Dietary supplementation with 25-hydroxycholecalciferol and phytase in growing-finishing pigs: II. Effects on intestinal antioxidant status, immunity and bone quality

Abstract

The objective of this study was to determine the effects of dietary 25-hydroxycholecalciferol (25OHD3) and phytase supplementation alone and in combination on intestinal antioxidant status, immunity and bone quality in growing-finishing pigs fed low-phosphorus (P) diets. A total of 80 crossbred pigs with an initial body weight (BW) of 49.38 ± 0.54 kg were allotted to 4 diets with 5 replicate pens per treatment (2 barrows and 2 gilts per pen) according to BW and sex. The treatments were designed as a 2 × 2 factorial arrangement: low-P diet (C); low-P diet + 1,000 U phytase/kg diet (C + phytase); low-P diet +50 μg 25OHD3/kg diet (C + 25OHD3); low-P diet + 1,000 U phytase/kg diet +50 μg 25OHD3/kg diet (C + phytase + 25OHD3). The experiment consisted of 3 phases including phase 1 (days 1–28), phase 2 (days 29–60) and phase 3 (days 61–88). Dietary 25OHD3 supplementation deceased (P < 0.05) serum bone-specific alkaline phosphatase (BALP) level on days 60 and 88, and decreased serum parathyroid hormone (PTH) level on day 66. Phytase significantly decreased (P < 0.05) serum BALP level on day 88. 25OHD3 significantly increased glutathione peroxidase (GSH-Px) activity in duodenal mucosa and activities of catalase (CAT) and GSH-Px in ileal mucosa, as well as decreased tumour necrosis factor-α (TNF-α) level in jejunal mucosa. Phytase increased (P < 0.05) activities of CAT and GSH-Px in ileal mucosa, as well as decreased (P < 0.05) contents of interleukin-1β (IL-1β) and TNF-α in jejunal mucosa. The Ca content, bone mineral content (BMC) and breaking strength was higher (P < 0.05) as well as bone mineral density (BMD) and stiffness tended to be higher in the metacarpal bone of growing-finishing pigs fed with 25OHD3. Phytase increased (P < 0.05) Ca content, P content, BMC, BMD, breaking strength and stiffness in the metacarpal bone. 25OHD3 and phytase could help improve serum parameters, intestinal antioxidant capacity, immune function, and bone quality of growing-finishing pigs fed with low P diets.