The present invention relates to methods and compositions for modulating gastrointestinal microflora of a canine. In one embodiment, a method of modulating gastrointestinal microflora in a canine can comprise administering to the canine a pet food composition comprising from about 25% to about 60% protein, from about 5% to about 30% carbohydrates, fat, and fiber； where after administration, the Bacteroidetes to Firmicutes (B/F) ratio of the canine is less than 0.8.
