NUTRITIONAL STRATEGIES FOR IMPROVING THE SUSTAINABILITY OF SWINE FARMING

The rising demand for animal-based products, alongside the need for a more sustainable livestock sector, presents a major challenge. Nutritional strategies offer a cost-effective and fast-acting solution to address this issue. Swine farming, second only to ruminants in environmental impact, plays a significant role due to its nitrogen emissions, its high consume of feedstuffs in competition with human consumption, such as cereals, and its high reliance on soybean products, an ingredient characterized, especially in Europe because of the high amount imported, by a high carbon footprint, and the use of antibiotics that poses a threaten related with the worldwide increase of the antimicrobial resistance. In this thesis we analysed on these aspects, testing different ingredients potentially interesting in helping improving the environmental sustainability of swine farming in a multisectoral approach involving: i) the use of a Yucca schidigera extract as feed additive to reduce the emissions of nitrogenous and odorous compounds in the finishing phase; ii) the use of alternative protein sources to reduce feed-food competition and the European protein gap in pigs’ early life stages; iii) the use of biochar as an ingredient to improve the health status of post-weaning piglets. The first research project evaluated a commercial Yucca schidigera extract, with 10.8% of saponins, through an in vitro and in vivo trial. The in vitro study aimed to identify the optimal dose to test in the in vivo trial and assess the extract's impact on diet digestibility and fermentation in the large intestine by measuring total gas, ammonia and volatile fatty acid production. The in vivo trial focused on growth performance, diet digestibility, carcass and meat quality, nitrogen balance, blood protein profile, and behaviour in Pietrain-derived finishing pigs. Results showed that yucca supplementation did not affect growth, meat quality or the overall welfare, but may improve nitrogen use efficiency and reduce nitrogen emissions, despite a slight decrease in crude protein digestibility. The second research project investigated the effects of Tenebrio molitor meal in growing pigs and lupin seed meal in post-weaning piglets, with a primary focus on gut microbiota. Tenebrio molitor meal had no impact on growth performance but induced temporary beneficial shifts in microbiota, demonstrating its potential as a sustainable protein alternative. In contrast, lupin seed meal reduced growth performance and crude protein digestibility in post-weaning piglets, though it did not affect diarrhoea incidence or blood parameters. Concluding, lupin can be used as a partial substitute for soybean or alongside other alternative proteins to help mitigate its negative impact on performance. The final study assessed the inclusion of biochar in post-weaning piglet diets over a 28-day period. Biochar improved nutrient digestibility, in particularly of protein, therefore suggesting a possible reduction in the nitrogen emissions. While it did not enhance growth performance, it lowered diarrhoea incidence and reduced blood dROMs, indicating improved oxidative status. In conclusion, biochar shows promise as a functional ingredient that supports piglet health and promotes more sustainable swine production.