Within-farm Variability in Number of Females Mated Per Week During a One-year Period and Breeding Herd Productivity on Swine Farms

Objective: To determine the effect of within-farm variability in the number of females mated per week during a 1-year period on annual breeding herd productivity in swine breeding herds and to apply statistical process control charts to measures of within-farm variability.

Design: Longitudinal study.

Sample Population: 84 swine farms with a female inventory of 390 to 1,491 sows and gilts (mean, 761 females).

Procedure: As a measure of within-farm variability in a breeding herd, SD for the number of females mated per week during a 1-year period was evaluated. Two types of production records for 84 farms were evaluated. One file contained within-farm variability (SD) in mated females for each farm, and the second included annual productivity 19 weeks after week of mating. We also defined forewarning limits as mean +/- 2 SD, using a statistical process control chart.

Results: Larger within-farm variability in number of mated females was associated with lower annual measurements, such as fewer pigs weaned per mated female per year and lower farrowing rate. In addition, farms that did not have any weeks outside the forewarning limits for number of mated females produced more pigs weaned per mated female per year than those with 1 or more weeks of over- or underproduction. Furthermore, the number of weeks outside of forewarning limits was positively associated with within-farm variability in number of mated females.

Clinical Implications: We recommend that farm managers determine a target range for the number of females mated per week to prevent large week-to-week variations in breeding herd operations.