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Effect of cereal type, disintegration method and pelleting on
stomach content, weight and ulcers and performance in growing
pigs
*
E.K. Nielsen, K.L. Ingvartsen
Department of Animal Health and Welfare, Danish Institute of Agricultural Sciences, Research Centre Foulum, P.O. Box 50,
DK-8830 Tjele, Denmark
Received 4 April 1999; received in revised form 27 October 1999; accepted 10 January 2000
Abstract
The purpose of this study was to investigate the effects of cereal type and feed processing on the prevalence of gastric lesions in pars oesophagea, stomach size, stomach content and firmness and performance in growing pigs. Data from 320 pigs were included in a 23232 factorial experiment. The factors investigated were cereal type (barley or wheat), disintegration method (grinding or rolling) and feed form (pelleted or non-pelleted). Gastric lesions were investigated at slaughter and scored on a scale from 0 (normal) to 10 (very severe changes). The ground feed was produced on a hammer-mill, mounted with a 3-mm screen for barley and a 4.5-mm screen for wheat. Only 20% of the ground feed consisted of particles bigger than 1 mm in diameter, whereas it was approximately 50% of the rolled feed. Disintegration method and pelleting did not influence performance significantly and the differences between wheat and barley were due to the higher energy content in wheat rather than wheat per se. Wheat, ground feed and pellets reduced the empty stomach weight. Non-pelleted rolled feed increased both the firmness and dry matter percentage of the stomach content compared to ground feed. Rolled barley could be pelleted without a decrease in firmness of the stomach content as opposed to wheat. Pigs receiving rolled barley or wheat in non-pelleted form had nearly no gastric lesions (average score50.7) as opposed to pigs receiving ground barley or wheat (average score52.8). Rolled barley could be used as pellets without causing a high level of gastric lesions (average score51.3), while rolled pelleted wheat caused a high level of gastric lesions (average score54.3). The combination of ground wheat as pellets resulted in the highest score of gastric lesions (average score54.9). A high firmness of the stomach content coincided with a low score of gastric lesions. 2000 Elsevier Science B.V. All rights reserved.
Keywords: Pig-feeding; Wheat; Barley; Rolled; Ground; Stomach weight and content; Gastric lesions
1. Introduction finishing pigs that has been published varies from 2 to 100% (O’Brien, 1992; Palomo et al., 1996). The
The prevalence of gastric lesions in growing– large variations in prevalence are, at least in part, due
to the subjective assessment of the ulcer condition. Still, gastric lesions in pigs appear to have increased
*Corresponding author. Tel.:145-899-915-05; fax:1
45-899-during the last two decades. In Germany, Frerking et
915-00.
E-mail address: [email protected] (K.L. Ingvartsen). al. (1996) have reported an increase in gastric ulcers
from 1.1% in 1965–1975 to 7.7% in 1995. In a weight and the firmness of the stomach content and
recent Spanish study, the prevalence of gastric ulcers performance in growing pigs.
has been found to be 9.8% (Palomo et al., 1996). In a Danish study including 4038 growing pigs at three Danish slaughterhouses, 36% of the pigs had
2. Materials and methods
changes in the pars oesophagea. Approximately 6% of the pigs had ulcers (Nielsen, 1998).
The effect of cereal type, disintegration method The development of gastric lesions may be
in-and feed form on the prevalence in-and severity of fluenced by a number of factors related to feeding
gastric lesions, stomach weight, stomach content and and housing (Friendship, 1999). In particular, fine
performance results was investigated in a 23232
feed structure, that is small feed particles, has been
factorial design. shown to increase the prevalence of gastric lesions
(Mahan et al., 1966; Reimann et al., 1968; Maxwell
et al., 1970; Pedersen et al., 1970; Flatlandsmo and 2.1. Animals, feeding, feed composition and
¨
Slagsvold, 1971; Simonsson and Bjorklund, 1978; housing
Blackshaw et al., 1980; Kirschgessner et al., 1985;
Nielsen, 1986; Potkins et al., 1989). The pelleting of The experiment included 320 crossbred pigs from
the feed may also increase the prevalence of gastric 40 litters each consisting of 8 pigs. The distribution
ulcers (Chamberlain et al., 1967; Nielsen, 1990), but by sex was 16% castrated males, 42% intact males
the bigger the particles were prior to pelleting, the and 42% female pigs. The average initial live weight
less severe the gastric lesions appeared to be (Flat- of the pigs was 25.060.12 kg (X6SEM). Based on
landsmo and Slagsvold, 1971; Nielsen, 1986). the sex and live weight, the eight pigs from each
Cereal type influences the risk of gastric ulcers. litter were divided as evenly as possible into the
Maize has been shown to predispose to gastric eight treatment groups. Block effect was included in
ulcers, while oats prevents these lesions (Reese et al., the model to account for time when the pigs entered
1966). Wheat appears to predispose to gastric ulcers the experiment and litter effects. Since each pen
more than barley (Smith and Edwards, 1996). The housed two pigs, each block consisted of two litters
likely predisposing factor of maize and wheat is the (16 pigs).
relatively low fibre content which influences the The pens in which the pigs were housed had a
firmness of the stomach content (Johansen et al., concrete floor, which was 1 m wide and 1.65 m deep
1996; Knudsen, 1997). Generally, feed utilisation is while the dung passage with slatted floor measured
improved with increased disintegration of the feed 130.7 m. The feed dispenser had a trough length of
¨
(Simonsson and Bjorklund, 1978; Nielsen, 1986; 25 cm.
Wondra et al., 1995; Sloth et al., 1998). However, a All pigs were weighed every second week and fed
high degree of disintegration may increase the risk of according to this weight. Feed composition is shown
gastric ulcers. Consequently, there has been an in Table 1. The pigs were fed twice daily and
interest in rolling rather than grinding cereal finely received |1 l of water per kg feed during the first
for pigs (Pedersen et al., 1970). Rolled cereals may week of the growth period increasing to |2 l in the
be fed to growing pigs without compromising per- course of 1 month. The daily amount of feed was
formance significantly (Madsen et al., 1970; Simon- kept constant per kg pig irrespective of cereal type in
¨
sson and Bjorklund, 1978; Nielsen, 1993; Svane, the feed mixture to avoid possible confounding
1995) but little is known about the effects on gastric between feed intake (kg) and gastric examination. As
health. the wheat mixture contained 6% more net energy per
The objective of the current experiment was to kg feed compared to the barley mixture, the feeding
examine the effect of cereal type (barley vs. wheat), level was proportionally higher for the pigs receiving
disintegration method (ground vs. rolled) and feed wheat. Furthermore, to get a homogeneous basis for
form (pelleted vs. non-pelleted) on the prevalence evaluating the stomach content, including amount,
Table 1 by spring-loaded rollers and by adjusting the grain Feed composition and energy content flow. To ensure a sufficient compression of the Feed component % on a weight basis cereal (high degree of rolling) and to minimise the content of whole and half grains, it was necessary to
Barley mix Wheat mix
reduce the grain flow to approximately half of
Barley 70.3 0
normal capacity even though the rollers were
tight-Wheat 0 70.1
ened to the maximum. The ground feed was
pro-Soya bean meal 24.0 24.0
Fat 2.0 2.0 duced on a President hammer mill, type 50S
(Kris-Molasses 1.0 1.0 tensen, 1991). Fig. 1 shows ground and rolled barley.
Dicalcium phosphate 1.2 1.2
In a pilot study of sieve analyses, it was found that
Calcium carbonate 0.8 0.8
a 3-mm screen should be used for barley and a
Sodium chloride 0.4 0.4
4.5-mm screen for wheat in the hammer mill to
Lysine mixture (40%) 0.1 0.3
Vitamin and micro mineral mixture 0.2 0.2 obtain approximately the same particle size in the ground feed. For each new batch of feed produced,
ME (MJ / kg feed, calculated) 12.8 13.4 a
FUp / kg feed (calculated) 1.00 1.06 samples were taken of the feed mixtures for sieve
a 21 21 21 analyses to determine particle size. These analyses
FUp kg DM 5MJ NE kg DM ?7.72 5MJ ME kg
21 were performed with Retsch sieves at Research
DM ?0.7521.88 (Just, 1982).
Centre Foulum. The sieves had the following hole sizes: 4, 2, 1, 0.50, 0.25, 0.125 and 0.063 mm. the two pigs in the pen were separated and fed
individually during the week prior to slaughtering.
2.4. Pelleting and particle size in pellets Feed and water were measured out precisely in the
ratio of 1 to 2, and the pigs were denied free access
Half of each feed lot was pelleted. In the pellet to water in the week prior to slaughtering.
press, the holes of the matrix had a diameter of 5 mm and a length of 35 mm. The feed was
steam-conditioned and reached a temperature of ¯808C
2.2. Cereal type
during pelleting (Tellefsen, 1996).
In order to investigate the influence of pelleting on The diet consisted of approximately 70% barley or
particle size, 50 g of pellets were completely macer-wheat (Table 1). The diets were not corrected for the
ated in water and sieved using a 1-mm sieve. The differences in energy and fibre content due to
content was poured onto filter paper to allow most of differences between the cereal types. Pigs receiving
the water to drain off before drying at 808C. The
barley consequently had more fibre than those
re-dried sample was gently crushed on the paper and ceiving wheat on a DM basis. The content of soluble
subsequently a sieve analysis was performed. It was and insoluble fibres are 5.6 and 16.6% for barley and
thus possible to measure the proportion of particles 2.5 and 11.3% for wheat, respectively (Knudsen,
bigger and smaller than 1 mm in the pelleted feed. 1997).
Maceration time was investigated by adding water to the pellets. The degree of maceration was controlled every 5th minute and the time spent to completely 2.3. Feed disintegration and particle size
macerate the pellets in water was registered.
The feed was produced at Research Centre
Foulum. The cereal was disintegrated either by 2.5. Slaughtering
rolling to obtain a coarse feed structure or by
grinding resulting in a fine feed structure. Rolling The pigs were slaughtered at an average live
was done on a small Mortensen industrial roller, weight of 96.860.45 kg (X6SEM) at the Danish
which had two smooth rollers that were rotating with Crown Slaughterhouse in Bjerringbro. All pigs had
Fig. 1. Ground (left) and rolled barley (right).
slaughter. Around 9.00 hours, the pigs were taken the difference between the weight of the stomachs
from the pens, transported to the slaughterhouse and with and without content. Having mixed the stomach
slaughtering was commenced immediately after arri- content manually, samples were taken to determine
val at the slaughterhouse at around 10.15 hours. dry matter content and crude fibre.
After removal of the gastrointestinal tract, the Pigs from six blocks (96 pigs) were chosen for
stomachs were marked with a metal number and the determination of the consistency of the stomach
matching pig number was registered. Subsequently, content. Consistency was scored on a scale from 1
the stomachs followed the transport system to the (thin / watery) to 5 (firm). pH was measured in mixed
intestinal department. samples of the stomach content approximately 3 h
after slaughtering.
2.6. Gastric investigations The scale used in the present study to score the
observed lesions in the pars oesophagea (po) area
The gastric examination comprised various mea- was based on the scale used by Baustad and Nafstad
surements of the stomach weight, stomach content (1969) but modified to a 0–10 points scale. Types of
and firmness, and an examination of pathological changes and the matching score are illustrated in Fig.
changes in the mucosal membrane in pars 2 and were as follows:
oesophagae. The judging of the pathological changes
was done without knowledge of the previous treat- 0 Normal (pars oesophagea, ¯6311 cm)
ment of the pigs. 1 Minor parakeratosis
Fig. 2. Examples of different degrees of gastric lesions in pars oesophagea.
3 Severe parakeratosis (erosion of the epi- 5 Medium–severe gastric lesion or scar
thelium: depending on the degree of erosion, 6 Severe gastric lesion or scar, and / or crater
0.5–1.5 points were added for parakeratosis) formation surrounding the entire oesophageal
7 Reduction of pars oesophagea to approximate- gm 5systematic effect of sex; castrates, males and
ly 336 cm caused by scar and / or contraction females or mixed, hm51, . . . ,6j
of the oesophageal opening to a diameter of Bn 5random effect of block, hn51, . . . ,20j
approximately 10 mm eijlmno5random residual variation
8 Reduction of pars oesophagea to
approximate-ly 234 cm caused by scar and / or contraction The results presented in Tables 2–8 are least
of the oesophageal opening to a diameter of square means from the above model.
approximately 7 mm. The oesophagus is often slightly callused
9 Reduction of pars oesophagea to
approximate-3. Results and discussion
ly 132 cm caused by scar and / or contraction of the oesophageal opening to a diameter of
No statistical effects of sex were observed in the approximately 4 mm. The oesophagus is
cal-present study and consequently not reported or lused
discussed in the following. 10 (a) The pig died from a bleeding ulcer.
(b) Lethal contraction of the oesophageal opening to a diameter of approximately 2
3.1. Particle size mm, and the oesophagus is very callused.
The pig could drink but feed could not
Particle distribution of the feed is shown in Table pass through to the stomach.
2. The ground feed contained more of the fine and less of the coarse feed particles compared to the In case of more than one change in the stomach,
rolled feed. The ground feed contained almost twice the severest change decided the score obtained.
as many particles smaller than 0.5 mm than the rolled feed, while the rolled feed contained three 2.7. Statistical methods
times as many feed particles bigger than 1 mm compared to the ground feed. The calculated average Average results from pigs in one pen were
re-particle size was considerably bigger for the rolled garded as the experimental unit. The experimental
compared to the ground feed, 0.88 vs. 0.50 mm. The
data were analysed using the procedurePROC MIXEDin
ratio between the amount of particles bigger and
SAS (SAS Institute, 1994; Little et al., 1996) using
smaller than 1 mm was ¯0.2 for the ground and 1.1
the following model:
for the rolled feed. The barley was ground a little Yijlmno5m 1 a 1 b 1 d 1 ab 1 ad 1 bdi j l ij il jl
more finely when using a 3-mm screen than wheat,
1abd 1 l 1ijl m Bn1eijlmno which was processed using a 4.5-mm screen.
m 5least square mean
Given a good rolling technique, whole grains can
ai 5systematic effect of disintegration method, be avoided. Fig. 3 shows particle fractions from a
hi5ground, rolledj
sieve analysis of rolled and ground wheat after it has
bj 5systematic effect of cereal type, hj5wheat, been processed in a feed-mixer normally used for
barleyj
mixing the feed components of the diet. The
process-dl 5systematic effect of pelleting, hl5pelleted, ing in the feed-mixer changes the coarse structure of
non-pelletedj
the cereals after the rolling. This change occurs
abij 5systematic effect of interaction between rapidly since the particle distribution was almost
disintegration method and cereal type
identical, irrespective of the mixing period being 1, 5
adil 5systematic effect of interaction between or 15 min.
disintegration method and pelleting
bdjl 5systematic effect of interaction between
cereal type and pelleting 3.2. Effect of pelleting on particle size
abd 5ijl systematic effect of interaction between
disintegration method, cereal type and pel- To obtain a measure of the degree of
Table 2
Distribution of particles in feed mixture of barley and wheat depending on disintegration method
Disintegration method Ground Rolled
Feed mixture with Barley Wheat Barley Wheat
Screen (mm) 3 4.5 3 4.5
Particle fraction (mm)
0.063–0.125 4.4 6.4 2.0 3.1
0.125–0.25 14.6 14.7 6.9 8.1
0.25–0.5 28.2 21.8 14.3 13.3
0.5–1 38.6 34.5 26.0 22.2
1–2 13.3 21.1 39.5 32.4
Average particle size (mm) 0.48 0.51 0.86 0.90
a
Calculated average diameter of feed particles (dgw).
process, sieve analyses of pelleted feed were per- 3.3. Performance
formed after preceding maceration and drying (Table
3). The proportion of particles bigger than 1 mm in The allocated barley and wheat feed mixtures per
pelleted feed was 10% units lower in rolled wheat kg pig were the same on a weight basis. The pigs
(33%) compared to rolled barley (43%). In non- receiving the wheat mixture thus consumed
approxi-pelleted feed mixtures with rolled barley and wheat, mately 6% more net energy (P,0.001) than pigs
approximately half of the feed (52%) consisted of receiving the barley mixture due to the higher energy
particles .1 mm (Table 3). This shows that the content in wheat. The higher energy intake increased
coarse particles in rolled wheat are crushed more the daily gain by 4% (P,0.001) (Table 4). Whether
when pelleted compared to rolled barley. Maceration the feed was ground or rolled, or whether it was
time for pellets of rolled barley was 20 min com- pelleted or not had no significant effect on the daily
pared to ¯1.5 h for pellets of rolled wheat. This gain. In contrast, Wondra et al. (1995) found that
difference is probably due to water penetrating the pelleted feed has a positive effect on average daily
coarse components of the barley pellets more rapidly gain and feed efficiency. The feed conversion was
than the more crushed particles in pellets of rolled 2% lower (P,0.01) when feeding wheat compared
wheat that also contain more fat. to barley.
In general, feed conversion is getting worse when feed particles increase in size (Simonsson and
¨
Bjorklund, 1978; Nielsen, 1986; Wondra et al., 1995;
Table 3
Sloth et al., 1998). In the present experiment, rolling
Influence of pelleting on particle size in feed based on rolled
of the feed did not decrease daily gain and feed
cereal (percentage of particles .1 mm) and maceration time of
pellets in water conversion ratio compared to the ground feed. The
reason for this is most likely that the endosperm was
Cereal type in feed mixture Barley Wheat
sufficiently crushed during rolling to enable an
Before pelleting, .1 mm (%) 51 53
effective feed conversion ratio. Despite an effective
Feed macerated and dried: rolling, the coarse structure was preserved, especially Non-pelleted feed mixture,.1 mm (%) 52 47
in the husks. The wheat mixture resulted in a lean
Pelleted feed mixture,.1 mm (%) 43 33
meat content which was 0.7 percentage units lower
Maceration time of pellets (min) 20 100
Table 4
Effect of cereal type, disintegration method and pelleting on feed intake, daily weight gain, feed conversion ratio and lean meat percentage
a a a
Treatment Cereal type Disintegration method Pellets S.E.
Barley Wheat Ground Rolled 1 2
No. of pens 80 80 80 80 80 80
Culled pigs 3 5 2 6 4 4
Initial live weight (kg) 24.9 25.1 25.0 25.0 25.2 24.2 2.33
b
Final weight (kg) 95.3 98.3** 96.6 97.0 96.8 96.9 5.67
FUp per pig daily 2.15 2.28*** 2.21 2.21 2.19 2.23* 0.10
Daily gain (g) 818 852*** 833 838 833 838 52.0
FUp per kg gain 2.63 2.69** 2.66 2.66 2.65 2.67 0.13
Lean meat percentage 59.7 59.0*** 59.5 59.2 59.3 59.4 1.08
a
*, ** or *** as superscript within a row and treatment are significantly different at P,0.05, P,0.01 or P,0.001, respectively. b
Final weight5warm carcass weight31.3.
This difference could be related to the higher energy pared to the wheat mixture. This indicates that the
content of wheat, inducing a higher energy density of retention time of wheat in the stomach is shorter than
the diet and a lower protein / energy ratio. Such that of barley. This can also explain that the
variations are known to affect the lean meat content stomachs weighed less when feeding wheat
com-(Jørgensen et al., 1985). pared to barley.
3.4. Stomach weight and content 3.4.2. Disintegration method
Rolled feed increased (P,0.001) stomach weight
3.4.1. Cereal type by 9% compared to ground feed (Table 5). Similarly,
The stomach of pigs receiving barley weighed 6% rolled feed increased (P,0.001) the dry matter
more (P,0.01) than stomachs of pigs receiving percentage and firmness of the stomach content
wheat (Table 5). The dry matter percentage was compared to ground feed, but only if the feed was
higher (P,0.01) when using the barley mixture non-pelleted (Table 6, Fig. 4). A similar interaction
compared to the wheat mixture (27.1 vs. 25.0%). between disintegration method and pelleting
mani-The barley mixture resulted in a 26% larger (P, fested itself with regard to consistency of stomach
0.001) amount of dry matter in the stomach com- content (P,0.05) (Table 6).
Table 5
Influence of cereal type, disintegration method and pelleting on stomach weight and content
a a a
Treatment Cereal type Disintegration method Pellets S.E.
Barley Wheat Ground Rolled 1 2
No. of pens 80 80 80 80 80 80
Stomach weight (g) 610 578** 569 620*** 579 610** 64.0
DM in stomach (g) 617 491*** 549 559 543 565 69
b
pH (4.36) (4.30) 4.40 4.26** (4.37) (4.28) 0.27
c
Consistency score 3.0 1.8*** (1.5) (3.3***) (2.1) (2.7*) 0.48
a
*,** or *** as superscript within a row and treatment are significantly different at P,0.05, P,0.01 or P,0.001, respectively. b
Interaction between cereal type and pelleting — results in brackets. c
Fig. 3. Different particle fractions of wheat. Rolled to the left and Fig. 4. Top: Example of firm stomach content, rolled feed, ground to the right. consistency score55. Bottom: Example of liquid stomach content,
ground feed, consistency score51.
The pH was lower (P,0.01) in the stomach is in accordance with a previous investigation where
content of pigs receiving rolled feed than in pigs pH was found to be above 4.7 when pigs were fed a
receiving ground feed (4.26 vs. 4.40). This shows cracked corn diet while pH was observed as low as
that a coarse feed structure increases the concen- 3.4 when the diet was finely ground (Maxwell et al.,
tration of acids in the stomach content. This finding 1970). Stomach content pH was found to be lower
(P,0.05) in non-pelleted wheat compared to
pel-leted wheat (4.21 vs. 4.40) while no difference was
Table 6
observed between pelleted and non-pelleted barley
Interaction between disintegration method and pelleting for dry
1 (4.36 vs. 4.35).
matter and consistency score in stomach content
Disintegration method Ground Rolled S.E.
3.4.3. Pelleting
Pelleted 1 2 1 2
Pelleted feed reduced (P,0.01) stomach weight
No. of pens 40 40 40 40 by 5% from 610 to 579 g (Table 5). Regarding the
a a a b
DM (%) 25.3 24.5 25.4 28.9 4.22 consistency of the stomach content, an interaction
No. of pens 12 12 12 12
2 a a b c between cereal type and pelleting was found for
Consistency score 1.5 1.5 2.6 3.9 0.48
rolled feed (P,0.05). Pelleted rolled barley resulted
1
Figures in the same row with different superscript letters are
in a considerably firmer stomach content than
pel-significantly different at least at the 5% level.
2 leted rolled wheat (consistency score of 3.9 and 1.4
Scale from 1 to 5 (15thin / watery; 55firm). Based on 96 pigs
points; Table 7). The hard husk and endosperm of
Table 7 the treatments. The appearance of the stomach Interaction between cereal type and pelleting for consistency score mucosa in pigs receiving rolled non-pelleted wheat
1 when feeding rolled feed
was very good (stomach score50.6). Pelleting of
Cereal type (rolled) Barley Wheat S.E. rolled wheat caused pathological changes as the Pelleted 1 2 1 2 stomach score increased from 0.6 to 4.3. Pelleting of rolled barley, however, only increased the stomach
No. of pens 12 12 12 12
a a a b score from 0.8 to 1.3 (Table 8). This interaction
pH 4.35 4.36 4.40 4.21 0.27
2 a a b a
Consistency score 3.9 4.0 1.4 3.8 0.48 (P,0.01) shows that rolled barley as opposed to
1 rolled wheat could stand pelleting without increasing
Figures in the same row with different superscript letters are
significantly different at least at the 5% level. the prevalence of lesions noticeably. As mentioned
2
Scale from 1 to 5 (15thin / watery; 55firm). above, this was probably due to the fact that feed
particles of rolled barley were better preserved during pelleting than wheat particles which affected
barley was probably the reason why its structure was the consistency of the stomach content (Table 7).
better preserved during pelleting than in the case of When comparing the consistency score in Table 7
wheat. with the stomach score for rolled feed in Table 8, it
All three experimental factors, cereal type, dis- appears that a firm stomach content coincides with a
integration method and pelleting thus influenced low stomach score in accordance with Muggenburg
stomach size and the properties of the empty et al. (1964). Despite a higher occurrence of gastric
stomach weight and content. lesions in pigs fed wheat they had a better
per-formance due to the higher energy content of that
3.5. Gastric lesions diet. This shows that a high performance is not
indicative of low levels of pathological changes of
The distribution of stomach scores and average the stomach.
stomach score is shown in Table 8. The percentage Rolling as disintegration method therefore appears
of pigs with parakeratosis or gastric lesions varied to be capable of crushing the endosperm sufficiently
between 9.6 to 97.1% dependent on the diet in to avoid a reduced feed conversion ratio.
Further-accordance with previous investigations (O’Brien, more, the grain (especially the husks) are crushed in
1992; Palomo et al., 1996). In general, barley and such a way that rolled feed protects pars oesophagea
rolling prevented pathological changes of the against pathological changes.
stomach, while wheat, grinding and pelleting in- The degree of rolling is, of course, important for
creased the prevalence and severity of the changes. the degree of crushing, and in the present
experi-There were, however, interactions between some of ment, the grains were crushed or divided into
Table 8
1 Influence of cereal type, disintegration method and pelleting on gastric lesions
Cereal type Barley Wheat S.E.
Disintegration method Ground Rolled Ground Rolled
Pelleted 1 2 1 2 1 2 1 –
No. of pens 20 20 20 20 20 20 20 20
2
Normal (score 0) (%) 8.8 25.7 53.4 90.3 2.9 3.4 13.8 91.2
2
Parakeratosis (score 1–3) (%) 47.1 57.1 40.0 6.4 25.7 55.4 31.0 8.8 2
Gastric lesions (score 4–6) (%) 35.3 14.3 3.3 3.2 48.6 31.0 38.0 – 2
Severe lesions (score 7–10) (%) 8.8 2.9 3.3 – 22.8 10.2 17.2 –
2 a b bc c d a a,d c
Average stomach score 3.7 2.1 1.3 0.8 4.9 3.5 4.3 0.6 1.42
1
Figures in the same row with different letters are significantly different at least at the 5% level. 2
Just, A., 1982. The net energy value of balanced diets for growing
relatively fine particles. If the roller had been
ad-pigs. Livest. Prod. Sci. 8, 541–555.
justed to a coarser structure, the pelleted feed
Jørgensen, J.N., Fernandez, J.A., Jørgensen, H.H., Just, A., 1985.
mixture would probably have resulted in fewer Anatomical and chemical composition of female pigs and
gastric lesions. Likewise a coarser grinding would barrows of Danish Landrace related to nutrition. Z. Tierphysiol. ¨
Tierernahrg. u. Futtermittelkde 54, 253–263.
probably have reduced the prevalence of gastric
Kirschgessner, M., Roth, F.X., Bollwahn, W., Heinritzi, K., 1985.
lesions. If the ratio of particles bigger and smaller
¨
Mastleistung, Nahrstoffverdaulichkeit und
Magenschleimhaut-than 1 mm in diameter is about 1, then the pars veranderungen von Schweinen bei unterschiedlicher Futter-¨
oesophagea was without changes. struktur. I. Einfluss eines unterschiedlichen Vermahlungsgrades
des Futters. Zbl. Vet. Med. A. 32, 641–651.
The fibre content of wheat is only approximately
Knudsen, K.E.B., 1997. Carbohydrate and lignin contents of plant
62% of that of barley (Knudsen, 1997), and the feed
materials used in animal feeding. Anim. Feed Sci. Tech. 67,
composition was not corrected to obtain the same 319–338.
fibre content in the two feed mixtures. The low fibre Kristensen, E.F. 1991. Formaling og valsning af korn [Grinding content of wheat is not the primary factor causing and rolling of grain]. SjF Beretning nr. 49. 27 pp. (In Danish). Little, R.L., Milliken, G.A., Stroup, W.W., Wolfinger, R.D., 1996.
pathological changes in the gastric mucosa, as pigs
SAS System For Mixed Models. SAS Institute, Cary, NC.
receiving rolled wheat in non-pelleted form had
Mahan, D.C., Pickett, R.A., Perry, T.W., Curtin, T.M., Featherston,
healthy stomachs. This suggests that the feed struc- W.R., Beeson, W.M., 1966. Influence of various nutritional
ture or particle size is of major importance to the factors and physical form of feed on esophagogastric ulcers in
prevalence and severity of gastric lesions. swine. J. Anim. Sci. 25, 1019–1023.
Madsen, A., Mortensen, H.P., Larsen, A.E. 1970. Byg høstet ved
In the present experiment, cereal type,
disinte-højt vandindhold og tilsat propionsyre [Barley harvested at
gration method, and pelleting influenced the
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