Field study on social behavior, boar taint and performance of male pigs fattened separately or in mixed groups

Fattening of entire male pigs as a consequence of changed legislation results in new challenges for the pork production. With regard to husbandry the question persists whether separate or mixed housing of male and female fatteners is the most appropriate. In this investigation, the effects of different housing regimes on social behavior, performance and boar taint were determined.

For the field study, 1440 male and female genetically defined fatteners were housed in unisex male (U) or mixed male/female (M) groups. Average daily weight gain (ADG) was calculated for each animal based on individual weight at start and at slaughter. Carcass characteristics were monitored by AutoFOM. Neck fat samples were analyzed for androstenone (A: ELISA) and skatole (S: HPLC). Sensory evaluation of boar taint was done on 180 randomized samples (evenly distributed) by a panel of trained assessors. Social behaviour (sexual and aggressive activities) was monitored during the last 3-7 weeks of fattening by the use of “indicator animals” (2/box; 2 times/week, 10 min). Mixed housed females were tested for pregnancy by ultrasonography directly before slaughter (123.3 kg). Statistical analysis was performed by procedure mixed (SAS 9.1). Differences between LS-means were tested by Scheffe-test p< 0.05.

Independent of housing only few aggressive activities were counted and no penis biting was observed during monitoring the behavior. Pigs in mixed groups tended to be more interested in their companions than unisex males. Boars in mixed groups were distinctively snuffling more often (p< 0.0267) than separately housed; in general boars tended to bite and fight more frequently than females. When females came in heat at the end of the fattening period their biting frequency increased (rp=0.37). Regarding sexual activities females tended to be less active. In one of the 374 tested females from mixed groups a pregnancy was detected. In the field trial daily weight gain (U:875; M:867g/d), carcass yield (U:76.7, M:76.5%), ham weight (U:18.0; M:18.1kg), loin weight (U:7.02; M:7.03kg) of males from unisex or mixed groups did not differ. Contents of A and S in neck fat of males were independent of housing. Results of sensory analyses were in good agreement with the chemical analyses.

In this field study, separate male and mixed housing of entire male and female pigs are feasible in the fattening period. Due to high daily weight gains the pigs were slaughtered at a comparably young age, i. e. without a longer period of sexual activity. Severe problems in behavior and pregnancies did not occur. Regarding performance and boar taint parameters both management-/housing systems can be recommended.

Disclosure of Interest: None Declared.