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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

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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,

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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

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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

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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

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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 B_n 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 Y_ijlmno5m 1 a 1 b 1 d 1 ab 1 ad 1 bd_i _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

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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

2–4 0.9 1.5 11.3 20.9

Percent.0.5 mm 52.8 57.1 76.8 75.5

Percent.1 mm 14.2 22.6 50.8 53.3

Particle ratio,.1 mm:,1 mm 0.17 0.29 1.03 1.14

Average particle size (mm) 0.48 0.51 0.86 0.90

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

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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

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

*, ** 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

pH (4.36) (4.30) 4.40 4.26** (4.37) (4.28) 0.27

Consistency score 3.0 1.8*** (1.5) (3.3***) (2.1) (2.7*) 0.48

*,** 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

Scale from 1 to 5 (15thin / watery; 55firm). Based on 96 pigs (48 pens). Interaction between disintegration method and pelleting (Table 6) and between cereal type and pelleting — results in brackets (Table 7).

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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

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

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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

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

Normal (score 0) (%) 8.8 25.7 53.4 90.3 2.9 3.4 13.8 91.2

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

Figures in the same row with different letters are significantly different at least at the 5% level. 2

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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

consis-high water content and added propionic acid]. Forsøgslab.

tency of the stomach content notably and the fre- _{Arbog, 99-102 (in Danish).}_˚

quency and severity of gastric lesions. Generally, Maxwell, C.V., Reimann, E.M., Hoekstra, W.G., Kowalczyk, T.,

factors increasing stomach content firmness are Benevenga, N.J., Grummer, R.H., 1970. Effect of diatary

particle size on lesion development and on the contents of

therefore expected to be able to prevent gastric

various regions of the swine stomach. J. Anim. Sci. 30, 911–

lesions.

922.

Muggenburg, B.A., McNutt, S.H., Kowalczyk, T., 1964. Pathol-ogy of gastric ulcers in swine. Am. J. Vet. Res. 25, 1354–1361. Nielsen, E.K., 1986. Foderets formalingsgrad, form og

fodring-References _{smetode (Feed structure, pelleting and feeding method).}

Hy-ologisk Tidskrift 7, 41–45, (in Danish).

Baustad, B., Nafstad, I., 1969. Gastric ulcers in swine. 4. Effects Nielsen, E.K. 1990. The influence of feeding on development and of dietary particle size and crude fiber contents on ulceration. health of slaughter pig stomachs and on appetite. 41th Ann. Path. Vet. 6, 546–556. Meet. EAAP, Toulouse, France, Vol. 2, p. 276.

Blackshaw, J.K., Cameron, R.D.A., Kelly, W.R., 1980. Effect of Nielsen, E.K. 1993. Indflydelse af kulhydraters struktur og

˚ ˚

feeding regimen on gastric ulceration of the pars oesophagea of foderets forarbejdning pa forekomst af mavesar hos svin intensively raised pigs. Austr. Vet. J. 56, 384–386. [Influence of carbohydrates and feed processing on gastric Chamberlain, C.C., Merriman, G.M., Lidvall, E.R., Gamble, C.T., lesions in pigs]. Internal Report 21, Danish Institute of Animal

1967. Effect of feed processing method and diet form on the Science, pp. 34-38 (in Danish).

incidence of esophagogastric ulcers in swine. J. Anim. Sci. 26, Nielsen, E.K. 1998. Foderets effekt pa mavens volumen,

mavein-˚

72–75. dholdets konsistens, mavesar og produktionsresultater hos

Flatlandsmo, K., Slagsvold, P., 1971. Effect of grain particle size slagtesvin. Effekt af kornart, foderstruktur, pelletering, fodring-and pellets on development of gastric ulcers in swine. J. Anim. smetode og strøelse [Effect of feed on stomach volume, Sci. 33, 1263–1265. consistency of stomach content, ulcers and performance in

¨ ¨

Frerking, H., Matschullat, G., Muller, E., Ikes, D., 1996. Todliche pigs. Effect of cereal type, feed structure, pelleting, feeding ¨ ¨

Magenschwurestandige Zunahme bei Schwein und Kalb. method and straw bedding]. Danish Institute of Agricultural ¨

Tierarztliche Umschau 51, 465–466. Sciences, Report no. 4., 52 pp. (in Danish).

Friendship, R., 1999. Gastric ulcers. In: Disease of Swine. Iowa O’Brien, B.B., 1992. Gastric ulcers. In: Disease of Swine. Iowa State Univ. Press, Ames, IO, pp. 685–694. State Univ. Press, Ames, IO, pp. 692–708.

¨ ´ ´

Johansen, H.N., Bach Knudsen, K.E., Sandstrom, B., Skjøt, F., Palomo, A., Carmona, L., Garcıa, A., Bravo, J., Sanchez, M., 1996. Effect of varying content of soluble dietary fibre from Pujadas, P., Dellalleau, J., 1996. Study about incidence of wheat flour and oat milling fractions on gastric emptying in gastroesophagic ulcers in Spanish pig production. In: Proc. of pigs. Br. J. Nutr. 75, 339–351. the 14th IPVS Congress, Bologne, Italy, p. 711.

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Pedersen, K.B., Nielsen, E.K., Madsen, A., 1970. Mavesar hos dhed, salmonella-forebyggelse og produktionsresultater hos svin (Gastric lesions in growing pigs). Ugeskrift for agronomer slagtesvin [The effect of particle size and heating treatment / 47, 952–955, (in Danish). pelleting of feed on gastric lesions, prevention of salmonellosis Potkins, Z.V., Lawrence, T.L.J., Thomlinson, J.R., 1989. and performance in growing pigs]. National Committee for Pig Oesophagogastric parakeratosis in the growing pig: effects of Breeding, Health and Production-Danish Bacon and Meat the physical form of barley-based diets and added fibre. Res. Council, Report no. 385 (in Danish)

Vet. Sci. 47, 60–67. Smith, W.J., Edwards, S.A., 1996. Ulceration of the pars Reese, N.A., Muggenberg, B.A., Kowalczyk, T., Hoekstra, W.G., oesophagea— the role of a factor in wheat. In: Proc. of the

Grummer, R.H., 1966. Effect of corn, wheat, oats and alfalfa 14th IPVS Congress, Bologne, Italy, p. 693.

leaf meal on the development of gastric ulcers in swine. J. Svane, M. 1995. Foderstrukturens betydning for produktionsresul-Anim. Sci. 25, 21–24. taterne og mave-tarmsundheden hos slagtesvin fodret med

Reimann, E.M., Maxwell, C.V., Kowalczyk, T., Benevenga, N.J., vadfoder [The effect of feed structure on performance and Grummer, R.H., Hoekstra, W.G., 1968. Effect of fineness of gastric lesions in slaughter pigs receiving wet feed]. National grind of corn on gastric lesions and contents of swine. J. Anim. Committee for Pig Breeding, Health and Production-Danish Sci. 27, 992–999. Bacon and Meat Council, Report no. 303 (in Danish).

SAS Institute, 1994. SAS / STAT* Software: Changes and En- Tellefsen, L., 1996. Handbog i Pilleteringsteknik (Handbook in hancements, Release 6.10. SAS, Cary, NC. Feed Pelleting Techniques). Sprout-Matador, Esbjerg, (in

Dan-¨

Simonsson, A., Bjorklund, N.-E., 1978. Some effects of the ish).

fineness of ground barley on gastric lesions and gastric contents Wondra, K.J., Hancock, J.D., Behnke, K.C., Stark, C.R., 1995. in growing pigs. Swed. J. Agric. Res. 8, 97–106. Effects of mill type and particle size uniformity on growth Sloth, N.M., Tybirk, P., Dahl, J., Christensen, G. 1998. Effekt af performance, nutrient digestibility, and stomach morphology in

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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

2–4 0.9 1.5 11.3 20.9

Percent.0.5 mm 52.8 57.1 76.8 75.5

Percent.1 mm 14.2 22.6 50.8 53.3

Particle ratio,.1 mm:,1 mm 0.17 0.29 1.03 1.14

Average particle size (mm) 0.48 0.51 0.86 0.90

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

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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

*, ** or *** as superscript within a row and treatment are significantly different at P,0.05, P,0.01 or P,0.001, respectively.

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

pH (4.36) (4.30) 4.40 4.26** (4.37) (4.28) 0.27

Consistency score 3.0 1.8*** (1.5) (3.3***) (2.1) (2.7*) 0.48

*,** or *** as superscript within a row and treatment are significantly different at P,0.05, P,0.01 or P,0.001, respectively.

Interaction between cereal type and pelleting — results in brackets.

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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

_{(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

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.

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

(48 pens)

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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

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

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

Normal (score 0) (%) 8.8 25.7 53.4 90.3 2.9 3.4 13.8 91.2

Parakeratosis (score 1–3) (%) 47.1 57.1 40.0 6.4 25.7 55.4 31.0 8.8

Gastric lesions (score 4–6) (%) 35.3 14.3 3.3 3.2 48.6 31.0 38.0 –

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

Figures in the same row with different letters are significantly different at least at the 5% level.

(5)

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

consis-high water content and added propionic acid]. Forsøgslab.

tency of the stomach content notably and the fre-

_{Arbog, 99-102 (in Danish).}_˚

quency and severity of gastric lesions. Generally,

Maxwell, C.V., Reimann, E.M., Hoekstra, W.G., Kowalczyk, T.,

factors increasing stomach content firmness are

Benevenga, N.J., Grummer, R.H., 1970. Effect of diatary particle size on lesion development and on the contents of

therefore expected to be able to prevent gastric

various regions of the swine stomach. J. Anim. Sci. 30, 911–

lesions.

922.

Muggenburg, B.A., McNutt, S.H., Kowalczyk, T., 1964. Pathol-ogy of gastric ulcers in swine. Am. J. Vet. Res. 25, 1354–1361. Nielsen, E.K., 1986. Foderets formalingsgrad, form og

fodring-References

_{smetode (Feed structure, pelleting and feeding method).}

Hy-ologisk Tidskrift 7, 41–45, (in Danish).

Blackshaw, J.K., Cameron, R.D.A., Kelly, W.R., 1980. Effect of Nielsen, E.K. 1993. Indflydelse af kulhydraters struktur og

˚ ˚

1967. Effect of feed processing method and diet form on the Science, pp. 34-38 (in Danish). ˚

incidence of esophagogastric ulcers in swine. J. Anim. Sci. 26, Nielsen, E.K. 1998. Foderets effekt pa mavens volumen, mavein-˚

72–75. dholdets konsistens, mavesar og produktionsresultater hos

¨ ¨

Frerking, H., Matschullat, G., Muller, E., Ikes, D., 1996. Todliche pigs. Effect of cereal type, feed structure, pelleting, feeding ¨ ¨

Magenschwurestandige Zunahme bei Schwein und Kalb. method and straw bedding]. Danish Institute of Agricultural ¨

Tierarztliche Umschau 51, 465–466. Sciences, Report no. 4., 52 pp. (in Danish).

¨ ´ ´

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Dan-¨

Simonsson, A., Bjorklund, N.-E., 1978. Some effects of the ish).