E V A L U A T I O N OF MOISTURE UPTAKE, AEROBIC A N D A N A E R O B I C
PHASES OF RECONSTITUTION UPON SORGHUM GRAIN DIGESTIBILITY
A N D PERFORMANCE OF STEERS 1
E. J. Simpson, Jr. 2 , L. M. Schake a , R. L. Pflugfelder 4
and J. K. Riggs 2'5
Texas A&M University,
College Station 77843
Summary
Experiments were conducted to determine
the effects of sorghum grain processing on grain
digestibility, rumen fermentation and yearling
steer performance. Cattle digestion and growth
studies were conducted with 1) dry sorghum,
2) sequential soaking in water (21 h), 3) soaking
with aerobic fermentation (21 h) and 4) soaking
plus aerobic fermentation followed by anaerobic
fermentation of 5 d. All grains were rolled
before feeding and were fed at 88% of the dry
matter in total mixed diets. High moisture
treatments of sorghum increased (P<.05) in
vivo dry matter, organic matter and starch
digestion compared with dry rolled sorghum.
Digestibility of crude protein was similar for all
treatments. Rate of ingesta dry matter passage
was 66% faster (P<.16) for 5-d reconstituted
sorghum than dry sorghum. In a 138-d feeding
trial, dry matter intake of treated (average
60.2% dry matter) grain was similar to that of
steers fed dry rolled sorghum. Feed efficiencies
improved (P<.12) for steers fed high moisture
sorghum compared with controls (8.61 vs
7.28). Ruminal butyric acid concentration
increased (P<.05) for steers fed the grain that
was soaked, aerobically and anaerobically
fermented compared with other grain treatments. Moisture uptake during 21 b of soaking
accounted for most of the observed improve1Technical article No. 19715, Texas Agr. Exp.
Sta.
2Dept. of Anim. Sci.
3Present address: Dept. of Anita. Sci., The Univ. of
Connecticut, Storrs 06268.
4Dept. of Soil and Crop Sci.
SAuthors wish to acknowledge support from the
Center for Energy and Mineral Resources, Texas A&M
Univ. and the Texas Cattle Feeders Assoc., Amarillo.
Received May 16, 1983.
Accepted October 3, 1984.
ments because sorghum treatments involving
aerobic and anaerobic fermentation resulted
in responses similar to those of cattle fed grain
soaked for 21 h. Grain that was soaked and
followed by aerobic and anaerobic fermentation
lost more (P<.05) dry matter (13.4%) than
other grain treatments, which was associated
with increases (P<.05) in soluble carbohydrates
and proteins.
(Key Words: Sorghum Grain, Soaking, Reconstitution, Digestibility, Cattle.)
Introduction
Sorghum grain has been shown to have 95%
of the dry matter digestibility of corn when
both were steam flaked and fed to cattle
(Schake et al., 1976). Reconstituting sorghum
to 30% moisture followed by 21 d of oxygenlimiting storage was as effective as steam flaking
for finishing cattle (Schake et al., 1972), and
was 13.8 times more efficient than steam
flaking in energy recovered as empty body
energy vs energy added for grain processing
(Schake et al., 1982).
Soaking sorghum to 30% moisture, or
greater, improved grain nutrient utilization by
cattle similar to that of conventional reconstitution and steam flaking (Martin et al., 1970;
Wagner and Schneider, 1970). Investigators
have reported that 21-d storage of reconstituted
grain may not be necessary to achieve improved
digestibility of grain fed to cattle (Florence and
Riggs, 1968; Pantin, 1969). Instead, the critical
factor may be the time required for the grain to
fully absorb water.
Another aspect of conventional reconstitution under field conditions that may be important in achieving favorable nutritional responses
with reconstituted grain is the short-term
aerobic fermentation phase. In the case of
877
JOURNAL OF ANIMAL SCIENCE, Vol. 60, No. 4, 1985
878
SIMPSON, JR. ET AL.
conventional reconstitution, water is combined
with whole grain before storage in anaerobic
structures. However, some air would be entraped
with the moist grain, providing an opportunity for aerobic fermentation before establishing
anaerobic fermentation. The influence of this
aerobic phase of conventional reconstitution
upon nutritional characteristics of grain has not
been investigated.
Objectives of this research were to determine
the specific effects of short-term sequences of
soaking whole sorghum grain followed by
aerobic and anaerobic fermentation on in vivo
digestibility, rumen fermentation, growth and
carcass characteristics of yearling steers.
Experimental Procedure
USDA No. 2 sorghum grain (IFN 4-04-383)
from one source but of an unknown heteroyellow variety, was used in Exp. 2, 3 and 4.
Grain was treated for feeding as follows: (1)
dry rolled sorghum (DR); (2) sorghum soaked
in water 21 h, drained and rolled before feeding
(S); (3) sorghum soaked in water 21 h, drained
before exposure to the atmosphere for 21 h and
rolied before feeding (SA); (4) sorghum soaked
in water 21 h, drained before exposed to the
atmosphere (21 h), reconstituted in air-tight
polyethylene bags for 5 d and rolled before
feeding (SAR). Grain was soaked for 21 h
to produce grain with at least 30% moisture.
This sequence of grain processing treatments
was selected to measure responses in grain
digestibility and cattle growth with each phase
of reconstitution (wetting followed by aerobic
and anaerobic fermentation).
Exp. 1. Loss of grain nutrients due to
soaking and fermentation was measured under
controlled laboratory conditions with a heteroyellow sorghum grain, variety A399 • TX2567.
This grain was treated in a manner similar to
that used for grain in the in vivo experiments.
Dry grain was treated as follows: (1) soaked (16
h) in tap water (24 C), (2) soaked followed by
aerobic exposure (24 h), (3) soaked, exposed
and reconstituted for 5 d, or (4) reconstituted
in a conventional manner (30% moisture) and
stored in 500-ml, air-tight glass jars and sampled
after 5, 13 and 21 d. A single .5-1iter sample
6Technicon Instrument Corp. Method No. 33474A/A (nitrogen) and No. 280-73A (reducing sugars).
Tarrytown, NY.
was prepared for each treatment combination.
Grain samples from each treatment were frozen
in plastic containers for later determination of
moisture (AACC, 1976) and dry matter loss
(Novellie, 1962). The remaining grain from
each treatment was dried at 50 C and finely
ground through a laboratory mill. Samples of
the ground material were extracted in citratephosphate buffer (pH 7) and 10% ethanolacetate buffer (pH 4.7) for determination of
soluble nitrogen and carbohydrate, respectively.
Automated colorimetric methods 6 were used to
analyze the extracts in triplicate for Kjeldahl
soluble nitrogen and total reducing sugars (after
hydrolysis).
Exp. 2. The effects of the four sorghum
processing methods on in vivo nutrient digestibility were compared using eight individually
fed, 255.7-kg Beefmaster-type steers in a
four-period switchback design experiment
(Lucas, 1956). Ytterbium nitrate was used as an
external marker in the supplement to provide
50/ag of Yb/g of feed dry matter. The indicator
supplement was mixed with each grain in a
horizontal ribbon mixer before feeding. Steers
were fed a diet of 88% sorghum grain and 12%
commercial roughage-protein-mineral supplement (dry matter basis). The granular supplement contained 35.3% crude protein (21%
soybean meal in supplement; IFN 5-04-600),
24.6% crude fiber primarily from ground
peanut hulls (35% of supplement; IFN 1-03629) and 5.6% Ca and .5% P. Each of the four
periods consisted of an 8-d adaptation followed
by a 6-d fecal collection period. The indicator
supplement was fed 10 d before the initial
collection and throughout the remainder of the
study. Fecal grab samples were collected from
each steer twice daily with the schedule advanced 4 h/d to include possible diurnal variations.
Fecal samples were immediately frozen at
- 1 5 C after collection. Upon thawing, samples
were analyzed for pH and then dried in a forced
draft oven at 50 C for 48 h. The dried samples
were composited by animal and period and
then ground through a l-ram screen for subsequent analysis. Feed samples were collected on
the second and fifth day of each fecal collection period, then ground and composited in the
same way as the fecal samples. Composited feed
and fecal samples were analyzed for Yb (Ellis,
1982). Crude protein was determined by
micro-Kjeldahl and ash by ashing in a muffle
furnace (AOAC, 1980). Organic matter was
THREE PHASES OF SORGHUM GRAIN RECONSTITUTION
calculated by difference 9 Starch was determined
by procedures of MacRae and Armstrong
(1968).
Exp. 3. The same eight steers used in the
digestion trial were allotted to two of the
sorghum treatments (DR and SAR) to estimate
rate of ingesta passage, using a single pulse dose
of Yb providing 500/ag of Yb/g of dry matter
consumed 9 Steers were fed the same respective
diets offered once per day as in Exp. 1. After
dosing, fecal grab samples were obtained every
6 h for 2 d and then every 12 h for the remainder of the 6-d collection period 9 Fecal
samples were dried, ground and analyzed for
Yb individually 9
Exp. 4. The same sorghum processing
treatments and diets used in Exp. 2 were
evaluated during a growth trial with 72 Beefmaster-type steers (initially 297.4 kg) that were
stratified b y weight and allotted to 12 similar
groups. Each group was assigned to one treatment in a completely randomized design with
three blocks/treatment. All steers were fed once
daily, ad libitum. Feed intakes and refusals
were recorded daily, and samples o f feed were
composited weekly for dry matter determination
in a forced draft oven at 50 C for 48 h. Ruminal
fluid samples were collected between 0600 and
0900 h at 112 d via esophageal tube from
one-half of the steers in each treatment and
were analyzed for pH and volatile fatty acids
(Byers, 1980). Steers were weighed on two
consecutive days to establish'initial and final
live weight 9 After a 138-d feeding period, steers
were slaughtered at a commercial packing plant
and carcasses were evaluated using USDA
(1975) quality and yield grade criteria.
Statistical analyses of data were accomplished
using the Statistical Analysis System's GLM
procedure for least-squares analysis of variance.
When a significant F value was identified,
treatment means were compared with Duncan's
New Multiple Range Test (Steel and Torrie,
1960).
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Results and Discussion
Soaking whole air-dry heteroyellow sorghum
grain in tap water for 21 h increased the moisture content from 9.8 to 39.8% for Exp. 2, 3
and 4. Subsequent exposure of this soaked
grain to the atmosphere for 21 h during the late
spring and summer of 1980 produced some
grains with a 5- to 6-ram radicle and a yeast-like
aroma upon rolling.
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880
SIMPSON, JR. ET AL.
Exp. 1. The reduction in soluble carbohydrates of dry grain under controlled laboratory
conditions from 2.74 to 1.75% could account
for the less than 1% dry matter loss in 16-h
soaked grain (table 1). Subsequently, soluble
carbohydrates increased to 2.51% of dry matter
after 24 h exposure and to 4.27% (P<.05) after
5 d of reconstitution. Nitrogen solubility of
grain was unaffected, except for the soaked,
exposed, 5<1 reconstituted treatment (P<.05).
Dry matter losses increased (P<.05) to 13.4%
for the soaked, exposed, 5-d reconstituted grain
treatment compared with other treatments.
These losses appeared to be influenced both by
carbohydrate and nitrogen solubility.
Exp. 2. Dry matter, organic matter and
starch digestibilities were relatively low and
similar for steers fed all high moisture sorghum
grains, but greater (P<.05) compared with
steers fed DR sorghum (table 2). Starch digestibility by steers fed S, SA and SAR grain was
improved 16.4% over those fed DR grain. Riggs
(1971) reported that conventional reconstitution of sorghum grain increased (P<.05) starch
digestion by steers compared with dry ground
sorghum. Organic matter digestibilities were
increased 32, 26 and 26% for steers fed S, SA
and SAR sorghums compared with DR controls.
Riggs and McGinty (1970) reported similar
differences in organic matter digestibility when
conventional reconstituted sorghum was compared with dry rolled sorghum.
Apparent crude protein digestibility was not
affected significantly by sorghum processing
treatments, although steers fed SAR sorghum
had slightly improved (9%) protein digestibility
over controls. Husted et al. (1968) also found
that soaking sorghum in water did not affect
protein digestibility, while Buchanan-Smith et
al. (1968) reported that reconstituting sorghum
improved protein digestibility slightly (9%).
Hibberd et al. (1982) found an increase in
soluble protein and a decrease in tannin content
associated with increased in vitro dry matter
disappearance using high tannin sorghum
grain reconstituted to 35% moisture for 1 d.
Exp. 3. Steers fed SAR sorghum had slightly
faster (P<.16) rates of dry matter passage than
did steers fed DR sorghum (table 2). These
results agree with those reported by Vandergrift
(1978), who observed slightly faster passage
rates for reconstituted sorghum compared with
dry sorghum. Fecal pH was slightly higher for
steers fed the high moisture sorghums compared with steers fed DR sorghum.
Exp. 4. Dry matter intake was not signific a n d y influenced b y sorghum treatment (table
3). Wagner and Schneider (1970) found that
cattle fed sorghum grain reconstituted to 30%
moisture and stored 5, 10 or 20 d, or soaked 48
h to 39.3% moisture, had reduced dry matter
intake compared with cattle fed dry roiled
sorghum. However, White and Totusek, (1969)
reported no difference in dry matter intake of
cattle fed sorghum soaked to 38% moisture,
drained and allowed to stand 1 d in an open
container before feeding compared with dry
rolled sorghum. In the present experiment,
TABLE 2. APPARENT NUTRIENT DIGESTIBILITIES OF PROCESSED SORGHUM GRAIN
FED TO STEERS
Sorghum treatmentsa
Item
Number of steersb
Digestibility, %
Dry matter
Organic matter
Crude protein
Starch
Rate of passage, %/h
Fecal pH
DR
8
49.02 c
53.67 c
55.16
79.00 c
4.50
6.62
S
8
SA
SAR
8
8
63.20 d
70.86 d
56.62
88.48 d
60.93 d
67.57 d
54.51
93.28 d
6.75
6.83
62.88 d
70.03 d
60.11
94.03 d
7.52
6.74
SE
3.31
3.47
3.31
3.04
.96
.09
acoded: DR -- dry rolled, S = soaked, SA ~ soaked + atmospheric exposure and SAR = soaked + atmospheric
exposure + reconstitution.
bAverage initial and final weight was 255.3 and 360.9 kg, respectively. Average dry matter intake was 6.2
kg/d.
c d Means wlthm
. rows with different
.
superscripts differ (P<.05).
THREE PHASES OF SORGHUM GRAIN RECONSTITUTION
881
TABLE 3. PERFORMANCE OF STEERS FED SORGHUM GRAIN
Sorghum treatmenta
Item
DR
Number of steers
Number of replicates/
treatment
Days fed
Initial weight, k~
Final weight, kg ~
Avg daily dry matter
intake, kgC
Avg daily gain, kg
Feed conversion (dry
matter) d
S
SA
SAR
18
17 e
18
18
3
138
295.7
404.6
3
138
295.2
431.8
3
138
295.7
420.7
3
138
296.1
427.2
SE
16.36
30.35
6.74
.78
7.01
1.00
6.90
.90
6.62
.95
.64
.08
8.61
7.03
7.69
7.13
.54
acoded: DR = dry rolled, S = soaked, SA = soaked + atmospheric exposure and SAR = soaked + atmospheric
exposure + reconstitution.
bAdjusted to average dressing percentage of 61.85.
CAverjage dry matter of diets were 86.72, 63.60, 65.58 and 65.00%, respectively, for DR, S, SA and SAR
treatments.
dlnfluenced by sorghum treatments (P<.12).
eone steer died of unknown causes.
feed efficiency was i m p r o v e d ( P < . 1 2 ) for steers
fed high m o i s t u r e s o r g h u m s over steers f e d d r y
rolled s o r g h u m b y 18.4, 10.7 a n d 17.2% f o r t h e
S, S A a n d S A R grain t r e a t m e n t s , respectively.
Riggs a n d M c G i n t y ( 1 9 7 0 ) also r e p o r t e d a 10 t o
15% i m p r o v e m e n t in feed e f f i c i e n c y for c a t t l e
fed c o n v e n t i o n a l r e c o n s t i t u t e d vs d r y g r o u n d
s o r g h u m . Average daily gain of steers f e d t h e
high m o i s t u r e grains was greater (15 to 28%),
b u t n o t significantly g r e a t e r t h a n c o n t r o l s .
W h i t e et al. ( 1 9 6 9 ) , Wagner a n d S c h n e i d e r
( 1 9 7 0 ) a n d Riggs a n d M c G i n t y ( 1 9 7 0 ) f o u n d
t h a t h i g h m o i s t u r e s o r g h u m grain t r e a t m e n t s
did n o t s i g n i f i c a n t l y i n f l u e n c e gain o f steers
compared with dry sorghums. Florence and
R i g g s ( 1 9 6 8 ) a n d M c G i n t y e t al. ( 1 9 6 8 ) conc l u d e d t h a t a 21-d r e c o n s t i t u t i o n i n t e r v a l m a y
n o t b e r e q u i r e d t o p r o d u c e desired grain processing responses. P e r f o r m a n c e of c a t t l e fed S
grain s u p p o r t s t h e research of M a r t i n et al.
( 1 9 7 0 ) , suggesting t h a t soaking s o r g h u m grain
t o m o i s t u r e levels in excess o f 30% m a y b e as
TABLE 4. RUMEN VOLATILE FATTY ACID CONCENTRATION (MOL/IO0 MOL) OF STEERS
FED PROCESSED SORGHUM GRAIN
Sorghum treatment a
Item
DR
S
SA
SAR
SE
Acetic
Propionic
Iso-butyric
Butyric
lso-valeric
Valeric
Acetic:propionic ratio
Rumen pH
33.80
38.26
2.05
16.49 b
5.58
3.82
.88
6.06
32.70
41.33
2.33
15.07 b
5.79
2.79
.79
6.12
:33.55
31.78
3.52
16.46 b
10.46
4.24
1.06
6.29
37.80
23.42
2.01
27.03 c
7.28
2.47
1.61
6.22
3.75
5.90
.64
3.38
1.68
.54
.16
acoded: DR = dry rolled, S = soaked, SA = soaked + atmospheric exposure and SAR = soaked + atmospheric
exposure + reconstitution.
b'CMeans within the row with different superscripts differ (P<.05).
882
SIMPSON, JR. ET AL.
effective as longer intervals o f reconstitution.
Carcass quality was u n a f f e c t e d b y sorghum
processing, which is consistent with m o s t
published data. The overall means were: dressing
percentage 61.9%, U S D A (1975) yield grade,
2.1 and quality grade, G o o d . Percentage abcessed
livers were 16.7, 29.4, 27.8 and 38.9%, respectively, for steers fed DR, S, SA and S A R grain.
There were no significant differences in
ruminal acetic, propionic, isobutyric, isovaleric
or valeric acid c o n c e n t r a t i o n s due to sorghum
t r e a t m e n t s (table 4). Steers fed t h e S A R grain
had higher ( P < . 0 5 ) ruminal butyric acid concentrations than steers fed o t h e r sorghum
treatments, which m a y indicate an increase in
soluble protein f o r m a t i o n in the anaerobic
phase o f t h e r e c o n s t i t u t i o n process (table 1).
R u m e n pH t e n d e d to be higher for steers fed
the high m o i s t u r e sorghum treatments, b u t was
n o t significantly different f r o m steers fed D R
grain.
In these studies, favorable responses were
consistent in digestibility of grain and p e r f o r m ance o f cattle fed all soaked grains c o m p a r e d
with D R grain-fed steers. F u r t h e r m o r e , the
t r e a t m e n t s involving soaking t e n d e d to offer
similar responses, suggesting 21 h soaking o f
grain as the primary factor involved in the
observed responses.
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