Maternal Removals During Treatment Pregnancy and Subsequent Lactation
The numbers of dams removed between the commencement of the study and entry into the farrowing house (d 25 to 109), or from late pregnancy through lactation to weaning (d 109 of pregnancy to weaning), were not different between parities or between maternal treatment groups overall (Table 3). From the commencement of treatments until entry into the farrowing house, however, numbers of gilts removed differed between treatments (P = 0.024) such that 12% of gilts treated with pST from d 25 to d 100 of pregnancy were removed before entry into the farrowing house, compared with a 5% removal rate in controls (P = 0.062). Although these removals reflected a variety of causes (including 4 d 25 to 100 pST-treated gilts not transferred to the farrowing house for unknown reasons), it is important to note that there were no differences in rates of pregnancy loss between treatments, and similar numbers of gilts in each treatment were culled for physical reasons (2 control, 1 d 25 to 50 pST, 3 d 25 to 100 pST). Maternal parity and treatment did not affect (P > 0.1) total dam removals during farrowing and lactation (Table 3). Rates of farrowing difficulties and lactation failure also did not differ (P > 0.1) between groups, despite differences in piglet size and lactational demand (Table 3).