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Myo-inositol is a breakdown product of phytate produced in the gut through the action of phytase. Although the effect of phytase-released phosphorus (P) on growth performance of animals has been well characterized, there is still little understanding of the effect of myo-inositol. The first objective of this study was to determine the effects of added myo-inositol to a phytate-rich low-protein diet on growth performance and apparent total tract digestibility (ATTD) in growing piglets. The second objective was to determine whether myo-inositol could directly affect intestinal epithelial cell proliferation and function for which we used intestinal porcine epithelial cells (IPEC-J2). A total of 128 weanling piglets were allotted to four dietary treatments consisting of eight replicates per treatment and four piglets per replicate in a randomized complete block design for 4 wk. The four experimental diets comprised the positive control [PC; 20% crude protein (CP)], negative control (NC; 17% CP), negative control plus 2.0g/kg myo-inositol (NC+INO; 17% CP), and negative control plus 3000FTU/kg phytase (NC+PHY; 17% CP). Average daily feed intake (ADFI), average daily gain (ADG), and gain-feed ratio (G: F) were recorded. Phytase supplementation in the protein-deficient NC diet increased the G:F ratio (P < 0.05) without myo-inositol effects on growth performance. Phosphorus digestibility in the phytase-supplemented group increased compared to the PC, NC, and NC+INO groups, whereas plasma myo-inositol concentration was significantly higher (P < 0.05) in the NC+INO group. Due to the lack of myo-inositol effect on growth performance, an additional in vitro study was conducted to determine the direct effect of myo-inositol on the intestinal epithelium that might not be reflected in growth performance. Myo-inositol increased the mRNA abundance of selected nutrient transporters in a concentration-dependent manner (P < 0.05). Myo-inositol also enhanced barrier integrity in the IPEC-J2 monolayer by increasing the transepithelial electrical resistance (TEER) with reduced paracellular permeability of FITC-dextran (P < 0.05). In conclusion, despite the lack of myo-inositol effect on animal performance, the in vitro data indicate that myo-inositol may directly regulate gut barrier integrity. Addition of myo-inositol to pig diets at levels that enhance intestinal epithelial cell function may result in effects on growth performance and gut health of pigs., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The study was conducted to determine the effects of high levels of phytase on growth performance, nutrient digestibility, phytate breakdown, and expression of mucosal tight junction and nutrient transporter genes in weanling pigs. A total of 128 barrows were penned in groups of four and used in a randomized completely block design and assigned to four treatments for a 28-d study. A two-phase feeding was implemented (phase 1: day 1 to 14; phase 2: day 15 to 28). The diets differed in dietary calcium (Ca) and phosphorus (P) levels (positive control [PC]: 8.1 to 7.1 g/kg Ca and 6.5 to 6.8 g/kg P; negative control [NC]: 6.6 to 5.5 g/kg Ca and 5.6 to 5.3 g/kg P) from phase 1 to phase 2, respectively. NC diets were supplemented with phytase at 0 (NC), 1,500 (NC + 1,500), or 3,000 (NC + 3,000) phytase units (FTU)/kg. Blood was collected after fasting (day 27) or feeding (day 28) for the measurement of plasma inositol concentrations. On day 28, two pigs per pen were euthanized. Duodenal-jejunal and ileal digesta samples and feces were collected to determine inositol phosphates (InsP3-6) concentrations. Phytase supplementation increased the body weight on days 14 and 28 (P < 0.05). Average daily gain and feed efficiency compared with NC were increased by phytase with the majority of its effect in phase 1 (P < 0.05). The apparent ileal digestibility and apparent total tract digestibility of P were increased in piglets fed phytase-supplemented diets (P < 0.01) compared with NC piglets. Disappearance of InsP6 and total InsP3-6 up to the duodenum-jejunum, ileum, and in feces was increased by both phytase application rates (P < 0.01). Plasma concentrations of myo-inositol were higher (P < 0.001) in the phytase-supplemented diets than PC and NC diets, irrespective of whether pigs were fed or fasted. Expression of claudin 3 was higher in pigs fed both phytase-supplemented diets in the duodenum and jejunum compared with PC and NC. Mucin 2 expression was lower in the ileum of NC + 3,000 fed piglets compared with PC (P < 0.05), whereas expression of GLUT2 (solute carrier family 2-facilitated glucose transporter member 2) was increased (P < 0.05) by the NC + 3,000 treatment in all sections. In summary, high phytase supplementation increased the growth performance of nursery pigs. The increased expression of GLUT2 by phytase may indicate an upregulation of glucose absorption from the intestine by phytase., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

This study was conducted to determine effects of high phytase use on growth performance, amino acid (AA) digestibility, intestinal phytate breakdown, and nutrient transporter expression in starter broiler chickens. Male Ross 308 chicks were allocated to 24 pens, at 15 birds/pen and assigned to one of 4 dietary treatments. Treatments were: a control diet (PCa+) that contained adequate levels of calcium (Ca) and phosphorus (P) for growing broiler chicks; a reduced Ca and P diet (PCa-:-1.5 g P/kg and -1.6 g Ca/kg), and 2 additional diets in which phytase was supplemented in the PCa- diet at 1,500 (PCa-Phy1500) and 3,000 (PCa-Phy3000) FTU/kg feed. A common starter diet was fed from day 1 to 8. From day 8 to 22, birds were fed the 4 experimental diets. On day 22, birds were killed for sample collection. From day 8 to 15, average daily gain and average daily feed intake were not different across treatments (P < 0.05) but gain-to-feed ratio (G:F) was reduced (P < 0.006) in the PCa- treatment compared with other treatments. There were no further performance differences, but a tendency of phytase treatments improving the overall G:F (P = 0.079; day 8-22). Up to both the duodenum-jejunum and ileum, phytate, P, and Ca disappearance were increased (P < 0.05) in the PCa-Phy1500 and PCa-Phy3000 treatments compared with PCa- treatment. Phytase dose dependently increased myoinositol (MI) concentration in the digesta from both the duodenum-jejunum and ileum (P < 0.001). The highest concentration of MI was found in the PCa-Phy3000 treatment. Plasma MI concentration was increased by phytase supplementation (P < 0.001). Prececal disappearance of Cys was lower (P < 0.05) in the PCa- treatment than in PCa1and PCa-Phy3000 treatment. Expression of MUC2 in the duodenum-jejunum was higher (P < 0.05) in the PCa-Phy3000 treatment than in other treatments. Phytase-induced hydrolysis of phytate led to elevated digesta and plasma MI concentrations and reduced digesta concentrations of phytate breakdown intermediates., (Copyright © 2019. Published by Elsevier Inc.)

Two experiments were conducted to determine the effects of myo-inositol and phytase on growth performance, plasma metabolites, and nutrient digestibility of growing pigs. In experiment 1, 96 growing pigs with average initial body weight (BW) of 26.2 kg were used in a 25-d growth performance study. Pigs were assigned to four dietary treatments with three pigs per pen and eight replicate pens per treatment in a randomized complete block design. The four treatments were control diet (CD); CD + 2 g/kg inositol; CD + 1,000 FYT/kg phytase and CD + 3,000 FYT/kg phytase. Pigs were weighed individually every week. On day 25, blood sample was collected from one pig per pen to measure plasma metabolites concentrations. In experiment 2, 16 barrows (initial BW 34.8 ± 8.2 kg) were surgically fitted with T-cannulas. Pigs were allotted to four blocks based on BW and assigned to a quadruplicate 4 × 2 incomplete Latin square design with same four dietary treatments and two periods. Ileal digesta samples were collected from each pig on days 6 and 7 of each period to determine apparent ileal digestibility (AID) of nutrients. Phytase supplementation increased final BW and average daily gain (ADG) compared with CD (P < 0.05) with no effects on average daily feed intake (ADFI) and gain to feed (G:F) was higher in 3,000 FYT/kg phytase (P < 0.05). Inositol supplementation had no effects on growth performance. Plasma myo-inositol concentration was increased by inositol supplementation, and 3,000 FYT/kg phytase increased myo-inositol in the plasma by 97.2% (P < 0.05). Plasma P concentration was increased by 1,000 or 3,000 FYT/kg phytase with no effects on alkaline phosphatase (ALP), glucose, triglycerides (TAG), calcium (Ca), and urea concentrations. Phytase supplementation reduced (P < 0.05) the phytate-P concentration in the ileal digesta and increased the digestibility of phytate-P and total P with no effects on the AID of dry matter (DM), gross energy (GE), nitrogen (N), and Ca. In conclusion, the beneficial effects of 3,000 FYT/kg phytase on feed efficiency may due to the increased release of both myo-inositol and phosphorus (P), and may not be solely due to myo-inositol release by this level of phytase., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The objective of this present study was to determine the effects of phytase dosing on growth performance, mineral digestibility, phytate breakdown, and the level of glucose transporter type 4 (GLUT4) in muscle plasma membranes of weanling pigs. A total of 160 barrows were used in a randomized completely block design and assigned to 4 treatments for a 7-wk study. Depending on the feeding phase, diets differed in dietary calcium (Ca) and phosphorus (P) levels (positive control [PC]: 8 to 6.8g/kg Ca; 7.3 to 6.3 g/kg P; negative control [NC]: 5.5 to 5.2 g/kg Ca; 5.4 to 4.7 g/kg P). NC diets were supplemented with phytase at 0 (NC); 500 (NC + 500 FTU); or 2,000 FTU/kg (NC + 2,000 FTU) phytase units/kg. Blood was collected after fasting (day 48) or feeding (day 49) for measurement of plasma inositol concentrations. On day 49, 2 pigs per pen were euthanized, and duodenal and ileal digesta samples were collected to determine inositol phosphates (InsP6-2) concentrations. High phytase supplementation increased BW on days 21, 35, and 49 (P < 0.05). Over the entire feeding period, ADG, ADFI, and feed efficiency were increased by NC + 2,000 FTU compared with the other treatments (P < 0.05). Postprandial plasma inositol concentration was increased in NC + 2,000 (P < 0.01), but there was only a tendency (P = 0.06) of a higher fasting plasma inositol concentration in this group. Inositol concentrations in the portal vein plasma (day 49) were not different among treatments. Duodenal digesta InsP5 and InsP6 concentrations were similar in PC and NC, but higher in these 2 treatments (P < 0.05) than those supplemented with phytase. Phytase supplementation decreased InsP6-4, resulting in increased InsP3-2 and myo-inositol concentrations. Similar effects were found in ileal contents. Compared with NC, phytase supplementation resulted in greater cumulative InsP6-2 disappearance (93.6% vs. 72.8% vs. 25.0%, for NC + 2,000 FTU, NC + 500 FTU and NC, respectively, P < 0.01) till the distal ileum. Longissimus dorsi muscle plasma membrane GLUT4 concentration was increased by NC + 2,000 FTU (P < 0.01) compared with NC. In summary, high phytase supplementation increased growth performance of nursery pigs. The higher myo-inositol release from phytate could contribute to the increased expression of GLUT4 in muscle plasma membranes. Further investigation is needed to determine whether this is associated with enhanced cellular glucose uptake and utilization., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The effect of the ingestion of diets containing either myo-inositol or exogenous phytase on plasma metabolites was examined using 29 kg barrows. The diets were: control (maize, soya, rapeseed, rice bran), control plus 2 g/kg myo-inositol, control plus 1000 phytase units (FYT)/kg or 3000 FYT/kg exogenous phytase. Pigs were housed in a PigTurn device and blood was collected, from jugular catheters, via an automated system at -30, (30 min before feeding), 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300 and 360 min post-feeding. The addition of 2 g/kg myo-inositol to the basal diet resulted in an increase in plasma myo-inositol concentration that was evident 45-60 min after diet introduction and persisted to 360 min post-feeding. Similarly, supplementation of the basal diet with either 1000 or 3000 FYT/kg exogenous phytase resulted in an increase in plasma myo-inositol concentration that was still rising 360 min post-feeding. Plasma P concentration was increased over time by the addition of 1000 and 3000 FYT/kg phytase, but not by the addition of myo-inositol. Other plasma metabolites examined were not affected by dietary treatment. It can be concluded that oral delivery of myo-inositol results in rapid increase in plasma myo-inositol concentrations that peak approximately 45-60 min after feeding. Use of supplemental phytase achieves similar increases in myo-inositol concentration in plasma but the appearance is more gradual. Furthermore, supplementation of pig diets with exogenous phytase results in rapid appearance of P in plasma that may be sustained over time relative to diets with no added phytase.

Two 21-d broiler experiments were conducted to assess the efficacy of a bacterial 6-phytase expressed in Aspergillus oryzae on growth performance, nutrient utilization, and intestinal molecular markers. Two hundred forty birds in 5 treatments (experiment 1) or 256 birds in 4 treatments (experiment 2) were used. The treatments included a negative control diet that was marginally deficient in P (NC) or NC plus tricalcium phosphate, 500, 1,000, or 2,000 phytase units/kg (experiment 1), and NC or NC plus monocalcium phosphate, 500 or 1,000 phytase units/kg (experiment 2). In both experiments, excreta were collected on d 19 to 21, whereas birds and feed were weighed and ileal digesta collected on d 21. For experiment 1, mucosa scraping was collected from the duodenum, jejunum, and ileum from all birds for quantification of expression level of gut level inflammatory cytokines, Toll-like receptors, and phosphate transporter (NaPi-IIb). In both experiments, tricalcium phosphate, monocalcium phosphate, and phytase supplementation improved (P < 0.05) weight gain and percentage tibia ash. Phosphorus and Ca retention and phytic acid disappearance improved (P < 0.05) with phytase supplementation (experiment 1) and there was an increase (P < 0.01) in Ca and P retention in response to phytase supplementation (experiment 2). Diets did not affect the expression of gut level cytokines, Toll-like receptors, or the mucin gene. Phytase supplementation tended to decrease (P < 0.10) the expression of NaPi-IIb. It was concluded from these studies that the bacterial 6-phytase was effective in enhancing growth of broilers receiving low-P diets as well as in increasing efficiency of P utilization and phytic acid degradation.