The effects of chemical treatment of whole canola seed on lipid and protein digestion by steers.

Abstract

Five Angus x Simmental steers (average BW 259 kg) cannulated in the rumen, proximal duodenum, and terminal ileum were fed five diets in a 5 x 5 Latin square design. Experimental periods were 14 d in length, with 10 d of diet adaptation and 4 d of sample collection. The basal diet contained (percentage of diet DM) ammoniated corn cobs (50%), alfalfa hay (22%), cornstarch grits (13%), corn (6.7%), cane molasses (5%), and urea (1.25%). Three canola seed-containing diets and a diet containing Ca salts of long-chain fatty acids (Ca-LCFA) were formulated by replacing cornstarch grits from the basal diet with the test feedstuffs. Whole canola seed untreated, crushed, or treated with a caustic alkaline solution and an oxidant were included at 10% of diet DM. The Ca-LCFA diet contained (percentage of diet DM) canola meal (5%) and Megalac (5%). Diets containing untreated, crushed, and treated canola seed and Ca-LCFA contained, on average, 5.6% more total fatty acids than the basal diet. Steers were fed 5.3 kg DM/d (2.05% of initial BW) in 12 equal portions (every 2 h). Ruminal fermentation characteristics and digestibilities of OM, GE, N, NDF, and ADF were unaffected (P > .05) by diet. Biohydrogenation of total 18-carbon unsaturated fatty acids was greater (P < .05) for steers fed the crushed canola seed-containing diet (72.0%) than for steers fed the untreated (27.9%) and treated (38.6%) canola seed-containing diets. Digestibility of total 18-carbon fatty acids in the small intestine was greater for steers fed the crushed canola seed (58.9% of duodenal flow) rather than the untreated canola seed (28.4% of duodenal flow) and intermediate for steers fed the treated canola seed (47.0% of duodenal flow). Chemical treatment of whole canola seed may be a viable method for the postruminal delivery of intestinally available unsaturated fatty acids to ruminants.

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Berger
C. G. Aldrich, N. R. Merchen, J. K. Drackley, S. S. Gonzalez, G. C. Fahey, Jr and L. L.
by steers
The effects of chemical treatment of whole canola seed on lipid and protein digestion
1997, 75:502-511.
J ANIM SCI
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502
1Research reported herein was supported in part by a gift from
DuCoa L.P., a DuPont-ConAgra company, Highland, IL.
2To whom correspondence should be addressed.
Received November 29, 1995.
Accepted September 4, 1996.
The Effects of Chemical Treatment of Whole Canola Seed on Lipid
and Protein Digestion by Steers1
C. G. Aldrich, N. R . Merchen,2J . K . Drackley, S. S. Gonzalez,
G. C. F ahey, J r., and L . L . Berger
Department of Animal Sciences, University of Illinois, Urbana 61801
ABST R ACT :
age BW 259 kg) cannulated in the rumen, proximal
duodenum, and terminal ileum were fed five diets in a
5 × 5 Latin square design. Experimental periods were
14 d in length, with 10 d of diet adaptation and 4 d of
sample collection. The basal diet contained (percen-
tage of diet DM) ammoniated corn cobs (50%), alfalfa
hay (22%), cornstarch grits (13%), corn (6.7%), cane
molasses (5%), and urea (1.25%). Three canola seed-
containing diets and a diet containing Ca salts of long-
chain fatty acids (Ca-L CF A) were formulated by
replacing cornstarch grits from the basal diet with the
test feedstuffs. Whole canola seed untreated, crushed,
or treated with a caustic alkaline solution and an
oxidant were included at 10% of diet DM. The Ca-
LCFA diet contained (percentage of diet DM) canola
meal (5%) and Megalac(5%). Diets containing
untreated, crushed, and treated canola seed and Ca-
LCFA contained, on average, 5.6% more total fatty
Five Angus × Simmental steers (aver-
acids than the basal diet. Steers were fed 5.3 kg DM/d
(2.05% of initial BW) in 12 equal portions (every 2
h). Ruminal fermentation characteristics and digesti-
bilities of OM, GE, N, NDF, and ADF were unaffected
( P>.05) bydiet. Biohydrogenation
18-carbon unsaturated fatty acids was greater (P <
.05) for steers fed the crushed canola seed-containing
diet (72.0%)than for steers fed the untreated
(27.9%) and treated (38.6%) canola seed-containing
diets. Digestibility of total 18-carbon fatty acids in the
small intestine was greater for steers fed the crushed
canola seed (58.9% of duodenal flow) rather than the
untreated canola seed (28.4% of duodenal flow) and
intermediate for steers fed the treated canola seed
(47.0% of duodenal flow). Chemical treatment of
whole canola seed may be a viable method for the
postruminal delivery of intestinally available unsatu-
rated fatty acids to ruminants.
oftotal
Key Words: Steers, Canola, Fatty Acids, Digestibility
J . Anim. Sci. 1997. 75:502±511
Introduction
Recent interest in the use of canola oil as a source of
lipid for increasing the energy density of diets of high-
producing ruminants has resulted because the seed
contains both a high level of lipid (40 to 60%) and a
moderate quantity of protein (>20%) and because the
lipid fraction is primarily unsaturated (>85%), with
oleic acid (18:1) accounting for a majority of the total
fatty acids (56 to 62% of total fatty acids; St. J ohn et
al., 1987; Ackman, 1990; Khorasani et al., 1992;
J enkins and J enny, 1992).
Consumption of a high level of unsaturated fatty
acids by ruminants may be responsible for depressed
ruminal digestibility of fiber (Devendra and Lewis,
1974),
composition,
(Palmquist and J enkins, 1980). Unsaturated fatty
acids are biohydrogenated extensively by the ruminal
microflora (Wu et al., 1991). Thus, fatty acids flowing
to the small intestine for absorption and utilization
are primarily saturated. Escalating pressure from the
medical profession to reduce total and saturated fat
intake has led to the public perception that fat from
ruminant products is unhealthy. To address this issue
and to circumvent alterations to ruminal metabolism,
it has been suggested that methods for the postrumi-
nal delivery of monounsaturated fatty acids need to be
developed (Grummer, 1991).
In cattle, whole canola seed is resistant to digestion
in both the rumen and intestine unless it is processed
(K horasani et al., 1992). The resistance of canola seed
to microbial and enzymatic digestion may be due in
part to the high concentration of lignin in the seed
hull (12 to 26% of the seed hull DM; Bell, 1984; Blair
and Reichert, 1984). It was our hypothesis that the
whole canola seed, by virtue of its resilient seed coat,
altered ruminal
and
VFApatterns
mineral
and milk
availabilitydecreased
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DIGESTION OF LIPIDS IN WHOLE CANOLASEED
503
may serve as a natural capsule for the postruminal
delivery of unsaturated fatty acids. The processing
method would need to be gentle enough to allow the
whole canola seed to remain largely intact and
undegraded by ruminal digestion, but severe enough
that the seed contents would be accessible to intestinal
enzymatic degradation and absorption. The method
proposed involved a mild chemical treatment with
sodium hydroxide and hydrogen peroxide.
The objectives of this study were to determine the
effects of a chemical treatment of whole canola seed on
the intestinal flows and sites of digestion of OM, GE,
N, NDF, ADF, and long-chain fatty acids and on
ruminal biohydrogenation of unsaturated fatty acids
by cattle.
Materials and Methods
Animals. Five Angus × Simmental steers (average
BW 259 kg) cannulated in the rumen, proximal
duodenum, and terminal ileum were fed five diets in a
5 × 5 Latin square design (Steel and Torrie, 1980).
Pliable plastic T-type cannula were utilized in this
study. Experimental periods were 14 d in length, with
10 d of diet adaptation and 4 d of sample collection.
Steers were tethered by neck chains in a temperature-
controlled (22°C ) room under continuous lighting.
Steers werepreparedsurgically
anesthesia by a clinical veterinarian at the University
of Illinois College of Veterinary
Animal Clinic. The surgical procedures and justifica-
tion were approved by the Laboratory Animal Care
Advisory Committee at the University of Illinois.
Steers were monitored for a minimum of 2 wk of
recovery.
Diets. Diets contained (percentage of diet DM)
ammoniated corn cobs (50%) and alfalfa hay (22%)
as forage sources (Table 1). Hay was chopped to pass
through a 2.54-cm screen before being fed. Each diet
also included cornstarch grits (3 to13%), corn (6.7 to
7.7%), cane molasses (5%), and urea (1.25 %). Urea
was added to ensure that ruminal N availability did
not limit microbial growth. The basal diet contained
no canola seed, added protein, or added lipid. The
canola seed diets and a diet containing the calcium
salts of long-chain fatty acids (the Ca-L CF A diet)
were formulated by replacing cornstarch grits from the
basal diet with the test feedstuffs. All canola seed
( Brassica napus cv. Ceres) for the canola seed diets
was harvested from a single farm during the summer
of 1992. Canola seed was included at 10% of the diet
DM, an amount estimated prior to the experiment to
provide 4% added fat (DM basis). The untreated
canola seed diet contained whole canola seed in its
native form. The crushed seed diet contained whole
canola seed that had been ground through a roller mill
until all seed hulls were cracked. The treated canola
seed diet contained whole canola seed that was
undergeneral
Medicine Large
exposed to an alkaline hydrogen peroxide treatment at
another location, transported to our laboratory in
barrels, and stored at ambient temperature for the
duration of the study. The alkaline hydrogen peroxide
treatment was performed by mixing whole canola seed
with an aqueous solution containing 5 to 10% (of DM
weight of the canola seed) NaOH. This was followed
by adding and mixing a solution of .5 to 2.5% H2O2to
the NaOH-treated canola seed. Calcium salts of long
chain fatty acids were added to the fifth diet as the
commercially available ruminally inert fat Megalac
(Church & Dwight Co., Princeton, NJ ).
Chromic oxide was added to the diets as an external
marker for the determination of duodenal and ileal
digesta flow and fecal output. To achieve a steady-
state concentration of the marker, 15 g of Cr2O3was
mixed thoroughly in the diet during daily preparation,
divided into 12 approximately equal portions, and fed
every 2 h by an automatic feeder. Feed intake was
restricted to 5.3 kg DM/d (2.05% of initial BW).
Sample Collection and Analyses. Steers were ad-
justed to each diet for 10 d. Following adjustment,
duodenal and ileal samples (300 mL ) were collected
20 times over a 4-d period. Five sampling times were
evenly spaced within each day with sampling times
shifted ahead each day such that samples were
collected at20 equally
24-h day. Fecal grab samples were collected at every
other intestinal sampling. Duodenal and ileal samples
were composited on an equal volume basis for each
steer within each period and frozen for later process-
ing. Intestinal digesta was later thawed, subsampled,
lyophilized, and ground through a Wiley mill (1-mm
screen). Fecal samples were composited for each steer
within each period and were frozen before being oven
dried at 55°C and ground through a Wiley mill (1-mm
screen). Feed samples (individual ingredients) were
collected during the final 5 d of each period. All feed
samples were placed in a forced air oven at 55°C until
dry and then ground through a Wiley mill (1-mm
screen). Representative samples of whole ruminal
contents were collected four times during the collec-
tion period (F irkins et al., 1986a). Subsamples of
ruminal fluid (50 mL ) were obtained from whole
ruminal contents by straining through eight layers of
cheesecloth. Ruminal fluid pH was measured immedi-
ately, and samples were acidified with 1 mL of 6 N
HCl and stored frozen. Acidified ruminal fluid was
later thawed and then centrifuged at 25,000 × g for 20
min, and VFA in the supernatant were analyzed
according to the procedures of Chaney and Marbach
(1962) and Merchen et al. (1986), respectively. A
bacteria-rich fraction was isolated from whole ruminal
contents as described by Firkins et al. (1986b).
Feed, orts, duodenal, ileal, fecal, and bacterial
samples were analyzed for DM, OM, Kjeldahl N
(AOAC, 1984), and GE (1261 Isoperibol calorimeter,
Parr Instrument, Moline, IL ). Chromium concentra-
tions in duodenal, ileal, and fecal samples were
spaced intervals overa
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ALDRICH ET AL.
504
Table 1. Ingredient composition and nutrient profile (percentage of diet dry matter) of diets fed to steersa
aDiets fed as total mixed rations 12 times daily at 2-h intervals.
bCa-LCFA = calcium salts of long-chain fatty acids.
cTrace mineral salt contained sodium chloride(97%), zinc (.35%), iron (.20%), manganese (.18%), copper (350 ppm), iodine (100 ppm),
selenium (90 ppm), and cobalt (60 ppm).
dVitamin premix contained vitamin A (3,303,965 USP/kg), vitamin D3(330,396 USP/kg), vitamin E (44,053 USP/kg), vitamin K (.22%),
vitamin B12(17 ppm), riboflavin (.44%), pantothenic acid (1.21%), niacin (1.65%), and choline chloride (16.52%).
Whole canola seed diets
Item Basal diet UntreatedCrushedTreated Ca-LCFAbdiet
Ingredient
Ammoniated corn cobs
Alfalfa hay (chopped)
Canola seed
Canola meal
Ca-LCFAb
Corn (ground)
Cornstarch grits
Cane molasses
Urea
Trace mineral saltc
Vitamin premixd
Limestone
Dicalcium phosphate
Nutrient profile
DM, %
OM, % of DM
GE, Mcal/kg DM
N, % of DM
NDF, % of DM
ADF, % of DM
Total fatty acids, % of DM
50.0
22.0
Ð
Ð
Ð
6.72
13.0
5.0
1.25
.30
.03
.60
1.10
50.0
22.0
10.0
Ð
Ð
7.07
3.0
5.0
1.25
.30
.03
.75
.60
50.0
22.0
10.0
Ð
Ð
7.07
3.0
5.0
1.25
.30
.03
.75
.60
50.0
22.0
10.0
Ð
Ð
7.07
3.0
5.0
1.25
.30
.03
.75
.60
50.0
22.0
Ð
5.0
5.0
7.67
3.0
5.0
1.25
.30
.03
Ð
.75
62.7
91.1
4.23
2.44
45.6
31.0
1.36
62.8
91.3
4.53
2.70
46.9
30.9
7.41
62.8
91.3
4.51
2.68
47.4
31.5
6.92
62.6
91.0
4.48
2.66
51.6
33.3
6.59
63.0
91.2
4.53
2.73
48.1
33.5
6.85
determined by the technique of Williams et al. (1962).
Duodenal and bacterial samples were analyzed for
total purines by the method of Zinn and Owens
(1986). Acid detergent fiber was determined in feed
ingredients, digesta, and fecal samples by the proce-
dure of Goering and Van Soest (1970). Neutral
detergent fiber was determined in feed ingredients,
digesta, and fecal samples using the termamyl proce-
dure of J eraci et al. (1988). The one-step extraction-
transesterification procedure of Sukhija and Palm-
quist (1988) using 5.0 mL of a solvent mixture of
methanol-benzene-acetyl chloride (20:27:3) was used
to prepare methyl esters of fatty acids in samples of
feed, digesta, and feces (50- to 500-mg samples
containing 10 to 50 mg fatty acids). Fatty acid
analysis of methylated samples was performed on a
Hewlett-Packard 5890 gas-liquid chromatograph. The
temperature of the SP-2340 fused silica capillary
column (.32 mm i.d. × 30 m; film thickness .20 mm;
Supelco, Bellefonte, PA) was programmed from 100 to
180°C at 4°C/min with helium as the carrier gas; the
split ratio was 100:1. Fatty acids were identified by
comparison of their retention times with those of
external standards, and fatty acids were quantified by
reference to an internal standard (C24:1; Sigma
Chemical, St. Louis, MO).
Calculations and Statistics. Nutrient flows at the
duodenum and ileum and fecal output were calculated
by reference to Cr2O3. Individual flows of bacterial N
to the duodenum were calculated by dividing the mean
N:purine ratio of the bacteria-rich fraction for each
treatment by the N:purine ratio of duodenal digesta
for each animal within each period. Statistical ana-
lyses were performed using the GLM procedure of SAS
(1988). Model sums of squares were separated into
animal, period, and treatment effects. Means were
compared by the F-test protected least significant
difference method (Carmer and Swanson, 1973).
Treatment means were considered different at the P <
.05 level unless otherwise specified.
Results and Discussion
Ingredient composition and nutrient profiles of diets
are presented in Table 1. The canola seed and Ca-
LCFAdiets were designed to be isonitrogenous,
isoenergetic, and isolipid. The diets containing canola
seed and Ca-LCFA had, on average, 5.6% total fatty
acids added from the test ingredients. The fatty acid
profile of canola seed fed in this experiment is
presented in Table 2. The seed contained over 85% of
total fatty acids as C18 unsaturated fatty acids,
primarily from 18:1 (>60% of the total fatty acids).
Also noteworthy is the undetectable concentration of
erucic acid (22:1) for which modern canola seed, but
not rapeseed, has been selected.
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DIGESTION OF LIPIDS IN WHOLE CANOLASEED
505
Table 3. Intake and digestion of organic matter by steers fed diets containing
whole canola seed or calcium salts of long-chain fatty acids (Ca-LCFA)
a,b,cWithin the same row, means with unlike superscripts differ (P = .08).
d,e,fWithin the same row, means with unlike superscripts differ (P < .05).
Whole canola seed diets
ItemBasal diet UntreatedCrushedTreated Ca-LCFA dietSEM
Intake, g/d
Ruminal disappearance
g/d
% of intake
Small intestinal disappearance
g/d
% entering
% of intake
Large intestinal disappearance
g/d
% entering
% of intake
Apparent total tract digestibility
g/d
% of intake
4,7914,8004,504 4,744 4,79685.3
2,1131,9191,885 1,8162,212 137.1
3.31 44.340.0 42.238.246.3
687
24.8
14.3
721
22.5
15.1
834
29.4
18.4
886
29.3
18.9
798
30.1
16.5
201.8
5.63
4.02
758
37.2
15.7
534
23.4
11.1
444
24.2
9.7
583
28.4
12.3
447
25.5
9.4
101.4
3.75
2.04
3,558c
74.3f
3,174ab
66.2d
3,163a
70.2e
3,285abc
69.4de
3,457bc
72.2ef
104.7
1.09
Table 2. Fatty acid profile of whole
canola seed fed to steers
aND = not detectable.
Percentage of
total fatty acidsFatty acid
12:0
14:0
14:1
16:0
16:1
17:0
18:0
18:1
18:2
18:3
20:0
20:1
22:0
22:1
24:0
Total fatty acids, % of DM
.51
.12
NDa
5.71
.36
.04
1.44
60.87
20.76
6.74
.52
1.53
.29
ND
.06
56.30
Organic matter intakes and duodenal OM flows
were not different among treatments (average 4,727
and 2,738 g/d, respectively; Table 3). Ruminal, small
intestinal, and large intestinal OM digestibilities were
not different among treatments (average 42.2, 16.6,
and 11.6% of intake, respectively). Steers fed the
canola seed diets had lower total tract OM digestibili-
ties ( P < .05) than steers fed the basal diet. Ruminal
(F erlay et al., 1992) and total tract (Murphy et al.,
1990; Ferlay et al., 1992) OM digestibilities have been
reported to be lower for cows fed rapeseed-containing
diets than for cows fed a control diet (no rapeseed).
Steers fed the Ca-LCFA diet had similar flows and
sites of OM digestibility compared with steers fed the
basal diet, which agrees with Klusmeyer et al. (1991)
that Ca-LCFAdoes not influence OM
Within the canola seed treatments, steers fed the
untreated canola seed had a lower ( P < .05) total tract
OM digestibility than steers fed the crushed canola
seed diet, whereas steers fed the treated seed diet had
an intermediate OM digestibility. Several reports have
indicated that processing canola seed has had little
impact on OM digestibility. Ferlay et al. (1992)
reported that total tract OM digestibilities by cows fed
a diet containing raw rapeseed (crushed) were not
different from those for cows fed extruded rapeseed
diets. Murphy et al. (1990) reported that cows fed
unground rapeseed had total tract OM digestibilities
similar to those of cows fed ground rapeseed. In the
current study, ruminal and intestinal OM digestibili-
ties were not affected by treatment, but total tract OM
digestibility was affected. This is likely due to the
greater variation associated with the measurement of
ruminal and intestinal digestibilities than total tract
digestibility.
Data from the current study confirm the assertion
of Khorasani et al. (1992) that processing (i.e.,
crushing or chemical treatment) is necessary to
increase digestion of whole canola seed. This process-
ing, however, would increase the access of ruminal
microbes to the mono- and polyunsaturated fatty acids
in the canola seed. Feeding diets high in canola oil has
been shown to alter fiber digestion and ruminal
fermentation characteristics under ad libitum feeding
(J enkins and J enny, 1992); however, under restricted
DM intake with frequent feeding (fed every 2 h),
digestion.
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