Zhè / fèn / yán / jiū / bào / gào / bǐ / jiào / le / bù / tóng / pǐn / zhǒng / de / pìn / mǔ / bǐ / lì这份研究报告比较了不同品种的牝牡比例。This research report compares the male-to-female ratios of different breeds.