This study investigates how adding letrozole (LE) to the diet affects the growth, blood hormones and metabolites, rumen fermentation, and gut microbes of weaned female Turpan Black sheep. The results could help guide strategies to enhance female growth and open new avenues for research. The study selected 60 weaned female lambs of the Turpan Black sheep breed, aged 2 months, with an average body weight of (19.93 ± 0.46) kg and in good health, which were randomly divided into the Con group (basel