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Osteochondrosis in six breeds ofslaughter pigsS.A. Goedegebuure a , H. J. Häni b , P. C. van der Valkc & P. G. van der Wal da Department of Veterinary Pathology , StateUniversity of Utrecht , Biltstraat 172, Utrecht, 3572BP, the Netherlandsb Institut für Tierpathologie , Länggasstrasse 122,Bern, 3000, Switzerlandc Department of Veterinary medicine , State Universityof Utrecht , Yalelaan 10, Utrecht, 3584 CM, theNetherlandsd Research Institute for Animal Husbandry‘Schoonoord’ , Driebergseweg 10 d, P.O. Box 501,Zeist, 3700 AM, the NetherlandsPublished online: 01 Nov 2011.

To cite this article: S.A. Goedegebuure , H. J. Häni , P. C. van der Valk & P. G. van derWal (1980) Osteochondrosis in six breeds of slaughter pigs, Veterinary Quarterly, 2:1,28-41, DOI: 10.1080/01652176.1980.9693755

To link to this article: http://dx.doi.org/10.1080/01652176.1980.9693755

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Osteochondrosis in six breeds of slaughter pigs

I. A morphological investigation of the status ofosteochondrosis in relation to breed and level offeeding

S. A. Goedegebuuret, H. J. Eldni2, P. C. van der Valk3 andP. G. van der Wa14

SUMMARY

The severity and extent of osteochondral lesions have been examined, macroscppi-cally, radiographically as well as histopathologically, in six different breeds of pigs(Belgian Landrace (B), Duroc (D), Dutch Landrace (N), Dutch Yorkshire (G),Hampshire (H) and Pietrain (P)). In these pigs three different levels of feedingwere used.Duroc pigs had significantly more severe lesions in the fore limbs than DutchLandrace (N), Dutch Yorkshire (G), Hampshire (H) and Pietrain (P) pigs, whileBelgian Landracepigs(B)had significant more severe lesions than Dutch Yorkshire(G) pigs. The differences between breeds related more to the degree of severityof the lesions in the articular surfaces of the distal humerus and pro.ximal radius-ulna and in the distal ulnar growth plate than to the presence of the lesions per se.In the hind limbs Belgian Landrace pigs (B) had significantly more severeosteochondral lesions than all other breeds, while Dutch Landrace pigs (N) hadsignificantly more severe lesions than Duroc (D), Dutch Yorkshire (G), Hamp-shire (H) and Piétran (P) pigs.Pigs with the highest growth rate showed sginificantly more severe osteochondrallesions in the distal ulnar growth plate and in the medial fe, m oral condyle thanpigs with a more restricted growth rate.

INTRODUCTIONOsteochondrosis can be defined as gene-ralized disturbance of enchondral ossifi-cation as well in joint cartilage andgrowth plates. Formerly, arthrosis defor-mans tarsi, epiphysiolysis capitis femoris,apophysiolysis tuberis ischiadici,osteoarthrosis and polyarthrosis were

considered as separate entities. In recentyears these lesions have been recognizedas being of the same nature and are nowconsidered to be expressions of a genera-lized disease. The term osteochondrosiswas first suggested by Ljunggren andReiland (14) and has been now wellaccepted. The incidence of osteochon-

I Department of Veterinary Pathology, State University of Utrecht, Biltstraat 172, 357e BP Utrecht,the Netherlands.

2 At the time staffmember of the same Institute; present adress: Institut für Tierpathologie, LAnggas-strasse 122, 3000 Bern, Switzerland.

3 Department of Veterinary medicine, State University of Utrecht, Yalelaan 10, 3584 CM Utrecht, theNetherlands.

4 Research Institute for Animal Husbandry 'Schoonoord', Driebergseweg 10 d, P.O. Box 3700 AMZeist, the Netherlands.

28 TIIE VETERINARY QUARTERLY, VOL 2, No. I, JAN. 1980

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drosis in modern pigs is nearly 100%. Thedisease occurs in slaughter and breedingpigs with world wide distribution. Thelesions are generally characterized byaseptic predominantly mechanical inju-ries of growing cartilage. The macrosco-pical, microscopical and radiographicalfeatures of osteochondral lesions are welldocumented (4, 6, 7, 8, 9, 12, 16, 19, 21,22, 23). This applies especially for thepredilection sites of the lesions, such asthe medial femoral condyle and thegrowth plates of the distal ulna, proximalfemur and humerus. For that reason adetailed description of the different typesof lesions found in this study will not berepeated here. Apparently many factorscause or aggravate the osteochondrallesions. However it is generally believedthat mechanical overloading, induced bya constant selection for rapid growth andmuscle mass, which results in a severeunbalance between live weight and theimmature skeletal frame, is the mostimportant factor.According to the literature (4, 8, 9, 16, 19,23) there is a strong relationship betweenosteochondrosis and leg weakness, a cli-nical syndrome characterized by anoma-lies of attitude and gait and difficulties torise and mount.In the Netherlands there are only fewreports about leg weakness and osteo-chondrosis (7, 13, 15, 23). At the end of1975 a study committee was establishedby the coordination committee 'Huis-vesting en verzorging' of the 'Neder-landse Raad van LandbouwkundigOnderzoek' (NRLO), with the instruc-tion to analyse the problem of leg weak-ness by literature review and torecommend concrete possibilities forinvestigation of the problem in theNetherlands. The work of this study com-mittee resulted in an extensive literaturereview (1). It was concluded that criteriacharacterizing the severity and extent ofosteochondrosis should be established.Further work should deal with the pos-sible correlation between the severity ofleg weakness and the extent and severityof osteochondrosis.In the present paper osteochondrosis isclassified to extent and severity. Lesion

Tim VETERINARY QUARTERLY, VOL 2, No. I. JAN 1980

scores will be correlated with differentbreeds and levels of feeding.

MATERIAL AND METHODS

Six lines of pigs from the Research Institute forAnimal Husbandry 'Schoonoord' (IVO) at Zeistwere used. These lines of pigs were of six differentbreeds: Belgian Landrace (B), Duroc (D), DutchLandrace (N), Dutch Yorkshire (G), Hampshire(H) an Piétrain (P) (Table 1).All pigs were housed in an environmentally control-led piggery with 64 individual pens. All pens hadpartly slatted and partly insulated, concrete floors.No bedding was used. The piglets came into thepiggery at a live weight of 19 to 24 kg.Pigs were fed appropriate diets (3). The level offeeding was based on a regime for Piétrain pigs (3).Pigs were divided in three groups with differentlevel of feeding (food intake) (3): one group was fedad libitum (A), one group received a middle (M)level (+ 8% of the Pietrain regime) and one receiveda low (L) level (-6% of the Piétrain regime) (Table1).

A total of 119 castrated male pigs were used. Thepigs were slaughtered when a live weight between 96and 100 kg was reached. The average time in daysbetween arrival in the piggery and slaughter depen-ded of the feeding regime: for the A-group 107(85-165); for the M-group 135 (91-155) and for theL-group 152 (111-174).At slaughter all pigs were dissected according to theIVO dissection method (2). Humerus, radius-ulna,femur and os ischii of the right carcass were exa-mined at osteochondral lesions. The joint cartilageof the proximal and distal humerus, radius-ulnaand femur were investigated macroscopically. Then2-3 mm thick bone slabs were sawed from the centreof the proximal humerus, femur, the tuber ischiadi-cum and the distal radius-ulna and in a sagittalplane of the medial femoral condyle with a bandsaw. The growth plates and theosteochondral junc-lions were than inspected macroscopically. Radio-graphs were made of all slabs using a Faxitron(Hewlett-Packard, McMinnville, U.S.A.) andindustrial films (Structurix D 4, Agfa-Gevaert, Bel-gium). After formalin fixation, the slabs were decal-cified using a mixture of formic acid and sodiumformiate, and paraffin embedded, 6 IA sections weremade and stained with haematoxylin-eosin andAzan.The breed and level of feeding of the pig wasunknown at the time of post-mortem examination.Information obtained from the macroscopical,radiographical and histological findings weregathered and expressed as a lesion score for each ofthe different areas of bone and cartilage examined.Statistical analysis was made of the three feedinglevels and within the six breeds, according to stan-dard methods of statistical analysis. P-valuescalcu-lated by t-test were always performed by comparingtwo breeds or feeding groups.Pathomorphological data were unavailable fromsome areas in some pigs, hence there is some varia-bility in the total numbers of locations examined.

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Table I. Number of pigs used to determine the presence and severity og osteochondrosis. dividedin six breeds of pigs on three levels of feeding.

Breed Total number Number of pigs of each breed in groupswith different levels of feedingad libitum (A) middle (M) low (L)

Belgian Landrace (B) 16

Duroc (D) 18

Dutch Landrace (N) 26

Dutch Yorkshire (G) 21

Hampshire (H) 19

Pietrain (P) 19

Total 119

RESULTS

Proximal humerus. The head of thehumerus toward the intertuberal grooveshows in nearly all cases shrunken areasof thin reddish cartilage, and with nodemonstrable changes in the subchon-dral bone tissue. However, the severityand extent of the joint cartilage lesionsdiffered in each individual animal, thedifferences diverged too little to scorethem. However a better classificationcould be made of the other structuralchanges. Due to degenerative changes inthe growth plates and by a differentgrowth potential of the cartilage thedevelopment of the growth plates of thehumoral head and the lateral tuberosityis altered, resulting in flattening andmedial displacement of the head of thehumerus. At the same time a partial pre-mature closure of the growth plate occursand epiphyseal and metaphyseal trabecu-lar bone fuse focally, forming a counter-balance for the medial displacement.

5 , 4 7

6 9 3

7 9 10

6 7 8

6 7 6

4 7 8

4234 43

According to Dämmrich and Unshelm(6) the increased severity and extent ofthese changes were expressed in a scorefrom 0 to 3.0: normal structure; the growth plate

forms a flat convex arch, the head andtuberosity are separated by a verti-cally running cartilage plate

I: flattening of the head; the growthplate shows at the top an obviousbend, while the growth plate itself itnot interrupted

2: as 1, but at the same time an interrup-ted growth plate is present betweenthe head and the tuberosity

3: as I, but an interrupted growth plateby trabecular bone from epiphysis tometaphysis is present.

In nearly 75% of the cases examinedlesions were found and the distribution isas follows: 33 of type 1; 31 of type 2; 25 oftype 3 and 28 were normal. There was nosignificant difference noted betweenbreeds and feed groups (Table 2).

Table 2. Mean lesion scores of structural changes in the proximal humerus in six breeds of pigson threedifferent levels of feeding.

-Breed n x Sx Level of feeding

15

18

26

20

19

19

Sx

42 1.5 1.2

41 1.5 1.1

A 34 1.4 1.0

Total 117 1.5 1.1

Total 117 1.5 1.1

No significant differences between the breeds or between the groups with different levels of feeding.

30 THE VETERINARY QUARTERLY, VOL 2, No. I, JAN. 1980

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1.7 1.1

1.5 1.1

1.5 9.91.5 1.1

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Distal humerus. The severity and extentof joint cartilage lesions were expressedin a score from 0 to 3, as outlined below.0: normal cartilage1: small atrofic lesions, invaginations or

grooves in the joint cartilage2: as 1, but larger and with more severe

irregularities3: large areas with defects, cartilage

exostoses or osteochondrosisdissecans.

With the exception of some cases thesechanges were always noted in the lateralcondyle. The following distribution waspresent: 32 of type 0, 52 cases of type 1,18of type 2 and 7 of type 3. The mean lesionscore for Duroc pigs (D) was significantmore severe than for Dutch Landrace(N), Hampshire (H) and Piétrain (P)pigs, while for Belgian Landrace pigs (B)it was significantly more severe thanDutch Landrace pigs (N). There was nosignificant difference between pigs with adifferent level of feeding (Table 3).Proximal radius and ulna. Lesion scores,0 to 3, were based on the severity andextent of the osteochondral changes inthe synovial grooves and articular sur-face of the semilunar notch and the gle-noid cavity. The different grades were

nearly similar as those for the distalhumerus. Lesions were found in all pigsand had the following distribution, 66 oftype 1, 46 of type 2 and 7 of type 3. Durocpigs (D) had significantly more severechanges than Dutch Yorkshire (G) andPiétrain (P) pigs. There was no signifi-cant difference between pigs with a diffe-rent level of feeding (Table 4).Distal ulna. Changes in the growth plateand the resulting changes in enchondralossification in the metaphysis were classi-fied in a lesion score from 0 to 5 (Fig. 1).Whereas 0 was normal, in type I and 2there were small focal or severe genera-lized degenerative changes in the growthplate, characterized by unevenly thick-ened cartilage with clefts and necrosis. Intype 3, 4 and 5 there were also disturban-ces in the metaphysis, varying from smallfocal irregularities to changes affectingthe entire area. These changes were cha-racterized by diminished enchondralgrowth, trabecular collapse, necrosis,hemorrhages, fibrosis, islets of cartilageand sclerosis. Type 0, 1 and 2 could onlybe classified at microscopical level, whiletypes 3, 4 and 5 could be seen macro-scopically and on radiographs. In onlyone case were no lesions found, 22 pigs

Table 3. Mean lesion scores of osteochondrosis in the distal humerus in six breeds of pigs on threedifferent levels of feeding.

Breeds n x Sx Level of feeding n x Sx

16 1.4 1.0 39 1.1 0.9

18 1.4 0.8 40 1.0 0.8

20 0.6 0.8 A 30 0.8 0.9

19 0.9 0.8

19 0.8 1.0Total 109 1.0 0.9

17 0.9 0.6

Total 109 1.0 0.9

D significantly worse than Nxx, Hx and Px 1)

B significantly worse than Nx

1)x.05>P>.01 (t-test according to Student)

xx.01>P>.001

xxx. P<.001

THE VETERINARY QUARTERLY, VOL 2, No. 1, JAN. 1980 31

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Table 4. Mean lesion scores of osteochondrosis in the proximal radius and ulna in six breeds of pigson three different levels of feeding.

Breed n x Sx Level of feeding n x Sx

16 1.7 0.9 42 1.6 0.718 1.8 0.6 43 1.5 0.626 1.5 0.5 A 34 1.4 0.621 1.3 0.5

Total 119 1.5 0.619 1.5 0.619 1.4 0.5

Total 119 1.5 0.6

D significantly worse than Gx and Px 1)

See Table 3.

had lesions of type 1, 34 of type 2, 29 oftype 3, 28 of type 4 and 5 of type 5.Duroc pigs (D) had the most severe le-sions, followed by the Belgian Landracepigs (B) and Dutch Landrace pigs (N).These three breeds were significantlymore severe than the Hampshire pigs(H),Pietrain pigs (P) and Dutch Yorkshirepigs (G), in that order. Pigs fed ad libitumhad significantly more severe lesions thanthose fed at L or M levels (Table 5).Proximal kinur. Joint cartilage and sub-

chondral bone lesions could not bescored. The other structural changeswere similar to those seen in the proximalhumerus.

With increasing severity the head of thefemur slips down dorso-laterally, is flat-tened and broadened and the trabeculaehave interrupted the lateral part of thegrowth plate. The following lesion scorefrom 0 to 3 was made (Fig. 2), accordingto Dämmrich and Unshelm (6).

Table 5. Mean lesion scores of osteochondrosis in the distal growth plate of the ulna in six breeds of pigson three different levels of feeding.

32

Breed n Sx Level of feeding n x Sx

16 3.1 1.2 42 2.2 1.018 3.4 1.2 43 2.6 1.226 3.0 1.1 A 34 3.2 1.121 2.1 1.2

Total 119 2.6 1.219 2.2 0.919 2.1 0.9

Total 119 2.6 1.2

D significantly worse than Gxx, Hxx and Pxxx 1)N significantly worse than Gxx, Hx and PxxB significantly worse than Gxx, Hxx and PxxA significantly worse than Lxxx and MxxSee Table 3.

THE VETERINARY QUARTERLY, VOL. 2. Na I. JAN 1980

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Fig.

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34 THE VETERINARY QUARTERLY, VOL, 2, No. I JAN. 1980

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Fig. 2. Radiographs of a frontal section of the proximal femur with different stages of structural changes.A. type 0, normal structure. B. type I, broadened and flattened femoral head to lateral with initiating crestforming (arrow). C. type 2, as B, but with irregular trabecular structure in the metaphysis (arrow).D. type 3, as B, but more pronounced and with a growth plate interrupted by fusion of epiphyseal andmetaphyseal trabeculae (arrow).

0: normal structure, the head is nearly ahalf circle, the growth plate of thehead is divided by a protuberanceinto a large medial and a small lateralportion

I: broadening and flattening of thehead, with normal growth plate

2: as I, but more severe and with irregu-lar trabecular structure in themetaphysis

3: as 2, but with a growth plate interrup-ted by fusion of epiphyseal andmetaphyseal trabeculae.

45 Cases were classified 0, 33 as I, 26 as 2and 7 as 3. The Belgian Landrace pigs (B)and Dutch Landrace pigs (N) had more

severe lesions and were both significantlymore severe than the other four breeds,while the Hampshire pigs (H) were, sig-nificantly, the best. There was no signifi-cant difference between pigs with adifferent level of feeding (Table 6).Distal femur. Lesions-in the lateral partof the medial femoral condyle includedifferent stages of osteochondrosis disse-cans. In normal condyles (type 0) theshape of the articular surface is convexwith regular thickness and regularenchondral ossification. The differentstages of a development into the endstage of osteochondrosis dissecans wereclassified from type I to type 5 (Fig. 3).

Table 6. Mean lesion scores of structural changes in the proximal femur in six breeds of pigs on threedifferent levels of feeding.

Breed n x Sx Level of feeding n-x Sx

16 1.6 1.0 39 1.2 1.0

18 0.7 0.8 38 0.9 1.0

20 1.6 0.9 A 34 0.8 0.9

21 0.8 0.9

19 0.3 0.5Total 111 1.0 0.9

17 0.8 0.7

Total III 1.0 0.9

Cxx, Bxxx px 1)N significantly worse than Dxx,B significantly worse than Dxx, Gx, Hxxx and Px

,Gx ,PxH significantly better than Nxxx and Bxxx

' See Table 3.

TIE VETERINARY QUARTERLY, VOL 2, No. I, JAN. 1980 35

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Fig.

3.

Sagi

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the

med

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and

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1: locally flattened and thickened articu-lar cartilage with small degenerativechanges

2: as 1, but with locally irregularenchondral ossification resulting inlack of trabeculae, and fibrosis

3: as 2, but with more extensive irregu-lar enchondral ossification and sepa-ration of the osteochondral junction

4: as 3, but more severe and with severedegenerative changes in the still intactarticular cartilage

5: as 4, but with splitting, separating,folding or absence of cartilage.

Six pigs were normal, while changes in 32pigs were classified as type 1, 34 as type 2,21 as type 3, 15 as type 4 and 4 as type 5.Pigs of .the Belgian Landrace (B) hadobvious more severe lesions and themean lesion score was significantly moresevere than the other five breeds. Secondin order were pigs of the Dutch Landrace(N) but the mean lesion score was onlysignificantly more severe than the Duroc(D), Hampshire (II) and Pietrain (P)pigs.The mean lesion score for pigs fed adlibitum (A) was more significant than themean lesion score of pigs fed at the Mlevel (Tabel 7).Tuber isehiadieum. Osteochondrallesions in the growth plate of the tuberischiadicum were present in most ani-

mals, but the variability in the lesions wastoo limited to draw conclusions aboutdifferences between breeds or levels offeeding. This applied also for osteochon-dral lesions found in the articular carti-lage of the distal radius and lateralfemoral condyle and in the growth plateof the distal radius and medial femoralcondyle.

The calculated combined lesion scoresfor fore limbs and hind limbs are summa-rized in Table 8 and 9. In total, fore limbsof Duroc pigs (D) had the most severelesions, even significantly more severethan Dutch Landrace (N), Dutch York-shire (G), Hampshire (H) and Piétrain(P) pigs. Next in order were Belgian Land-race (B) pigs, lesions in these pigs weresignificantly more severe than DutchYorkshire (G) pigs. Belgian Landrace (B)pigs also had significantly more severelesions than all other breeds in the totalfemur, followed by the Dutch Landrace(N) (significantly more severe thanDuroc (D), Dutch Yorkshire (G), Hamp-shire (H) and Piétrain (P) pigs) andDutch Yorkshire (G) (significantly moresevere than Hampshire (H) pigs) pigs.Pigs fed at the A and the L levels offeeding had significantly more severelesions in the femurs than pigs fed at theM level.

Table 7. Mean lesion scores of osteochondrosis in the medial femoral condyle in six breeds of pigs onthree different levels of feeding.

Breed n x Sx Level of feeding Sx

16 3.6 0.9 39 2.2 1.2

18 1.7 1.2 39 1.8 1.2

21 2.5 1.0 A 34 2.6 1.2

21 2.1 1.1

Total 112 2.2 1.219 1.6 1.0

17 1.7 1.2

Total 112 2.2 1.2

Nxx, exx, Hxxx pxxx 1)B significantly worse than Dxxx,

N significantly worse than Dx, Hxx and Px

A significantly worse than Mxx

See Table 3.

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Table 8. Mean combined lesion scores of osteochondral lesions of the long bones (see Table 2-5) of thefore limb in six breeds of pigs on three different levels of feeding.

Breed n2) Sx Level of feeding n2) -x Sx

B 15 7.2 1.6 L 38 6.3 1.7D 18 8.1 1.6 M 35 6.5 1.9N 16 6.3 1.8 A 30 7.0 2.0G 18 5.7 1.3 Total 103 6.6 1.8H 19 6.1 1.9

P 17 6.1 1.8

Total 103 6.6 1.8

xxx, Hxx and Pxx 1)D significantly worse than Nxx, G

B significantly worse than Gxx

' See Table 3.2 Comparisons were only made using animals from which the lesion score of all parts was known.

Combined mean lesion scores for all sitesexamined are given in Table 10. BelgianLandrace (B) pigs had far out the mostsevere combined mean lesion scores,which were more higher, significant, thanall other breeds. Next in order were theDuroc pigs (D)(significantly more severethan Dutch Yorkshire (G), Hampshire(H) and Piétrain (P) pigs), followed by

the Dutch Landrace (N) (significantlymore severe than Dutch Yorkshire (G)and Hampshire (H) pigs) pigs. Pigs fed atthe A level of feeding had significantlymore severe lesions than pigs fed at the Mlevel.

DISCUSSION

Breed differences in the occurence of leg

Table 9. Mean combined lesion scores of the osteochondral lesions of the femur (see Table 6 and 7) insix breeds of pigs on three different levels of feeding.

Breed n2). -

x Sx Level of feeding n2) -

x Sx

15 5.2 1.4 38 3.3 1.7

18 2.3 1.4 35 2.5 1.616 4.0 1.3 A 30 3.3 1.7

18 2.8 1.3 Total 103 3.0 1.719 1.8 1.2

17 2.5 1.5

Total 103 3.0 1.7

Nx, Cxxx, Hxxx ',XXX )B significantly worse than Dxxx,

N significantly worse than Dxx, Gx, Hxxx and Pxx

G signif icantly worse than HxA and L significantly worse than Mx

I See Table 2.2 See Table 8.

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weakness and osteochondrosis have beensuggested by several authors (5, 10, 11,16, 17, 18, 20, 23). However, it concernedin nearly all cases differences in occur-rence between the Yorkshire breed andseveral types of Landrace pigs, such asDutch, German, Norwegian and SwedishLandrace pigs (10, 11, 16, 17, 18, 20, 23).Only Dammrich et al. (5) investigateddifferences between some other breeds,such as Weideschwein, Pietrain, Manga-lica and Gottinger minipigs. In nearly allthe references mentioned above only oneor two predilection sites for osteochon-drosis were investigated; only Grondalen(10) considered all the predispositionsites for osteochondrosis in relation tobreed differences.A comparison between six breeds withregard to nearly all predilection sites hasnot been made previously. Only the lum-bar intervertebral joints could not be exa-mined (for technical reasons) in ourmaterial.In our material the animals were housedunder identical conditions, the only vari-able being three different levels of feed-ing. Therefore, the different rate ofgrowth resulted in different average timesbetween arrival in the piggery andslaughter. The six breeds of pigs were

approximately distributed among thethree feeding regiments, therefore, com-parison between breeds is justifiable. Thedifferences in osteochondral lesionswhich were observed should thereforereflect genetical factors.The great variability in time from arrivalto slaughter between individual pigs ofeach of the feeding groups was not causedby breed influence, however the numberof pigs of the various breeds in eachgroup was too small to draw definite con-clusions concerning the separate breeds;nor it was caused by the presence of clini-cal disease during life. This variability intime could not be explained.In all 119 pigs examined lesionswere pre-sent in various sites. The morphologyand sites of the osteochondral lesionswere similar to those descriptions byother authors (4, 6, 7, 8, 9, 12, 16, 19, 21,22, 23).In our material only right carcass halveswere examined, however it is well docu-mented (8, 16) that the extension and theseverity of osteochondrosis is bilateralsymmetrical.An order in the mean lesion scores ofvarious areas examined in the six diffe-rent breeds could be made. However sig-nificant breed differences were onlY re-

Table 10. Mean combined lesion scores of osteochondral lesions in the long bones (see Table 2-7) of thefore- and hind limbs in six breeds of pigs on three different levels of feeding.

Breed n2) -

Sx Level of feedingn2) -

x Sx

15 12.4 2.1 38 9.6 2.4

18 10.4 1.8 35 9.0 2.4

16 10.2 2.5 A 30 10.3 2.9

18 8.5 1.9

Total 103 9.6 2.619 7.9 2.3

17 8.6 2.2

Total 103 9.6 2.6

Nx, Cxxx, Hxxx pxxx I)B significantly worse than Dxx,

D significantly worse than Gxx, Hxxx and Px

N significantly worse than Gx,

A significantly worse than Mx

I See Table 3.2 See Table 8.

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lated to one or more areas and not allareas.The calculated mean combined lesionscores for all sites examined in both fore-and hind limb (Table 10) must be readcarefully. Areas of the fore limbs (fourdifferent areas) are overrepresented withregard to the hind limbs (two differentareas). For that reason Duroc (D) pigshave a relative high mean combinedlesion score. For Belgian (B) and DutchLandrace (N) pigs the data are morerepresentative.The differences in osteochondral lesionswhen comparing Landrace and York-shire pigs are in agreement with others (5,10, 11, 16, 20, 23). For the other breeds nodata are available.

Differences in degree of osteochondrallesions among Landrace and Yorkshirepigs are partly due to differences in ex-terior conformation (back length, struc-tural development of the hind quartersand femur length), joint stability and jointshape (10, 20). Unfavourable exteriorconformation, joint instability and unfa-vourable joint shape leads to local over-loading which results in more severeosteochondrosis (10). Unfavourable jointshape of the stifle and elbow joints is themost serious. In our material there wasalso a positive correlation between theseverity of the femoral osteochondrallesions and carcass length and relativeweight of the hams. The results of thisinvestigation are published elsewhere(24).However joint instability and joint shapecould not be measured in our material, itseems reasonable to assume that differen-ces in these characteristics are also partlyresponsible for the differences in degreeof osteochondrosis between the variousbreeds.In spite of different age, it was found thatpigs with a high growth rate (group A)had significantly more severe lesions thanpigs of the other groups (L and M) in thedistal ulnar growth plate and in themedial femoral condyle. These areas arethose in which lesions were most consist-antly found. When evaluating separatebreeds this significance was present in allbreeds, with the exception of the Piétrain

40

(P) pigs in the medial femoral condyle;however the number of pigs of thevarious breeds in each group was toosmall to draw definite conclusions con-cerning the separate breeds. The relationbetween high levels of feeding and moresevere osteochondral lesions at these siteshas been demonstrated by others too (6).The finding of significantly more severelesions for the L group with regard to theM group in the total femur (Table 9)could not be explained.The relationship between osteochondrallesions and the degree of leg weakness inindividual pigs can not be answered bythis study and will be the subject of an-other study.

CONCLUSIONS

In all pigs of the six breeds there wasno pig without osteochondral lesions.Between some breeds significant dif-ferences in severity of osteochondrallesions were found in several joints orgrowth plates examined.Duroc pigs have the most severeosteochondral lesions in the articularsurfaces and growth plates of the forelimb, these lesions are significantlymore severe than in most otherbreeds.Belgian and Dutch Landrace pigshave significantly more severe osteo-chondral lesions in the femur thanother breeds.Belgian Landrace pigs have signifi-cantly more severe osteochondrallesions in the entire skeleton thanother breeds, next in order are theDutch Landrace pigs.Pigs with a rapid growth have signifi-cantly more severe osteochondrallesions in the growth plate of the dis-tal ulna and in the medial femoral con-dyle than pigs with a lower growthrate.

ACK NOWLEGEM ENTS

The authors thank Dr. P. W. Poulos Jr. for assis-tance in translation; Messrs. van Amerongen, vanEssen, Heystek, Nederhof, Prestifilippo and Vel-ders for technical assistance; and Mrs. A. Runia fortyping.

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2. Bergstrom, P. L. and Kroeske, D.: Methods of carcass assessment in research on carcass qualityin the Netherlands. I. Description of the methods. Proc. Meeting of the Sub-commission on PigProgeny Testing. 9th Study Meeting of the European Association for Animal Production, Dublin,(1968).

3. Cop, W. A. G. and Buiting, G. A. J.: Feed intake in six lines of pigs and its influence on growth andcarcass traits. I. Feeding twice daily for 20 minutes per session. Anim. Prod., 25, 291, (1977).

4. Dämmrich, K.: Die Polyarthrose der Mastschweine als Konstitutionell bedingte Aufzuchtkrankheit.BerL Manch. TierdrztL Wschr., 83, 450, (1970).

5. Dammrich, K. und Unshelm, J.: Entwicklung und entwicklungsabhangige Veranderungen des Osfemoris bei 205 Tage alten Schweinen unterschiedlicher Nutzungsrichtung und Grösse. Zbl. Vet.Med. A. 19, 445, (1972).

6. Dämmrich, K. und Unshelm, J.: Die EinflOsse externer Unterschiede in der Nahrstoffversorgungauf die Entwicklung der Skeletts und das Vorkommen von Skelettveränderungen bei Schweinender Deutsche Landrasse. Zbl. Vet. Med. A, 22, 1, (1975).

7. Goedegebuure, S. A.: Macroscopical and microscopical features of osteochondropathies in swine.Proc. of the 3rd Intern Conference on Production disease in farm animals, Wageningen, (1976).

8. Grondalen, T.: Osteochondrose and arthrosis in pigs. I. Incidence in animals up to 120 klg liveweight. Acta Vet. Scand., 15, 1, (1974).

9. Grendalen, T.: osteochondrosis and arthrosis in pigs. II. Incidence in breeding animals. Acta Vet.Scand., 15, 26, (1974).

10. Grendalen, T.: osteochondrosis and arthrosis in pigs. III. A comparison of the incidence in younganimals of the Norwegian Landrace and Yorkshire breeds. Acta Vet. Scand., 15, , (1974).

I 1. Hansen, H. J. and Reiland, S.: Joint disease in breeding pigs. In: Naring-Halsa. P. A. Norstedt,Stockholm, (1968).

12. Herrman, H. J.: Zur pathologische Morphologie, Pathogenese und Atiologie der Osteoarthropathiender Schweines. Arch. exp. Vet. med., 26, 617, (1972).

13. Kerk, P. van der: Untersuchungen Ober die Knochenmatrix und Mineralisation der Knochen beSchweinen mit Beinschwache. Tiertirztl. Umschau, 2, 98, (1974).

14. Ljunggren, G. and Reiland, S.: Osteochondrosis in adolescent animals; an endocrine disorder?Calc. Tiss. res., 4, 150, (1970).

15. Meyer, P., Goudswaard, J., Goedegebuure, S. A., and Budhai, S.: Immunological, bacteriological andmorbid-anatomical features of arthrosis/arthritis of the stifle joint in swine. Tijdschr. Diergeneesk.,100, 1109, (1975).

16. Reiland, S.: Osteochondrosis in the pig. Thesis, Stockholm, (1975).17. Sabec, D.: Untersuchungen Ober eine Arthrosis des sprunggelenks beim Schwein. Thesis, Hannover,

(1960).18. Sabec, D.: Untersuchungen Ober die Ablosung der SitzbeinhOcker (Apophysiolysis) bei Jungsauen.

Dtsch. Tierdrztl. Wschr., 74, 489, (1967).19. Sabec, D.: Aktuelle Probleme der Osteochondropathien beim Schwein. Wien. tierdrztl. Wschr., 61,

1, (1974).20. Schilling, E.: Rassenunterschiede am Skelett des Beckens und der Hinterextremitaten beim Schwein.

Zschr. Tierdrztl. Akin. Biol., 78, 293, (1963).21. Thurley, D. C.: Changes in the epiphyseal cartilage of immature pigs without clinical lameness. Path.

Vet., 6, 217, (1969).22. Vaughan, L. C.: Leg weakness in pigs. Vet. Rec., 89, 81, (1971).23. Verdijk, A. Th. M.: Bewegingsstoornissen en beenzwakte bij varkens. Tijdschr. Diergeneesk., 94,

1649, (1969).24. Wal, P. G. van der, Valk, P. C. van der, Goedegebuure, S. A., and Essen, G. van: Osteochondrosis in

six breeds of slaughter pigs. II. Data concerning carcass characteristics in relation to osteochondrosis.The Vet. Quarterly. 2, 42, (1980).

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