Microplastics contamination in ruminant feeds of Northwestern Italy: a preliminary assessment

Ruminant feeds are a crucial link in microplastics (MPs) contamination through the trophic chain, representing one of the potential primary sources of MPs exposure for ruminants. Plastic is widely used for storing feeds and in cultivating crops intended for animal consumption. Additionally, atmospheric agents can transport plastics and MPs onto crops and feeds. Despite this, most research to date has focused on the presence of MPs in ruminant bodies, their feces, and animal products, leaving a significant gap in understanding one of the possible sources of MPs in ruminants: their feeds. This preliminary study aimed to assess MPs contamination in three among the most commonly used feed types in three dairy farms of Northwestern Italy: corn silage (CSG), hay (HAY), and high protein feedstuff (HPF) of Northwestern Italian farms. MPs were extracted through a specific protocol previously optimized for ruminant feeds. After the extraction, MPs were quantified and identified using a stereomicroscope and micro-Fourier transform infrared spectroscopy. CSG resulted to be the most significant polluted feed (37.9 ± 7.94 items/g), followed by HAY (16.4 ± 3.81 items/g) and HPF (16.3 ± 3.76 items/g). Transparent fiber-shaped MPs were the most abundant items in all feeds. MP lengths ranged from 0.030 to 5 mm and low-density polyethylene was the most common polymer in feeds, reflecting its extensive use in agricultural practices.