Livestock Production Science 66 2000 271–282 www.elsevier.com locate livprodsci
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 2 3 2 3 2 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 score 5 0.7 as opposed to pigs
receiving ground barley or wheat average score 5 2.8. Rolled barley could be used as pellets without causing a high level of gastric lesions average score 5 1.3, while rolled pelleted wheat caused a high level of gastric lesions average
score 5 4.3. The combination of ground wheat as pellets resulted in the highest score of gastric lesions average score 5 4.9. 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: 145-899-
during the last two decades. In Germany, Frerking et
915-00. E-mail address
: klausl.ingvartsenagrsci.dk K.L. Ingvartsen.
al. 1996 have reported an increase in gastric ulcers
0301-6226 00 – see front matter
2000 Elsevier Science B.V. All rights reserved. P I I : S 0 3 0 1 - 6 2 2 6 0 0 0 0 1 6 5 - 2
272 E
.K. Nielsen, K.L. Ingvartsen Livestock Production Science 66 2000 271 –282
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 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 2 3 2 3 2 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
1 3 0.7 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, and severity of gastric lesions, empty stomach
consistency, and dry matter of the individual pigs,
E .K. Nielsen, K.L. Ingvartsen Livestock Production Science 66 2000 271 –282
273 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
normal capacity even though the rollers were tight-
Wheat 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 the same speed. The degree of rolling was adjusted
their last meal at 7.30–8.00 hours on the day of
274 E
.K. Nielsen, K.L. Ingvartsen Livestock Production Science 66 2000 271 –282
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, ¯ 6 3 11 cm ment of the pigs.
1 Minor parakeratosis The amount of stomach content was determined as
2 Medium-severe parakeratosis
E .K. Nielsen, K.L. Ingvartsen Livestock Production Science 66 2000 271 –282
275
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
4 Minor gastric lesion or scar entrance into the stomach
276 E
.K. Nielsen, K.L. Ingvartsen Livestock Production Science 66 2000 271 –282
7 Reduction of pars oesophagea to approximate- g
5systematic effect of sex; castrates, males and
m
ly 3 3 6 cm caused by scar and or contraction females or mixed, hm51, . . . ,6j
of the oesophageal opening to a diameter of B
5random effect of block, hn51, . . . ,20j
n
approximately 10 mm e
5random residual variation
ijlmno
8 Reduction of pars oesophagea to approximate- ly 2 3 4 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
