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Entire male pigs are more active than castrated male pigs and their social behaviour may be harmful to their pen-mates. Even if the average number of skin lesions does not differ between castrated and entire males, it is possible that the distribution of injurious interactions among individuals is different and that the welfare of highly affected individuals is compromised.
Objective and methods: Therefore, using data from 531 ear-tagged entire males (39 groups) and 305 castrates (22 groups) from five organic farms, we examined whether higher standard deviations (SD) of skin lesions on the front or the rear body indicated a higher concentration of injurious interactions on some individuals in groups of entire compared to castrated males, and whether the proportion of moderately and severely injured pigs differed. Potential effects of space allowance, female contact, and weight heterogeneity per group were also considered. We further investigated what characterised individual entire or castrated males with a higher number of skin lesions and whether more entire than castrated males were repeatedly injured. Pigs were weighed at the start and end of fattening, Additionally, they were scored for skin lesions at around 80 kg and 130 kg live weight, and after first split marketing.
Results: Compared to castrates, the proportions of moderately and severely injured pigs per group and the SD of skin lesions were higher in entire males with no direct contact to females, but did not differ when entire males were kept next to female pigs. Individual castrated but not entire males with a lower relative live weight at the start of fattening had more lesions, and castrates with more lesions also had lower lifetime weight gain. Together this may point to some differences in motivation for agonistic interactions between castrated and uncastrated male pigs. There was a general mitigating effect of higher space allowances, with a higher importance for entire males on the individual level. Rates of repeated moderate or severe injury at around 80 kg and 130 kg liveweight did not differ with 15 % (castrated) and 16 % (uncastrated) injured pigs.
Conclusion: The fattening of entire males under organic conditions can bear a higher injury risk for some individuals, but that this can be prevented by appropriate husbandry conditions, such as housing female pigs in the neighbouring pen. In general, higher space allowances help to reduce negative consequences of social behaviour.
Jeannette C. Lange, Ute Knierim, Social behaviour in groups of castrated and uncastrated organic fattening male pigs - consequences for the individual, Applied Animal Behaviour Science, Volume 288, 2025, 106676, ISSN 0168-1591, https://doi.org/10.1016/j.applanim.2025.106676