soya oil is shown in Table 2.
2.2. Combined growth and balance study
Birds used in the experiment were male broilers of the Lohmann strain. They were
obtained from a local hatchery. A total of 288 day-old broilers was divided into 12 groups
of 24 birds, having an initial mean body weight of 420.4 g. The birds were placed in
metabolism cages (4 birds per cage 6 replicates per group) and the experimental diets
and water were provided for ad libitum consumption. Feed intake and live weight were
recorded at 14 and 28 days of age. TiO2 was added as an indigestible marker to all diets at
a rate of 5 g kgÿ1 from Day 24 of age until the end of the experiment. Excreta were
collected from each cage from 26 to 28 days of age. Digesta from segments of the small
intestine were collected at 29 days of age. Broilers were killed by decapitation after
cervical dislocation, the intestines were quickly excised and subsequent segments
(duodenum, jejunum, ileum) were ligated. The duodenum was de®ned from the pylorus
to the entrance of the main pancreatic and biliary ducts, the jejunum from the end of the
duodenum to Meckel's diverticulum and the ileum from the end of the jejunum to 1 cm
from the ileo-caecal-junction. Jejunal and ileal digesta of birds from each cage were
pooled and thoroughly mixed. Pooled jejunal samples were divided in two sub-samples,
one was kept on ice before being centrifuged for viscosity measurements. The remaining
jejunal digesta sample and the whole ileal digesta sample were frozen immediately in
liquid nitrogen and kept frozen until used for determination of digestibility of fat and fatty
acids. The empty weights of the duodenum, jejunum and ileum were also recorded.
2.3. Sample preparation
The pooled and homogenized digesta samples for viscosity measurements were
centrifuged at 15 000g for 15 min.
Excreta and digesta samples for lipid analysis were freeze-dried. The samples were
ground in a freezer mill (Model 6700-230, SPEX CertiPrep, NJ) under liquid nitrogen in
order to produce a ®ne powder and to minimize nutrient losses during preparation.
Group
T0ÿ/T0a
282
Table 1
Composition of the experimental diets (g kgÿ1)
T20ÿ/T20a
T40ÿ/T40a
Beef tallow
Maize starch
Cellulose
Soya oil
Calculated composition:
Crude protein
Crude fat
AMEN (MJ/kg)
Lysine
Methionine
MetCys
Threonine
Tryptophan
Ca
P
Na
a
T80ÿ/T80a
60
30
20
40
80
40
10
20
T100ÿ/T100a
613.8
181
28.7
5.4
3
1.4
4.2
2.5
10
±
±
50
100
20
10
40
80
40
20
30
60
100
50
±
±
230.0
110.0
13.31
12.50
7.0
9.4
9.9
2.7
9
7
1.4
Avizyme 1300, 1 g/kg, at the expense of starch or cellulose.
Variety `Marder,' insoluble pentosans, 66.2 g/kg DM, soluble pentosans, 35.5 g/kg DM.
c
Vitamin±mineral premix provided per kg of diet: Fe, 60 mg; Cu, 5 mg; Zn, 51.4 mg; Mn, 60.8 mg; Se, 0.2 mg; I, 0.6 mg; Vitamin A, 12 000 IU; Vitamin D3,
3000 IU; Vitamin E, 42 mg; Vitamin B1, 2.1 mg; Vitamin B2, 6.6 mg; Vitamin B6, 4.1 mg; Vitamin B12, 20.7 mg; pantothenic acid, 15 mg; nicotinic acid, 36 mg; folic
acid, 1 mg; biotin, 102 mg; choline chloride, 700 mg; ethoxyquin, 120 mg; and Zn-bacitracin, 50 mg.
b
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
Components:
Ryeb
Isolated soya protein
Dicalcium phosphate
Limestone
NaCl
DL-Methionine
L-Lysine-HCl
L-Threonine
Premixc
T60ÿ/T60a
283
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
Table 2
Pro®le of main fatty acids of rye oil, soya oil and tallow (g kgÿ1)
C
C
C
C
C
16:0
18:0
18:1 n-9
18:2 n-6
18:3 n-3
Free fatty acids
a
Rye oil
Soya oil
Beef tallow
188.2
15.4
150.7
434
49.3
94.9
31.6
245.7
439.8
65.1
253.8
204.5
272.6
18.2
2
N.A.a
21.3
34.7
N.A., not analyzed.
2.4. Analysis
Viscosity of jejunal and ileal digesta supernatant was measured using a Brook®eld
viscometer (model DV-IILV) at 408C.
Crude fat content of diets, digesta and excreta samples were analyzed according to the
methods of the Verband Deutscher Landwirtschaftlicher Untersuchungs-und Forschungsanstalten (Naumann and Bassler, 1993) by extraction with chloroform±methanol,
following acidi®cation with 6 N HCl. Fatty acids from the fat extracts were methylated
with trimethylsulphoniumhydroxide and the resulting methyl esters were identi®ed from
their retention time using a gas chromatography system which consisted of a HP 5890
gas-chromatograph, HP 7673 autosampler and HP 3365 data-station. The FFAP-fused
silica column used for separation had a length of 30 m and an inner diameter of 0.53 mm.
He was used as a carrier gas with a ¯ow of 9 ml/min. A ¯ame ionization detector was
used for detecting the fatty acid derivatives. TiO2 in feed, digesta and excreta was
analyzed according to Brandt and Allam (1987). Gross energy of diets and excreta were
measured using an adiabatic bomb calorimeter (model C 4000, Heitersheim, Germany).
Total nitrogen in diets and excreta was analyzed as Kjeldahl-N and free fatty acids of
soya oil and beef tallow as described by Naumann and Bassler (1993).
2.5. Calculations and statistics
Apparent digestibility coef®cient of fat and fatty acids and metabolizability of gross
energy were calculated as follows:
TiO2 in diet
Digestibility 1 ÿ
TiO2 in digesta or excreta
Nutrient or energy in digesta or excreta
Nutrient or energy in diet
The values calculated for fat digestibility at the faecal level also include fat excretions
and should, strictly speaking, be considered as utilization values. However, in view of the
fact that urinary fat excretion in broilers is negligible, the digestibility term will be used.
Digestibility coef®cients are apparent and not true as no allowance was made for endogenous
fat. In addition, no allowance for possible fatty acid transformations was made.
284
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
Metabolizable energy (ME) was corrected for zero-nitrogen retention using a factor of
36.5 kJ gÿ1 N retained (Titus et al., 1959) to yield N-corrected apparent metabolizable
energy (AMEN).
A complete six-by-two two-factorial arrangement of analysis of variance (ANOVA)
was applied:
yijk m ai bj axbij eijk
where yijk is the kth observation subjected to fat proportion i and enzyme supplementation
j, ai the tallow proportion (g kgÿ1; 0, 20, 40, 60, 80 and 100), bj the enzyme
supplementation (without or with supplementation), (axb)ij the interactions between ai
and bj, and eijk the error term.
Non-linear regressions were estimated in order to describe the relationships between
the dietary ratio of unsaturated to saturated fatty acids and several parameters (viscosity,
AMEN and fatty acid digestibility coef®cients). All statistics were carried out using the
Statistica for the Windows operating system (StatSoft Inc., 1994).
3. Results
3.1. Performance
Live-weight gain and feed-to-gain ratio for the experimental period are shown in
Table 3. Signi®cant tallow proportion and enzyme effects were detected, both for live
weight gain and for feed-to-gain ratio. Both parameters were improved as the dietary soya
oil proportion increased (and tallow proportion decreased) and enzyme supplementation
generally exerted a positive effect on growth performance. The bene®t of enzyme
addition tended to be greater as the tallow proportion increased (interactions between
tallow proportion and enzyme addition, signi®cant for live-weight gain).
3.1.1. Intestinal viscosity and weight of segments of small intestine and AMEN content of
diets
Jejunal viscosity and empty weights of segments of the small intestine are shown in
Table 3. Viscosity was found to be highly variable even within dietary treatments which
resulted in non-signi®cant differences for the effect of tallow proportion despite the fact
that an exponential increase was observed as dietary tallow proportion was increased.
However, enzyme supplementation signi®cantly reduced viscosity in jejunal supernatant.
Enzyme supplementation signi®cantly reduced the empty weights of small intestine.
Increasing the proportion of tallow in the diet resulted in increased weight of small
intestine. Metabolizability of gross energy and AMEN of experimental diets decreased
with increasing tallow inclusion rate, an effect which was especially pronounced in the
non-supplemented groups (Table 3). In groups receiving xylanase, this trend became
obvious only when >60 g kgÿ1 tallow was included.
3.1.2. Fat and fatty acid digestibility coef®cients at different sites of the intestinal tract
Apparent fat digestibility at the jejunal, ileal and total tract level was found to
signi®cantly decrease as tallow proportion increased (Table 4). This trend was also found
Tallow content of added dietary fat (g kgÿ1)
0
20
ÿc
d
40
ÿ
Viscosity (mPas)
209
59
272
67
ÿ1
Small intestine (g kg
59.1
39.4
70.3
60
80
100
ÿ
ÿ
ÿ
241
111
551
106
626
115
1335
184
682
42.1
939
74.6
589
47
945
71.4
538
50.1
865
90.6
418
ANOVA (p-values)
effects of:
Orthogonal effects
of T (P-values)
Tallow
Enzyme
TE Linear Quadratic
content (T) addition (E)
ÿ
live weight)
41.7
63.4
Live-weight gain (g per bird)
793 990
648
959
Pooled
SEMb
47.2
815
269.3
0.447
0.029
3.6
0.001
84 (2000) 279±294
Interactions between dietary fat type and enzyme
supplementation in broiler diets with high pentosan
contents: effects on precaecal and total tract
digestibility of fatty acids, metabolizability
of gross energy, digesta viscosity
and weights of small intestine
S. DaÈnickea,*, H. Jerocha, W. BoÈttchera, O. Simonb
a
Institut fuÈr TierernaÈhrung und Vorratshaltung, Landwirtschaftliche FakultaÈt, Martin-Luther-UniversitaÈt
Halle-Wittenberg, Emil-Abderhalden-Straûe 26, 06108 Halle (Saale) Wittenberg, Germany
b
Institut fuÈr TierernaÈhrung, Freie UniversitaÈt Berlin, BruÈmmerstraûe 34, 14195 Berlin, Germany
Received 15 June 1999; received in revised form 19 October 1999; accepted 10 January 2000
Abstract
One hundred grams fat, based on blends of beef tallow and soya oil (0:100, 20:80, 40:60, 60:40,
80:20 and 100:0) which corresponded to dietary ratios of unsaturated to saturated fatty acids (U:S
ratio) of 5.47, 3.23, 2.11, 1.45, 1.00 and 0.69, respectively, was incorporated into a rye-based broiler
diet (610 g kgÿ1). All diets were tested without or with supplementation of a xylanase-containing
enzyme preparation in a combined growth test and balance study. Increasing the proportion of
dietary tallow resulted in depression in live-weight gain and increased feed conversion ratio,
exponential increase in jejunal supernatant viscosity, increased empty weight of small intestine and
reduced digestibility of fat and fatty acids and metabolizability of gross energy. The bene®cial
effect of addition of xylanase was greatest at higher tallow concentrations.
In diets which were not supplemented with enzyme, it was shown that small incremental
increases in U:S ratio up to 1.5 resulted in distinct incremental increases in digestibility, whereas
ratios exceeding this value had virtually no further bene®t. Such effects were less pronounced in
enzyme supplemented groups.
*
Corresponding author. Present address: Institute of Animal Nutrition, Federal Agricultural Research Centre,
Braunschweig (FAL), Bundesallee 50, D-38 116 Braunschweig, Germany; Tel.: 49-531-596-436; fax: 49531-596-376.
E-mail address: [email protected] (S. DaÈnicke)
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 1 6 - 4
280
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
In conclusion, addition of an exogenous xylanase to a rye-based broiler diet containing 100 g
added fat/kg gives results which very much depend on the U:S ratio. As the ratio increases up to
maximum of 1.5 U:S, which corresponds to 40 g soya oil and 60 g tallow/kg, the enzyme effects are
greatly pronounced in terms of growth performance, fat and fatty acid digestibility and
metabolizability of energy. Beyond this U:S ratio effects of xylanase are more limited. # 2000
Elsevier Science B.V. All rights reserved.
Keywords: Broiler; Tallow; Soya oil; Xylanase; Fat digestibility
1. Introduction
Several investigators have shown that the effect of exogenously supplied xylanases is
dependent on the dietary fat type when diets with high concentrations of soluble
pentosans are fed to broilers. It was demonstrated that enzyme effects were much more
pronounced in diets containing animal fat compared with plant oil (Smulikowska
and Mieczkowska, 1996; DaÈnicke et al., 1997a; Langhout et al., 1997). Intestinal
viscosity was found to interfere with digestibility of saturated fatty acids more
dramatically than with digestibility of unsaturated fatty acids in rye-based diets (DaÈnicke
et al., 1997b) which partially explained the greater effectiveness of xylanase addition in
such diets. Furthermore, fatty acid utilization from saturated fat sources, such as beef
tallow, can be improved by the addition of small amounts of an unsaturated fat, such as
plant-derived oils (Garrett and Young, 1975; Leeson and Summers, 1976; Sibbald, 1978;
Sibbald and Kramer, 1978; Muztar et al., 1981; Wiseman and Lessire, 1987). Moreover,
the ratio of unsaturated-to-saturated fatty acids (U:S ratio) in the diet in¯uences
digestibility of fat and metabolizable energy (ME)-contents of fats or fat blends (Ketels
and De Groote, 1989; Wiseman et al., 1991). This relationship was described by nonlinear regression models characterized by saturation kinetics. Such models considered
that, at low ratios (more saturated fats), fat digestibility and ME responded more
dramatically to addition of unsaturated fats than at higher ratios (mainly unsaturated fats).
The physiological basis of this synergistic effect between unsaturated and saturated
fatty acids is most likely due to the greater emulsifying capacities of the former and
the dependence of long chain saturated fatty acids on such emulsifying agents for
effective digestion and absorption. However, it is not known how dietary fat blends,
which differ markedly in their U:S ratios, interact with intestinal viscosity and
effectiveness of xylanase addition. This is of particular importance from a practical
point of view, since fat blends are commonly used in broiler diets rather than pure plant
oils or fats of animal origin.
The aim of the current study was to investigate the effects of increasing U:S ratios by
blending soya oil with beef tallow under conditions of high intestinal viscosity, as
mediated by dietary rye inclusion, on the performance of male broilers, precaecal and
total tract digestibility of fat and fatty acids and ME-values of experimental diets. A
further aim was to study the ef®cacy of xylanase addition under the various conditions on
the same parameters.
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
281
2. Material and methods
2.1. Experimental design
A rye-based diet (610 g kgÿ1) varying in dietary proportions of beef tallow and soya oil
(beef tallow:soya oil, g kgÿ10:100, 20:80, 40:60, 60:40, 80:20 and 100:0, respectively)
was tested in an intestinal milieu differing largely in viscosity which, in turn, was markedly
altered through absence or presence of a xylanase-containing enzyme preparation (Avizyme
1300, Finnfeeds, Marlborough, UK). Hence, each diet was tested without (ÿ) or with ()
xylanase supplementation. The xylanase preparation was obtained from Trichoderma
longibrachiatum and contained 3000 IU/g, measured at pH 6.0 on the basis of formation
of reducing substances. û-Glucanase and cellulase activities measured under the same
conditions were very low, 40 and 14 IU/g, respectively. The inclusion rate of the enzyme
preparation was 1 g kgÿ1 of the diet. The composition of the experimental diets is given in
Table 1 and fatty acid pro®le of beef tallow and soya oil is shown in Table 2.
2.2. Combined growth and balance study
Birds used in the experiment were male broilers of the Lohmann strain. They were
obtained from a local hatchery. A total of 288 day-old broilers was divided into 12 groups
of 24 birds, having an initial mean body weight of 420.4 g. The birds were placed in
metabolism cages (4 birds per cage 6 replicates per group) and the experimental diets
and water were provided for ad libitum consumption. Feed intake and live weight were
recorded at 14 and 28 days of age. TiO2 was added as an indigestible marker to all diets at
a rate of 5 g kgÿ1 from Day 24 of age until the end of the experiment. Excreta were
collected from each cage from 26 to 28 days of age. Digesta from segments of the small
intestine were collected at 29 days of age. Broilers were killed by decapitation after
cervical dislocation, the intestines were quickly excised and subsequent segments
(duodenum, jejunum, ileum) were ligated. The duodenum was de®ned from the pylorus
to the entrance of the main pancreatic and biliary ducts, the jejunum from the end of the
duodenum to Meckel's diverticulum and the ileum from the end of the jejunum to 1 cm
from the ileo-caecal-junction. Jejunal and ileal digesta of birds from each cage were
pooled and thoroughly mixed. Pooled jejunal samples were divided in two sub-samples,
one was kept on ice before being centrifuged for viscosity measurements. The remaining
jejunal digesta sample and the whole ileal digesta sample were frozen immediately in
liquid nitrogen and kept frozen until used for determination of digestibility of fat and fatty
acids. The empty weights of the duodenum, jejunum and ileum were also recorded.
2.3. Sample preparation
The pooled and homogenized digesta samples for viscosity measurements were
centrifuged at 15 000g for 15 min.
Excreta and digesta samples for lipid analysis were freeze-dried. The samples were
ground in a freezer mill (Model 6700-230, SPEX CertiPrep, NJ) under liquid nitrogen in
order to produce a ®ne powder and to minimize nutrient losses during preparation.
Group
T0ÿ/T0a
282
Table 1
Composition of the experimental diets (g kgÿ1)
T20ÿ/T20a
T40ÿ/T40a
Beef tallow
Maize starch
Cellulose
Soya oil
Calculated composition:
Crude protein
Crude fat
AMEN (MJ/kg)
Lysine
Methionine
MetCys
Threonine
Tryptophan
Ca
P
Na
a
T80ÿ/T80a
60
30
20
40
80
40
10
20
T100ÿ/T100a
613.8
181
28.7
5.4
3
1.4
4.2
2.5
10
±
±
50
100
20
10
40
80
40
20
30
60
100
50
±
±
230.0
110.0
13.31
12.50
7.0
9.4
9.9
2.7
9
7
1.4
Avizyme 1300, 1 g/kg, at the expense of starch or cellulose.
Variety `Marder,' insoluble pentosans, 66.2 g/kg DM, soluble pentosans, 35.5 g/kg DM.
c
Vitamin±mineral premix provided per kg of diet: Fe, 60 mg; Cu, 5 mg; Zn, 51.4 mg; Mn, 60.8 mg; Se, 0.2 mg; I, 0.6 mg; Vitamin A, 12 000 IU; Vitamin D3,
3000 IU; Vitamin E, 42 mg; Vitamin B1, 2.1 mg; Vitamin B2, 6.6 mg; Vitamin B6, 4.1 mg; Vitamin B12, 20.7 mg; pantothenic acid, 15 mg; nicotinic acid, 36 mg; folic
acid, 1 mg; biotin, 102 mg; choline chloride, 700 mg; ethoxyquin, 120 mg; and Zn-bacitracin, 50 mg.
b
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
Components:
Ryeb
Isolated soya protein
Dicalcium phosphate
Limestone
NaCl
DL-Methionine
L-Lysine-HCl
L-Threonine
Premixc
T60ÿ/T60a
283
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
Table 2
Pro®le of main fatty acids of rye oil, soya oil and tallow (g kgÿ1)
C
C
C
C
C
16:0
18:0
18:1 n-9
18:2 n-6
18:3 n-3
Free fatty acids
a
Rye oil
Soya oil
Beef tallow
188.2
15.4
150.7
434
49.3
94.9
31.6
245.7
439.8
65.1
253.8
204.5
272.6
18.2
2
N.A.a
21.3
34.7
N.A., not analyzed.
2.4. Analysis
Viscosity of jejunal and ileal digesta supernatant was measured using a Brook®eld
viscometer (model DV-IILV) at 408C.
Crude fat content of diets, digesta and excreta samples were analyzed according to the
methods of the Verband Deutscher Landwirtschaftlicher Untersuchungs-und Forschungsanstalten (Naumann and Bassler, 1993) by extraction with chloroform±methanol,
following acidi®cation with 6 N HCl. Fatty acids from the fat extracts were methylated
with trimethylsulphoniumhydroxide and the resulting methyl esters were identi®ed from
their retention time using a gas chromatography system which consisted of a HP 5890
gas-chromatograph, HP 7673 autosampler and HP 3365 data-station. The FFAP-fused
silica column used for separation had a length of 30 m and an inner diameter of 0.53 mm.
He was used as a carrier gas with a ¯ow of 9 ml/min. A ¯ame ionization detector was
used for detecting the fatty acid derivatives. TiO2 in feed, digesta and excreta was
analyzed according to Brandt and Allam (1987). Gross energy of diets and excreta were
measured using an adiabatic bomb calorimeter (model C 4000, Heitersheim, Germany).
Total nitrogen in diets and excreta was analyzed as Kjeldahl-N and free fatty acids of
soya oil and beef tallow as described by Naumann and Bassler (1993).
2.5. Calculations and statistics
Apparent digestibility coef®cient of fat and fatty acids and metabolizability of gross
energy were calculated as follows:
TiO2 in diet
Digestibility 1 ÿ
TiO2 in digesta or excreta
Nutrient or energy in digesta or excreta
Nutrient or energy in diet
The values calculated for fat digestibility at the faecal level also include fat excretions
and should, strictly speaking, be considered as utilization values. However, in view of the
fact that urinary fat excretion in broilers is negligible, the digestibility term will be used.
Digestibility coef®cients are apparent and not true as no allowance was made for endogenous
fat. In addition, no allowance for possible fatty acid transformations was made.
284
S. DaÈnicke et al. / Animal Feed Science and Technology 84 (2000) 279±294
Metabolizable energy (ME) was corrected for zero-nitrogen retention using a factor of
36.5 kJ gÿ1 N retained (Titus et al., 1959) to yield N-corrected apparent metabolizable
energy (AMEN).
A complete six-by-two two-factorial arrangement of analysis of variance (ANOVA)
was applied:
yijk m ai bj axbij eijk
where yijk is the kth observation subjected to fat proportion i and enzyme supplementation
j, ai the tallow proportion (g kgÿ1; 0, 20, 40, 60, 80 and 100), bj the enzyme
supplementation (without or with supplementation), (axb)ij the interactions between ai
and bj, and eijk the error term.
Non-linear regressions were estimated in order to describe the relationships between
the dietary ratio of unsaturated to saturated fatty acids and several parameters (viscosity,
AMEN and fatty acid digestibility coef®cients). All statistics were carried out using the
Statistica for the Windows operating system (StatSoft Inc., 1994).
3. Results
3.1. Performance
Live-weight gain and feed-to-gain ratio for the experimental period are shown in
Table 3. Signi®cant tallow proportion and enzyme effects were detected, both for live
weight gain and for feed-to-gain ratio. Both parameters were improved as the dietary soya
oil proportion increased (and tallow proportion decreased) and enzyme supplementation
generally exerted a positive effect on growth performance. The bene®t of enzyme
addition tended to be greater as the tallow proportion increased (interactions between
tallow proportion and enzyme addition, signi®cant for live-weight gain).
3.1.1. Intestinal viscosity and weight of segments of small intestine and AMEN content of
diets
Jejunal viscosity and empty weights of segments of the small intestine are shown in
Table 3. Viscosity was found to be highly variable even within dietary treatments which
resulted in non-signi®cant differences for the effect of tallow proportion despite the fact
that an exponential increase was observed as dietary tallow proportion was increased.
However, enzyme supplementation signi®cantly reduced viscosity in jejunal supernatant.
Enzyme supplementation signi®cantly reduced the empty weights of small intestine.
Increasing the proportion of tallow in the diet resulted in increased weight of small
intestine. Metabolizability of gross energy and AMEN of experimental diets decreased
with increasing tallow inclusion rate, an effect which was especially pronounced in the
non-supplemented groups (Table 3). In groups receiving xylanase, this trend became
obvious only when >60 g kgÿ1 tallow was included.
3.1.2. Fat and fatty acid digestibility coef®cients at different sites of the intestinal tract
Apparent fat digestibility at the jejunal, ileal and total tract level was found to
signi®cantly decrease as tallow proportion increased (Table 4). This trend was also found
Tallow content of added dietary fat (g kgÿ1)
0
20
ÿc
d
40
ÿ
Viscosity (mPas)
209
59
272
67
ÿ1
Small intestine (g kg
59.1
39.4
70.3
60
80
100
ÿ
ÿ
ÿ
241
111
551
106
626
115
1335
184
682
42.1
939
74.6
589
47
945
71.4
538
50.1
865
90.6
418
ANOVA (p-values)
effects of:
Orthogonal effects
of T (P-values)
Tallow
Enzyme
TE Linear Quadratic
content (T) addition (E)
ÿ
live weight)
41.7
63.4
Live-weight gain (g per bird)
793 990
648
959
Pooled
SEMb
47.2
815
269.3
0.447
0.029
3.6
0.001