Microplastics contamination in ruminant feeds: an emerging issue for livestock sector

Microplastics (MPs) are emerging environmental pollutants responsible for interconnected risks to environmental, human, and animal health. The livestock sector is highly affected by this issue, in fact MPs presence was recently detected in sheep faeces, follicular fluid, blood, milk and meat of cows. The MPs contamination in ruminants could be due to the intensive usage of plastic materials in farms. The main ones are silage bags, bale wraps, and plastic bunker silo covers, made mainly in low-density polyethylene (LDPE). Although feeds might be the main source of MPs for ruminants, and consequently for their production chain, very little work has been conducted on them. Therefore, the aim of this work was to investigate the MPs contamination in three feeds highly used in livestock farms: corn silage, hay, and high protein feedstuff. Feed samples were collected in a farm located in N-W Italy, dried at 60°C overnight and grounded with a mill (5mm sieve). The MPs extraction was done using a protocol specifically optimized to extract five MP polymers from feeds: LDPE, high-density polyethylene (HDPE), polyamide (PA), polyethylene terephthalate (PET) and polystyrene (PS). The protocol involved three steps: 1. basic digestion, 2. Fenton reactions, 3. recovering and quantification of MPs. MPs were found in all the feeds analysed: 13.3±3.21 MPs/g of corn silage, 39.3±7.02 MPs/g of hay and 8.3±3.51 MPs/g of high protein feedstuff. This study is part of a project that has the aim to detect MPs in ruminant diets and feeds of different farms.