Effect of immunocastration on body lesions in heavy pigs: preliminary results

Immunocastration is an interesting alternative to surgical castration in piglets. Studies have shown promising results in terms of production performance (e.g., maintaining adequate meat quality) also in heavy pig production; and improvement of animal welfare (e.g., preventing distress and pain caused by surgical castration). Aggressive and mounting behaviours, that often result in body lesions, seems to be reduced in light pig production; however, no studies have yet investigated animal welfare of heavy pigs subjected to immunocastration. This study aimed at evaluating the effect of immunocastration on welfare of heavy pigs by monitoring body lesions during growing and fattening period. Commercial-hybrid male pigs were randomly allocated to treatment groups: Immunocastration (IC; N=94), pigs receiving 4 doses of Improvac® at 15, 22, 32, and 36 weeks of age; Surgical Castration (SC; N=94), pigs surgically castrated at 4 days of age. IC and SC pigs received the same feeding regimen, they were housed in the same conditions and their management complied with Dir. 2008/120/EC. Before each Improvac® administration, body lesions were recorded through direct observations and scored on a three-point scale (none, mild, severe). Independent T-test was used to determine differences between groups at each considered time point. Before the first administration of Improvac® (15 weeks of age), IC pigs showed a significantly higher body lesion score (0.60±1.04) compared to SC (0.2±0.48) (P=0.001). The body lesion score remains higher in the other time points, but the difference between groups is not significant. A high level of agonistic behaviour before the suppression of testicular function suggests anticipating the vaccination protocol in relation to the onset of puberty and to increase the number of interventions in heavy pigs. Further research is needed to evaluate the sustainability of different timing of immunocastration, maintaining high level of animal welfare together with productive and economic benefits of the procedure.