120 Y
.-L. Yin et al. Livestock Production Science 62 2000 119 –132
P . 0.05. However, with the WB diet the improvements for all three parameters were approximately 2 for overall apparent digestibility and 4 for ileal apparent digestibility.
2000 Elsevier Science B.V. All rights reserved.
15
Keywords : Wheat; Wheat by-products; Overall and ileal apparent digestibility;
N-isotope technique; Endogenous N flow; VFA production; Xylanase
1. Introduction NSP degrading enzyme xylanase. One source of
wheat var. Soissons and its by-products was used to There is considerable interest in the use of fibrous
eliminate differences due to the nature and com- feeds for pigs. However, pigs do not produce the
position of dietary fibre. Ground wheat was com- endogenous enzymes required to break down cell
pared with its recombined fractions flour 1 bran 1 wall non-starch polysaccharides NSP. The negative
middlings; designated recombined wheat to deter- relationship between dietary fibre and digestibility of
mine the extent to which physical separation of the nutrients is well established Low, 1985; McClean,
components might affect digestion. This experiment 1993; Yin, 1994; Jørgensen et al., 1996. The
was conducted in collaboration with the Research reduced apparent digestibility of energy from high-
Institute for the Biology of Farm Animals, Depart- fibre feeds can be attributed to differences in the
ment of Nutritional Physiology ‘‘Oskar Kellner’’, physical or chemical structure of feeds and the
Rostock, Germany. The same diets were used at both shorter transit time of digesta Graham et al., 1986.
institutions, except that the WR diet was only used in The decreased apparent digestibility of crude protein
Belfast. Whereas PVTC cannulae were used in and amino acids, however, might be due to increased
Belfast, the end-to-end ileo-rectal anastomosis IRA endogenous nitrogen N secretion de Lange et al.,
method was used in Rostock. 1990 or reduced digestibility of feed N due to the
physical and chemical structure of the feed affecting accessibility of protein-degrading enzymes or a
2. Materials and methods
combination of both. Addition of exogenous enzymes to diets based on
2.1. Experiment 1 barley and wheat improves both nutrient digestibility
and performance of pigs Taverner and Campbell, 2.1.1. Animals and experimental design
¨ 1988; Bohm, 1990; Li et al., 1994; Dierick and
Twelve male Large White 3 Landrace pigs, ap- Decuypere, 1995; Baidoo et al., 1997. Therefore,
proximately 26 kg, were fitted with post valve ‘‘T’’ the enzymes are capable of reducing some of the
caecal cannulae PVTC, according to the procedures anti-nutritive properties of cell wall NSP. In broiler
of van Leeuwen et al. 1991. The pigs were chickens, reduced digesta viscosity, following en-
randomly allocated, in a four period crossover de- zyme supplementation of barley- and wheat-based
sign, to eight diets based on wheat W, wheat 1 diets, is correlated with improved performance,
middlings WM, wheat 1 bran WB or recombined particularly in relation to feed efficiency Bedford
wheat WR, given without or with xylanase addition and Classen, 1992; Choct et al., 1994; Preston,
Finnfeeds International Ltd Table 1. Each of the 1997. Similar relationships have not been estab-
four main diets was mixed as a single batch and then lished in pigs Bedford et al., 1992.
divided for addition of the enzyme. The bran, flour The aims of this experiment were to determine the
and middlings were the mill fractions from the same extent of ileal and overall digestion of the nutrients
whole grain wheat and were produced in a commer- in pig diets containing wheat and its by-products, the
cial flour mill Andrews Milling to normal spe- contribution of microbial action VFA apparent
cifications. The wheat was the French variety, Sois- production and endogenous secretion of N in the
sons, which had been grown in England. The diets, small intestine to digestion and interactions with an
which contained both TiO and Cr O as indigest-
2 2
3
Y .-L. Yin et al. Livestock Production Science 62 2000 119 –132
121 Table 1
followed by two 12 h collections of ileal digesta
a
Composition of experimental diets g kg
08.00 to 20.00 h on consecutive days.
Diet W
WR WM
WB
2.2. Experiment 2
Wheat 760
380 380
Wheat flour 570
Wheat bran 60
380
2.2.1. Animals and experimental design
Wheat middlings 130
380
Thirty German Landrace barrows were obtained
Soybean meal 170
170 170
170
from the farm of the Research Institute for the
Fish meal 30
30 30
30
Biology of Farm Animals Dummerstorf, Rostock,
Soybean oil 10
10 10
10 Dicalcium phosphate
5 5
5 5
Germany. When the pigs weighed approximately 15
Limestone 10.1
10.1 10.1
10.1
kg an ileo-rectal anastomosis was performed accord-
Lysine 0.4
0.4 0.4
0.4
ing to the procedure described by Hennig et al.
b
Binder 9
9 9
9
c
1986. In each series, six of the diets used in Belfast
Mineral vitamins 2.5
2.5 2.5
2.5
d
W, WM and WB, each without or with xylanase
Markers 3
3 3
3
addition were allocated at random to five pigs per
a
Enzyme xylanase, Trichoderma longibrachiatum, 0.321 g kg
diet.
diet, guaranteed minimum enzyme activity 5000 units kg diet,
On day 10 after surgery, the pigs were individual-
added to one half of each diet. Enzyme activity was determined by the manufacturer, Finnfeeds International Ltd..
ly housed in metabolism cages and given the appro-
b
Lignobond 2X Lignotech, Norway.
priate experimental diet. On day 15 following the
c
Pigmv No. 2 Devenish Feed Supplements, Belfast, sup-
IRA surgery two indwelling silicone Silastic, Dow
plying per kg diet: vitamin A 8000 i.u.; vitamin D 2000 i.u.;
3
Corning, Michigan catheters internal diameter 1.5
vitamin E 40 mg; vitamin K 1 mg; vitamin B 2 mg; vitamin B
2 12
mm were surgically implanted into the pig, one into
0.012 mg; iodine 0.85 mg; selenium 0.2 mg; cobalt 0.54 mg; iron
15
58 mg; zinc 72 mg; manganese 42 mg; copper 15 mg; calcium
the external jugular vein for the infusion of N-
500 mg; anti-oxidant 10 mg.
leucine and the other into the carotid artery for
d
TiO 1 g kg and Cr O 2 g kg were added to each diet.
2 2
3
blood sampling, according to the procedures de- scribed by Weirich et al. 1970. The animals were
allowed 48 h to recover from the second surgical ible markers, were cold-pelleted 3 mm die and fed
manipulation before starting a ten-day experimental dry.
period. In order to minimise between-pig variation the
experiment was based on a cross-over design with 2.2.2. Feeding regimen and sampling of ileal
each pig undergoing four collection periods. This digesta and blood
meant that each of the eight dietary treatments was Feed intake was 500 g d for each diet and the pigs
replicated six times. Pigs were randomly allocated to were fed in two equal portions at 07:30 and 18:30 h
individual pens according to the initial randomisation during the entire experimental period. In order to
of the treatments. compensate for by-passing the caecum and colon, the
diets Table 1 were additionally supplemented with 2.1.2. Feeding regimen and sampling of faeces
sodium chloride 4 g kg diet, sodium bicarbonate and ileal digesta
4 g kg diet and a vitamin mix 1 g kg diet. Two Pigs were fed daily at 08:00 and 17:00 h 20:00 h
days after insertion of the catheters, a 10 day
15 15
during the faeces and ileal digesta collection continuous infusion of
N-leucine 95 N-enrich-
periods. They were given a fixed allowance which ment via the jugular catheter was initiated. On the
was kept constant during each experimental period. day prior to the start of the 10 day infusion period,
The amount given was the intake of the pig with the ileal digesta and blood samples 10 ml were taken
15
lowest consumption during the first 2 days of the from each animal to determine the background
N- adjustment period. Feed intakes were 1400, 1533,
enrichment of the trichloroacetic acid TCA-soluble 1713 and 1838 g d in periods 1, 2, 3 and 4. After a 5
fraction of blood plasma and ileal digesta. Each day adaptation period, 7 day faecal collections were
animal was infused with 50 ml d of sterile 0.9
122 Y
.-L. Yin et al. Livestock Production Science 62 2000 119 –132
15
NaCl solution containing 1.5 mg N-leucine 95
trated phosphoric acid, using a Pye Unicam 304 gas
15
N labelled. An infusion pump Harvard 22, Har- chromatograph with a 10 m Hewlett Packard HP-
vard instruments, Cambridge, USA was used to 20M Carbowax column.
infuse the solution.
15
From the first day of infusion of the N-leucine to
2.4. Calculation and statistical analysis the last day, blood samples 10 ml were taken twice
a day 8:00 and 19:00 from the carotid catheter. The results obtained from the PVTC method
Immediately after sampling, the blood was cen- Belfast were analysed using the ANOVA procedure
trifuged 10 min 3000 3 g, temperature 48C and the of the statistical package Genstat 5 1993 corre-
plasma was removed. The plasma protein was pre- sponding to the 12 pigs 3 4 periods partially bal-
cipitated by mixing 5 ml plasma with 5 ml 10 TCA anced change over design six replicates per treat-
and centrifuging at a speed of 4000 g at a tempera- ment. This removed the effects of pigs and periods
ture of 48C. The supernatant fluid TCA-soluble and tested for the main effect of diets and xylanase
fraction from the samples taken from each animal and their interaction.
per day were stored at 2 208C for further analyses. The amount of endogenous N five replicates per
Ileal digesta were collected for 5 days from the 6th
15
treatment was calculated from the ratio of N-
day after infusion to the last day of the experiment. enrichment in ileal digesta Ed to that in the TCA-
At the end of each experiment a last blood sample
15
soluble blood plasma of the corresponding day using was taken from each animal for
N-enrichment the following formula according to Souffrant et al.
analysis and the animals were killed by euthanasia 1981 and de Lange et al. 1990:
with Hexobarbital-Na Hexobarbital Natrium AWD, VEB Arzneimittelwerke, Dresden.
Ne 5 Nd 3 [Ed–Enf Epl–Enpl] 2.3. Chemical analysis
where Ne is the endogenous N loss g d or g kg Samples of faeces and ileal digesta were freeze-
DM intake; Nd is the total amount of N in the ileal
15
dried and pooled within period and pig for each digesta g d or g kg DMI; Ed is the
N-enrich-
15
dietary treatment. The proximate analysis was car- ment in ileal digesta; Enf is the background
N-
15
ried out according to AOAC 1984. Amino acid enrichment in the digesta; Epl is the
N-enrichment AA analyses of diets and ileal digesta were carried
in the TCA-soluble blood plasma; and Enpl is the
15
out on an LKB 4400 Amino Acid Analyser using background
N-enrichment in the TCA-soluble norleucine as the internal standard, after hydrolysis
blood plasma. The factor [Ed–Enf Epl–Enpl], for 22 h in 6N HCl. Gross energy of diets, ileal
referred to as the dilution factor, was calculated for digesta and faeces was determined using an adiabatic
each animal for each individual day of ileal digesta bomb calorimeter Gallenkamp, Model CBA-305.
collection.
15
TiO was measured according to Leone 1973.
Daily values for the N-enrichment excess were
2
Cr O was measured according to the method of
subjected to non-linear regression Proc. NLIN,
2 3
Saha and Gilbreath 1991 by atomic absorption modified Gauss–Newton method, SAS, 1990 ac-
spectrophotometry. Soluble
and insoluble
NSP cording to the formula given by Souffrant et al.
15
sugars and uronic acids and total NSP in diets were 1993, to calculate the steady state
N-enrichment determined by gas chromatography Pye Unicam
of total N in the chosen precursor pool. 304 according to Englyst and Cummings 1984.
The results obtained from the IRA method Ros-
15
N-enrichment of the ileal digesta and TCA-soluble tock were analysed by analysis of variance accord-
blood plasma samples were analysed by the method ing to the 3 diets32 enzymes factorial design. In
of Souffrant et al. 1982. Volatile fatty acids VFA contrast to the changeover design in Experiment 1,
in fresh ileal digesta were determined after centrifu- the treatments were compared using between-pig
gation and treatment of the supernatant with concen- variation.
Y .-L. Yin et al. Livestock Production Science 62 2000 119 –132
123
3. Results Conversely, the total NSP content was highest for
