In the WMI 0–6 and 7–12 day groups, the first reservice group had the most PBA (P < 0.05; Table 2). In the non-return to service group, sows with WMI 7–12 days had the fewest PBA (P < 0.05). In the first and second or later reservice groups, no differences in PBA were found between the WMI groups.
The mean of RI in 13,183 reservice records was 44.5 ± 0.28 days. Gilts had RI similar to sows at parity 1 and 2, and had longer RI than those at parity 3–5 and ≥ 6 (P < 0.05; Table 3). The first reservice group had 2.2 days longer RI than the second or later reservice group (P < 0.05). No significant interaction of the number of services × parity with RI was found.