Risk factors for signs of tail biting in intact-tailed weaner pigs: A cross-sectional study.

Tail biting in growing pigs is both a sign and cause of impaired welfare. On one-day visits to ten Finnish farms, we assessed weaned pigs between approximately 4 to 10 weeks of age. On each farm, tail health was assessed at the pen level in 2-15 rooms (n = 81) selected randomly within age strata (n = 3), and on individual level in one high-prevalence pen per age category (n = 37 pens). Risk factors for tail biting were assessed in 2-3 age-representative rooms per farm according to 57 resource- and animal-based questions on environment, hygiene, health, feeding and enrichment. Tail health data were reduced into three pen- and three individual-level principal components. Component scores were used as outcome variables when establishing effects of risk factors on tail health using regression tree analysis and mixed modelling. Tail health deteriorated over the weaner period, especially from the first to the second third. Besides age, risk factors for impaired tail health consisted predominantly of shortcomings related to basic needs, such as adequate resting areas and enrichment. In the individual-level data, different risk factors could be associated with different types of tail lesions in problem pens, suggesting distinct aetiologies. In conclusion, improvements to the early environment in the farms studied here may have a significant positive impact on the well-being of pigs, not only post-weaning, but potentially permanently if experiencing less tail biting in early life leads to prevention later.