A questionnaire survey about postweaning management procedures of sows to improve reproductive performance in Japanese commercial breeding herds

The objective of the present study was to advance the development of standard operating procedures for postweaning sows by determining associations between the operating procedures and sow reproductive performance. Questionnaires were sent to 115 herds that use the same recording system. The questionnaires included questions about procedures for weaned sows in 2008, such as the type of boar contact for estrus detection, time of insemination and the feeding procedure after insemination. Data from 95 completed questionnaires (82.6%) were coordinated with the reproductive data for relevant individual females (71,743 service records) extracted from the recording system. Two-level mixed-effects models were applied using a herd at level 2 and an individual record at level 1 to determine associations between the surveyed procedures and farrowing rate or pigs born alive. Sows were separately analyzed by four weaning-to-first-mating interval (WMI) groups: WMI 4, 5, 6, and 7 days or later. Means (+- SEM) of farrowing rate and pigs born alive were 86.9 +- 0.13% and 11.0 +- 0.01 pigs, respectively. The farrowing rate and pigs born alive were associated with the use of direct boar contact, the timing of first insemination and decreasing diet quantity after insemination (P<0.05). More specifically, decreasing diet quantity after insemination was associated with improving farrowing rate of parity 1 sows. Parity 1 sows with WMI 4, 5 and 7 days or later had 0.1-5.7% higher farrowing rates in the herds that decreased diet quantity after insemination compared to those in the herds that did not decrease diet quantity (P<0.05). However, there were no such differences in sows at parity 2-5 and 6 or higher. Our survey indicates that postweaning management procedures should take account of WMI and parity.