Unlocking Phytate with Phytase: A Meta-Analytic View of Meat-Type Chicken Muscle Growth and Bone Mineralization Potential

The inclusion of exogenous phytase in P- and Ca-deficient diets of broilers to address the growing concern about excessive P excretion into the environment over the years has been remarkably documented. However, responses among these studies have been inconsistent because of the several factors affecting P utilization. For this reason, a systematic review with a meta-analysis of results from forty-one studies published from 2000 to February 2024 was evaluated to achieve the following: (1) quantitatively summarize the size of phytase effect on growth performance, bone strength and mineralization in broilers fed diets deficient in P and Ca and (2) estimate and explore the heterogeneity in the effect size of outcomes using subgroup and meta-regression analyses. The quality of the included studies was assessed using the Cochrane Collaboration's SYRCLE risk of bias checklists for animal studies. Applying the random effects models, Hedges' g effect size of supplemented phytase was calculated using the R software (version 4.3.3, Angel Food Cake) to determine the standardized mean difference (SMD) at a 95% confidence interval. Subgroup analysis and meta-regression were used to further explore the effect size heterogeneity (PSMD ≤ 0.05, I2 > 50%, n ≥ 10). The meta-analysis showed that supplemental phytase increases ADFI and BWG and improves FCR at each time point of growth (p < 0.0001). Additionally, phytase supplementation consistently increased tibia ash, P and Ca, and bone strength (p < 0.0001) of broilers fed P- and Ca-deficient diets. The results of the subgroup and meta-regression analyses showed that the age and strain of broiler, dietary P source, and the duration of phytase exposure significantly influence the effect size of phytase on growth and bone parameters. In conclusion, phytase can attenuate the effect of reducing dietary-available phosphorus and calcium and improve ADFI, BWG, and FCR, especially when added to starter diets. It further enhances bone ash, bone mineralization, and the bone-breaking strength of broilers, even though the effects of bone ash and strength can be maximized in the starter phase of growth. However, the effect sizes of phytase were related to the age and strain of the broiler, dietary P source, and the duration of phytase exposure rather than the dosage.

Effects of Alhagi camelorum Fisch polysaccharide from different regions on growth performance and gastrointestinal microbiota of sheep lambs

Polysaccharides derived from Alhagi camelorum Fisch possess diverse activities, making them a potential prebiotic candidates for enhancing lamb health. This study investigated the immunomodulatory effects of Alhagi camelorum Fisch polysaccharides from Aksu (AK) and Shanshan (SS) regions on sheep lambs. The results showed that sheep lambs in the SS group exhibited significantly increased (p < 0.05) average daily gain, levels of growth hormone (GH), insulin (INS), IgA and IgM, and cytokines IL-4, IL-10, IL-17, TNF-α and IFN-γ compared to those in the control check (CK) group. Moreover, the SS treatment significantly increased the diversity and abundance of beneficial bacteria, while concurrently diminishing the prevalence of harmful bacteria. Additionally, it modulated various metabolic pathways, promoted lamb growth, improved immunity, reduced the risk of gastrointestinal disease and improved the composition of gastrointestinal microbiota. In summary, our findings highlight the potential of SS treatment in enhancing gastrointestinal health of sheep lambs by improving intestinal function, immunity, and gut microbiome. Consequently, these results suggest that Alhagi camelorum Fisch polysaccharides derived from Shanshan regions holds promising potential as a valuable intervention for optimizing growth performance in sheep lambs.

Ileal mineral digestibility and expression of nutrient transporter genes of broiler chickens in response to variable dietary total Ca and phytase supplementation are influenced by time on experimental diet and age of the birds

Two experiments were conducted to determine the impact of Ca, phytase, sampling time, and age on the digestibility (AID) of Ca and P and the expression of their transporters. Cobb 500 male chicks (N = 600) were used in each experiment and allocated to cages with 10 (Exp 1, 8-11 d) or 5 (Exp 2, 21-24 d) birds/cage and 10 (Exp 1) or 20 (Exp 2) reps/treatment. Treatments were a 2 × 3 factorial arrangement, with low (LOW) or standard (STD) Ca level and 3 phytase (PHY) levels (0, 300, or 3,000 FYT/kg). Ileal digesta were collected at 8, 12, 24, 48, and 72 h, and jejunum tissues at 12, 48, and 72 h after the start of feeding experimental diets. In Exp 1, there was no effect of Ca or phytase on the AID of Ca at 8, 12, or 24 h. Phytase increased the AID of P (P < 0.05) at all time points, and the magnitude was influenced by Ca. At 12 h, the mRNA level of P (NaPi-IIb) and Ca (CaSR) transporters was greatest in the LOW diets without phytase (Ca × PHY, P ≤ 0.06). In Exp 2, the STD diet decreased the AID of Ca and P (P < 0.05) at 8, 24, 48, or 72 h. Phytase increased the AID of Ca (P < 0.05) at 8, 12, and 24 h, and decreased the AID of Ca (quadratic, P < 0.05) in the STD diet (48 h). The AID of P (P < 0.05) increased with phytase at all sampling times. At 48 h, 3,000 FYT/kg decreased (P < 0.05) mRNA expression of NaPi-IIb and Ca transporter ATP2B1 in the STD diet (Ca × PHY, P < 0.05). In conclusion, to avoid adaptation of broilers to Ca and P deficiencies, the optimal time on experimental diets is ≤ 48 h for young broilers and ≤ 24 h in older birds due to up- or down-regulation of Ca and P transporters in response to dietary Ca, P, and phytase.

Efficacy and Equivalency of Phytase for Available Phosphorus in Broilers Fed an Available Phosphorus-Deficient Diet

This study was conducted to assess the effectiveness of phytase on the performance, carcass traits, nutrient digestibility, tibia characteristics, and inositol phosphorus (IP) degradation in broiler chickens. Additionally, the available phosphorus (AP) equivalency of phytase in AP-deficient diets was estimated for 35 days after hatching. A total of 336 one-day-old Ross 308 broiler chicks were allocated to one of seven dietary treatments with six replications with eight birds per cage. The dietary treatments were as follows: (1) positive control containing 0.45% AP of the starter and 0.42% AP of the grower diet (PC), (2) 0.10% AP deficiency from the PC (NC-1), (3) 0.15% AP deficiency from the PC (NC-2), (4) 0.20% AP deficiency from the PC (NC-3), (5) NC-3 +phytase (500 FTU/kg; NC-3-500), (6) NC-3 + phytase (1000 FTU/kg; NC-3-1000), and (7) NC-3 + phytase (1500 FTU/kg; NC-3-1500). On d 35, the NC-3 diet exhibited lower tibia weight compared to the other treatments (p < 0.001). The NC-3-1500 group had higher calcium and phosphorus contents in the tibia than the other treatments on d 35 (p < 0.01). Phytase supplementation led to a reduced IP6 concentration and increased IP3 concentrations in different sections of the gastrointestinal tract on d 21 and 35 compared to the control diet (p < 0.05). In conclusion, based on the tibia phosphorus content, this study determined that 500 FTU/kg phytase was equivalent to 0.377% and 0.383% AP in the diet on d 21, and 0.317% and 0.307% AP in the diet on d 35, respectively. Likewise, 1000 FTU/kg was determined to be equivalent to 0.476% and 0.448% AP on d 21, and 0.437% and 0.403% AP on d 35, respectively. Furthermore, 1500 FTU/kg was determined to be equivalent to 0.574% and 0.504% AP on d 21, and 0.557% and 0.500 AP on d 35, respectively.

Influence of two levels of phytic acid and particle size of oyster shell on the performance, calcium digestibility, gastrointestinal pH, and bone traits in broilers

1. Phytic acid (PA) is an antinutritional factor in poultry diets. The effect of high dietary PA in chicken diets might be exacerbated when the particle size of oyster shell (OS) is too fine. Thus, this study investigated the hypothesis that high PA with fine OS particle size would impair growth in broilers.2. Two hundred and eighty Cobb 500 broilers were assigned to four diets in a 2 × 2 factorial arrangement in a CRD. The factors were PA (low or high) and OS particle size (fine or coarse) in starter, grower and finisher diets. Data collected were performance, Ca digestibility, gastrointestinal pH and bone traits.3. On d 21, high PA increased intake (P < 0.05), gain (P = 0.099) and body weight (BW; P = 0.093) compared to low PA. On d 42, high PA increased BW (P = 0.086) and gain (P = 0.089) compared to low PA. High PA increased intake (P = 0.063), BW (P = 0.054) and gain (P = 0.056) compared to low PA on d 56. High PA improved liveability on d 56 (P < 0.05) compared to low PA. In birds fed coarse OS, crop and ileal pH were reduced (P < 0.05) by high PA on d 28. The OS × PA interaction was observed for ileal pH (P < 0.05) on d 56, where in birds fed coarse OS, low PA increased ileal pH. Fine OS increased crop (P = 0.056) and proventriculus pH (P < 0.05) on d 56. There were no treatment effects on calcium digestibility. In birds fed fine OS, high PA decreased the BS (P < 0.05).4. Overall, the study showed that a combination of high PA and coarse OS particle size improves the production performance of broilers, while low PA and coarse OS improve their bone health.

Production of fungal phytases in solid state fermentation and potential biotechnological applications

Phytases are important enzymes used for eliminating the anti-nutritional properties of phytic acid in food and feed ingredients. Phytic acid is major form of organic phosphorus stored during seed setting. Monogastric animals cannot utilize this phytate-phosphorus due to lack of necessary enzymes. Therefore, phytic acid excretion is responsible for mineral deficiency and phosphorus pollution. Phytases have been reported from diverse microorganisms, however, fungal phytases are preferred due to their unique properties. Aspergillus species are the predominant producers of phytases and have been explored widely as compared to other fungi. Solid-state fermentation has been studied as an economical process for the production of phytases to utilize various agro-industrial residues. Mixed substrate fermentation has also been reported for the production of phytases. Physical and chemical parameters including pH, temperature, and concentrations of media components have significantly affected the production of phytases in solid state fermentation. Fungi produced high levels of phytases in solid state fermentation utilizing economical substrates. Optimization of culture conditions using different approaches has significantly improved the production of phytases. Fungal phytases are histidine acid phosphatases exhibiting broad substrate specificity, are relatively thermostable and protease-resistant. These phytases have been found effective in dephytinization of food and feed samples with concomitant liberation of minerals, sugars and soluble proteins. Additionally, they have improved the growth of plants by increasing the availability of phosphorus and other minerals. Furthermore, phytases from fungi have played an important roles in bread making, semi-synthesis of peroxidase, biofuel production, production of myo-inositol phosphates and management of environmental pollution. This review article describes the production of fungal phytases in solid state fermentation and their biotechnological applications.

The effects of dietary microbial 6-phytase on growth parameters, intestinal morphometric properties and selected intestinal genes expression in rainbow trout (Oncorhynchus mykiss, Walbaum 1876)

This study investigated the effects of dietary 6-phytase, produced by a genetically modified Komagataella phaffii, on growth performance, feed utilisation, flesh quality, villus morphometric properties, and intestinal mRNA expression in rainbow trout. Six iso-nitrogenous, iso-lipidic, and iso-caloric diets were formulated and fed to triplicate groups of juvenile rainbow trout weighing 32.57 ± 0.36 g (mean ± SD) for 90 days. The dietary treatments included two positive controls (PC), one formulated with 400 g/kg of fish meal named T1, and the other formulated with 170 g/kg of fish meal plus 1% avP derived from monocalcium phosphate named T2. The remaining dietary treatments consisted of a negative control (NC) formulated with 170 g/kg of fish meal (T3), NC+ 750, NC+ 1500, and NC+ 3000 OTU/kg levels of phytase designated as T4, T5, and T6 diets respectively. Compared to T1, weight gain (WG) increased by 16.29, 13.71 and 11.66% in T4, T5 and T6, respectively (p < 0.05). Feed conversion ratio (FCR) was lowered by 3.2 and 0.8% in T4 and T5 compared to T1 (p < 0.05). WG, feed intake (FI), FCR, final body length, bone ash, bone ash P, and intestinal morphometry were negatively affected in T3 fed fish (p < 0.05). Whole-body fish nutrient, bone ash, bone ash phosphorus (P) compositions and mucosal villus morphometric properties improved in rainbow trout fed diets supplemented with phytase dose ranging from 750-3000 OTU. Bone ash increased by 6.12% in T5 compared to T1 (p < 0.05). Phytase inclusion enhanced the profitability of feeding juvenile rainbow trout such diets as it reduced the feed price and economic conversion rate. Dietary inclusion of phytase down-regulated mRNA expression of genes responsible for fatty acid synthesis and lipogenesis in juvenile rainbow trout. Dietary phytase up-regulated the mRNA expression of genes (SLC4A11 and ATP1A3A) responsible for nutrient uptake and down-regulated intestinal expression of MUCIN 5AC-like genes (mucus secreting genes) in juvenile rainbow trout. Along with improving performance parameters, the inclusion of phytase in rainbow trout diet containing plant-based protein sources, can preserve intestinal morphology by regulating the mRNA expression of genes responsible for fatty acid synthesis, lipogenesis and nutrient uptake and transport.

Accentuating the positive and eliminating the negative: Efficacy of TiO2 as digestibility index marker for poultry nutrition studies

Inert digestibility index markers such as titanium dioxide are universally accepted to provide simple measurement of digestive tract retention and relative digestibility in poultry feeding trials. Their use underpins industry practice: specifically dosing regimens for adjunct enzymes added to animal feed. Among these, phytases, enzymes that degrade dietary phytate, inositol hexakisphosphate, represent a billion-dollar sector in an industry that raises ca. 70 billion chickens/annum. Unbeknown to the feed enzyme sector, is the growth in cell biology of use of titanium dioxide for enrichment of inositol phosphates from extracts of cells and tissues. The adoption of titanium dioxide in cell biology arises from its affinity under acid conditions for phosphates, suggesting that in feeding trial contexts that target phytate degradation this marker may not be as inert as assumed. We show that feed grade titanium dioxide enriches a mixed population of higher and lower inositol phosphates from acid solutions. Additionally, we compared the extractable inositol phosphates in gizzard and ileal digesta of 21day old male Ross 308 broilers fed three phytase doses (0, 500 and 6000 FTU/kg feed) and one inositol dose (2g/kg feed). This experiment was performed with or without titanium dioxide added as a digestibility index marker at a level of 0.5%, with all diets fed for 21 days. Analysis yielded no significant difference in effect of phytase inclusion in the presence or absence of titanium dioxide. Thus, despite the utility of titanium dioxide for recovery of inositol phosphates from biological samples, it seems that its use as an inert marker in digestibility trials is justified-as its inclusion in mash diets does not interfere with the recovery of inositol phosphates from digesta samples.

Effect of Bacterial Phytase on Growth Performance, Nutrient Utilization, and Bone Mineralization in Broilers Fed Pelleted Diets

The influence of a bacterial 6-phytase on growth performance, coefficient of apparent ileal digestibility (CAID) of nutrients, blood parameters, and bone mineralization in broilers was evaluated. A total of 630 one-day-old male broilers were allocated to 7 dietary treatments, including positive control (PC) diet containing dicalcium phosphate, the PC marginally reduced in available P (avP) by 0.1% and calcium (Ca) by 0.2% vs. PC (NC1) or moderately reduced by 0.15 and 0.3% vs. PC (NC2), respectively, and four further diets comprising the NC1 and NC2 supplemented with 500 or 1000 FTU/kg of phytase in starter and finisher phases. A constant Ca to avP ratio was maintained across all diets. The body weight gain (BWG) and feed per unit gain (FCR) of birds fed NC1 and NC2 diets supplemented with phytase (500 and 1000 U/kg) was equivalent to that of birds fed the PC diet at 35 days. Phytase supplementation in the NC1 diet linearly increased the CAID of nitrogen (N) (p < 0.01), phosphorus (P) (p < 0.01), and Ca (p < 0.05). Additionally, phytase reduced (p < 0.01) excreta P concentration by approximately 27%, improved (p < 0.001) toe ash, and tended to increase tibia ash (p = 0.08), comparable with the PC. In conclusion, the addition of bacterial 6-phytase dosed in the range of 500-1000 FTU/kg was effective in replacing 1.5 g/kg avP and 3 g/kg Ca in broilers fed pelleted diets, using bone quality, BWG, and FCR as outcome measures.

Comparison of mucosal phosphatase activity, phytate degradation, and nutrient digestibility in 3-week-old turkeys and broilers at different dietary levels of phosphorus and phytase

A comparison between 3-wk-old female turkeys (B.U.T. 6) and broilers (Ross 308) was performed to study the effects of species, dietary P, Ca, and phytase levels on gut mucosal phosphatase activity, myo-inositol hexakisphosphate (InsP6) degradation along the digestive tract, digestibility of P, Ca, and amino acids, and concentrations of myo-inositol in the digesta and blood. The experimental diets were corn-soybean meal-based and identical for both species. Two dietary P and Ca concentrations (CaP-: 4.1 g P/kg, 5.5 g Ca/kg and CaP+: 9.0 g P/kg, 12.0 g Ca/kg) and 2 levels of phytase supplementation (0 and 1,500 FTU/kg) were used in a 2 × 2 factorial design and fed to the animals for 7 d in their third week of age. Each diet was randomly assigned to 6 broiler and 6 turkey pens, with 10 birds each. After slaughter, blood, digesta from the crop, gizzard, duodenum, lower ileum, and mucosa from the jejunum were collected. When fed CaP- without phytase supplementation, there were no differences between species in gut mucosal phosphatase activity, prececal InsP6 disappearance, and P and Ca digestibility, indicating a similar intrinsic capacity for phytate degradation in both species. When fed CaP+ without phytase supplementation, turkeys showed higher prececal InsP6 disappearance than broilers. Phytase supplementation increased prececal InsP6 disappearance and digestibility of P and Ca in both species. However, the phytase-induced increase in prececal InsP6 disappearance was more pronounced in broilers than in turkeys, possibly due to more adequate conditions for phytase activity in the broiler crop. In broilers, phytase supplementation increased amino acid digestibility overall, whereas, in turkeys, it increased with CaP+ and decreased with CaP-. In addition, the relationship between myo-inositol concentration in the ileum and blood differed between species, indicating differences in myo-inositol metabolism. It was concluded that 3-week-old turkeys and broilers differ in nutrient digestibility and InsP degradation in some segments of the digestive tract but have similar endogenous InsP6 degradation when fed low P and Ca diets.

Mucosal phosphatase activity, phytate degradation, and mineral digestibility in 6-week-old turkeys and broilers at different dietary levels of phosphorus and phytase and comparison with 3-week-old animals

Female turkeys (B.U.T. 6) and broilers (Ross 308) were compared at 6 wk of age to evaluate the effects of species, dietary P, Ca, and phytase levels on myo-inositol hexakisphosphate (InsP₆) degradation along the digestive tract, gut mucosal phosphatase activity, P and Ca digestibility, and myo-inositol concentrations in the digesta and blood. The environmental conditions and experimental corn-soybean meal-based diets were the same for both species. Four diets with either combination of 2 levels of P and Ca (CaP-: 4.0 g P/kg, 5.4 g Ca/kg and CaP+: 6.0 g P/kg, 8.0 g Ca/kg) and 2 levels of phytase supplementation (0 and 1,500 FTU/kg) were fed to the animals for 7 d at their sixth wk of age. Each diet was randomly assigned to 6 pens per species, with 10 birds each. After slaughter, blood, digesta from the crop, gizzard, duodenum, lower ileum, and jejunal mucosa were collected. Endogenous mucosal phosphatase activity in the jejunum was higher in turkeys than in broilers. Prececal InsP₆ disappearance was also higher in turkeys than in broilers when phytase was not supplemented. Phytase supplementation led to a higher prececal InsP₆ disappearance in broilers than in turkeys, likely due to different crop conditions such as moisture content. However, prececal P digestibility was higher in turkeys than broilers. Different relationships between myo-inositol concentration in the ileum digesta and blood were found, depending on the species. A comparison of the results with those obtained in 3-wk-old birds of a companion study showed that in diets with low Ca and P levels, prececal InsP₆ disappearance increased with age in turkeys, but not in broilers. This coincided with changes in the conditions of the digestive tract, such as the water content in the crop, gizzard pH, and mucosal phosphatase activity. In conclusion, occurrence of differences in phytate degradation between turkeys and broilers, fed the same feed, depended on age and can be explained by different physiological development of the digestive tract.

Nutritional and Functional Roles of Phytase and Xylanase Enhancing the Intestinal Health and Growth of Nursery Pigs and Broiler Chickens

This review paper discussed the nutritional and functional roles of phytase and xylanase enhancing the intestinal and growth of nursery pigs and broiler chickens. There are different feed enzymes that are currently supplemented to feeds for nursery pigs and broiler chickens. Phytase and xylanase have been extensively studied showing consistent results especially related to enhancement of nutrient digestibility and growth performance of nursery pigs and broiler chickens. Findings from recent studies raise the hypothesis that phytase and xylanase could play functional roles beyond increasing nutrient digestibility, but also enhancing the intestinal health and positively modulating the intestinal microbiota of nursery pigs and broiler chickens. In conclusion, the supplementation of phytase and xylanase for nursery pigs and broiler chickens reaffirmed the benefits related to enhancement of nutrient digestibility and growth performance, whilst also playing functional roles benefiting the intestinal microbiota and reducing the intestinal oxidative damages. As a result, it could contribute to a reduction in the feed costs by allowing the use of a wider range of feedstuffs without compromising the optimal performance of the animals, as well as the environmental concerns associated with a poor hydrolysis of antinutritional factors present in the diets for swine and poultry.

Phytase dose-dependent response of kidney inositol phosphate levels in poultry

Phytases, enzymes that degrade phytate present in feedstuffs, are widely added to the diets of monogastric animals. Many studies have correlated phytase addition with improved animal productivity and a subset of these have sought to correlate animal performance with phytase-mediated generation of inositol phosphates in different parts of the gastro-intestinal tract or with release of inositol or of phosphate, the absorbable products of phytate degradation. Remarkably, the effect of dietary phytase on tissue inositol phosphates has not been studied. The objective of this study was to determine effect of phytase supplementation on liver and kidney myo-inositol and myo-inositol phosphates in broiler chickens. For this, methods were developed to measure inositol phosphates in chicken tissues. The study comprised wheat/soy-based diets containing one of three levels of phytase (0, 500 and 6,000 FTU/kg of modified E. coli 6-phytase). Diets were provided to broilers for 21 D and on day 21 digesta were collected from the gizzard and ileum. Liver and kidney tissue were harvested. Myo-inositol and inositol phosphates were measured in diet, digesta, liver and kidney. Gizzard and ileal content inositol was increased progressively, and total inositol phosphates reduced progressively, by phytase supplementation. The predominant higher inositol phosphates detected in tissues, D-and/or L-Ins(3,4,5,6)P4 and Ins(1,3,4,5,6)P5, differed from those (D-and/or L-Ins(1,2,3,4)P4, D-and/or L-Ins(1,2,5,6)P4, Ins(1,2,3,4,6)P5, D-and/or L-Ins(1,2,3,4,5)P5 and D-and/or L-Ins(1,2,4,5,6)P5) generated from phytate (InsP6) degradation by E. coli 6-phytase or endogenous feed phytase, suggesting tissue inositol phosphates are not the result of direct absorption. Kidney inositol phosphates were reduced progressively by phytase supplementation. These data suggest that tissue inositol phosphate concentrations can be influenced by dietary phytase inclusion rate and that such effects are tissue specific, though the consequences for physiology of such changes have yet to be elucidated.

Apparent digestibility of energy and nutrients and efficiency of microbial phytase is influenced by body weight of pigs

An experiment was conducted to test the hypothesis that regardless of pig body weight (BW), increasing dietary phytase results in increased phytate degradation and improved digestibility of minerals, amino acids (AA), and gross energy (GE). Eighteen pigs were equipped with a T-cannula in the distal ileum and allotted to a triplicated 6 × 3 Youden square design with six diets and three collection periods of 7 d, for a total of nine replicate pigs per diet. This design was repeated four times to simulate four production phases, and there was a 7-d resting period before each collection phase started (BW at start of collections: 29.3, 53.6, 85.1, and 114.4 kg for phases 1, 2, 3, and 4, respectively). Six corn-soybean meal diets were formulated by including 0, 250, 500, 1,000, 2,000, or 4,000 phytase units/kg feed (FTU). The six diets were used throughout the experiment. Samples of feces and ileal digesta were collected in each period. Results indicated that regardless of pig BW, increasing inclusion of phytase increased (quadratic; P < 0.05) apparent ileal digestibility (AID) of crude protein (CP) and most AA, increased apparent total tract digestibility (ATTD) of Ca, P, K, Mg (linear and quadratic; P < 0.05), and Na (linear; P < 0.05), but decreased (linear and quadratic; P < 0.05) AID and ATTD of GE. In all phases, ileal concentrations of inositol phosphate (IP) 6, IP5, IP4, and IP3 decreased (linear and quadratic; P < 0.05), whereas ileal inositol increased (linear and quadratic; P < 0.05) with increasing dietary phytase. However, as pig BW increased, AID of GE, CP, and AA increased (linear, P < 0.05), and the AID of a few AA (Met, Phe, Thr, Trp, Ala, Asp, Gly, and Ser) also increased quadratically (P < 0.05). The ATTD of GE, K, and Mg increased (linear and quadratic; P < 0.05), but ATTD of Ca and Na (linear; P < 0.05) and of P (linear and quadratic; P < 0.05) decreased as pig BW increased. Ileal IP6 and IP3 (linear and quadratic; P < 0.05) and ileal IP5 and IP4 (linear; P < 0.05) increased, whereas ileal inositol decreased (linear; P < 0.05) as pig BW increased. In conclusion, regardless of pig BW, increasing dietary phytase increased phytate degradation and inositol release in the small intestine, and consequently increased mineral and AA digestibility. Older pigs have reduced Ca, P, and Na digestibility, but increased K, Mg, AA, and GE digestibility compared with younger pigs. The efficiency of dietary phytase to degrade phytate appears to decrease as pigs get older.

Investigating possible impact, and interaction, of phytase supplementation during pre-experimental and experimental phases on assay of true phosphorus pre-caecal digestibility and total tract retention

1. Two experiments were conducted to investigate whether the use of phytase in the pre-experimental or experimental phases of true pre-caecal phosphorus digestibility (TPD) assay influenced the assayed TPD values. In experiments 1 and 2, broiler chickens were randomly allocated to 12 treatments in a 2 × 2 × 3 factorial arrangement. The factors were pre-experimental phytase supplementation (+ or -), experimental phase phytase supplementation (+ or -) with varying soybean meal inclusion levels (450, 560, or 670 g/kg).2. The diets in the pre-experimental phase were based on maize-soybean meal, whereas the diet used during the experimental phase was semi-purified, with soybean meal as the only source of P. Both TPD and true phosphorus retention (TPR) were determined using regression for the P output (g/kg, dry matter basis), pre-caecal or total tract, against P intake (g/kg). Data for TPD and TPR were analysed as a 2 × 2 factorial (with or without pre-experimental or experimental phase phytase).3. In both experiments 1 and 2, there were no significant effects for pre-experimental phytase supplementation nor interaction of pre- and experimental phytase supplementation on any of the pre-caecal digestibility responses. Phytase supplementation during the experimental phase increased (P < 0.01) pre-caecal P digestibility and retention, as well as digestible and retained P intake, and decreased (P < 0.01) P output.4. In experiment 1, pre- and experimental phytase supplementation increased (P < 0.01) the coefficient of TPR. In experiment 2, there was no significant effect of pre-experimental phytase supplementation on coefficient of pre-caecal TPD. However, phytase supplementation in the experimental phase increased (P < 0.01) the coefficient of pre-caecal TPD.5. In conclusion, whether or not phytase was supplemented to a P-adequate diet in the pre-experimental phase of the TPD assay, it had no influence on assayed TPD or TPR value.

Evaluation of High Doses of Phytase in a Low-Phosphorus Diet in Comparison to a Phytate-Free Diet on Performance, Apparent Ileal Digestibility of Nutrients, Bone Mineralization, Intestinal Morphology, and Immune Traits in 21-Day-Old Broiler Chickens

The supplementation of feed with phytases enables broilers to utilize more efficiently phosphorus (P) from phytic acid (IP6), the main storage form of P in plants. The current study evaluated the addition of 500, 1000, and 3000 FTU of phytase per kg to a phytate-containing diet with low P level (LP) fed to broilers from 1 to 21 days of age and compared it to a hypoallergenic phytate-free diet (HPF). There was a linear improvement in performance parameters with increasing levels of phytase in the LP diet (p < 0.001). Apparent ileal digestibility of crude protein, P, and some amino acids, increased with phytase. Crude ash, P, and the calcium content of tibia bones linearly increased with increasing levels of phytase (p < 0.001). Crypt depth (related to body weight) in the jejunum epithelium linearly decreased with phytase addition (p < 0.001). Cecal crypt depth decreased with phytase supplementation (p = 0.002). Cecum tissue showed lower counts of CD3-positive intraepithelial lymphocytes in broilers receiving the phytase in comparison to LP (p < 0.001), achieving similar counts to HPF-fed broilers. Although results from the current study seem to point out some mechanisms related to the immune response and mucosal morphology contributing to those overall beneficial effects, no clear differences between different phytase doses could be demonstrated in these specific parameters.

The Growth Performance, Nutrient Digestibility, Gut Bacteria and Bone Strength of Broilers Offered Alternative, Sustainable Diets Varying in Nutrient Specification and Phytase Dose

This study assessed the use of locally sourced sustainable feed ingredients, rapeseed meal (RSM) and maize dried distiller grains with solubles (DDGS) in diets over traditional ingredients on the growth performance, bone strength and nutrient digestibility of broilers. This work also investigated the effects of supplementing exogenous phytase in two doses (500 vs. 1500 FTU/kg). Using male Ross 308 chicks (n = 320) assigned to receive one of four experimental diets: (1) Positive control diet 1 (PC1), a wheat, soya-based diet + 500 FTU/kg phytase. (2) Positive control diet 2, RSM/DDGS diet + 500 FTU/kg phytase (PC2). (3) Negative control (NC) reduced nutrient RSM/DDGS diet, no phytase. (4) The NC diet plus 1500 FTU/kg phytase (NC+). PC1 birds displayed higher feed intake and body weight gain consistently throughout the trial (p < 0.001) as well as increased body weight by 28 d and 42 d (p < 0.001). Whole-body dual emission X-ray absorptiometry (DXA) analysis revealed PC1 birds also had higher bone mineral density (BMD), bone mineral content (BMC), total bone mass, total lean mass and total fat mass than birds offered other treatments (p < 0.01). Diet had no significant effect on bone strength. Phytase superdosing improved the digestibility of dry matter (DM), neutral detergent fibre (NDF), gross energy (GE), calcium (Ca), potassium (K) and magnesium (Mg) compared to birds in other treatment groups. The phytase superdose also improved performance in comparison to birds offered the NC diet. Phytase superdosing increased the IP6 and IP5 degradation and increased the ileal inositol concentration of the birds. N excretion was lower for birds offered the traditional wheat−soya diet and highest for those offered the high-specification RSM/DDGS diet with a commercial dose of phytase. The addition of a phytase superdose to the negative control diet (NC+) reduced P excretion of birds by 15% compared to birds offered NC.

Effect of supplemental myo-inositol on growth performance and apparent total tract digestibility of weanling piglets fed reduced protein high phytate diets and intestinal epithelial cell proliferation and function

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 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 four weeks. 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), 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 effect 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 lack of myo-inositol effect on growth performance, an additional in vitro study was conducted to determine 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 indicates 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.

Effect of phytase supplementation on plasma and organ myo-inositol content and erythrocyte inositol phosphates as pertaining to breast meat quality issues in chickens

‘Woody breast’ (WB) and ‘white striping’ in broiler meat is a global problem. With unknown etiology, WB negatively impacts bird health, welfare and is a significant economic burden to the poultry industry. New evidence has shown that WB is associated with dysregulation in systemic and breast muscle-oxygen homeostasis, resulting in hypoxia and anaemia. However, it has been observed that phytase (Quantum Blue (QB) a modified, E. coli-derived 6-phytase) super dosing can reverse dysregulation of muscle-oxygen homeostasis and reduces WB severity by ~5%. The objective of this study was to assess whether levels of Ins(1,3,4,5,6)P5, the main allosteric regulator of haemoglobin, are influenced by changes in plasma myo-inositol arising from super dosing with phytase. To enable this, methods suitable for measurement of myo-inositol in tissues and inositol phosphates in blood were developed. Data were collected from independent trials, including male Ross 308 broilers fed low and adequate calcium/available phosphate (Ca/AvP) diets supplemented with QB at 1,500 phytase units (FTU)/kg, which simultaneously decreased gizzard InsP6 (P<0.001) and increased gizzard myo-inositol (P<0.001). Similarly, male Cobb 500 broiler chicks fed a negative control (NC) diet deficient in AvP, Ca and sodium or diet supplemented with the QB phytase at 500, 1000 or 2,000 FTU/kg increased plasma (P<0.001) and liver (P=0.007) myo-inositol of 18d-old birds at 2,000 FTU/kg. Finally, QB supplementation of Cobb 500 breeder flock diet at 1,250 FTU/kg increased blood myo-inositol (P<0.001) and erythrocyte Ins(1,3,4,5,6)P5 (P=0.011) of their 1d-old hatchlings. These data confirmed the ability of phytase to modulate inositol phosphate pathways by provision of metabolic precursors of important signalling molecules. The ameliorations of WB afforded by super doses of phytase may include modulation of hypoxia pathways that also involve inositol signalling molecules. Elevations of erythrocyte Ins(1,3,4,5,6)P5 by phytase supplementation may enhance systemic oxygen carrying capacity, an important factor in the amelioration of WB and WS myopathy.

Effects of phytase and 25-hydroxyvitamin D3 supplementation on growth performance and bone development in weaned piglets in Ca- and P-deficient dietary

BACKGROUND

The beneficial function of phytase and 25-hydroxyvitamin D3 (HyD) on the feed utilization rate has been widely investigated. However, studies concerning its influence on weaned piglets largely lag behind. The aim of this study was to investigate the effects of phytase and HyD supplementation on the growth performance and bone development in weaned piglets under dietary Ca and P deficiency.

RESULTS

The results showed that dietary Ca and P deficiency decreased (P < 0.05) the content of serum P in 6-10 kg piglets, as well as reducing (P < 0.05) the contents of serum Ca and P, average daily gain (ADG), bone mineral density (BMD), breaking force (BF), bone ash and femur Ca in 10-20 kg piglets. Compared with the control group, the feed-to-gain ratio (F/G) of 6-10 kg piglets in the Phy group was decreased (P < 0.05), whereas the ADG, blood Ca and P, BMD, BF, bone ash, P apparent digestibility, Ca and P retention rate of 10-20 kg piglets were increased (P < 0.05). The contents of serum osteocalcin and HyD in 6-10 kg piglets and ADG were higher than in the control group (P < 0.05), as well as the contents of serum Ca and HyD in 10-20 kg piglets in the HyD treatment group. Supplementation with both Phy and HyD decreased the F/D (P < 0.05) and increased the contents of serum Ca, P and HyD in 6-10 kg piglets as well as enhancing the ADG, BMD, BF, bone ash, femur Ca and P, serum Ca and P, HyD, and the apparent digestibility and retention of Ca and P (P < 0.05) in 10-20 kg piglets. Supplementation with Phy and HyD in Ca- and P-deficient dietary decreased bone resorption, and improved tight arrangement of collagen fibers and oblique fibers in weaned piglets.

CONCLUSION

These data indicated that supplementation with both 1500 U kg^-1 Phy and 50 μg kg^-1 HyD could enhance dietary Ca and P utilization and promote bone development in low Ca and P dietary, and supplementation with both Phy and HyD had a significant synergy effect compared to single supplement. © 2021 Society of Chemical Industry.

Increased microbial phytase increased phytate destruction, plasma inositol, and feed efficiency of weanling pigs, but reduced dietary calcium and phosphorus did not affect gastric pH or fecal score and reduced growth performance and bone ash

An experiment was conducted to test two hypotheses: 1) reducing dietary Ca and P reduces gastric pH and diarrhea in weanling pigs; 2) negative effects of low Ca and P on pig growth performance may be overcome if phytase is added to the diets. A total of 320 weanling pigs (6.35 ± 0.87 kg) were allotted to eight corn-soybean meal-based diets in a randomized complete block design with five pigs per pen. Two phase 1 (days 1 to 14) control diets containing 100 or 50% of total Ca and digestible P relative to the requirement, and six diets in which 500, 2,000, or 16,000 units of phytase/kg feed (FTU) were added to each control diet were formulated. Phytase was assumed to release 0.16% total Ca and 0.11% digestible P. Common diets were fed in phases 2 (days 15 to 27) and 3 (days 28 to 42). Growth performance data were recorded within each phase. Data for fecal scores and gastrointestinal pH were recorded for phase 1. Colon content (day 14), the right femur (days 14 and 42), and blood samples (days -1, 14, 27, and 42) were collected from one pig per pen. In phase 1, reducing Ca and P did not reduce gastric pH or fecal score, but pigs fed the 50% diets had reduced (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) compared with pigs fed the 100% diets. In both 50% and 100% diets, phytase above 500 FTU increased (P < 0.05) gain:feed ratio (G:F) and tended (P < 0.10) to reduce gastric pH of pigs. From days 1 to 42, pigs fed the 50% diets tended (P < 0.10) to have reduced ADG and ADFI compared with pigs fed the 100% diets, but among the 100% diets, pigs tended (P < 0.10) to have a linear increase in G:F as phytase level increased. Pigs fed the 50% diets had reduced (P < 0.05) concentrations of inositol phosphate esters (IP) in the colon and reduced bone ash (days 14 and 42) compared with pigs fed the 100% diets. Phytase did not affect bone ash or most blood metabolites. Concentrations of IP in the colon decreased, whereas plasma inositol increased (d 14; P < 0.05) in pigs fed diets with phytase (≥ 500 FTU). In pigs fed the 100% diets, IP in the colon linearly decreased (P < 0.05), but plasma inositol linearly increased (P < 0.05) with increasing levels of phytase. In conclusion, reducing Ca and P in diets for weanling pigs did not influence gastric pH or fecal score, but compromised growth performance and bone ash. However, regardless of dietary Ca and P, high doses of phytase increased phytate degradation and inositol absorption, which consequently increased G:F of pigs.

Investigation of a potential electrogenic transport-system for myo-inositol in the small intestine of laying hens

1. Myo-inositol (MI) is an essential metabolite for cell function in animals and humans. The aim of this study was to characterise the transport mechanism of MI in the small intestine of laying hens as there is a lack of knowledge about the MI uptake mechanisms. The hypothesised secondary active, cation coupled transport of MI was assessed by electrophysiological measurements with Ussing chambers, and was compared to the electrophysiology of glucose transport.2. Twenty-six laying hens were used. The potential ion-dependent transport was tested in tissue of the small intestine. Barrier function of the tissue was shown by determining the transepithelial resistance. During the experiments, mucosal and serosal buffers were sampled to measure time-dependent changes in MI concentrations. Samples from eight hens were further used for Western blot analyses of the jejunal apical membranes.3. Active MI transport, indicated by changes in the short circuit current after MI addition, could not be demonstrated in the Ussing chambers experiments. MI was further not detectable in the serosal buffer, nor in the lysates of mucosal tissue cytoplasm nor lipids. Thus, there was no evidence for a MI transport or absorption. However, Western blot analyses of the jejunal apical membrane revealed signals indicated the expression of the MI transport proteins SMIT-1 and SMIT-2.4. In conclusion, the MI transport process in the chicken intestine is more complex than it was presumed and is probably influenced by still unknown regulations or metabolic processes.

Contrasting the effects of phytase and pure myo-inositol on the performance, digestibility, blood and egg yolk inositol levels and digestion physiology of laying hens

ABSRACT1. An experiment was designed to compare the effects of supplementing laying hen diets with phytase and myo-inositol (inositol).2. Five diets were formulated: high balanced protein (HBP - 840 mg of Dlys/hen/day), HBP with inositol (HBP+I - 0.16%), reduced balance protein (RBP - 672 mg of Dlys/hen/day), RBP with inositol (RBP+I - 0.16%) and RBP with phytase (RBP+P - 3000 FTU/kg).3. Laying hen production, inositol concentrations, digestive tract morphology, amino acid digestibility and intestinal inositol transporters transcript abundance were evaluated. Data were analysed with a one-way ANOVA in SAS 9.4. Contrasts were used to assess the effect of protein, inositol, phytase and phytase vs. inositol. Differences were accepted when P ≤ 0.05.4. No effect on hen-day egg production or feed efficiency was found. However, feed intake and the incidence of abnormally shaped eggs were 0.77 g/h/d and 0.17% higher, respectively, in inositol treatments. Inositol decreased egg specific gravity from 1.088 to 1.0865.5. Inositol concentration in egg yolk was similar among HBP+I, RBP+I and RBP+P, and higher than for the HBP and RBP diet groups. Both gizzard and ileal digesta were enriched in inositol in all supplemented treatments, and phytase supplementation decreased the level of IP5 and IP6 in the gizzard and ileum. Generally, neither phytase or inositol affected amino acid digestibility.6. Inositol increased transcript abundance of alkaline phosphatase in the ileum, while phytase upregulated duodenal alkaline phosphatase and SMIT1, jejunal SMIT2 and reduced ileal HMIT and SMIT1 abundance.7. In conclusion, no effect of phytase or inositol was found for laying hen production performance or amino acid digestibility, but egg quality was reduced by inositol supplementation. Inositol concentration in egg yolk was similar among supplemented treatments.

Reevaluation of Phytase Action Mechanism in Animal Nutrition

The release of phosphorus from phytates occurs via sequential cleavage of phosphate groups. It was believed that, regardless of the properties of phytases, the rate of phytate dephosphorylation is limited by the first cleavage of any phosphate group. The position of the first cleaved-off phosphate group depending on the specificity of phytase. The inhibition of dephosphorylation initiation is not associated with the action mechanism of the enzyme and can be rather due to the insufficient phytase activity or low availability of phytates. The analysis of the transformations in the inositol hexakisphosphate (IP₆)→inositol (I) reaction chain shows that IP₆ dephosphorylation as a whole limits the phosphate group removal from I(1,2,5,6)P₄ (third reaction from the beginning of hydrolysis of phosphate bonds in PA). The lower availability of nutrients in the presence of phytates is not due to action of phytates, but is caused by PA anions (IP_6-3), which bind positively charged metal ions, amino acids, and proteins. The availability of nutrients increases as a result of the decrease in their binding caused by the decrease in the concentration of IP_(6-3) anions under the action of phytases. Phytases added to feeds play a lesser role in the digestion of phytates compared to natural enzymes and complement their action. The concept of extra-phosphoric effect has no scientific justification, since phytases exhibit only the phosphohydrolase activity and are not able to catalyze other reactions.

Influence of exogenous phytase supplementation on phytate degradation, plasma inositol, alkaline phosphatase, and glucose concentrations of broilers at 28 days of age

Inositol is the final product of phytate degradation, which has the potential to serve as an indicator of phytase efficacy. An experiment was conducted to evaluate effects of supplementing broiler diets with phytase on phytate degradation and plasma inositol concentrations at 28 d of age. Twenty-four Ross × Ross 708 male chicks were placed in battery cages (4 birds per cage) from 1 to 21 d of age and individually from 22 to 28 d of age. At 27 d of age, a catheter was placed in the brachial vein of broilers to avoid repeated puncture of the vein during blood collection. At 28 d of age, broilers received 1 of 3 experimental diets formulated to contain 0, 400, or 1,200 phytase units (FTU)/kg, respectively, in diet 1, 2, and 3. Blood was collected 1 h before feeding experimental diets and from 20 to 240 min after feeding experimental diets at 20-min intervals with a final blood collection at 480 min to determine plasma inositol concentrations. Inositol phosphate (IP) ester degradation was determined in gizzard contents and ileal digesta. Broilers provided the 1,200 FTU/kg phytase diet had 60% less (P < 0.01) IP6 concentration in gizzard content (1,264 vs. 4,176 nmol/g) and ileal digesta (13,472 vs. 33,244 nmol/g) than birds fed the 400 FTU/kg diet. Adding phytase at 1,200 FTU/kg increased (P < 0.01) inositol concentrations in gizzard content and ileal digesta of broilers by 2.5 (2,703 vs. 1,071 nmol/g) and 3.5 (16,485 vs. 4,667 nmol/g) fold, respectively, compared with adding 400 FTU/kg. Plasma inositol concentration of broilers was not different (P = 0.94) among the dietary treatments at each collection time. Inositol liberation in the digesta of broilers fed diets with 1,200 FTU/kg phytase did not translate to increased plasma inositol concentrations, which warrants further investigation.

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 2. Inositol phosphate esters hydrolysis, intestinal permeability, hematology, jejunal gene expression and intestinal morphology

This study investigated the hypothesis that feeding broilers over-processed meat and bone meal (MBM) would impair gut health in the absence of phytase and in turn, affect inositol phosphate (inositol x-phosphate, IPx: IP3, IP4, IP5 and IP6) ester hydrolysis, intestinal permeability, hematology, jejunal gene expression and intestinal morphology during necrotic enteritis (NE). Ross 308 male broilers (n = 768) were assigned to one of 8 dietary treatments in a 2 × 2 × 2 factorial arrangement, with 6 replicate pens per diet and 16 birds per pen in a completely randomized design. Factors were: NE challenge (no or yes), phytase level (500 or 5,000 FTU/kg) and MBM processing (as-received or over-processed). For the NE challenge, half of the birds were challenged with field strains of Eimeria spp. on d 9 and 10⁸ CFU/mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15. A 3-way challenge, phytase and MBM processing interaction was detected for IP5 (P < 0.05) and IP6 (P < 0.05) levels in the ileum. Birds fed low phytase had increased IP5 and IP6 in unchallenged birds only when diets contained over-processed MBM. Challenge with NE increased intestinal permeability as measured by serum fluorescein isothiocyanate dextran (FITC-d; P < 0.001), increased white blood cells (WBC; P < 0.001), decreased mean corpuscular volume (MCV; P < 0.001) and mean corpuscular hemoglobin (MCH; P < 0.05), and decreased crypt-to-villi ratio (P < 0.05). The over-processed MBM reduced the villi-to-crypt ratio (P < 0.05). A 3-way challenge × phytase × MBM processing interaction was detected for mucin 2 (MUC-2) expression (P < 0.05) where only in unchallenged birds fed over-processed MBM did high phytase reduce MUC-2 expression. A lower expression of aminopeptidase N (APN; P < 0.001) and vitamin D receptor (VDR; P < 0.001) were recorded in NE challenged birds. In conclusion, NE has a negative impact on the gut and hematology of broilers, but its effect on phytate hydrolysis is minimal.

Inositol and gradient phytase supplementation in broiler diets during a 6-week production period: 2. Effects on phytate degradation and inositol liberation in gizzard and ileal digesta contents

An experiment was conducted to evaluate effects of dietary phytase and inositol supplementation on phytate degradation in gizzard and ileal digesta contents of broilers from 1 to 43 d of age. One thousand nine hundred and twenty Yield Plus × Ross 708 male chicks were placed in 64 floor pens (30 birds/pen). Each pen received 1 of 8 dietary treatments from 1 to 43 d of age. Treatment 1 was formulated to contain 0.165 and 0.150% lower calcium and phosphorus, respectively, than treatment 7. Treatments 2 to 6 were formulated by adding phytase at 500, 1,500, 4,500, 13,500, and 40,500 phytase units (FTU)/kg, respectively, to treatment 1. Treatment 8 was established by adding inositol to treatment 7 based on the maximum inositol liberation in treatment 6. At 15, 29, and 43 d of age, gizzard contents, ileal digesta, and blood were collected for analysis of inositol and inositol phosphate (IP) 2, 3, 4, 5, and 6 concentrations. Increasing phytase from 0 to 40,500 FTU/kg resulted in log-quadratic reductions (P < 0.01) of inositol pentaphosphate and inositol hexakisphosphate concentrations in the gizzard and ileal digesta contents of broilers at 15, 29, and 43 d of age. The increase in phytase doses in treatments 1 to 6 reduced IP3 and IP4 concentrations in a log-quadratic manner (P < 0.05) at each collection period in gizzard contents but only at 43 d of age in the ileal digesta of broilers (P < 0.01). Log-quadratic increases (P < 0.05) of inositol concentrations were observed in gizzard and ileal digesta contents when increasing phytase activity from 0 to 40,500 FTU/kg at each collection period, which translated to a log-quadratic increase (P < 0.01) in plasma inositol concentration of broilers at 15, 29, and 43 d of age. Phytase supplementation up to 40,500 FTU/kg may benefit broilers by reducing phytate concentrations in the gizzard and ileal digesta contents. Moreover, inositol release in the ileal digesta may translate to increased plasma inositol concentration.

Inositol and gradient phytase supplementation in broiler diets during a 6-week production period: 1. effects on growth performance and meat yield

An experiment was conducted to evaluate effects of inositol and gradient phytase supplementation on growth performance and meat yield of broilers from 1 to 41 d of age. A total of 1,920 Yield Plus × Ross 708 male chicks were placed in 64 floor pens (30 birds per pen). Each pen received one of the 8 dietary treatments (8 replicate pens) from 1 to 15, 16 to 29, and 30 to 40 d of age. Treatment 1 was formulated to contain 0.165 and 0.150% lower calcium and phosphorus, respectively, than treatment 7 (positive control). Phytase was added to treatment 1 at concentration of 500, 1,500, 4,500, 13,500, and 40,500 phytase units (FTU)/kg to establish treatments 2 to 6, respectively. Treatment 8 was formulated by adding inositol to treatment 7 based on the expected inositol liberation in treatment 6. Feed and birds were weighed at 1, 15, 29, and 40 d of age to determine BW gain, feed intake, and feed conversion. Twelve birds per pen were processed at 41 d of age to determine carcass characteristics. From 1 to 40 d of age, log-quadratic effects of phytase (treatments 1–6) were observed for BW gain (P = 0.002) and feed conversion in broilers (P = 0.018), whereas feed intake increased log-linearly (P = 0.045). The addition of 40,500 FTU/kg of phytase increased cumulative BW gain (P = 0.001) and decreased cumulative feed conversion (P = 0.005) by 4.7 and 2.6%, respectively, compared with birds subjected to treatment 8. Log-quadratic effects of phytase additions were observed for carcass (P < 0.001) and breast meat weights (P = 0.004). Growth performance and carcass characteristics of broilers subjected to treatment 7 were similar (P > 0.05) to those of birds subjected to treatment 8. These data demonstrate that the extraphosphoric effects of phytase may be associated with increased feed intake of broilers. Inositol supplementation did not provide additional benefits to broilers in this study.

Interactive effect of dietary calcium and phytase on broilers challenged with subclinical necrotic enteritis: part 2. Gut permeability, phytate ester concentrations, jejunal gene expression, and intestinal morphology

Calcium has the capacity to interact with phytate-P to form Ca-phytate complexes and decrease the ability of exogenous phytase to degrade phytic acid. This study investigated the hypothesis that high dietary Ca would impair gut permeability, phytate esters (inositol x-phosphate, IPx: IP3, IP4, IP5, and IP6) degradation, jejunal gene expression, and intestinal morphology. Ross 308 day-old male broilers (n = 768) were distributed into 48-floor pens each housing 16 birds in a factorial arrangement. Factors were NE challenge-no or yes; phytase level of 500 or 1,500 FTU/kg, and Ca level 0.6 or 1.0% starter, 0.5 or 0.9% grower, 0.4 or 0.8% finisher with available P in each phase. Challenged birds were gavaged with 3 field strains of Eimeria on day 9 and 108 CFU per mL of Clostridium perfringens Strain EHE-NE18 on day 14 and day 15. A phytase × Ca interaction was observed in the ileum for IP3 (P < 0.01), IP4 (P < 0.05), and IP6 (P < 0.01). The IP3 and IP4 concentrations were similar for both doses of phytase in the presence of low Ca, but with high Ca, both increased significantly but to a greater extent when the high dose of phytase was used. While IP6 concentrations were low and similar between both doses of phytase at low Ca levels, increasing dietary Ca levels increased IP6 concentrations regardless of phytase dose, but the effect was greater in the low phytase diet. A phytase × Ca interaction was detected for vitamin D receptor (VDR) (P < 0.05) expression where bird fed low phytase and low Ca recorded the highest expression of VDR, all other treatments being equivalent. The challenge decreased crypt depth to villus height ratio (P < 0.001). Challenge birds had higher fluorescein isothiocyanate dextran (P < 0.05) in blood compared with unchallenged birds. Thus, high Ca and high phytase, while not the best for IP6 destruction, did not lead to huge reductions in indicators of gut health.

Research Note: Jejunum phosphatases and systemic myo-inositol in broiler chickens fed without or with supplemented phytase

As a constituent of animal cells, myo-inositol (MI) has been hypothesized to be crucial in several metabolic and regulatory pathways. Recently, it was shown that dietary phytase contributes to release of MI from phytate in the poultry digestive tract, increasing its systemic concentrations. This study investigated the activities of phosphatases in the jejunum and systemic plasma MI concentration in broilers not supplemented or supplemented with phytase through analyses based on modifications from commercial enzyme activity kits. Three hundred sixty male Ross 308 broilers were randomly allocated to 24 pens (15 birds per pen) in 4 dietary groups. The positive control group was fed with an adequate basal diet. The negative control group (NC) was fed with a reduced level of P and Ca. Groups Phy1500 and Phy3000 were fed with the NC diet plus 1,500 or 3,000 FTU of phytase per kilogram of feed, respectively. One bird per pen was selected for the measurement of jejunal phosphatase activity; MI concentration in plasma, the liver, and the kidney; and key MI enzyme concentrations (liver inositol monophosphatase 1 [IMPase 1] and kidney myo-inositol oxygenase [MIOX]). Endogenous phytase and alkaline phosphatase activity as well as IMPase 1 and MIOX expression were not statistically different among the dietary groups. The supplementation of 1500 FTU of phytase per kilogram of feed resulted in increase of plasma (P < 0.001) and kidney (P < 0.05) but not liver MI concentrations. The results indicated that systemic MI might reflect MI released from dietary sources; however, it did not appear to change expression of enzymes related to endogenous MI synthesis in the liver and catabolism in the kidney. New and larger studies are necessary to reach stronger evidence on the effects of dietary phytase on intestinal and systemic MI concentrations in broilers.

Interactive effect of 2 dietary calcium and phytase levels on broilers challenged with subclinical necrotic enteritis: part 1-broiler performance, gut lesions and pH, bacterial counts, and apparent ileal digestibility

This study investigated the hypothesis that high dietary calcium (Ca) would stimulate necrotic enteritis (NE) and reduce performance, gut health, and nutrient digestibility, and if increased, phytase would reduce NE. Ross 308 male broilers (n = 768) were randomly distributed to 8 treatments in a factorial arrangement. Factors were NE challenge (no or yes), phytase level (500 or 1,500 FTU/kg using 500 FTU/kg matrix values), and Ca level (0.6 or 1.0% starter, 0.5 or 0.9% grower, 0.4 or 0.8% finisher) with the same level of available P (0.40 S, 0.35 G, and 0.35 F). There were 48 pens, 16 birds per pen and 6 replications. Half of the birds were challenged with Eimeria spp on day 9 and 10⁸ CFU per mL of Clostridium perfringens strain EHE-NE18 on day 14 and 15. Gain was higher in birds fed high phytase on day 14 (P < 0.01), day 21 (P < 0.01), day 28 (P < 0.01), and day 35 (P < 0.01). Birds fed high phytase had greater livability on day 21 (P < 0.01). Ca was more digestible in high-Ca diets on day 16, and an NE × Ca interaction (P < 0.05) showed this effect to be more pronounced in unchallenged than in challenged birds. A challenge × Ca interaction for apparent ileal digestibility (AID) of crude protein (CP) (P < 0.05) indicated lower AID of CP in challenged birds fed high Ca. The challenge decreased AID of Ca (P < 0.01). Ca level had no impact on C. perfringens count, but it decreased Lactobacillus (P < 0.05) and Bifidobacteria (P < 0.05) populations in the ceca. High dietary Ca decreased feed conversion ratio. Overall (42 D), the highest WG was observed in unchallenged birds fed high Ca and high phytase with the lowest WG observed in NE-challenged birds fed low Ca and low phytase. The results suggest that full matrix values for high doses of phytase may be appropriate during NE challenge.

Phytase dosing affects phytate degradation and Muc2 transporter gene expression in broiler starters

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.

Comparative aspects of phytase and xylanase effects on performance, mineral digestibility, and ileal phytate degradation in broilers and turkeys

Two experiments were performed, using broilers or turkeys, each utilizing a 3 × 2 factorial arrangement, to compare their response to phytase and xylanase supplementation with growth performance, nutrient digestibility, and ileal phytate degradation as response criteria. For both experiments, 960 Ross 308 or 960 BUT 10 (0-day-old) birds were allocated to 6 treatments: (1) control diet, containing phytase at 500 FTU/kg; (2) the control diet with xylanase (16,000 BXU/kg); (3) the control diet supplemented on top with phytase (1,500 FTU/kg); (4) diet supplemented with 1,500 FTU/kg phytase and xylanase (16,000 BXU/kg); (5) the control diet supplemented with phytase (3,000 FTU/kg); and (6) diet supplemented with 3,000 FTU/kg phytase and xylanase (16,000 BXU/kg). Each treatment had 8 replicates of 20 birds each. Water and diets based on wheat, soybean meal, oilseed rape meal, and barley were available ad libitum. Body weight gain and feed intake were measured from 0 to 28 D, and feed conversion ratio (FCR) corrected for mortality was calculated. Ileal digestibility for dry matter and minerals on day 7 and 28 were analyzed in addition to levels of inositol phosphate esters (InsP6-3) and myo-inositol. Statistical comparisons were performed using ANOVA. Xylanase supplementation improved 28D FCR in broilers and turkeys. Increasing doses of phytase reduced FI and improved FCR only in broilers. In broilers, the age × phytase interaction for phosphorous digestibility showed that increasing phytase dose was more visible on day 7, than on day 28. Mineral digestibility was lower in 28-day-old turkey compared with 7-day-old turkey. InsP6 disappearance increased with increasing phytase levels in both species, with lower levels analyzed in turkeys. InsP6 disappearance was greater in younger turkeys (day 7 compared with day 28). In conclusion, although broilers and turkeys shared several similarities in their growth and nutrient utilization responses, the outcomes of the 2 trials also differed in many aspects. Whether this is because of difference in diets (InsP or Ca level) or differences between species needs further investigation.

Dietary phytate has a greater anti-nutrient effect on feed conversion ratio compared to body weight gain and greater doses of phytase are required to alleviate this effect as evidenced by prediction equations on growth performance, bone ash and phytate degradation in broilers

Cobb 400, male broilers (n=4,752) were fed one of 12 diets, with 12 pens/diet and 33 birds/pen. Treatments consisted of 3 levels of phytate P (0.24, 0.345, or 0.45%) and 4 doses of phytase (0, 500, 1,000, or 2,000 phytase units (FTU)/kg). Diets were formulated with reduced Ca (0.22%), available P (0.20%), energy (80 to 120 kcal/kg), and amino acids (1 to 5%) when compared with breed requirements. Prediction equations suggested feeding dietary phytate P > 0.275, 0.295, or 0.319% reduced feed intake (FI) and body weight gain (BWG) and increased feed conversion ratio, respectively, from day 0 to 21. Supplementing phytase at 561, 1,285, or >2,000 FTU/kg resulted in the maximum FI, BWG, or feed efficiency, respectively. From day 0 to 42, maximum BWG or feed efficiency were achieved at phytate P concentrations <0.281 or 0.25%, respectively. Supplementing phytase at 449 or 2,000 FTU/kg maximized BWG or feed efficiency, respectively. Tibia ash weight, percent or Ca concentration were maximized at phytate P concentrations <0.24, 0.296, or 0.24%, respectively and phytase supplementation at 822 or >2,000 FTU/kg maximized tibia ash weight or percent respectively. In the absence of phytase, phytate (IP6) concentration in the gizzard was greatest in birds fed 0.45% phytate P and phytase supplementation between 1,132 to 1,285 FTU/kg resulted in the lowest IP6 concentration in the gizzard. There was no effect of dietary phytate P on the concentration of phytate esters (IP5 or IP4) in the gizzard, which were minimized at 1,208 FTU/kg of phytase. In the absence of phytase, the concentration of phytate ester (IP3) or inositol in the gizzard was greatest in birds fed 0.345% phytate P and phytase supplementation at ∼500 FTU/kg minimized IP3, whereas 2,000 FTU/kg maximized inositol, except in birds fed 0.45% phytate P, which was maximized at 202 FTU/kg of phytase. Prediction equations can be useful to determine the influence of phytase and phytate P on broiler performance, phytate degradation and bone ash.

Sulfate and hydroxychloride trace minerals in poultry diets - comparative effects on egg production and quality in laying hens, and growth performance and oxidative stress response in broilers

Two experiments investigated the effect of sulfate and hydroxychloride trace minerals (TM), Zn, Cu, and Mn, in laying hens and broiler chickens. In Expt. 1, Lohmann Brown pullets (total of 1,344) at 21 wk of age were used for a 24-wk experiment. Each of the two treatments had 32 replicates with 21 hens per replicate. At 45 wk of age, three eggs per cage were randomly selected and used for internal quality assessment. In Expt. 2, Ross 308 broilers (total of 1,080) were allocated to two treatments. Each treatment had 30 replicates with 15 chicks per replicate. On day 28, after weighing, three birds were randomly selected from 15 randomly selected pens per treatment. The birds were euthanized and blood was collected for analysis for uric acid, C-reactive protein and methylmalonic acid. Samples were also taken from pectoralis muscle of each chicken and analyzed for mRNA expression of protein synthesis or hydrolysis genes. On day 35, 7 birds per pen were used for carcass evaluation. In Expt. 1, egg weight was greater (P < 0.01) in birds receiving sulfate TM from week 16 (of experiment) onwards whereas the percentage of cracked eggs was lower (P < 0.01) in hens receiving hydroxychloride TM. Percentage hen-day production tended to be greater (P < 0.10) in hens receiving hydroxychloride TM in weeks 4 to 8 only. In Expt. 2, birds receiving hydroxychloride TM had greater (P < 0.05) weight gain and tended to have greater (P < 0.10) feed intake on day 35. Expression of the gene, PSMA1, was lower (P < 0.05) whereas plasma level of uric acid and methyl malonic acid tended to be lower (P < 0.10) in birds receiving hydroxychloride TM. It was concluded that hydroxychloride TM reduced egg loss in hens at peak production and that improved growth performance response in broilers can be partly explained by reduction in proteolytic activities in the pectoralis muscle and greater resilience to oxidative stress.

Myo-inositol: its metabolism and potential implications for poultry nutrition-a review

Myo-inositol (MI) has gained relevance in physiology research during the last decade. As a constituent of animal cells, MI was proven to be crucial in several metabolic and regulatory processes. Myo-inositol is involved in lipid signaling, osmolarity, glucose, and insulin metabolism. In humans and rodents, dietary MI was assessed to be important for health so that MI supplementation appeared to be a valuable alternative for treatment of several diseases as well as for improvements in metabolic performance. In poultry, there is a lack of evidence not only related to specific species-linked metabolic processes but also about the effects of dietary MI on performance and health. This review intends to provide information about the meaning of dietary MI in animal metabolism as well as to discuss potential implications of dietary MI in poultry health and performance with the aim to identify open questions in poultry research.

Influence of graded concentrations of phytase in high-phytate diets on growth performance, apparent ileal amino acid digestibility, and phytate concentration in broilers from hatch to 28 D post-hatch

An experiment was conducted to evaluate graded doses of phytase in high-phytate diets. Ross 308, male broilers (n = 600) were assigned to one of 4 diets, with 10 replicate pens/diet and 15 birds/replicate pen. Diets were a nutrient adequate positive control (PC), a negative control (NC) diet with a reduction of Ca by 0.22%, available P by 0.20%, energy by 120 kcal/kg, and amino acids by 1 to 5% compared with the PC. The NC diet was supplemented with 0, 2,000, or 4,000 phytase units (FTU)/kg. Phytase increased (linear, P < 0.05) weight gain from hatch to day 18. Birds fed the NC + 4000 FTU/kg ate and gained more (P < 0.05) than birds fed the PC. The apparent ileal digestibility (AID) of all nutrients and amino acids were reduced (P < 0.05) in birds fed the NC compared with birds fed the PC. Phytase increased (linear, P < 0.10) AID of most nutrients. Digestibility was lower (P < 0.10) in birds fed the NC + 4000 FTU/kg compared with birds fed the PC. Using daily intake and AID to determine digestible nutrient intake resulted in no differences between birds fed the PC or NC + 4000 FTU/kg diets. Digestible intake of methionine or glutamate was better correlated with BW gain (P < 0.0001) than AID (P > 0.10). Phytase reduced (linear, P < 0.01) phytate concentration and increased inositol (linear, P < 0.01), phytate hydrolysis (linear, P < 0.05), and jejunal expression (linear, P < 0.05) of SNAT-1 and LAT-4 transporters. Supplementation of increasing doses of phytase in high-phytate, low-nutrient dense diets improved gain and digestibility through nearly complete phytate destruction. Digestible nutrient intake may be a better indication of broiler gain than AID alone.

Dietary Inositol Reduces Fearfulness and Avoidance in Laying Hens

Simple Summary

Brain inositol is known to affect memory, and the incidence of depression, anxiety, and obsessive-compulsive disorder in mammals. Phytate, a naturally occurring inositol ester in plants, binds other nutrients, making them unavailable for digestion. The addition of phytase, the enzyme capable of hydrolyzing phytate, to diets increases the release of both inositol and nutrients for absorption in the chicken digestive tract. In this study, we assessed how dietary phytase or pure inositol affected laying hen behaviour, fearfulness, aggression, and stress levels. To increase the probability of seeing effects, hens were not beak treated and were fed two balanced protein levels differing in digestible amino acid sufficiency. Inositol did not affect stress levels, as measured by heterophil-to-lymphocyte ratio, or the number of hen comb or skin lesions. However, regardless of the source, pure inositol or phytase derived inositol reduced the number of feathers in the vent area, suggesting an increase in feather pecking. Pure inositol reduced fearfulness in laying hens, but phytase-derived inositol did not.

Abstract

Myo-inositol (inositol) affects memory, and the incidence of depression and anxiety in mammals. An experiment was designed to determine if pure inositol (0.16%), or high levels of phytase (3000 FTU/kg) affect the behaviour of fully beaked Lohmann LSL lite hens fed amino acid sufficient (19% crude protein (CP)) and deficient diets (16% CP), from 19 to 59 weeks of age. The data collected included live-scan behaviour observations and novel object (NO) tests (both at 1, 10 and 40 weeks of the trial); heterophil-to-lymphocyte (H/L) ratios (week 1 and week 40 of the trial); end of trial feather cover, and comb and skin lesions; and daily mortality. Reducing CP increased sitting by 2.5%. Inositol, but not phytase, reduced the latency to peck at the NO by 300 sec. Inositol reduced vent feather cover by 12% and tended to increase mortality by 13%. No effects on H/L ratio, and comb or skin lesions were found. In conclusion, regardless of the source, inositol reduced vent feather cover, while it tended to increase mortality. Only pure inositol reduced fearfulness in laying hens.

Dietary phytase and myo-inositol supplementation are associated with distinct plasma metabolome profile in broiler chickens

Phytase enzyme is used as a dietary supplement in broiler nutrition to improve phosphorous bioavailability. Phytase deliberates phosphate groups from phytic acid and produces myo-inositol after total dephosphorylation. Myo-inositol is a bioactive compound having beneficial modulatory effects on metabolism in humans. However, it is not well understood if and how phytic acid degradation products, particularly myo-inositol, can modulate metabolism in broiler chicken. The purpose of this study was to investigate effects of dietary supplements of phytase and myo-inositol on the blood plasma metabolome profile of broiler chickens. Broilers were provided a nutrient-adequate control diet or the same diet supplemented with either 3.5 g myo-inositol or 500, 1500 or 3000 units of phytase, per kilogram of feed (grower diet). Broilers were group-housed in floor pens (eight pens per diet) and provided one of the treatment diets for 22 days. Then, blood was collected from one bird per pen, resulting in eight replicated measurements per diet. A targeted metabolomics approach was applied to the heparin plasma. Body weight of the birds was not significantly affected by the treatments. Plasma myo-inositol concentrations were significantly increased by myo-inositol supplementation and phytase supplementation at 500 and 1500 units/kg. Metabolites generally affected by phytase supplementation belonged to the groups of acyl-carnitines, phosphatidylcholines, sphingomyelins, lysophosphatidylcholine, biogenic amines and amino acids. Compared to the control diet, phytase supplements had significantly higher plasma concentrations of kynurenine and creatinine, but lower concentrations of histamine and cis-4-hydroxyproline. Myo-inositol supplementation significantly increased plasma concentrations of dopamine and serotonine. While some metabolites were similarly affected by myo-inositol and phytase supplementation, others were distinctly differently affected. We conclude that myo-inositol, either as a directly added supplement or indirectly released from phytate upon phytase supplementation, can affect specific metabolic pathways. Additional effects found on phytase supplementation may be related to intermediary phytate degradation products. Results are indicative for innovative hypothesis to be tested in future experiments, for instance, with regard to relationships between phytase or myo-inositol supplements and bird immunity or behaviour.

Effect of different phytases derived from E. coli AppA gene on the performance, bone mineralisation and nutrient digestibility of broiler chicken

This study evaluated the effects of three different thermostable phytase variants, based on the AppA gene fromE. coli(AppAT1, AppAT2 and AppAT3) on growth performance, nutrient digestibility and bone mineralisation in broiler chickens at inclusion levels of 250 and 500 FTU/kg. The eight treatment groups included a positive control (PC) which was sufficient in Ca and P, a negative control (NC, the same basal formulation as the PC, but reduced in Ca and P), and NC supplemented with AppAT1 at 250 and 500 FTU/kg (AppAT1-250 and AppAT1-500), AppAT2 at 250 and 500 FTU/kg (AppAT2-250 and AppAT2-500) and with AppAT3 at 250 and 500 FTU/kg (AppAT3-250 and AppAT3-500). Over the entire feeding period, body weight (BW) and average daily gain (ADG) were significantly higher in the PC group, with all phytase supplemented groups being statistically the same, compared to the NC group. Feed conversion (FCR) for the PC-fed birds (1.479) was significantly (P&lt;0.05) better compared to the NC birds (1.582) and those fed the AppAT3-250 diet (1.523). Reduced levels of Ca and P in the NC group led to significantly (P&lt;0.05) lower tibia ash (40.9%) compared to the PC group (47.4%). Birds fed the phytase diets had significantly higher tibia ash compared to the NC birds, with those from the AppAT2-500 and AppAT3-500 groups being statistically the same as the PC group. Diets AppAT1-500, AppAT2-250, AppAT2-500 and AppAT3-500 significantly increased Ca digestibility compared to the NC. Apparent total track digestibility (ATTD) of P was improved for AppAT1-500 and AppAT2-250. The ATTD of Ca and P for all of the phytase supplemented groups reached the same level of the PC and AppAT1-500 group. It was concluded that adding any of the phytases tested, especially when included at 500 FTU/kg to a feed reduced in Ca and P, led to improved performance and bone mineralisation back to the same levels as seen for the Ca and P sufficient diet.

Sampling duration and freezing temperature influence the analysed gastric inositol phosphate composition of pigs fed diets with different levels of phytase

This experiment was conducted to determine the effects of time and freezing temperature during sampling on gastric phytate (myo-inositol [MYO] hexakisphosphate [InsP₆]), lower inositol phosphates (InsP_2–5) and MYO concentrations in pigs fed diets containing different levels of phytase. Forty pigs were fed 1 of 4 wheat-barley diets on an ad libitum basis for 28 d. The diets comprised a nutritionally adequate positive control (PC), a similar diet but with Ca and P reduced by 1.6 and 1.24 g/kg, respectively (NC), and the NC supplemented with 500 (NC + 500) or 2,000 (NC + 2000) FTU phytase/kg. At the end of the experiment, chyme were collected from the stomach, thoroughly mixed and 2 subsamples (30 mL) were frozen immediately: one snap-frozen at −79 °C and the other at −20 °C. The remaining chyme were left to sit at room temperature (20 °C) and further subsamples were collected and frozen as above at 5, 10 and 15 min from the point of mixing. There were linear reductions in gastric InsP₆ concentration over time during sampling (P < 0.001), irrespective of diet or freezing temperature. Moreover, InsP₆ concentration was influenced by a diet × freezing temperature interaction (P < 0.05), with less InsP₆ measured in chyme frozen at −20 °C than at −79 °C; however, this difference was greater in the control diets than the phytase supplemented diets. Freezing chyme at −79 °C recovered more ∑InsP_2–5 + MYO than freezing at −20 °C in pigs fed phytase supplemented diets; however, this difference was not apparent in the diets without phytase (diet × freezing temperature, P < 0.01). It can be concluded that significant phytate hydrolysis occurs in the gastric chyme of pigs during sampling and processing, irrespective of supplementary phytase activity. Therefore, to minimise post-slaughter phytate degradation and changes in the gastric inositol phosphate profile, chyme should be snap-frozen immediately after collection.