In situ Rumen Degradability, in vitro Digestibility and in vitro Gas Production of Full Fat Canola Seeds
The objective of this study was to determine the chemical
composition, in vitro gas production, in vitro digestibility
and in situ rumen degradability of canola hybrids. In the study,
canola seeds of four different hybrids (Bristol, Eurol, Capitol and Licrown),
which were obtained from the Institute of Karadeniz Agricultural Research
in Samsun, Turkiye were used. Two rams aged 2 years with permanent ruminal
fistulated were used in gas production and in situ nylon bag techniques.
All of the feedstuffs were incubated for 3, 6, 9, 12, 24, 48, 72 and 96
h in in vitro incubations for gas production. Feedstuffs were incubated
for 48 h in nylon bag technique. The results of the present study suggested
that there were no differences among the hybrids in terms of feed value.
All of the hybrids had low in vitro gas production values due to
their high fat contents. Licrown variety had the lowest production level
up to 48 h of the incubation, but there were no differences after 24 h
of the incubation (p>0.05). There were not significant differences
among the hybrids in terms of estimated parameters except for gas production
rate (c). The gas production rate of Licrown was significantly (p<0.05)
lower than that of Bristol. While, in vitro enzyme digestibility
Dry Matter Digestibility (DMD), Organic Matter Digestibility (OMD) and
Metabolisable Energy (ME)) was not different among the hybrids (p>0.05),
rumen degradabilities Dry Matter Degradability (DMD48), Organic
Matter Degradability (OMD48) and Crude krotein Degradability
(CPD48) were significantly different (p<0.01).
Canola is an oil-seed crop developed from rapeseed (Brassica napus and
Brassica campestris/rapa) by the Canadian plant breeders in 1970s.
Unlike traditional rapeseed, canola contains low levels of erucic acid and anti-nutritional
compounds called glucosinolates in the meal fraction (Mailer
et al., 2008).
Canola (Brasicca napus Oleifera sp.) has two physiologic phases such
as wintry and summery. Canola can be produced in every location of our country.
Canola is usually planted in winter in Turkiye. Canola seed containing 38-50%
Ether Extract (EE) and 16-24% Crude Protein (CP) can be used as a protein and/or
lipid source in ruminant rations (Shahidi, 1990; Khorasani
et al., 1992). Inclusion of canola seed containing high level of
lipids helps to increase energy density of the ration, which is an important
aspect particularly for todays high producing cows. In addition, canola
oil fraction contains higher content of unsaturated fatty acids. Since, canola
seed has a highly lignified seed coat, which is resistant to both ruminal and
small intestinal degradation, some form of processing is necessary for effective
utilization of canola seed (Khorasani et al., 1992;
Leupp et al., 2006).
Chichlowski et al. (2005) reported that 3.9%
added fat from ground canola seed for a total of 6.4% dietary fat
(DM basis) to lactating cow diets favorably altered the fatty acid
profile in milk fat. The changes in fatty acid profile were not associated
with reduced milk yield or composition. Adding ground canola seed
to the diets of lactating dairy cows resulted in an increase in the
proportions of C18 monounsaturated fatty acids including vaccenic
acid and isomers of conjuge linoleic acid in milk fat. Ammonia and
total volatile fatty acids tended to be lower in ruminal fluid from
ground canola seeds cows, however, rumen pH was unchanged. Feeding canola
seed to lactating dairy cows resulted in milk fat with higher proportions
of healthful fatty acids without affecting milk yield or composition
The amount of whole canola seed used in diets for beef and dairy cattle and
sheep depends upon the total fat level in the diet. At higher concentrations
usually above 5.5 to 6% of total diet dry matter, fat interferes with fiber
digestion and may reduce feed intake. However, fat at lower levels if properly
formulated into the diet becomes a safe and efficient way of adding energy (Prairie
and Christensen, 2004).
Whole canola seed can be used to advantage for growing and finishing animals
and also for wintering beef cows. In feedlot diets, the oil content is levels
up to 20% of total diet dry matter have successfully been fed providing total
dietary fat on a dry matter basis is below 6%. This could be 10% of whole canola
if 40% or 15% whole canola at 27% oil (Prairie and Christensen,
Protected canola seeds decreased dry matter intake. Feeding canola
seeds reduced the content of C8 to C16 fatty
acids in milk and increased the content of oleic acid (C18:1c9).
Canola seeds had no significant effects on insulin, triglycerides,
or cholesterol present in serum, but increased the concentration
of nonesterified fatty acids; a greater increase was obtained with
protected canola seeds (Delbecchi et al.,
High production dairy diets may use some added fat in the diet to provide
additional energy in a form other than starch. Similar rules apply to dairy
as for beef cattle with whole canola seed. Added dietary oil levels of up to
400 g per cow per day can be used. Because interference with fiber digestibility,
high levels of fat are not well tolerated without lowering butterfat levels
or reducing feed intake (Prairie and Christensen, 2004).
Furthermore, oil obtained from canola varieties with high erucic acid
levels are used as biofuel in industry and in electric transformers of
countries such as France and Germany. Biodiesel production from canola
oil has increased during recent years.
The objective of the study was to determine the chemical composition,
in vitro gas production, in vitro enzyme technique and in
situ rumen degradability of four canola hybrids.
MATERIALS AND METHODS
This study was conducted over the period from January 2006 to March 2007
at University of Ondokuz Mayis, Faculty of Agriculture, Department of
Animal Science in Samsun Province of the Republic of Turkiye.
In this study, canola (Brassica napus) seeds from 4 different winter
variety hybrids (Bristol, Eurol, Capitol and Licrown) obtained from the
Institute of Karadeniz Agricultural Research in Samsun, Turkiye were used.
Canola seed grains were milled in a hammer mill to pass through a 1 mm
sieve for subsequent analysis.
Dry Matter (DM) was determined by drying samples at 105°C overnight. Organic
Matter (OM) content was determined by ashing in a muffle furnace at 550°C
for 8 h. Nitrogen (N) content was determined using Kjeldahl method (AOAC,
1990). Crude protein was calculated as Nx6.25. Crude Fiber (CF) and EE were
determined by the methods described by AOAC (1990) and
Nitrogen Free Extract (NFE) was determined by difference [100 - (CP + EE + CF
+ash)]. Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Acid ketergent
Lignin (ADL) contents were determined by the methods of Van
Soest (1991). Total phenolic matter was determined according to the method
proposed by Gurses and Artik (1987). Volatile fatty acids
and NH3-N contents in the rumen fluid were determined using Markham
Steam Distillation procedure (Markham, 1942). All chemical
analyses were carried out in triplicate.
In vitro Gas Production
Approximately, 200 mg dry weight of samples was weighted in triplicate into
100 mL calibrated glass syringes following the procedures of Menke
and Steingass (1988). The syringes were pre-warmed at 39°C before the
injection of 30 mL rumen fluid-buffer mixture consisting of 10 mL strained rumen
fluid and 20 mL buffer solution into each syringe followed by an incubation
in a water bath at 39°C. Rumen fluid from three fistulated Sakýz
x Karayaka rams was collected before the morning feeding and strained through
two layers of muslin. Sheep were fed twice daily (08.30-16.30) with a diet of
grass hay (60%) and concentrate (40%). Gas volume was recorded at 0, 3, 6, 9,
12, 24, 48, 72 and 96 h of incubation. Total gas volumes were corrected for
blank incubations. Cumulative gas production data were fitted to the model of
Orskov and McDonald (1979) by NEWAY computer package
where, a is the gas production from the immediately soluble fraction
(mL), b is the gas production from the insoluble fraction (mL), c is the
gas production rate constant for the insoluble fraction (mL h–1),
a+b is potential gas production (mL), t is incubation time (h), y is gas
produced at time t.
Organic matter digestibility (Menke et al., 1979)
and ME (Close and Menke, 1986) contents of canola seeds
were estimated using equations given below:
where, GP is 24 h net Gas Production (mL/200mg DM), CP is crude protein
(%), EE is Ether Extract (%)
Cellulase Method (In vitro Enzyme Technique)
In vitro digestibility of DM and OM were determined according to
Alcicek and Wagener (1995) as follows: ONUZUKA cellulase
enzyme was used in this study.
where, S1 is sample amount as (DM), T0 is weight of crucible
(105°C, 48 h), T1 is dry sample (105°C, 24 h)+T0,
T2 is ashed sample (550°C, 4 h)+T0, A1
is crude ash amount of sample, (g). Metabolisable Energy (ME) was estimated
using equations given below (Jarrige, 1989; Malossini
et al., 1993). Calculated values were converted to MJ kg–1
In situ Nylon Bag Technique
The in situ degradability characteristics of samples were measured
using the nylon bag technique of Orskov and McDonald (1979).
Two rumen fistulated SakýzxKarayaka rams were used in in situ
study. Three bags for each feed in each of the rams were incubated for 48 h.
Triplicate bags containing about 5 g DM were placed into the rumen and incubated
for 48 h. After incubation, bags were rinsed in running tap water to remove
adhering digesta and then washed twice in a pool of water (30°C) for 5 min
to remove rumen fluid. They were dried at 65°C for 72 h. In a forced-drought
oven, allowed to air equilibrate and weighed. After incubation, DM, OM and CP
degradability (DMD, OMD and CPD) for each bag, for each incubation period and
for each ram were calculated separately with formulas suggested by Susmel
et al. (1990). Metabolizable Energy (ME) contents of canola seeds
were estimated using equations given below (Bhargava and Orskov,
where, DMD is rumen dry matter degradability for 48 h.
One-way Analysis of Variance (ANOVA) was carried out to compare the chemical
composition, gas production kinetics, ME, NEL and OMD values
using General Linear Model (GLM) of SPSS 10.0 package programs. Significance
between individual means was identified using the Duncans multiple
Chemical composition and Total Phenolic Matter (TPM) content of whole
fat canola seeds were given in Table 1. Rumen pH, ammonia
N (NH3-N) and total Volatile Fatty Acid (VFA) contents determined
for rumen liquid using in vitro gas production technique were;
6.18 (5.88-6.45), 321 mg L–1 (293-438 mg L–1)
and 112 mmol L–1 (93-128 mmol L–1),
All varieties had low gas production levels. Licrown variety had the
lowest production level up to 48 h of the incubation, but there were no
differences after 24 h of the incubation (p>0.05). There were not significant
differences among the hybrids in terms of estimated parameters except
for gas production rate (c). The gas production rate of Licrown was significantly
(p<0.05) lower than that of Bristol (Table 2).
There were no differences among the hybrids in terms of DMD, OMD and
ME values (p>0.05). (Table 3). There were significant
differences among the hybrids in terms of DMD48, OMD48,
ME (P<0.001) and CPD48 (p<0.01) (Table
4). The DMD48 and ME values of Eurol and Licrown are higher
than those of Capitol and Bristol (p<0.001). OMD48 (p<0.001)
and CPD48 (p<0.01)values were found different between Eurol
||Chemical compositions and TPM contents of whole fat
canola seeds, %DM
|DM: Dry matter, CP: Crude protein; EE: Ether extract,
NDF: Neutral detergent fiber, ADF: Acid detergent fiber, ADL: Acid
detergent lignin, TPM: Total phenolic matter, SEM: Standard error
of mean, NS: Non significant. Means in the same row with different
letter(s) indicate significance. p<0.01
||In vitro gas productions, gas production kinetics
and estimated parameters of whole fat canola seeds
|DM: Dry matter, a: Gas production from the immediately
soluble fraction (mL), b: Gas production from the insoluble fraction
(mL), c: Gas production rate constant for the insoluble fraction (mL
h–1), ME: Metabolisable energy, OMD: Organic
matter digestibility, SEM: Standard error of mean, NS: Non significant;
Means in the same row with different letters indicate significance.
||DMD, OMD and ME contents of whole fat canola seeds
|DMD: Dry matter digestibility, OMD: Organic matter digestibility,
ME: Metabolisable energy, SEM: Standard error of mean, NS: Non significant
||In situ DMD48, OMD48, CPD48 and ME values of
|DMD48: Dry matter degradability, OMD48: Organic matter
degradability, CPD48: dry matter degradability, ME: Metabolisable
energy, SEM: Standard error of mean, NS: Non significan. Means in
the same row with different letters indicate significance. **p<0.01,
In vitro gas production, gas production kinetics, estimated parameter
values are largely influenced by the differences in the chemical cosmpositions
of feedstuffs. The increase in ash contents of the feedstuffs leads to a decrease
in the amount of gas produced (Menke and Steingass, 1988).
The similarity of varieties in terms of ash content can be one of the reasons
for similar total gas production levels.
Feedstuffs with high CP result in low gas production (Chenost
et al., 2001). Lower gas production level observed for Licrown variety
might be attributed to its higher CP content. Feedstuffs should contain at least
10% CP for optimum microbial activity in the rumen (Norton,
1998). Feedstuffs with below 10% CP can cause a reduction in the microbial
activity in the rumen, thus can lead to less gas production. The hybrids used
in the present study did not affect microbial activity significantly. Khorasani
et al. (1992) reported that supplementation of ruminally protected
canola seed, at levels>3% of the diet, decreased concentrations of total
ruminal VFA and molar proportions of acetate, propionate and butyrate.
Licrown had numerically the lowest gas volumes up to 48 h of the incubation.
This can be attributed to higher TPM content in Licrown compared to other hybrids
(Kilic and Saricicek, 2006). Furthermore, gas production
rate differs with relation to the amount and availability of rumen microorganisms
(Mauricio et al., 2001). Low gas production rate
in Licrown might be caused by higher TPM content which had influence on amount
of rumen microorganisms. However, there were no differences among the varieties
in terms of gas production levels. Low gas production levels in canola varieties
can be attributed to their higher crude fat contents due to the fact that oils
decrease VFA concentration and hence gas production in the rumen (Wettstein
et al., 2000).
There is a strong relationship between the OMD of feedstuffs and the rate of
gas production (Chenost et al., 2001). In the
present study, Licrown variety with lowest c value had numerically the lowest
OMD value. This finding is consistent with the results of Chenost
et al. (2001). However, Kilic and Saricicek (2006)
suggested that feeds with lowest c value do not always have lowest OMD value.
Lower c value of Licrown compared to Bristol explains why the Licrown had lower
gas production level up to 48 h of the incubation. As expected, the feeds with
lower c values had lower gas productions at the beginning of the incubation.
Thus, the lack of difference with the progression of incubation explains this
Data from cattle fed with whole canola suggest that the seeds are relatively
resistant to digestion in the rumen and intestine unless processed (Khorasani
et al., 1992; Leupp et al., 2006).
Gralak et al. (1997) reported 71.90 and 74.98%
values for effective DM degradability and CP degradability of whole canola seeds.
This finding is consistent with present findings. Micronized whole canola seeds
had higher gas productions and lower DM and CP degradability compared to unprocessed
seeds (Wang et al., 1997). DM and CP degradability
found in this study are similar to present findings.
At 5%/h flow rate, effective CP degradability of WCS was 86.7.2%. Extrusion
did not affect WCS and rumen CP degradability. Without some form of protection
whole canola seed CP is obviously, highly degradable (Deacon
et al., 1986, 1988). These results are in
agreement with our findings. The highest degradability values were found for
If whole canola seed makes up more than 12-14% of the ration it may lead to
depressed rumen function reduced feed intake and digestibility of nutrients.
Conversely, fed dairy cows whole canola seeds, raw or extruded, at 14% of the
diet without effecting Crude Fibre digestibility (Ellwood,
2004). Murphy et al. (1987) reported reduction
in rumen digestibilities of DM, NDF and cellulose, however hindgut fermentation
compensated for the reduction at 1 kg/day Whole Canola Seed supplementation,
but not at 2 kg day–1.
Although, there were no differences between the canola hybrids in terms of
dry matter digestibility, organic matter digestibility and in vitro ME
values in enzyme technique, Bristol, which had the lowest CP value, also had
the lowest CPD48 value in in vitro gas production technique.
Variability in feeds and also their production locations is one of the most
important factors affecting the results of nylon bag technique (Kilic
and Saricicek, 2004). Yilmaz (1997a, b)
found wide variations for SunFlower Meal (SFM) samples obtained from 12 different
locations and for Alfalfa Hay (AH) samples obtained from 15 different locations
in terms of degradability characteristics. The author reported a value, from
which DMD was calculated, as 3.90 -60-72% for SFM and 0.00- 41.75% for AH. This
explains why the large variations were observed among the canola varieties used
in present study.
ME values found in in vitro gas production technique and in in vitro
enzyme technique were not different, but there were differences among the hybrids
in in situ bag technique. This can be attributed to the fact that the
varieties have significant effects on the results of nylon bag technique (Yilmaz,
1997a, b; Kilic and Saricicek,
2004). ME values found in in vitro gas production technique were
lower than those found in in vitro enzyme technique and in situ
nylon bag technique due to the lower gas productions of the canola seeds. This
difference might be due to the fact that high oil levels found in all the canola
varieties prevent gas production.
Leupp et al. (2006) reported that supplementation
with canola seed at 8% of dietary DM did not affect intake or fiber digestion
in low-quality forage diets. Canola supplementation increased apparent and true
ruminal CP degradation but decreased small intestinal CP digestion. Canola supplementation
decreased ruminal pH and the molar proportion of acetate. Decrease in acetate
content explains the lower gas productions in canola seeds. The researchers
explanained that their study results suggest that ground canola included at
8% of the diet can alter ruminal VFA concentrations and increase in situ
degradation of canola seed when offered as a supplement for cattle fed low-quality
The results of the present study indicate that feed value of different
canola seed varieties is similar. Furthermore, they have lower in vitro
gas production values due to their higher oil content. While there were
no differences among the hybrids in in vitro enzyme technique,
there were significant differences in in situ technique (p<0.01).
If whole canola seed makes up more than 12-14% of the ration it may lead
to a depressed rumen function, reduced feed intake and digestibility of
the nutrients. However, canola seeds should be used up to 20% of the total
ration dry matter or the oil supplied from canola should not exceed the
6% of the total oil content of the ration.It can be said that canola seeds
incorporated into the ration can decrease the feed energy waste in rumen
due to lower gas production levels.
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