Effects of grinding, pelleting and expanding on
nutritive value of barley in pig diets

Matti Näsi

Näsi, M. 1992. Effects of grinding, pelleting and expanding on nutritive value of
barley in pig diets. Agric. Sei. Finl. 1: 461-469. (Univ. Helsinki, Dept. Anim. Sci.,
SF-00710 Flelsinki, Finland.)

Nutrient digestibility and protein utilization responses ofgrowing pigs to different pro-
cesses of barley were evaluated. The assayed treatments of barley were grinding
methods: hammer milling (FIM) and rolling (RM), pelleting (FIP, RP), expanding
(HE, RE) and their combination (HEP, REP). The study comprised a 8 x 8 Latin square
designed digestibility and nitrogen balance trial with a 2 x 2 x 2 factorial arrangement
of treatments. The average grist size ofHM barley was smaller and wider than that of
RM. Pelleting and expanding reduced the grist size and made the distribution wider
compared to untreated ones. HM compared to RM achieved improved pellet quality,
but expanding had no effect on pellet durability. Only small differences were found in
the proximate composition or sugar content indicating a gelatinization degree of differ-
ently processed barleys. Grinding method had no effect on organic matter (OM)
digestibility, whereas RM improved protein (CP) digestibility (P<0.001) but led to
lower ether extract (EE) digestibility (P<0.001). Pelleting significantly improved
digestibility ofall barley constituents (P<o,ol, 0.001), the magnitude being 0.02 com-
pared to meal form barley. A significant interaction between the grinding method and
pelleting was noticed in CP (P<0.05) and EE (P<0.001) digestibility. Except for the
digestibility of crude fibre (P<0.001), there were no significant differences between
the treatments in response to the expanding process of barley. Significant interactions
in digestibilities were foundbetween grinding methods and expanding. RM compared
to HM achieved significantly higher N-retention (P<0.001) and protein utilization
(P<0.001) and decreased urinary urea-N excretion (P<0.001). Pelleting significantly
improved protein absorption (P<0.001) and tended to decrease urinary-N excretion,
but N-retention was unaffected by the physical form of the barley. Expanding had no
effect on protein absorption or N-retention, but achieved a small significant improve-
ment in biological value ofprotein (P<0.01).

Key words: grinding, pelleting, expanding, digestibility, nitrogen balance, pig, barley

Introduction

The major contribution of barley in pig diets has
stimulated the development of various techniques
for grain processing in order to increase the effi-
ciency of utilization of dietary nutrients and pig
performance. Barley has rather high total fibre con-

tent including both insoluble and soluble fibre
(Åman and Hesselman 1984). Thus, it is important
to reduce particle size or by some other processing
means to increase accessibility to the digestive
enzymes of the pig.

Cereal grains are not all completely broken down
during mastication and some may pass unutilized

461

Agric. Sei. Finl. 1 (1992)

https://www.c-info.fi/en/info/?token=TAQgyUM9dJvjt0lk.jWP1TPxsuxtXYa0W54EHQg.JOfMT3UuS_pZvJXDRmDyUwyG681ZM-N8utyfqRLkcP-HSFP20RgzgFAY8Es56k_m5V4AQoDwCrw7cacftQ7GEvKjIsgeAEOm9yx6f_PREJRmCAHgkC7jOSiomql-shFHuHGWCML4fWTatRoajNn6FIXrGP2-rE0FKTFoKYtN8tFB_4JLyAnauyPjUWV6LdGFqUcjOI5XlShKPal3YCykVs9hpHOL1BWJHz9R6YGn4FHP6fwQp0dJ3CTyjxq0UVuqE1OmpnSu


through the alimentary tract. Fineness of grind will
affect utilization of grain. It has been shown that
screen sizes of up to five mm diameter are unlikely
to impair utilization significantly, but screen size of
nine mm or above will have a deleterious effect
(Lawrence 1970, Simonsson 1978a). Compared
with this, efficient rolling, so that each grain is
throughout flattened, would appear capable ofelicit-
ing as efficient a response as any of the grinding pro-
cedures when using screen sizes up to five mm
diameter (Lawrence 1978, Simonsson 1978b).
There is evidence of a relationship between cereal
particle size and ulceration, the finer the grinding the
higher the incidence of ulceration in the oesophageal
region of the pig (Lawrence 1972, Simonsson and
Björklund 1978, Kirchgessner et al. 1985).

The use of pelleted feeds for pigs is associated
with an improvement in feed utilization efficiency,
due principally to reduced feed wastage and
improved nutrient digestibility. It has been pro-
posed that the following are the advantages of pel-
leted over meal feeds: reduced selective feeding,
reduced segregation, increased bulk density and
improved handling and flowability. A tendency for
digestibility of nutrients and performance ofpigs to
improve has been noticed when the fibre content of
the diet is increased (Vanschoubroek et al. 1971,
Lawrence 1983).

With the expander, it is possible to achieve
higher temperatures and pressures compared to a
conventional pellet mill. The advantages of a com-
bination ofexpander and pellet mill are claimed to
be: improved pellet quality, digestibility and reduc-
tion of bacteria (Wettstein and Wild 1990).

Three of the more important production techno-
logies in producing pig feeds will be dealt with
here; grinding, pelleting and expanding and their
combinations of treating barley. The objectives of
the current study were to investigate the effects of
various processes on nutrient digestibility and pro-
tein utilization in pigs fed barley based diets.
A subsequent study where performance and oeso-
phagogastric lesion responses of pigs to hammer
milled and rolled barley diets were investigated will
be published by Alaviuhkola et al. (to be pubi.)

Material and methods

The processing treatments ofbarley were two grind-
ing methods, pelleting, expanding and their combi-
nation. The hammer milling was made with a perip-
herally fed mill, 1500 rpm to pass 3.5 mm sieve
(HM) and the roll milling with a smooth roller
(RM). Both of the ground barleys were divided into
two baches, of which one was pelleted with a
Bidder DPGC mill, to yield pellets of 4.5 mm dia-
meter, at temperature of 65°C (HP, RP). Then, a
part of each of the the bathes was either expanded
(Kahl expander, temperature 95-100°C (HE, RE) or
pelleted after expanding (HEP, REP). The grist
spectrum of the barleys after different treatments is
outlined in Table 1. They were measured with a test
sieve shaker for 5 min after soaking 50 g feed in
250 ml water for 2 h and rinsing with water during
sieving. Oversized feed on the sieves was kept at
room temperature overnight and weighted. Quality
of the pellets was measured by screening and count-
ing the proportion of whole pellets retained on the

Table 1. Particle size distribution of differently treated barley.

Particle diameter, mm HM HP HEP HE RM RP REP RE

4.0 <
.... 0.306 0.006 - 0.004

1.6 -4.0 0.104 0.140 0.178 0.186 0.354 0.414 0.312 0.372
1.0- 1.6 0.228 0.244 0.224 0.144 0.074 0.182 0.196 0.186

0.3 - 1.0 0.332 0.314 0.304 0.280 0.050 0.152 0.164 0.138
<0.3 0.336 0.302 0.294 0.390 0.216 0.246 0.328 0.300

The treatments: hammer milling (HM), rolling (RM), pelleting ofhammer milled and rolled (HP, RP), expanding ofhammer
milled and rolled (HE, RE) and the combination of expanding and pelleting of hammer milled anfrolled (HEP, REP)

462

Agric. Sei. Fint. 1 (1992)



4 mm screen. The pellets were circulated for 1 min
in a pneumatic transfer with a Holmenpellet tester.

A 8 x 8 balanced Latin square with growing pigs
of castrated males (Landrace xLarge White), initial
weight of 28.6 (SE 1.85) kg and final weight of
97.4 (SE 3.75) kg with a 2 x 2 x 2 factorial arrange-
ment of treatments, was carried out to determine
the effects of grinding, pelleting and expanding and
their combinations on nutrient digestibility and
protein utilization of barley based diets. Eight diet-
ary treatments were used and the diets consisted of
treatedbarley 850 g/kgand soybean meal 150 g/kg.
The pigs were fed twice daily according to a
restricted feeding regime and their diets were ad-
equately fortified with minerals and vitamins(Salo
et al. 1990). The pigs were kept during the whole
experiment in metal metabolism cages equipped
with collection trays, allowing separate collection
of faeces and urine. Each period comprised 5 days
of adjustment and 5 days of total collection of
faeces and urine. The details of the procedure are
the same as described by Näsi (1984). All animals
completed the experiment successfully and the aver-
age daily weight gain during the entire experiment
was 860 g. No differences in palatability of the
variously treated barley diets were observed. Re-
fusals of the diet were negligible.

The digestibilities of the barleys treated with dif-
ferent processes were calculated by difference
method. Feed values of the ingredients were com-
puted according to Salo et al. (1990) and Andersen
and Just (1983). The data were analyzed by analysis
of variance BxB Latin square with a 2 x 2 x 2 facto-
rial arrangement of treatments. The sums ofsquares
for treatment effect were further separated into
single degrees of freedom for comparisons of the
dietary treatments (Snedecor and Cochran 1967).

Results and discussion

Barley ground in a roller mill had a considerably
coarser average grist size. The particle distribution
of rolled barley was more narrow compared to
hammer milled, but pelleting and expanding re-
ducedthe grist size and made the distributionwider

(Table 1). Pellet durability was measured as a pro-
portion ofmeal passing through a 4 mm sieve. The
mealy proportions were 0.10, 0.12, 0.19 and 0.19
for treatments HP, HEP, RP and REP, respectively.
Prior to pelleting, hammer milled compared to rol-
led barley achieved better pellet quality. The aver-
age particle size of the ground product has an in-
fluence on pellet quality. In many cases, pellet qual-
ity can be improved most economically by re-
ducing the average particle size. With an expander
the temperatures and pressures are higher than in
pellet die, thus it couldbe expected thatpellet dura-
bility is improving the pelleting followed after
expanding. Here pellet quality was unaffected
probably due to low process temperature and limit-
ed use of steam, which is in accordance with the
gelatination degree judged from sugar content.

Only small differences were found in the proxi-
mate composition of differently processed barleys
(Table 2). HM-barley had a little higher crude pro-
tein content compared to the others. The prelimi-
nary samples taken after processing were similar,
thus higher content is caused by some contamina-
tion when transported. Rolled barleys showed a
little higher fibre content compared to milled ones.
Only a small variation is shown in sugar or starch
contents of treated barleys, indicating only a minor
gelatinization effect from heating in pelleting or
expanding processes. The gelatinization temper-
ature of barley starch is relative low 59 - 64°C
(Doggett 1970), but here the actual hydrothermal
stage of the processing was rather short and the
moisture content was quite low for higher gelatini-
zation.

Grinding method had no effect on organic matter
or carbohydrate digestibility (Tables 3 and 4).
However, rolling led to better crude protein digest-
ibility (P<0.001), although resulting in lower ether
extract digestibility (P<0.001). This is supported by
the observation that larger grist sizes of barley,
ground by roller milling, has been utilized to the
same extent as the smaller grist sizes, resulting
from a peripherally fed hammer mill (Simonsson
1978a). Neither did Lawrence (1970) find differ-
ences in performance ofpigs given diets containing

463

Agric. Sei. Fint. 1 (1992)



Table 2. The chemical composition of the experimental feeds

Treatment of feed HM HP HEP HE RM RP REP RE Soy
Composition, g/kg DM bean

meal

Dry matter 868 864 861 853 862 860 859 849 871
Ash 32 27 26 28 29 27 26 27 70
Crude protein 133 120 116 116 121 119 119 119 491
Ether extract 39 37 36 36 37 37 36 37 33
Crude fibre 49 44 47 52 50 49 44 45 55
Nitrogen free extract 747 772 775 769 764 767 774 773 352
NDF 180 177 181 194 197 197 179 183 114
ADF 42 39 42 48 45 47 41 41 47
Hemicellulose 138 138 139 146 152 150 139 142 67
Starch 539 602 597 581 555 555 567 583
Sugars 43 45 42 41 44 43 41 42

The treatments: hammer milling (HM), rolling (RM), pelleting of hammer milled and rolled (HP, RP), expanding ofhammer
milled and rolled (HE, RE) and the combination of expanding and pelleting ofhammer milled anf rolled (HEP, REP)

barley which had been either rolled or ground to
widely different degrees. Efficient rolling may
overcome most of the problems caused by fine
grind eg. dusty, unpalatable, sticky and pasty in the
mouth of a pig, and gastric lesions. The rolling mill
has been found to achieve rolled grain pores which
are made up of fissures and cavities in the particle.
These pores increase the surface area of a particle.
Pore size distribution of HM- and RM-barleys was
measured with a Hg-porosimeter, and the prelimi-
nary observations showed RM-barley to have very
many small pores (Unpubl). Total pore volume
and pore size distribution can also be determined
from gas absorption isotherms. External and pore
surfaces may have a significant effect over a wide
range of phenomena, particularly ad- and absorp-
tion of liquids and enzymes, which determines
digestibility as well as particle size.

Pelleting significantly improved (P<o.ol, 0.001)
digestibility of all the organic constituents, the
magnitude being approximately 0.02 compared to
meal form barley. A significant interaction between
the grinding method and pelleting was noticed in
CP (P<0.05) and EE (P0.001) digestibility. In the
pelleting process, cereals are subjected to pressure
of being forced through the die of the pelleter.
There is a frictional heating effect and excess, but
prior to this, the grain is steam heated. Pelleting

appears to modify molecular fractions of the feed.
This is suggested from the fact that when pellets
have been ground into meal before being fed, the
beneficial effect ofpelleting has still been obtained.
Both chemical and physical changes are indicated
which are involved in improving digestibility
(Lawrence 1978).

The extensive review prepared by Vanschou-
broek et al. (1971) indicated that feeding of pelle-
ted rations results in significant responses in the
performance and food utilization in growing pigs.
Present results are in accordance with data present-
ed by Lawrence (1970) who found pelleting to
improve dry matter and energy digestibility. The
physical form ofthe diet, however, had only a small
non-significant effect on the digestibility of energy
and ME/DE ratio according to the data of Patter-
son (1989). The digestibility of nitrogen was sig-
nificantly improved by pelleting, and nitrogen
retention was also increased but not significantly
(Patterson 1989).Furthermore, Yen et al. (1971)
found improved amino acid digestibility, which is
in accordance with present results. Rarely is the
cereal component subjected to pelleting alone. The
effects of pelleting on the complete diet could be
different, as here, when barley was alone. The
effect of pelleting varies according to the method,
pelleting cold versus steam. Skoch et al. (1983)

464

Agric. Sei. Fint. 1(1992)



Agric. Sei. Fint. 1 (1992)

Table
3.

Digestibility
of
nutrients
in
pigs
ondiets

based
on

differently
treated

barley.

Digestibility
HM

HP

HEP
HE

RM

RP

REP

RE

SEM
M

P

M*P
E

M*E
P*E
M* P*E

Dry
matter

0.808
0.823
0.815
0.804
0.798
0.816
0.829
0.816
0.002
NS

*•*

NS

NS
NS

Organic
matter

0.834
0.848
0.840
0.829
0.823
0.839
0.853
0.842
0.002
NS

***

NS

**

***

NS
NS

Ash

0.290
0.287
0.274
0.259
0.276
0.320
0.303
0.271
0.011
NS

**

NS

NS

NS

NS
NS

Crude
protein

0.797
0.806
0.802
0.793
0.792
0.825
0.829
0.815
0.005

***

***

*

NS

*

NS
NS

Ether
extract
0.503
0.538
0.528
0.519
0.411
0.527
0.506
0.465
0.008
***

***

***

NS

NS

***

*

Crude
fibre

0.201
0.220
0.217
0.203
0.162
0.202
0.264
0.227
0.012
NS

**

NS

***

***

NS
NS

NEE

0.908
0.914
0.907
0.900
0.899
0.904
0.914
0.908
0.002
NS

***

NS

NS

***

NS
NS

NDF

0.478
0.512
0.476
0.466
0.463
0.489
0.513
0.492
0.009
NS

**

NS

NS

***

NS
NS

ADF

0.075
0.083
0.065
0.098
0.022
0.074
0.103
0.123
0.014
NS

*

***

NS

NS

NS
NS

Hemicellulose
0.612
0.651
0.614
0.598
0,607
0.621
0.640
0.626
0.008
NS

«**

NS

NS

***

NS
NS

The
treatments:

hammer
milling
(HM),
rolling
(RM),
pelleting
of
hammer
milled
and

rolled
(HP,
RP),
expanding
of
hammer
milledand

rolled
(HE,
RE)
and
the

com-

bination
of
expanding
and
pelleting
of
hammer
milled
anf

rolled
(HEP,
REP)

M
=

grinding
method,
P
=

pelleting
and
E
=

expanding

SEM
=

standard
errorof

the
means;

significance:
NS
=

non-significant,
*

P<0.05,
**

P<o.ol,
***P<o.ool

Table
4.

Digestibility
of
nutrients
of

differently
treated

barley
in

pigs.

Digestibility
HM

HP

HEP

HE

RM

RP

REP

RE

SEM
M

P

M*P
E

M*E
P*E
M* P*E

Dry
matter

0.803
0.822
0.812
0.798
0.792
0.813
0.829
0.814
0.003
NS

***

NS

**

***

NS
NS

Organic
matter

0.834
0.850
0.841
0.828
0.821
0.840
0.856
0.843
0.003
NS

***

NS

**

***

NS
NS

Ash

0.091
0.048
0.007
-0.004
0.035
0.115
0.073
0.005
0.002
NS

NS

�*

**

NS

NS
NS

Crude
protein

0.769
0.780
0.772
0.756
0.757
0.815
0.822
0.796
0.009
***

***

*

NS

**

NS
NS

Ether
extract

0.480
0.520
0.508
0.498
0.371
0.508
0.482
0.433
0.010
***

***

***

NS

NS

***

*

Crude
fibre

0.194
0.217
0.214
0.197
0.145
0.195
0.272
0.226
0.014
NS

**

NS

***

***

NS
NS

NFE

0.906
0.914
0.905
0.898
0.897
0.912
0.913
0.907
0.002
NS

***

NS

NS

***

NS
NS

The
treatments:

hammer
milling

(HM),
rolling
(RM),
pelleting
of
hammer
milled
and

rolled
(HP,
RP),
expanding
of
hammer
milled
and

rolled
(HE,
RE)
and
the

com-

bination
of
expanding
and
pelleting
of
hammer
milled
anf

rolled
(HEP,
REP)

M
=

grinding
method,
P
=

pelleting
and
E
=

expanding

SEM
=

standard
errorof

the
means;

significance:
NS
=

non-significant,
*

P<0.05,
**

P<o.ol,
***P<o.ool

465



466

Table
5.

Nitrogen
balance
and

protein
metabolism
in

pigs
fed

differently
treated

barley
based

diets.

Nitrogen
balance
HM

HP

HEP
HE

RM

RP

REP
RE

SEM
M

P

M*P
E

M*E
P*E
M*P*E

N

intake,
g/d

57.7

53.8

53.0
52.1
54.2

53.8
52.0

53.3

0.53
*

**

NS

***

*

*

***

N
in

faeces,
g/d

11.6

10.2

10.2
10.6
10.8

9.3

8.7

9.6

0.29
***

***

NS

**

NS

NS

NS

N

absorbed,
g/d

46.1

43.6
42.8
41.5
43.3

44.5
43.3

43.7
0.52
NS

NS

NS

***

**

NS

***

N

digestibility
0.797
0.806
0.802
0.793
0.792
0.825
0.829
0.815
0.0050

***

***

*

NS

*

NS

NS

N
in

urine,
g/d

24.1
20.7
20.4

19.1

19.8

20.3
19.8

19.9

0.48
**

NS

NS

***

***

**

***

N

retained,
g/d

22.0

22.9
22.3
22.4
23.5

24.2
23.4

23.8

0.50
***

NS

NS

NS

NS

NS

NS

-of
intake

0.389
0.434
0.429
0.435
0.440
0.456
0.458
0.455
0.0066
***

**

NS

**

NS
**

*

-of
absorption

0.489
0.541
0.537
0.550
0.559
0.553
0,554
0.560
0.0081

***

NS

*

*

*

**

**

-
g/kg
W°

75

1.054
1.105
1.056
1.056
1.111
1.139
1.124
1.141

0.0208
***

NS

NS

NS

NS

NS

NS

Urea
N,
g/d

20.8

17.2

17.3
15.9
15.0

17.1
16.7
17.1

0.64
**

NS

*

NS

***

NS

***

UreaN,
g/W

075

0.939
0.766
0.763
0.714
0.684
0.769
0.755
0.755
0.0242
**

NS

**

*

***

NS

***

Biological
value
0.562
0.615
0.613
0.627
0.633
0.625
0.626
0.633
0.0076
***

NS

*

**

**

**

**

Daily
gain,
g/d

853

791

886

801

881

913

830

833

40.7
NS

NS

NS

NS

NS

NS

NS

Thetreatments:
hammer

milling
(HM),
rolling
(RM),
pelleting
of

hammer
milled
and

rolled
(HP,
RP),

expanding
of

hammer
milled
and

rolled
(HE,
RE)
and
thecom-

bination
of

expanding
and

pelleting
of

hammer
milled
anf

rolled
(HEP,
REP)

M
=

grinding
method,
P
=

pelleting
and
E
=

expanding

SEM
=

standarderror
of
themeans;

significance:
NS
=

non-significant,
*

P<0.05,
**

P<o.ol,
***P<o.ool

reported improvements in FCR of 0.071 and 0.055
...of cold and steam-press pellets, respectively, in

comparison to meal with increases in energy of
0.018 and 0.016.

Except for the digestibility of crude fibre
(P<0.001), there were no significant differences
between the treatments in response of other nu-

-1

trients to expanding process of barley. Significant
interactions in digestibilities of CP (P<0.01), CF
and NFE (P<0.001) were found between grindingv ' ° °

methods and expanding. Pigs fed extruded barley
diet have had higher ileal digestibility for dry mat-
ter, energy and starch, but no significant dif-

. ....... „ ,ferences m faecal digestibility were found (Fadel
etal. 1988), which is in accordance with the present
data. Extrusion of yellow com or com and wheat
middling diet has been found to improve energy
and DM digestibility, but has not affected the
digestibility of lysine or N at the terminal ileum
(Skoch et al. 1983, Flerkelman et al. 1990).
Expanding and extrusion are rather similar proces-

, . . . ~ , rr . ■ ~ses, despite stronger hydrothermal effect in the
extruder. An improvement of0.13 over the controls
in daily gain of piglets fed expanded diet has been
reported by Bolduan and Peisker (1992), but
product temperature of 115°C was higher than in
present treatment. The thermal processing ot the
present expanding treatment proved to be quite
slight, so that the effect on nutrient digestibilies
was \vc3K.

The results of the N balance and various calculat-
e(j parameters of protein utilization are shown in
Table 5. Rolling of barley compared to hammer
milling achieved significantly higher N-absorption
(P0.001) and lower urinary-N and urea-N excre-
tion (P<0.01). A rolled barley diet gave signific-
antly higher N-retention (22.4 vs. 23.7 g/d,
P<0.001) and proportions of N-retention in relation
to intake of N were improved by 0.03 (P<0.001).
Biological value is significantly higher on the roll-
ccj barley diet, which was in accordance with the
tendency of improved daily gain.

Pelleting of barley improved diet N-digestibility
(P<0.001) and tended to decrease urinary-N excre-
tion (P<o.l). N-retention was unaffected by the



Table 6. Calculated feed values of the differently treated barleys.

Feed value HM HP HEP HE RM RP REP RE

FU/kg DM 1.118 1.147 1.135 1.116 1.098 1.132 1.152 1.133
FU/kg 0.97 0.99 0.97 0.95 0.95 0.97 0.99 0.96
DCPg/kgDM 103 94 89 87 91 97 98 95
DCP g/FU 92 82 79 78 83 86 85 83
ME MJ/kg DM 14.70 15.03 14,84 14.59 14.39 14.85 15.11 14.84
NE MJ/kg DM 9.14 9.39 9.25 9.06 8.91 9.26 9.45 9.25
FE 1.184 1.216 1.198 1.174 1.154 1.199 1.225 1.19s

The treatments: hammer milling (HM), rolling (RM), pelleting ofhammer milled and rolled (HP, RP), expanding ofhammer
milledand rolled (HE, RE) and the combination of expanding and pelleting of hammer milled anf rolled (HEP, REP)
FU = feed units, 0.7 kg starch equivalent, DCP = digestible crude protein, ME = metabolizable energy, NE =net energy,
FEs =Danish net energy system forpigs

physical form of the barley. Protein utilization was
improved by pelleting to a small degree. The obser-
vation is similar to thatofPatterson (1989). Daily
gain of the pigs fed on a pelleted diet improved 842
vs 855 g/d, being consistent with earlier results
given in the literature. The better performance of
pigs fed a pelleted diet over meal form has obvi-
ously resulted from the higher digestibility of
energy yielding components and from avoiding
most of the feed wastage rather than improved pro-
tein utilization.

Expanding had no effect on N-digestibility or N-
retention. Urinary-N excretion (P<0.001) and para-
meters indicating protein utilization (P<o.ol, 0.05)
were improved by using an expander as a treat-
ment. In contrast to this, the daily gain was slightly
inferior in pigs fed expanded barley compared to
untreated ones. There was a small difference in the
N-intake which may have had an effect on the para-
meters measured. Hydrothermal processes are
directed to rupture cell wall matrix and modify the
chemical structure of cereal constituents. These
processes are aimed at rendering nutrients more
susceptible to enzyme degradation in the small

intestine, thus improving the digestibility and util-
ization, especially amino acids. Two explanations
for the lack of response could be either that the
expanding process was too mild or that no further
improvement can be achieved in the endogenous
enzymes of barley or intestinal bacteria which can
sufficiently degrade cell structure (Graham et al.
1986) (Table 6).

In conclusion, rolled barley showed highernutrit-
ive value compared to hammer milled and if the
incidence of gastric lesions caused by small grist
size could be depressed by using rolled cereal, then
it is preferable from the nutritional point of view.
Pelleting improved feed value of barley over the
milled form. Expanding had no benefical effect on
pellet quality or nutritive value ofbarley.

Acknowledgements. The author is grateful to Ms. Kirsi Par-
tanen, M. Agr. Sc., for computing the results and to Mr. Pasi
Laurinen for the care of the experimental animals. The co-
operation with Mr. Juhani Vuorenmaa, M. Agr. Sc. and Ms.
Stina Hakuiin, Lic. Tech. Sc. in processing the experimental
feeds and financial support from Hankkija Rehuteollisuus
Oy are greatly acknowledged.

467

Agric. Sei. Finl. 1 (1992)



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Manuscript received August 1992

Matti Näsi
University ofHelsinki
Department of Animal Science
SF-00710 Helsinki, Finland

468

Agric. Sei. Finl. 1 (1992)



SELOSTUS

Jauhatustavan, rakeistuksen ja ekspanderkäsittelyn vaikutus
ohran rehuarvoon lihasian ruokinnassa

MattiNäsi
Helsingin yliopisto

Tutkimuksessa selvitettiin vasararnyllyjauhatuksen ja litis-
tyksen, rakeistuksen sekä ekspanderkäsittelyn vaikutusta
lihasioille syötettävän ohran ravintoaineiden sulavuuteen ja
valkuaisen hyväksikäyttöön. Tutkimus tehtiin 2*2*2 fakto-
rikokeena B*B latinalaisen mallinmukaan 29 - 97 kg elopai-
noisilla lihasioilla. Litistetyn ohran partikkelikoko »li keski-
määrin suurempaa kuin vasaramyllyjauhetun. Rakeistus ja
ekspanderkäsittely pienensivät partikkelikokoa. Litistettyä
ohraa käytettäessä rakeiden laatu oli heikompi kuin vasara-
myllyjauhettua käytettäessä. Ekspanderkäsittelyllä ei ollut
parantavaa vaikutusta rakeiden kestävyyteen. Litistetyn

ohran raakaproteiinin sulavuus oli parempi kuin jauhetun.
Rakeistus paransi ohran kaikkien ravintoaineiden sulavuuk-
sia keskimäärin 0.02. Ekspanderkäsittely paransi raaka-
kuidun sulavuutta. Rakeistuksen ja ekspanderkäsittelyn sekä
jauhamistavan välillä oli sulavuudessa yhdysvaikutuksia.
Litistettyä ohraa saaneet siat pidättivät enemmän typpeä ja
valkuaisen hyväksikäyttö olitehokkaampaa kuin vasaramyl-
lyjauhettua saaneilla. Rakeistus paransi valkuaisen imeyty-
mistä, mutta sillä ei ollut vaikutusta typen pidättymiseen.
Ekspanderkäsittely ei vaikuttanut valkuaisen imeytymiseen
eikä typen pidättymiseen.

469

Agric. Sei. Fint. 1 (1992)