Second or later reserviced females had fewer PBA than non-returned and first reserviced females (P < 0.01; Table 2). In addition, the 2 two-way interactions of the number of services × parity and the number of services × WMI with PBA were also found (P < 0.05). At parity 1 and 2, the first reservice group had the most PBA (P < 0.05). In contrast, at parity 0, 3–5, and ≥ 6, no difference in PBA was found between the number of service groups.