Objective The objective of this study was to investigate effects of mixed organic acids (MOA) on nutrient digestibility, volatile fatty acids composition and intestinal microbiota in growing-finishing pigs fed high wheat bran diet. Methods Six crossbred barrows (Duroc×Landrace×Yorkshire), with an average body weight 78.8±4.21 kg, fitted with T-cannulas at the distal ileum, were allotted to a double 3×3 Latin square design with 3 periods and 3 diets. Each period consisted of a 5-d adjustment period followed by a 2-d total collection of feces and then a 2-d collection of ileal digesta. The dietary treatments included a corn-soybean-wheat bran basal diet (CTR), mixed organic acid 1 diet (MOA1; CTR+3,000 mg/kg OA1), mixed organic acid 2 diet (MOA2; CTR+2,000 mg/kg OA2). Results Pigs fed MOA (MOA1 or MOA2) showed improved (p<0.05) apparent total tract digestibility (ATTD) of gross energy, dry matter and organic matter, and pigs fed MOA2 had increased (p<0.05) ATTD of neutral detergent fiber compared to CTR. Dietary MOA supplementation decreased (p<0.05) pH value, and improved (p<0.01) concentrations of lactic acid and total volatile fatty acids (TVFA) in ileum compared to CTR. Pigs fed MOA showed higher (p<0.05) concentration of acetic acid, and lower (p<0.05) content of formic acid in feces compared to CTR. Pigs fed MOA1 had increased (p<0.05) concentration of TVFA and butyric acid in feces. Pigs fed MOA1 showed higher concentration of Lactobacillus and lower concentration of Escherichia in feces compared to CTR. Conclusion Dietary supplementation of MOA 1 or 2 could improve nutrients digestibility, TVFA concentration and intestinal flora in growing-finishing pigs fed high fiber diet.

BACKGROUND: With the development of intensive farming, long-term exposure of pigs to poor light conditions is not conducive to the production of vitamin D 3 , and vitamin D 3 deficiency could affect absorption and metabolism of calcium (Ca) and phosphorus (P). 25-Hydroxyvitamin D 3 (25OHD 3 ) has higher bioactivity than regular vitamin D 3 . This study investigated the effects of 25OHD 3 on performance, serum parameters, fecal microbiota, and metabolites in weaned piglets fed with low Ca-P diet.RESULTS: It was found that a low Ca-P diet supplemented with 50 ∼g/kg 25OHD 3 (NC + 25-D) improved (P < 0.05) average daily gain (ADG) in phase 2 and in the overall period of the experiment, and increased (P < 0.05) the immunoglobulin G (IgG), immunoglobulin A (IgA), catalase (CAT), bone-specific alkaline phosphatase (BALP), and osteocalcin (OC) serum content on day 28 compared with a low Ca-P diet (NC), but no differences were observed between a normal Ca-P diet (PC) and the NC + 25-D diet. Compared with NC, the abundance of Firmicutes was higher (P < 0.05) in PC and NC + 25-D. NC + 25-D decreased (P < 0.05) the abundance of Streptococcaceae compared with PC and NC, and increased (P < 0.05) the abundance of Lachnospiraceae compared with NC. Serum 25OHD 3 was negatively correlated with the abundance of fecal Streptococcaceae (P < 0.05), and positively correlated with the abundance of fecal Lachnospiraceae (P < 0.05).CONCLUSION: Supplementation of 25OHD 3 in a low Ca-P diet improved serum immunity, bone biochemical parameters, and fecal microbiota such as decreased Streptococcaceae abundance and increased Lachnospiraceae abundance, which could subsequently promote growth of piglets. The effects were similar to that of a normal Ca-P diet.

BACKGROUND 25‐Hydroxycholecalciferol (25OHD3) is a new feed additive, which is a potential alternative to vitamin D3 in swine nutrition. The objective of this study was to determine the effects of different doses of 25OHD3 supplementation on performance, immunity, antioxidant capacity, intestinal morphology and bone quality in piglets. RESULTS As dietary 25OHD3 supplementation increased, the average daily gain (ADG) improved (P < 0.05) quadratically during days 1–14, and tended to increase (P = 0.06) quadratically during the overall period of the experiment. Increasing 25OHD3 supplementation increased (linear effect, P < 0.05) the serum 25OHD3 level and serum glutathione peroxidase (GSH‐Px) activity. On day 14, serum immunoglobulin A (IgA) was increased (linear and quadratic effects, P < 0.05) as dietary 25OHD3 supplementation increased. On day 28, serum IgA level was higher (P < 0.05) linearly and the complement 3 (C3) level was reduced (P < 0.05) linearly as dietary supplementation of 25OHD3 increased. The mucosal GSH‐Px activity of the small intestine was higher (quadratic effect, P < 0.05) with increasing 25OHD3 supplementation. Jejunal villus height (P = 0.06) and villus height to crypt depth ratio (P = 0.07) tended to increase quadratically, and the villus height to crypt‐depth ratio of the ileum increased (P < 0.05) linearly and quadratically with increasing 25OHD3 supplementation. Dietary supplementation with an increasing level of 25OHD3 increased breaking strength of tibias and femurs (quadratic effect, P < 0.05). CONCLUSION Increasing dietary 25OHD3 supplementation partly improved performance, immunity, antioxidant status, intestinal morphology, and bone properties of weaned piglets. © 2020 Society of Chemical Industry