Health and performance of fattening pigs reared in grassland and agroforestry systems in a temperate maritime climate

Outdoor pig production is often seen as more welfare-friendly than indoor production. However, unless restricted to concrete runs, it is often carried out on grassland. This offers little protection from adverse climatic conditions and grassland is susceptible to poaching during rainy periods. Both can be expected to negatively impact pig health, whereas the use of wooded areas can limit such issues as trees provide shelter and promote water evaporation. To investigate this, we compared the health of pigs kept in grassland and agroforestry plots from 8 weeks of age until slaughter. Two batches of pigs were used, which were kept in groups of six boars, with four groups per treatment for each batch. As expected, sunburn was significantly less common for the agroforestry treatment than for the grassland treatment, although severe sunburn was absent overall. Growth and feed disappearance were significantly greater in the agroforestry treatment, without affecting feed conversion, body condition score or faecal consistency. The treatments had a statistically significant but limited effect on some other measured variables. Ear damage and body lesions were somewhat more frequent in the agroforestry treatment than in the grassland treatment (significantly so for the body lesions and tending towards significance for ear damage). Furthermore, gait scores were slightly but significantly worse in the agroforestry treatment than in the grassland treatment for most of the experiment, although the opposite relation was found during the last weeks. Gait scores may have reflected terrain conditions more than leg health, as no difference between the treatments was found when pigs were later re-scored when on concrete. Several of the expected health issues were either completely or nearly absent, including tail damage (even though tails were undocked), swellings, ecto- and endoparasites, melena, hematochezia, nasal discharge and reduced cleanliness. In conclusion, we found that the agroforestry treatment protected fattening pigs from sunburn and increased their growth, whilst some other health aspects were affected negatively but only to a marginal extent. Overall, health status was good for both treatments, likely in part due to the use of pigs and plots that had no history of pathogen build-up, and the fact that all pigs had access to rootable soil preventing a redirection of damaging behaviour to other pigs.