Intensified livestock farming increases antibiotic resistance genotypes and phenotypes in animal feces

<p class="MsoNormal"><span>Animal feces from livestock farming can be a major source of antibiotic resistance to the environment, but a clear gap exists on how the resistance reservoir in feces alters as farming activities intensify. Here, we sampled feces from eight Chinese farms, where yak, sheep, pig, and horse were reared under free-range to intensive conditions, and determined fecal resistance using both genotype and phenotype approaches. </span><span>A</span><span>nimals reared </span><span><span>intensively</span></span><span> exhibited increased </span><span><span>diversity</span></span><span> of antibiotic resistance genes (ARGs) and greater resistance phenotypes in feces, which were cross-correlated. Furthermore, a</span><span>t the metagenome contig level, ARGs</span><span> </span><span>were </span><span><span>co-located</span></span><span> with </span><span>mobile genetic elements </span><span>at a higher frequency (27.38%) </span><span>as farming intensified, </span><span>with</span><span> associated resistance phenotyp</span><span><span>e</span></span><span>s </span><span>being less coupled with bacterial phylogeny. </span><span>I</span><span>ntensified farming also expanded the multidrug resistance preferentially carried on pathogens in fecal microbi</span><span>omes</span><span><span>.</span></span><span> Overall, </span><span><span>farming intensification </span></span><span>can </span><span><span>increase </span></span><span>antibiotic resistance</span><span> <span>genotypes and phenotypes in </span></span><span>domestic animal </span><span><span>feces</span></span><span>, with implications for environmental health.</span></p> <p> </p>