PLANT-BASED STRATEGIES TO CONTROL THE ZINC AND THE COPPER OUTPUT FROM SWINE LIVESTOCK

The current state of agriculture, where demand for safe food is increasing rapidly as a consequence of growing population, raises a number of questions related to the one health approach and sustainable animal production with minimal impact on the environment. Swine production is an important branch of food production where weaning is the most vulnerable phase for piglets, often associated with decrease of growth performance and diarrhoea. The maintenance of gut health is therefore a complex endeavour where nutrition is crucial in order to reduce the intestinal disorders. Antimicrobial resistance is also a significant global concern. Reducing antibiotic use in animal production systems decreased prevalence of antibiotic-resistant bacteria in animals about 15%. In the last decade, the European Union banned the antibiotic use as growth promoters in livestock (EU Reg. 1831/2003). The first antibiotic alternative was the wide application of essential nutrients such as zinc (Zn) and copper (Cu) salts in the form of premix in the diets of animals to control digestive disorders. Due to their low bioavailability, Zn and Cu are commonly found in animal’ manure as a reflection of their content in the feed. The use of Zn and Cu in feed may also have contributed to the emergence of methicillin-resistant Staphylococcus aureus (MRSA). Despite antibacterial and anti-inflammatory activities, the first adopted alternative against in-feed antibiotics became unsafe due to heavy metal’ pollution in livestock wastewater. In order to reduce the high concentration of Zn and Cu and the antibiotic use in animal diets, plant extracts and different phytochemicals are of potential interest due to their antimicrobial, antioxidant and anti-inflammatory properties. However, if nutritional ecology’ strategy is not sufficient to reduce the wastewater pollution of heavy metals from livestock production, the development of efficient methods such as multidisciplinary phytoremediation approach is required. First, the preliminary aim was to overview of the role and the main challenges related to the content of essential heavy metals in animal feed and to evaluate the concentration of heavy metals from feed and faeces in animal rearing systems in northern Italy. Based on an overview, the main second aim was to develop a plant-based integrated approach to reduce the input and output of both Zn and Cu as well as the use of antibiotic compounds in pig production. Hence, in order to reduce input, the first aim was to test several natural plant-based phytochemicals compounds (tannins and leonardite) in vivo and to test of the anti-inflammatory effects of peppermint oil and spearmint oil with porcine alveolar macrophages in vitro. The last aim was to assess the ability of two aquatic species, Typha latifolia and Thelypteris palustris to control the Zn and Cu output from contaminated livestock wastewaters as a cost-efficient phytoremediation strategy. The in vivo data revealed that natural plant extracts (leonarditre and tannins) improved animal health. High doses of tannins (1.25%) supplementation showed slight reduction of diet digestibility and protein utilization, however this did not influence on feed intake and growth performance of animals. The inclusion of 0.25% leonardite improved the zootechnical performance, serum lipid profile and gut epithelium integrity, indicating a good general health status. In vitro study results showed that both mint oils significantly reduced TNF-α secretion from macrophages. To conclude, leonardite supports an improved stress response in weaned piglets, high dose of tannins did not impair growth performance and both peppermint and spearmint oils had anti-inflammatory activities in vitro. Moreover, results obtained from the phytormediation trial showed that Typha latifolia and Thelypteris palustris can accumulate and translocate Zn and Cu from contaminated wastewater. Thus, phytoremediation was effective to counteract the output of zinc and copper, and possibly other heavy metals from the livestock industry. Hence, an integrated nutritional ecology strategy and phytoremediation approach, in accordance with the modern principles of agroecology is needed to reduce the antibiotics use and heavy metals pollution in food-producing animals. Moreover, plant-based strategy guarantees the improvement of the health status of human and animal and leads to increase of the sustainability in animal rearing systems.