Microbial signatures and enterotype clusters in fattening pigs: implications for nitrogen utilization efficiency under marginal lysine supply

As global demand for pork continues to rise, strategies to enhance nitrogen utilization efficiency (NUE) in pig farming have become vital for environmental sustainability. This study explored the relationship between the faecal microbiota, their metabolites, and NUE in crossbreed fattening pigs with a defined family structure. The results indicate an influence of sire, sampling period (SP), and sex on the faecal microbiota. Streptococcus emerged as a potential biomarker in comparing high and low NUE pigs in SP 1, suggesting a genetic predisposition to NUE regarding the faecal microbiota. A total of 892 faecal samples were grouped into two enterotype-like clusters named cluster LACTO and cluster CSST. Pigs' affiliation with enterotype-like clusters alters over time and might be sex-dependent. The stable cluster CSST demonstrated the highest NUE despite containing pigs with lower performance characteristics such as average daily gain, dry matter intake, and daily nitrogen retention. This research contributes with valuable insights into the microbiome's role in NUE, paving the way for future strategies to enhance sustainable pig production.