J. L. Gentry, H. S. Hussein, L. L. Berger and G. C. Fahey, Jr
Spent cellulose casings as potential feed ingredients for ruminants
J ANIM SCI 1996, 74:663-671.
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663
1We gratefully acknowledge the support of Viskase Corp.
(Chicago, IL) for their support of this research and for supplying
the spent cellulose casings. Viskase is committed to making use of
their spent byproducts to sustain environmental quality. We also
thank Tom Nash, beef farm manager, for his assistance with the
steer experiment.
2To whom correspondence should be addressed: 132 ASL, 1207
W. Gregory Drive.
Received May 30, 1995.
Accepted October 25, 1995.
Spent Cellulose Casings as Potential Feed Ingredients for Ruminants1
J. L. Gentry, H. S. Hussein, L. L. Berger, and G. C. Fahey, Jr.2
Department of Animal Sciences, University of Illinois, Urbana 61801
ABSTRACT: Cellulose casings are used to contain
and form meat and poultry emulsions during the
smoking and cooking process. Casings then are
stripped from the cooked product and traditionally
disposed of in landfills. Because of the bulk of the
spent cellulose casings (SCC), rapid composting
technology may be used to reduce bulkiness. The
following SCC were evaluated in vitro and in vivo:
fibrous ground (FG), fibrous composted (FC),
NOJAXâ ground (NG), and NOJAXâ composted
(NC). In vitro digestibility was determined by incubating
SCC with mixed ruminal bacteria for 0, 6,
12, 24, 36, 48, and 72 h. In vivo data were collected
using four ruminally cannulated Holstein steers in a 4
´ 4 Latin square design. Diets consisted of a 50:50
ratio of alfalfa hay-wheat middlings with 5% cornsteep
liquor. Diets contained no SCC (CON) or 25%
(DM basis) of the FC, FG, or NC SCC substrate.
Casings were high in structural carbohydrate and salt
content but low in CP, ether extract, and lignin
concentrations. In vitro OM digestibility at 24 h was
highest ( P < .05) for FC and lowest ( P < .05) for NG;
FG and NC were intermediate. Composting tended to
reduce fiber content and increase digestion. In vivo
intakes and digestibilities were not adversely affected
by inclusion of SCC in the diet. Thus, SCC have the
ability to partially replace more traditional forages,
such as alfalfa hay and wheat middlings, in high-fiber
diets for growing beef cattle. Limitations in the use of
SCC as a partial replacement of traditional feedstuffs
will likely be because of high salt concentrations in the
casings resulting from product brine chilling.
Key Words: Cellulosic Fibers, Chemical Composition, In Vitro, Composting, Digestibility, Cattle
J. Anim. Sci. 1996. 74:663–671
Introduction
Cellulose casings are used by the meat industry in
the production of skinless frankfurters and other
cooked meat products. Traditionally, natural animal
casings (intestines) were used to contain and form a
meat or poultry emulsion during the smoking and
cooking process. However, due to their ease of
handling and hygienic nature, cellulose casings have
replaced natural casings as the preferred casing
material. Annual U.S. production of cellulose casings
currently exceeds 14 million kg. Unlike natural
casings, cellulose casings must be peeled from the
finished product. Disposal of the peeled spent cellulose
casings ( SCC) has become a serious economic concern
for the meat industry. As the cost of landfill disposal of
SCC continues to rise, alternatives for disposal (e.g.,
composting) are being developed.
Ruminants are capable of using large quantities of
cellulose. Fermentation of cellulose in the reticulorumen
yields VFA, which are used by the animal as its
primary energy source. Therefore, the ruminant may
be able to convert the waste SCC into edible products
(i.e., meat, milk). A major unknown as regards this
alternative to landfill disposal is the acceptability and
digestibility of the SCC by ruminant animals when
the products are incorporated into practical diets. The
problem of disposal will not be solved by cycling
wastes through the animal if there is no net disappearance
of waste components in the process (Van
Soest, 1973). Therefore, it is important to determine
the nutritive value of SCC substrates with feeding
potential. The objectives of these experiments were 1)
to determine the chemical composition, mean particle
size, and in vitro digestibility of SCC, and 2) to
determine the effects of SCC incorporation into
growing beef cattle diets on nutrient intake, apparent
digestibility, and ruminal characteristics using ruminally
cannulated steers.
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664 GENTRY ET AL.
Materials and Methods
Test Substrates. Four SCC products were obtained
from Viskase Corporation (Chicago, IL). These included
ground fibrous ( FG) , ground NOJAXâ ( NG) ,
composted fibrous ( FC) , and composted NOJAXâ
( NC) SCC. The NOJAXâ casings are a regenerated
pure cellulosic film prepared by the viscose process
(Nicholson, 1991). The conversion of raw cellulosic
material, sulfite wood pulp or cotton linters, into the
regenerated films is via the xanthate derivative
(Treiber, 1985; Franz and Blaschek, 1990). The raw
cellulose is first converted to alkali cellulose by
treatment with NaOH to free the pulp or linters from
residual hemicelluloses. This also allows the cellulose
to be readily solubilized and xanthated by CS2. The
viscose solution, xanthate dissolved in dilute NaOH,
then is acidified in a bath of H2SO4 and Na2SO4
during the spinning process to produce the regenerated
films (Franz and Blaschek, 1990).
Cell-OH NaOH >
Cell-ONa CS2 >
/ /
S
H2SO4
Cell-O-C >
\
S–Na+
Na2SO4
Cell-OH + CS2 + NaHSO4
The fibrous casings are a composite of cellulosic fibers,
a nonwoven web often made of long-fibered abaca
hemp, embedded in a matrix of regenerated cellulose.
The resultant fibrous film is stronger than either of its
components (Nicholson, 1991). In addition to the
different manufacturing methods, the SCC also underwent
two types of physical processing. The FG and NG
products were ground after stripping from the cooked
meat emulsion, whereas the FC and NC products were
rapidly composted (Bohnensieker, 1994). During a
3-d composting process, the SCC were continually
ground and kept moist, hot, and aerated. The major
advantages of composted cellulose casings are a
reduction in particle size, odor, and bacterial activity
and an increased storage stability. Additionally, composted
casings have approximately 50% of the volume
of SCC. The rapid composting system also decomposes
non-cellulosic materials and partially degrades the
cellulose of the SCC.
The NOJAXâ casings are a small diameter casing
(15 to 40 mm) and are designed for the production of
frankfurters, dry mini-salamis, coarsely ground fresh
sausages, and other small diameter cooked sausages.
The fibrous casings are larger in diameter (40 to 195
mm) and are designed for the production of a variety
of products, including boneless hams, cooked and dried
sausages, and items intended for slicing, such as
bologna.
Chemical Composition. Samples of FG, NG, FC, NC,
alfalfa hay, and wheat middlings were dried at 55°C
in a forced-air oven and ground through a Wiley mill
(2-mm screen). Dry matter (DM) , organic matter
(OM) , and Kjeldahl N were determined using AOAC
procedures (1990). Fat content was measured using
the acid hydrolysis technique (AOAC, 1990). The
procedure of Prosky et al. (1985) was used to
determine the total dietary fiber ( TDF) content of the
substrates. Neutral detergent fiber was measured
using the Jeraci et al. (1988) procedure. Acid
detergent fiber and acid detergent lignin (ADL) were
determined using the procedures of Goering and Van
Soest (1970). The procedure of Crampton and Maynard
(1938) was used to measure cellulose content. In
addition, test substrates were analyzed for Na, Cl,
nitrate, and nitrate using AOAC procedures (1990).
The particle size distributions of test substrates were
estimated using a dry-seiving technique (Waldo et al.,
1971). For each substrate, fractions were weighed
that remained on screens of 9,500, 6,300, 4,750, 3,350,
2,360, and 1,180 mm for FG; 6,300, 4,750, 3,350, 2,360,
1,700, and 1,180 mm for NG; 2,360, 1,700, 1,180, 850,
600, and 300 mm for FC; and 850, 600, 420, 300, 150,
and 75 mm for NC. Difficulty was encountered during
seiving of FC particles due to particle agglomeration.
In Vitro Experiment. The ground samples of the
cellulose casing substrates were evaluated in an in
vitro experiment. In addition, alfalfa hay (AH) and
wheat middlings (WM) , the major dietary ingredients
in the in vivo study, were included. The experiment
was a completely randomized design for each incubation
time period. Ruminal fluid was obtained from two
ruminally cannulated Holstein steers that were given
ad libitum access to medium-quality clover hay. The
procedure of Tilley and Terry (1963) was used with
minor modifications. McDougall’s buffer was mixed in
a Waring blender (Waring Products Division, New
Hartford, CT) with ruminal particulate matter and
strained through eight layers of cheesecloth prior to
addition of an equal volume of ruminal fluid that also
had been strained through eight layers of cheesecloth.
This was done to provide an inoculum containing
mixed ruminal bacteria through which CO2 was
continuously bubbled to maintain an anaerobic environment.
The tubes containing approximately .5 g of
substrate were inoculated with 30 mL of the mixed
ruminal fluid, purged with CO2, and stoppered with a
rubber stopper equipped with a one-way gas release
valve. Tubes then were incubated at 39°C for 6, 12, 24,
36, 48, and 72 h with occasional swirling at 0, 2, 4, 6,
8, 12, 24, 30, 36, 48, and 60 h. Immediately after
removal from the incubator, tubes were unstoppered
and any residue on the stoppers rinsed into the tube
with distilled water. Tubes were refrigerated (5°C) to
stop fermentation for a minimum of 12 h and a
maximum of 24 h before filtration. Three consecutive
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CELLULOSE CASINGS AS POTENTIAL FEEDS 665
hot distilled water rinses of the residue were carried
out. The residue was analyzed for DM and OM.
Additionally, DM and OM solubilities of the cellulose
casing substrates were determined by incubating .5 g
of each substrate in distilled H2O for 30 min at 39°C.
Extent of disappearance of substrate DM and OM
after various lengths of in vitro incubation was
calculated. Data for each time period were analyzed as
a completely randomized design (Steel and Torrie,
1980) according to the GLM procedure of SAS (1989).
Model sums of squares included only substrate effects.
Substrate means for each incubation time were
compared by Fisher’s least significant difference test
(Carmer and Swanson, 1973) when the F-test was
significant ( P < .05).
In Vivo Digestion Trial. Four Holstein steers (394 ±
31 kg [mean ± SD]) fitted with permanent ruminal
cannulas were used in a 4 ´ 4 Latin square design
experiment. The project was conducted under a
research protocol approved by the Campus Laboratory
Animal Care Advisory Committee, University of Illinois,
Urbana-Champaign. Steers were housed in a
temperature-controlled (20°C) room under continuous
lighting in individual stalls (1.22 m ´ 2.45 m). Steers
were not exercised during experimental periods. Each
experimental period consisted of a 10-d adjustment
phase followed by a 4-d collection period. Dietary
ingredients were weighed individually for each steer
based on the previous day’s consumption and mixed
daily. Diets were offered at 110% of ad libitum intake
in two equal portions at 0800 and 2000. A bolus
containing 7.5 g of Cr2O3 was placed in the rumen of
each steer via the ruminal cannula at the time of
feeding. Fresh water and trace mineralized salt were
available at all times.
Diets consisted of coarsely chopped (2.54-cm
screen) alfalfa hay (mid-bloom), wheat middlings,
test substrate, and corn-steep liquor. Each test substrate
(FG, FC, and NC) was included at 25% of the
diet, and the corn-steep liquor was included at 5% of
the diet. The NG test substrate was not included in
the in vivo experiment because of extreme spoilage of
the material. The remainder of the diets was composed
of a 50:50 ratio of alfalfa hay-wheat middlings.
In addition to the test diets, a control diet was
formulated to contain only the 50:50 ratio of alfalfa
hay-wheat middlings and 5% corn-steep liquor.
Representative samples of feed ingredients and
mixed diets were taken daily on d 10 to 13 of each
period. Samples of orts were taken daily on d 11 to 14
of each period. Fecal grab samples (200 g) were
collected at 4-h intervals beginning on d 11 of each
period. The sampling schedule was advanced 1 h each
morning such that 12 samples (one sample for each
hour between 0800 and 2000) were collected over the
4-d period. Diets, orts, and feces were composited for
each steer by period. Feeds, diets, orts, and feces were
dried at 55°C in a forced-air oven and ground through
a Wiley mill (2-mm screen) before analysis. Samples
of ruminal fluid (50 mL) were collected from the
ventral sac of the rumen at each hour between 0800
and 2000 of d 14 using a suction strainer placed
through the ruminal cannula. Ruminal fluid pH was
measured immediately using a pH meter (model 31,
Beckman Instruments, Palo Alto, CA), and samples
were then acidified with 2 mL of 6 N HCl and frozen
until subsequent analysis of VFA and ammonia N
(NH3 N)concentrations.
Diets, orts, and feces were analyzed for DM, OM,
and Kjeldahl N (AOAC, 1990), NDF (Jeraci et al.,
1988), ADF (Goering and Van Soest, 1970), and
cellulose (Crampton and Maynard, 1938). Additionally,
DM was determined on individual feed ingredients
to ensure that the correct ratio of ingredients
was mixed.
Chromium concentration in the feces was determined
by the procedure of Williams et al. (1962).
Fecal DM output (grams/day) was calculated by
dividing Cr intake (milligrams/day) by fecal Cr
concentration (mg of Cr/g of feces). Fecal nutrient
outputs were calculated by multiplying DM output by
the concentration of the nutrient in fecal DM.
The procedure of Chaney and Marbach (1962) was
used to determine the NH3 N content of the ruminal
fluid samples at each sampling time. Before measurement
of VFA concentrations by gas chromatography,
ruminal fluid samples were composited across sampling
times for each animal in each period and
centrifuged at 20,000 ´ g for 20 min. Concentrations of
VFA were determined in the supernatant using a gas
chromatograph (model 5890A, Hewlett-Packard, Mt.
View, CA) on a glass column (180 cm ´ 4 mm i.d.)
packed with GP 10% SP-1200/1% H3PO4 on 80/100
Chromasorb WAW (Supelco, Bellefonte, PA). Nitrogen
was used as a carrier gas with a flow rate of 75
mL/min. Oven temperature was 125°C, detector temperature
was 180°C, and injector temperature was
175°C.
Data were analyzed as a 4 ´ 4 Latin square design
according to the GLM procedure of SAS (1989). Model
sums of squares were separated into treatment,
period, and animal effects. When significant ( P < .05)
treatment effects were detected, individual treatment
means were compared by the F-test protected least
significance difference method (Carmer and Swanson,
1973). Data collected at different times after feeding
(ruminal pH and concentration of NH3 N) were
analyzed as a split-plot design using the GLM
procedure of SAS (1989). Main plot variables were
treatment, period, steer, and the treatment ´ period ´
steer interaction. Subplot variables were sampling
time and the time ´ period, time ´ steer, and time ´
treatment interactions. The treatment period ´ steer
interaction was used as the divisor in the F-tests for
testing the significance of main plot variable effects.
No significant ( P < .05) interactions occurred. Treatment
means were separated by the F-test protected
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666 GENTRY ET AL.
least significance difference method (Carmer and
Swanson, 1973).
Deviations from the methods described were encountered
during the trial. One steer experienced a
left displaced abomasum during the third period of the
experiment that required surgical correction. Following
recovery, the third (FC) and fourth (CON)
periods were conducted with that steer approximately
6 wk after conclusion of the original trial. The fourth
period was shortened to 7 d adjustment and 4 d
collection for all animals due to lack of availability of
one test substrate. Finally, statistical analysis was
performed on the animal data as a complete Latin
square design and as a Latin square with two missing
cells to determine the effects of the missing periods.
The main effects were maintained when analyzing the
nutrient intakes, intakes as a percentage of BW,
apparent digestibilities, and digestible nutrient intakes
as a Latin square with two missing cells.
However, statistical significance was lost for NDF
intake, NDF intake as a percentage of BW, and
digestible CP and ADF intakes. The ruminal pH and
concentration of NH3 N means were not estimable in
the Latin square with two missing cells due to
analysis as a split-plot design. Significance was lost
for total VFA concentration. The general trends in
total VFA concentration and VFA molar proportions
were the same as those for the Latin square with no
missing cells. Data reported are for the complete Latin
square.
Results and Discussion
Chemical Composition. Mean particle size and
chemical composition of SCC substrates are presented
in Table 1. Mean particle size varied among substrates,
and composting greatly reduced particle size.
Composting increased DM and CP contents of the
casings. The increase in CP content of the composted
substrates was expected because microbial action
during the composting process caused a concentration
effect. The same effect was noted for ash content
(100% - %OM) of NOJAXâ substrates. Ether extract
and ADL concentrations were changed slightly by the
composting process, and the fibrous casings had
higher contents of these moieties than the NOJAXâ
casings. The contents of CP, ether extract, and ADL in
the substrates were very low in comparison to
structural carbohydrate content. Composted NOJAXâ
casings had considerably lower TDF and NDF values
than NG casings, which had the highest fiber content
of all the substrates. In addition to having the highest
fiber content, NG also had the highest moisture
content. No effect of composting was observed on the
contents of TDF and NDF in the fibrous casings. Acid
detergent fiber and cellulose concentrations were
reduced by composting for both fibrous and NOJAXâ
casings. Composting had no effect on NaCl content of
fibrous casings (FG, 8.5%; FC, 8.4%) but increased
the NaCl content of NOJAXâ casings (NG, 4.3%; NC,
14.9%). The production of cellulose casings should
yield a pure cellulosic substance (Treiber, 1985;
Nicholson, 1991). However, the chemical composition
of the SCC substrates revealed the presence of
components other than cellulose. The CP, ether
extract, and NaCl content of the SCC substrates
varied as a result of both residual meat adhering to
the casings when they were stripped from the cooked
meat product and processing differences; final brine
treatments used with NOJAXâ-type casings increased
the moisture and Cl contents. The adherence of
residual meat also may account for the lower structural
carbohydrate content (TDF, cellulose) of the FG
casings in comparison to the NG casings. This
disparity in structural carbohydrate content is
reduced with composting, suggesting that more meat
product adheres to and is composted with the fibrous
casings vs the NOJAXâ casings for which a larger
composting effect on the casing itself was noted. This
could be explained by preferential growth of cellulolytic
microbes during composting of NOJAXâ casings,
whereas preferential growth of noncellulolytics occurred
during composting of fibrous casings. All
substrates were low in nitrite and nitrate concentrations.
In Vitro Experiment. In vitro OM disappearances
( OMD) of the SCC substrates, AH, and WM are
presented in Table 2. The OMD at 6 h were less ( P <
.05) for all SCC substrates than those of the AH and
WM. The OMD at 12 and 24 h followed a similar
trend. However, FC had a greater OMD ( P < .05) at
12 and 24 h than did the other SCC substrates. By 36
h, FC reached an OMD similar to that of AH, and by
72 h FC reached an OMD similar to those of AH and
WM. In addition, FG and NC reached levels comparable
to that of AH by 72 h. In contrast, NG had a lower
OMD ( P < .05) at 24 h than the other SCC substrates.
This lower OMD was maintained for the remainder of
the in vitro incubation.
The decreased digestibility of cellulose II (regenerated)
allomorphs (any of two or more distinct
crystalline forms of the same substance) compared
with cellulose I (native) allomorphs (Weimer et al.,
1990) may explain the decreased OMD observed for
the SCC substrates. Weimer et al. (1990) found that a
cellulose II allomorph had a considerably slower rate
and longer lag time than a standard type-I allomorph.
On a normalized scale, with the type-I allomorph rate
constant and lag time equal to 1.00, the type-II
allomorph rate constant was .57 and lag time was
1.92. Weimer et al. (1991) confirmed the slower rate
and longer lag time of type-II cellulose allomorphs.
With the type-I normalized rate constant of degradation
equal to 1.00 and the lag time equal to 12.2 h, the
rate constant of degradation was .49 and the lag time
was 17.8 h for the type-II cellulose allomorph. This
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CELLULOSE CASINGS AS POTENTIAL FEEDS 667
Table 1. Mean particle size and chemical composition of spent cellulose casings
aFC = fibrous composted; FG = fibrous ground; NC = NOJAXâ composted; NG = NOJAXâ ground.
bFC particles agglomerated during sieving.
cND = not detected.
Cellulose casing substratesa
Item FC FG NC NG
Particle size, mm 1,752b 3,897 430 2,539
DM, % 84.7 61.0 63.9 35.5
% of DM
OM 89.8 90.4 83.8 94.6
CP (N ´ 6.25) 6.5 4.8 4.1 2.2
Ether extract 4.4 5.5 3.6 2.1
Total dietary fiber 75.0 74.8 75.2 92.3
NDF 76.9 77.6 75.4 92.4
ADF 69.0 74.3 69.4 87.7
ADL 1.6 .7 .5 .5
Cellulose 65.5 72.0 66.7 84.0
Sodium 3.6 3.6 5.8 1.7
Chloride 4.8 4.9 9.1 2.6
Nitrite, ppm NDc .5 ND .9
Nitrate, ppm 7.1 1.6 ND ND
Table 2. Percentage of disappearance of spent cellulose casings
OM after various durations of in vitro incubation
aFC = fibrous composted; FG = fibrous ground; NC = NOJAXâ composted; NG = NOJAXâ ground; AH =
alfalfa hay; WM = wheat middlings.
bOM solubility values for FC, FG, NC, and NG were .8, .4, .8, and .5%, respectively.
c,d,e,f,gWithin a column means with different superscript letters differ (P < .05).
Fermentation time, h
Substratea 6 12 24 36 48 72
% Disappearanceb
FC 5.4e 17.1e 44.1e 51.0d 57.6d 60.6cd
FG 5.7e 9.0f 24.1f 33.8e 44.6e 58.7d
NC 4.4e 5.4f 20.3f 30.0f 42.1e 55.7d
NG 1.9e 2.8f 13.1g 21.9g 31.1f 46.9e
AH 29.2d 36.1d 49.1d 51.7d 55.7d 54.9d
WM 39.0c 46.8c 61.6c 65.0c 68.2c 67.6c
SEM 1.9 2.3 1.4 .6 1.4 2.3
may be due to substrate specificity, as suggested by
Weimer (1992), or it may be due to the physical
structure of cellulose II. Cellulose II is more densely
packed, strongly interbound, and thermodynamically
stable than cellulose I (Kra¨ ssig, 1985; Franz and
Blaschek, 1990).
The lower OMD noted for the SCC substrates
seemed to lessen with composting. The OMD values
were consistently higher, except for 6 and 12 h, for the
composted substrates than for their respective ground
substrates. In the case of FC, the OMD values met or
exceeded those of AH relatively early (36 h) in the in
vitro incubation.
The in vitro and chemical composition results
suggest that FC, and possibly FG and NC, may be
incorporated into ruminant diets as high-fiber, lowprotein
energy sources. Fibrous ground and FC should
be able to be used at higher levels than the NC
because the salt level is approximately half.
In Vivo Digestion Trial. Ingredient and chemical
composition of the diets is presented in Table 3. The
control diet (CON) consisted of feedstuffs (AH, WM,
and corn-steep liquor) that are readily available to
beef cattle producers in the Midwest region of the
United States. The AH-WM-based diet was chosen as
a representative high by-product, high fiber-containing
diet that might be fed to growing feedlot cattle.
The FC, FG, and NC SCC substrates replaced 25% of
the AH-WM mix in the test diets. The corn-steep
liquor was included as a binding agent to ensure even
mixing of the diets and to suppress the dust associated
with the high DM content of the diets. Additionally,
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668 GENTRY ET AL.
Table 3. Ingredient and chemical composition of
diets fed to ruminally cannulated steers
aCON = Control diet, no cellulose casing substrates; FC = 25% fibrous composted; FG = 25% fibrous
ground; NC = 25% NOJAXâ composted.
bTrace mineralized salt was available free choice. Trace mineralized salt contained a minimum
percentage of the following minerals: zinc (.35), manganese (.28), iron (.175), copper (.035), iodine
(.007), and cobalt (.007).
cChopped through a 2.54-cm screen.
dDM on an as-fed basis. Water was added to the diets during mixing to control dust.
Dietab
Item CON FC FG NC
% of DM
Ingredient
Alfalfa hayc 47.5 35.0 35.0 35.0
Wheat middlings 47.5 35.0 35.0 35.0
Fibrous composted — 25.0 — —
Fibrous ground — — 25.0 —
NOJAXâ composted — — — 25.0
Corn-steep liquor 5.0 5.0 5.0 5.0
Chemical composition
DMd 72.0 65.8 68.8 69.3
OM 92.4 91.6 92.0 90.4
CP 16.5 14.3 14.0 13.8
NDF 46.0 52.8 53.9 52.4
ADF 23.8 33.4 36.4 35.0
Cellulose 15.5 27.2 29.2 28.8
water (approximately 2,000 mL) was added to all
diets at the time of mixing to further suppress the
dust. The diets contained an adequate amount (13.8
to 16.5%) of CP for growing steers (NRC, 1984).
Calcium (.56%), P (.47%), and K (1.06%) in the test
diets were supplied by AH, WM, and corn-steep liquor
(NRC, 1984). The test substrates were assumed to
contribute no Ca, P, or K. These values exceed NRC
(1984) recommendations for growing steers. The
NDF, ADF, and cellulose contents of the diets were
increased by approximately 6, 10, and 12 percentage
units, respectively, as a result of SCC incorporation
into diets.
Nutrient intakes, intakes as a percentage of BW,
apparent digestibilities, and digestible nutrient intakes
are presented in Table 4. Intakes of DM, OM,
and CP did not differ among groups. The test diet
intakes of NDF (5.8 to 6.3 kg/d), ADF (3.9 to 4.0 kg/
d), and cellulose (3.1 to 3.3 kg/d) were higher ( P <
.05) than CON intakes (NDF, 5.2 kg/d; ADF, 2.7 kg/d;
and cellulose, 1.8 kg/d). Intake as a percentage of BW
paralleled the quantitative intake values. The increased
intake of structural carbohydrates in the test
diets was due to similar DMI for all diets with
increased percentages of NDF, ADF, and cellulose in
the test diets.
Similar intake results were obtained by Moore et al.
(1992) using another cellulosic substrate, cotton.
Cotton is the most available source of pure cellulose
and, as such, may be used as a standard for comparing
cellulosic substrates. Sheep fed 55% concentrate-45%
fescue hay diets with up to 15% of the fescue hay
being replaced with short-fiber cotton not suitable for
textile use had no decrease in feed intake or rate of
gain (Moore et al., 1992). Steers fed pelleted alfalfa
diets containing 25% short-fiber cotton had no
decrease in feed intake (9.6 kg/d DM) or rate of gain
(.98 kg/d) compared with steers fed diets containing 0
or 25% fescue hay when consuming diets at 3% of BW
(Moore et al., 1992). Luginbuhl et al. (1994) found
that DM, NDF, and cellulose intakes increased
quadratically as a percentage of BW with increasing
percentage of short-fiber cotton in the diets. The shortfiber
cotton ranged from 40 to 90% of the diet, with the
remainder of the diets being bermudagrass and(or)
soybean meal. However, the intakes as a percentage of
BW were much lower than those in this study or those
in the study of Moore et al. (1992). Dry matter intake
ranged from 1.0 to 1.4% BW, NDF intake ranged from
.80 to 1.0% BW, and cellulose intake ranged from .46
to .69% BW. The higher intakes noted in this
experiment and in the Moore et al. (1992) study may
be attributed to the lower level of inclusion of the
cellulosic substrates.
Apparent digestibilities of DM, OM, CP, NDF, ADF,
and cellulose did not differ among treatments. Moore
et al. (1992) reported a DM digestibility of 51.9%, and
Luginbuhl et al. (1994) reported a DM digestibility of
58% for the diet containing the lowest percentage of
cotton. The DM digestibility for the diets containing
SCC substrates was higher than that reported for
short-fiber cotton-containing diets and may be due to
the highly fermentable WM contained in the diets. In
addition, the inclusion of WM also may mask the
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CELLULOSE CASINGS AS POTENTIAL FEEDS 669
Table 4. Least squares means for nutrient intake, apparent nutrient digestibility,
and digestible nutrient intake of spent cellulose casing diets
fed to ruminally cannulated steers
aCON = Control diet, no cellulose casing substrates; FC = 25% fibrous composted; FG = 25% fibrous
ground; NC = 25% NOJAXâ composted.
b,cWithin a row, means with different superscript letters differ (P < .05).
Dietab
Item CON FC FG NC SEM
Intake, kg/d
DM 11.3 11.9 10.9 11.3 .4
OM 10.4 11.0 10.0 10.3 .4
CP 1.9 1.7 1.5 1.6 .1
NDF 5.2c 6.3b 5.8b 6.0b .2
ADF 2.7c 4.0b 3.9b 4.0b .1
Cellulose 1.8c 3.3b 3.1b 3.3b .1
Intake, % of BW
DM 2.7 2.8 2.6 2.8 .1
OM 2.5 2.6 2.4 2.5 .1
CP .4 .4 .4 .4 .02
NDF 1.2c 1.5b 1.4b 1.5b .05
ADF .6c .9b .9b 1.0b .04
Cellulose .4c .8b .8b .8b .03
Apparent digestibility, %
DM 70.4 67.8 66.6 65.1 1.6
OM 72.1 68.6 67.4 65.6 1.4
CP 72.9 70.7 69.0 71.4 1.4
NDF 58.4 56.1 55.6 52.4 2.2
ADF 48.9 50.4 53.0 46.3 3.1
Cellulose 57.0 55.0 57.6 47.4 3.0
Digestible nutrient intake, kg/d
DM 7.9 8.0 7.2 7.4 .3
OM 7.5 7.5 6.7 6.8 .3
CP 1.4c 1.2b 1.1b 1.1b .04
NDF 3.0 3.5 3.2 3.1 .2
ADF 1.3c 2.0b 2.0b 1.9b .1
Cellulose 1.0 1.8 1.8 1.6 .1
advantage of increased fermentability of the FC seen
in the in vitro study. Lignification of the AH explains
the observation that ADF is less digestible than
cellulose. Although no statistical significance was
detected, the cellulose in the NC diet was 16.8% (9.6
percentage units) less digestible than that of the CON
diet. If the cellulose in the FC and FG diets also was
less digestible than that in the CON diet, the
conclusion that SCC substrates in diets decrease
cellulose digestibility could be made. However, this is
not the case. Because the FC and FG cellulose
digestibility was numerically similar to the CON diet,
the suggestion that the type of cellulose in the SCC
substrate is the determinant of digestibility arises.
The decreased digestibility of cellulose II (regenerated)
allomorphs compared with that of cellulose I
(native) allomorphs (Weimer et al., 1990) may
explain the decreased cellulose digestibility of the NC
diet. The NC substrate is a type-II allomorph, whereas
the FC and FG substrates include a type-I allomorph
embedded in a type-II matrix. The higher digestibility
of the FC and FG diets may be due to the native
cellulose being digested at a faster rate than the
regenerated matrix. This increased rate of digestion
for native celluloses has been shown by Weimer et al.
(1990, 1991) as explained previously.
Overall, cellulose digestion was less than the 74.7%
reported by Luginbuhl et al. (1994) for the 40% shortcotton
fiber diet. This also may be attributed to
substrate specificity as suggested by Weimer (1992),
lower intakes in the Luginbuhl et al. (1994) study, or
decreased ruminal pH in this study adversely affecting
cellulolytic microorganisms.
Digestible DM and OM intakes were not affected by
inclusion of SCC substrates in diets. Digestible CP
intake for the CON diet (1.4 kg/d) was greater ( P <
.05) than that of the FC (1.2 kg/d), FG, and NC (1.1
kg/d each) diets. Although the CP intake and apparent
digestibility were not affected by diet, the values
were numerically smaller for the SCC-containing
diets. When these effects were combined, digestible CP
intake became significantly greater for the CON diet.
The opposite effect was noted for NDF and cellulose.
The intakes of FC, FG, and NC were greater ( P < .05)
than that of CON, but the digestibilities were
numerically lower. This resulted in numerically
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670 GENTRY ET AL.
Table 5. Ruminal characteristics of ruminally cannulated steers
consuming diets containing spent cellulose casings
aCON = Control diet, no cellulose casing substrates; FC = 25% fibrous composted; FG = 25% fibrous
ground; NC = 25% NOJAXâ composted.
b,c,dWithin a row, means with different superscript letters differ (P < .05).
Dietab
Item CON FC FG NC SEM
pH 5.97 5.99 6.16 6.09 .03
NH3N 15.27b 10.39d 10.64d 12.99c .3
Total VFA, mM 116.3b 110.9b 102.6c 97.8c 2.3
VFA molar proportions, mol/100 mol
Acetate 61.4 61.9 62.7 62.2 .7
Propionate 21.4 22.1 21.3 21.3 1.0
Butyrate 13.5 12.8 13.2 13.2 .7
Isobutyrate .9 .8 .8 .9 .05
Valerate 1.7 1.5 1.3 1.6 .1
Isovalerate 1.1 .9 .7 .7 .1
larger, but nonsignificant, digestible NDF and cellulose
intakes for the FC, FG, and NC diets. Digestible
ADF intake was increased ( P < .05) by SCC substrate
inclusion.
The effects of SCC substrates on ruminal pH,
ruminal NH3 N concentration, and ruminal VFA
concentrations and molar proportions are presented in
Table 5. Averaged across sampling times, ruminal pH
was not affected by inclusion of SCC substrates in the
diets. Ruminal pH fell immediately after eating to
values of 5.9 or less and remained there for approximately
6 h. This decrease in pH corresponds to the
time period in which the highly fermentable WM
would be digested. The CON diet tended to have
smaller values during this time period, further suggesting
an effect of the WM in reducing ruminal pH.
Our ruminal pH values were less than the 6.6 value
reported by Luginbuhl et al. (1994). The lower
ruminal pH observed in this study may have adversely
affected cellulose digestion. Cellulose digestion was
less (54.3%) than the 74.7% value reported by
Luginbuhl et al. (1994) for the 40% short-cotton fiber
diet. Mertens (1979) suggested that maximal fiber
degradation occurred between pH 6.7 and 7.1 and that
fiber degradation was reduced at a pH below 6.0.
Ruminal NH3 N concentration, averaged across
sampling times, was greatest ( P < .05) for the CON
treatment (15.3 mg/dL), whereas the NC-fed steers
had a greater ( P < .05) value (13.0 mg/dL) than the
FC- and FG-fed steers (10.4 and 10.6 mg/dL, respectively).
Concentrations varied throughout the
12-h sampling period, peaked approximately 3 h after
feeding (1100 h), and slowly fell to prefeeding levels
by 4 h before the evening feeding (2000 h). An
increased amount of rapidly degradable CP from the
AH and WM may explain the greater NH3 N
concentration of the CON treatment. Wilkins (1981)
suggested that the addition of fermentable carbohydrates
to a grass silage diet reduced ruminal NH3 N
concentrations. It is possible that the more extensively
fermented FC and FG resulted in an increased supply
of energy that may have increased microbial use of
NH3 N for protein synthesis. Although FG was not as
rapidly fermented as FC in vitro, FG may be as
extensively fermented as FC in vivo due to a much
larger particle size that would lead to a longer
ruminal residence time. This would account for the
lower NH3 N concentrations noted with the FC and
FG treatments in comparison to the NC treatment.
Ruminal NH3 N concentrations were apparently not
limiting because of the high nutrient digestibilities
and digestible nutrient intakes for all diets.
The lower ( P < .05) total VFA concentrations noted
for FG (102.6 mM) and NC (97.8 mM) treatments
compared with FC (110.9 mM) and CON (116.3 mM)
treatments may be due to the slower rate of fermentation
of these substrates. This complements the NH3 N
concentration results for the SCC-containing diets,
higher NH3 N concentration corresponding to lower
total VFA concentration, and provides further evidence
that the addition of fermentable carbohydrates
reduced NH3 N concentrations due to increased
microbial use of NH3 N. Although total VFA concentrations
differed, no effect was noted in molar
proportions of individual acids. Ruminal acetate concentration
was less (62.1 mol/100 mol) and ruminal
propionate concentration was greater (21.5 mol/100
mol) than those of Luginbuhl et al. (1994), who
reported a ruminal acetate concentration of 73.1 mol/
100 mol and a ruminal propionate level of 16.3 mol/
100 mol for the 40% short-cotton fiber-containing diet.
The decreased acetate and increased propionate molar
proportions noted in this study may be due to the high
fermentability of the WM.
The chemical composition data and in vitro digestibilities
suggested that FG, FC, and NC may be
incorporated into ruminant diets as high-fiber, lowprotein
energy sources. This was substantiated by the
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CELLULOSE CASINGS AS POTENTIAL FEEDS 671
in vivo trial. Intakes and digestibilities were not
adversely affected by inclusion of SCC substrates into
AH-WM-based diets. Ruminal pH was lower than
expected for high-fiber diets. If ruminal pH could be
increased, then digestibilities might also be increased.
Ruminal NH3 N concentration was lowered by the
presence of SCC in diets; however, this may be due to
increased microbial use. Total VFA concentrations
were less for the FG and NC treatments, suggesting a
reduced fermentability of these diets, and VFA molar
proportions were not affected. Results suggest that
SCC may be incorporated at the 25% level (DM basis)
into AH-WM-based diets without adversely affecting
digestive processes in growing steers. However, the
moisture content of SCC presents handling problems
that must be addressed. The NG substrate was very
high in moisture content and spoiled before the in vivo
trial could begin, whereas the FC substrate was very
low in moisture content and presented difficulty in
diet mixing due to dust production. Moisture level can
be adjusted in the last stages of the rapid composting
process to achieve a performance optimum.
Implications
Incorporation of spent cellulose casings into highfiber
diets at a level of 25% (dry matter basis) did not
adversely affect feed intake or digestibility. Spent
cellulose casings have the ability to partially replace
more traditional forages, such as alfalfa hay and
wheat middlings, in growing diets for beef cattle. The
problem of waste disposal could be partially solved by
recycling spent cellulose casings through ruminants.
Economic advantages (i.e., reduction in landfill and
feed costs) may be realized by the meat manufacturer
and beef producer by using spent cellulose casings as
feed ingredients.
Literature Cited
AOAC. 1990. Official Methods of Analysis (15th Ed.). Association of
Official Analytical Chemists, Arlington, VA.
Bohnensieker, F. U. S. patent 5,292,637 (March 8, 1994).
Carmer, S. G., and M. R. Swanson. 1973. An evaluation of ten
pairwise multiple comparison procedures by Monte Carlo
methods. J. Am. Stat. Assoc. 68:66.
Chaney, A. L., and E. P. Marbach. 1962. Modified reagents for
determination of urea and ammonia. Clin. Chem. 8:130.
Crampton, E. W., and L. A. Maynard. 1938. The relation of cellulose
and lignin content to the nutritive value of animal feeds. J.
Nutr. 57:383.
Franz, G., and W. Blaschek. 1990. Cellulose. In: P. M. Dey (Ed.)
Methods in Plant Biochemistry, vol 2. p 291. Academic Press,
San Diego, CA.
Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses
(apparatus, reagents, procedures, and some applications).
Agric. Handbook No. 379. ARS, USDA, Washington, DC.
Jeraci, J. L., T. Hernandez, J. B. Robertson, and P. J. Van Soest.
1988. New and improved procedure for Neutral-detergent fiber.
J. Anim. Sci. 66(Suppl. 1):351 (Abstr.).
Kra¨ ssig, H. 1985. Structure of cellulose and its relation to properties
of cellulose fibers. In: J. F. Kennedy, G. O. Phillips, D. J.
Wedlock, and P. A. Williams (Ed.) Cellulose and its Derivatives:
Chemistry, Biochemistry, and Applications. p 3. Ellis
Horwood, Chichester, U.K.
Luginbuhl, J-M., K. R. Pond, J. C. Burns, and D. S. Fisher. 1994.
Short fiber cotton textile mill waste as a feed resource for
cattle. J. Anim. Sci. 72(Suppl. 1):382 (Abstr.).
Mertens, D. R. 1979. Effects of buffers upon fiber digestion. In: W.
H. Hale and P. Meinhardt (Ed.) Regulation of Acid-Base
Balance. p 65. Church and Dwight, Nutley, NJ.
Moore, J. A., K. R. Pond, M. H. Poore, L. W. Whitlow, and B. E.
Chase. 1992. Waste cotton as a feed resource for cattle and
sheep. J. Anim. Sci. 70(Suppl. 1):305 (Abstr.).
Nicholson, M. D. 1991. Flexible nonwoven composites for food packaging.
TAPPI 74:227.
NRC. 1984. Nutrient requirements of beef cattle (6th rev. ed.).
National Academy Press, Washington, DC.
Prosky, L., N. G. Asp, I. Furda, J. W. DeVries, T. F. Schweizer, and
B. F. Harland. 1985. Determination of total dietary fiber in food
and food products: Collaborative study. J. Assoc. Off. Anal.
Chem. 68:677.
SAS. 1989. SAS/STATâ User’s Guide (Version 6, 4th Ed.). SAS
Inst. Inc., Cary, NC.
Steel, R.G.D., and J. H. Torrie. 1980. Principles and Procedures of
Statistics: A Biometrical Approach (2nd Ed.). McGraw-Hill,
New York.
Tilley, J.M.A., and R. A. Terry. 1963. A two stage technique for the
in vitro digestion of forage crops. J. Br. Grassl. Soc. 18:104.
Treiber, E. E. 1985. Formation of fibers from cellulose solution. In:
N. P. Nevell and S. H. Zeronian (Ed.) Cellulose Chemistry and
Its Applications. p 455. Ellis Horwood, Chichester, U.K.
Van Soest, P. J. 1973. The uniformity and nutritive availability of
cellulose. Fed. Proc. 32:1804.
Waldo, D. R., L. W. Smith, E. L. Cox, B. T. Weinland, and H. L.
Lucas, Jr. 1971. Logarithmic normal distribution for description
of sieved forage materials. J. Dairy Sci. 54:1465.
Weimer, P. J. 1992. Cellulose degradation by ruminal microorganisms.
Crit. Rev. Biotechnol. 12:189.
Weimer, P. J., A. D. French, and T. A. Calamari, Jr. 1991. Differential
fermentation of cellulose allomorphs by ruminal cellulolytic
bacteria. Appl. Environ. Microbiol. 57:3101.
Weimer, P. J., J. M. Lopez-Guisa, and A. D. French. 1990. Effect of
cellulose fine structure on kinetics of its digestion by mixed
ruminal microorganisms in vitro. Appl. Environ. Microbiol. 56:
2421.
Wilkins, R. J. 1981. The nutritive value of silages. In: W. Haresign
and D.J.A. Cole (Ed.) Recent Developments in Ruminant
Nutrition. p 268. Butterworths, London.
Williams, C. J., D. J. David, and O. Iismaa. 1962. The determination
of chromic oxide in faeces samples by atomic absorption spectrophotometry.
J. Agric. Sci. 59:381.
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