Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Effect of mixing and pen size on pig APPs

Mixing of animals from different origin is a well-known stressful situation for pigs. There are different moments in the productive life of pigs in which mixing is unavoidable, as after weaning or at the entry to the fattening barn. After mixing, pigs must establish again the dominance hierarchy’s relationships through aggressive interactions. Previous works have shown that those initial aggressions, and probably stress, that follow mixing can reduce growth rate.

In this trial the effect of mixing animals from different pens than in nursery, at the entry to the fattening barn, on the levels of APP was studied. 240 pigs (Large White x Landrace-Large White), half entire males and half females, of 60 d of age, with and initial body weight of 20.2 + 0.9 Kg were randomly distributed in 24 pens. The experimental design consisted in a 2X2 factorial arrangement, with the following treatments: mixed or unmixed animals and two different number of animals per pen (8 or 12). Serum samples were obtained from 12 animals of each treatment, at experimental days 1, 5, 14 and 28.

Elevated levels of the positive APP (acute phase proteins) and a decrease in the concentration of negative APP were observed the day before moving the pigs to the experimental installations. Thus the stress caused by the change of place resulted in a significant APP response. The APP response was higher in the mixed animals than in the unmixed. The effect was especially significant for Pig-MAP (p=0.0007). No interactions between the number of animals per pen and mixing were found, indicating that in this trial crowding has no effect on the APP response caused by mixing.

More information on the APP IN PIG PRODUCTIO -project can be found at:


Carlos PIÑEIRO, (R&D Manager)
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