Influence of different straw bedding management on welfare of growing pigs in low environmental impact farming system

Low environmental farming system requires nutrient recycle and production of renewable energy. The anaerobic digestion of pig manure produces a low quality biogas; hence, the addition of plant biomass results necessary. Straw bedding is the most effective environmental enrichment for pigs housed in intensive farms, facilitating exploratory behaviours and reducing negative behaviours (e.g. excessive aggressiveness, cannibalism). The aim of this study is to evaluate welfare of growing pigs in a straw-based housing system with different frequencies of bedding removal. This research promotes the implementation of sustainable farming systems with respect of animal welfare and environmental protection. A total of 840 growing pigs were equally allocated to a 2x2 experimental design according to quantity of straw provided (LQ=250g/pig/die; HQ=450 g/pig/die) and frequency of removal (LF=additional bedding added at day 30; HF=bedding removed and replaced every 15 days). Pigs were housed for two months in identical pens with resting area on straw bedding and feeding area on partially slatted floor. Animals were fed ad libitum. Cleanliness of straw bedding and lesion and cleanliness of pigs were collected three times (at day: 30, 45, 60). Straw bedding resulted dirtier when low quantity of straw was provided (LQ=74.24%; HQ=61.97%). Significant differences were found for pig cleanliness both in LQ (P=0.002) and HQ (P=0.013) groups. Frequency of removal never influenced cleanliness of pigs and bedding. The incidence of lesions was always low without differences among groups. High quantity of straw provided showed advantages in terms of welfare compared to the quantity normally suggested in straw-based systems (200-250 g/pig/die), whereas adding straw during the production cycle is sufficient to assure a good management of the bedding. Further research is needed to evaluate the economic impact of the quantity provided, considering the adding value of a good quality and more sustainable biogas production.