Effect of By-Products from Pistachio Skin on Gastrointestinal Microbiota of Healthy Lambs as Sustainable Feeding Ingredient

Pistachio skin is a by-product that is considered a promising novel feed ingredient for ruminants; however, its role in shaping the lamb gastrointestinal tract microbiota is poorly studied. The present study aimed to investigate, through a metagenomics approach, the effects of integrating pistachio skin into the diet on the faecal and ruminal microbiota of healthy lambs. Faecal samples, collected at the beginning (d0) and 58 days after the start of the dietary treatment (d58), and ruminal samples, collected after slaughter, were subjected to Illumina MiSeq analysis of the 16S rRNA gene. The results revealed that, although temporal variations were observed, the supplementation of pistachio skin did not markedly affect the overall faecal microbiota structure. Conversely, specific rumen taxa were selectively modulated by the experimental diet. In conclusion, the use of pistachio skin as a feed ingredient can be considered a suitable and sustainable dietary strategy that modulates specific rumen microbial groups, thereby preserving the stability of the gut microbiota in lambs.