Abstract
Data from the meat inspection at a large regional abattoir in Norway was used to study the effect of different production systems and herd size on the occurrence of pathological lesions in pig carcasses. Three production systems were compared: combined production, production strictly in batches and continuous production. Only the former reared its own piglets. The data was collected in the period 1975–1977. The number of herds varied between 87 and 94, and between 26,000 and 30,000 bacon pigs were slaughtered each year. The herds were divided into three different size groups: ≤ 200, 201–400, and > 400 pigs slaughtered annually. Each year was considered separately.
The study showed that the highest frequency of sound carcasses occurred in the combined production group. There was no significant difference between the two production groups rearing purchased piglets. Moreover, there was an inverse relationship between the frequency of sound carcasses and herd size, but the positive effect of the small herd was estimated to be less important than that of production system.
The distribution of 16 different pathological lesions was also considered. Four lesions (pneumonia — moderate and severe —, pleurisy and scabies) were recorded at significantly different levels in the production systems all three years of recording.
Analysis of the effect of herd size also showed that in the cases of moderate pneumonia and pleurisy, the small herds were at an advantage. The other lesions had a rather casual distribution among the groups.
The statistical evaluation indicates however, that in cases of significant differences between the tested groups, only 20–40 % of the variation could be “explained” by our model comprizing production systems and herd size groups.
Keywords: disease recording, slaughter-house, bacon pigs, lesions, production systems, herd size, interrelations
Sammendrag
Data fra kjøttkontrollen ved Sentralslakteriet, Foras, Stavanger, har vært brukt for å undersøke hvilken innflytelse produksjonssystem og besetningsstørrelse måtte ha for forekomsten av patologiske funn hos griseslakt. Tre ulike driftsformer ble sammenlignet: Kombinert drift (egne smågriser), alt ut/alt inn og kontinuerlig drift. Besetningene ble også oppdelt i 3 forskj eilige størrelsesgrupper: ≤ 200, 201–400 og > 400 årsgris. Data ble innsamlet i perioden 1975–1977. Antall besetninger varierte mellom 87 og 94. Disse leverte mellom 26.000 og 30.000 slaktegriser pr. år. Hvert år ble behandlet separat.
Undersøkelsen viste at kombinert drift-gruppen hvert år hadde den høgeste frekvens av „friske“ slakt og kontinuerlig drift den lågeste. Den statistiske undersøkelsen viste at det ikke var noen signifikant forskjell mellom de to gruppene som kjøpte inn smågris, men mellom disse to og kombinert drift (P < 0.05). Man fant også en fallende frekvens av „friske“ slakt ved økende besetningsstørrelse, men den positive effekten av den lille besetning ble i analysen vurdert til å ha mindre betydning enn driftsformen.
En undersøkelse over fordelingen av de 16 vanligst forekommende patologiske funn viste at kun 4 forekom med signifikant forskj eilig nivå i en driftsform alle 3 år. Lungebetennelsene, sterk og moderat, og skabb forekom med et signifikant lagere nivå (P < 0.05) ved kombinert drift sammenholdt med de andre to, mens pieuritt hadde et signifikant høgere nivå i kontinuerlig drift gruppen sammenlignet med kombinert og „alt inn/alt ut“ gruppene.
Med hensyn til pyemi, abscess/-er, hvite leverflekker-multiple og få-, „andre leverforandringer“ og arthritt varierte resultatene fra år til år, men ved forskjell mellom gruppene kom kombinert drift nesten alitid best ut.
For de øvrige patologiske funn (atrofisk rhinitt, pericarditt, tuberkuloselignende forandringer i halslymfeknutene, peritonitt, polyarthritt og halesår) var det ingen signifikant forskjell mellom driftsformgruppene.
Den statistiske analysen indikerte at moderat lungebetennelse og pleuritt var patologiske funn hvor besetningsstørrelsen også hadde inflytelse på frekvensen.
Videre viste analysen at i de tilfeller hvor det forekom signifikant forskjell mellom produksjonssystemer eller størrelsesgrupper, ble kun 20–40 % av forskj ellen forklart utfra den anvendte modell.
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Footnotes
Supported by grants from the Norwegian Agricultural Research Council.
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