Effects of ventilation type on the performance and welfare parameters of female pigs during summer and winter conditions.

The objective of this study was to compare the effects of mechanical (MV) and natural ventilation (NV) systems body weight (BW) and weight gain (WG), aggression and welfare indices of female grower pigs under Mediterranean summer and winter conditions. Sixty-four (32 per season) female pigs (Landrace x Large White) of the same age and approximately the same weight, were used. During both seasons, pigs were randomly assigned into two adjacent pens (8 animals per pen), in two identical pig houses, one with an MV system and one with an NV system. Temperature/relative humidity sensors were used to record microclimate conditions in summer (May - July) and winter (December - February) periods, an FHD (1080p) camera to obtain body images for lesion and tail biting scoring and a commercial scale for BW measurements, taken weekly from the 13th week of age to the end of the production cycle. Tail biting (TB) was labelled according to severity and found to be lower under the natural ventilation system for both experimental periods. It was found that BW and WG were affected by the microclimate conditions irrespective of the type of ventilation. Temperatures within the thermal comfort zone, positively affected BW and WG (p < 0.05), under both ventilation systems. No particular body area was found to be preferable in inflicting lesions. Overall, the NV system generally resulted in improved welfare for growing/finishing pigs, due to significantly lower tail biting observed (p < 0.05), hence the NV systems could be preferable under Mediterranean similar to sub-Tropical regions.