Enhancement of selectivity, 25-hydroxyvitamin D3 level, alkaline phosphatase activity and reproductive performance in gilts and primiparous sows using 14-epimer of 25-hydroxyvitamin D3.

Selecting breed-worthy gilts as sow replacements is essential for continuity of pig production cycle. Though vitamin D3 (VD3) is known to enhance reproductive performance of multiparous sows, there is still a knowledge gap on its impact in developing gilts and primiparous sows. This study was aimed to quantify plasma 25-hydroxyvitamin D3 (25(OH)D3), serum alkaline phosphatase (ALP), and examine the reproductive performance of primiparous sows fed diets supplemented with regular VD3, and its 25(OH)D3 epimers. The study sample comprised 10-week-old replacement gilts (50 % Landrace x 50 % Yorkshire, N = 180) assigned in a randomized complete block design to three treatments [2,000 IU/kg of VD3 (T1), 25 µg/kg of 14‑epi-25(OH)D3, half dose (T2), and 50 µg/kg of 25(OH)D3 (T3)] equilibrated to 2,000 IU/kg in base diets. Selections occurred at 22, 27 and 35 weeks of age, respectively. Plasma 25(OH)D3, serum alkaline phosphatase (ALP), bone structure and reproductive performance were analyzed. Dietary treatments influenced carpus (P = 0.023), fore view stance (P = 0.017), infantile vulva (P = 0.014), inverted (P = 0.048), and prominent teat (P < 0.001). Post-partum 25(OH)D3 concentration and ALP activity were elevated by day 25 (P < 0.001). Treatment diets also influenced total born (P < 0.001), born alive (P = 0.048), and still born (P = 0.049). Two factors affect circulating 25(OH)D3 and ALP activity: physiological changes in sows during lactation, and dietary 25(OH)D3 intake. 14‑epi-25(OH)D3 is a potent metabolite for improving maturation of reproductive organs in developing gilts. It also reduces still birth in primiparous sows.