Animal type is the strongest driver of antibiotic resistance genes in livestock manure. Across five species and four production stages, layer litter and pig manure carried the highest resistance gene diversity and abundance. Growth stage shifted the abundance of individual genes such as blaTEM, sul1, tet(Q) and tet(M) without changing the overall resistome structure. Of 944 subtypes found on DNA, only 579 were actively transcribed, and just 29 turned up at both levels. Why manure resistance is a food chain problem The global chicken population went from 14.7 billion to 33.1 billion between 2000 and 2020. That is roughly a 120 percent increase in two decades, and chickens are only…