BackgroundVitamin D is essential for the reproductive efficiency in animals. There are indications that 1,25-vitD influenced the farrowing process and thus can decrease postpartum health problems. Therefore, the aim of this study was to investigate the effect of 1,25-vitD on postpartum health of the sow and uterine involution as well as the litter performance.ResultsThe rectal body temperature in the 1,25-vitD group was significantly (p < 0.05) lower during the first five days after farrowing compared to the negative control group (D1: 38.6 vs. 38.9 °C; D2: 38.5 vs. 38.7 °C; D3: 38.4 vs. 38.7 °C; D4: 38.4 vs. 38.6 °C; D5: 38.5 vs. 38.9 °C). Although there was no difference between the live born piglets after farrowing, a significant higher number of piglets at day 7 and at weaning (Dw) was detected in the 1,25-vitD group compared to the control group (D7: 14.1 ± 0.9 vs. 13.4 ± 1.0, p = 0.002; Dw: 14.0 ± 0.9 vs. 13.4 ± 1.0, p = 0.02). Furthermore, the litter weight gain was significantly higher in the 1,25-vitD group when compared to the control group (94.3 vs. 86.4 kg; p = 0.045), and the weight loss of the sows was significantly lower (52 vs. 59 kg; p = 0.03). No differences in other parameter were detected.ConclusionThis study showed a positive effect of 1,25-vitD on the body temperature, the litter performance and the body condition of the sows during lactation in comparison with the negative control group. However, more studies are needed to describe the mechanism of 1,25-vitD in detail.