Phytase Dose Research Articles

PSVII-20 Meta-analysis: Effect of increasing dietary calcium and phytase dose on phosphorus digestibility in weaning piglets and growing pigs

Abstract A meta-analysis was conducted to investigate the effect of dietary calcium (Ca) levels and phytase dose on apparent total tract digestibility (ATTD) of phosphorus (P) in pigs fed corn or wheat-based diets. A database was constructed using 19 studies (published and unpublished), contributing 766 data points with 464 in nursery pigs and 303 in growing pigs. A Buttiauxella sp. phytase was added at 4 doses (250, 500, 1,000 and 2,000 FTU/kg) to P and Ca deficient negative control diets (NC) among different studies. Total analysed dietary Ca, total P and calculated phytate P levels varied from 0.41 to 0.97%, 0.36 to 0.67%, and 0.21 to 0.31%, respectively among studies. Data were analysed using Mixed Model by JMP 14.0. Since no significant differences were observed in ATTD P between nursery pigs (average initial body weight 7.5kg) and growing pigs (average initial body weight 40.0kg), the data were combined for the meta-analysis. Nonlinear modelling was used to evaluate the effect of dietary Ca on ATTD P and P digestibility improvement over the NC at different phytase levels. Increasing phytase dose from 0 to 2000 FTU/kg, improved (P < 0.05) ATTD Ca and P in an exponential manner, with a greater ATTD P (P < 0.05) over NC. With multivariate analysis, ATTD P had a negative correlation (P < 0.05) with dietary Ca levels (-0.26), Ca:P ratio (-0.30) and dietary phytate content (-0.40). An interaction was found between Ca level and phytase dose for P digestibility improvement over NC, which was not significantly different at dose between 250 to 1000 FTU but increased (P < 0.05) at phytase dose of 2000 FTU/kg with increasing dietary Ca. These findings suggest that supplementation of 2000 FTU phytase /kg could restore Ca and P balance and mitigate the negative effects of increasing dietary Ca on P digestibility.

PSIV-13 Supplemental phytase increases phosphorus digestibility in pigs regardless of phytase source or feed pelleting

Abstract Two experiments were conducted to investigate the effects of phytase source and feed pelleting on digestibility of dry matter (DM), crude protein, organic matter (OM), and phosphorus (P) with different doses of phytase in pigs. In Exp. 1, ten barrows (31.4 ± 3.5 kg of BW) were individually housed in metabolic crates and allotted to a replicated 5 × 6 Latin square design with 5 diets and 6 periods. In Exp. 2, ten barrows (28.2 ± 3.2 kg of BW) were individually housed in metabolic crates and allotted to a replicated 5 × 5 Latin square design with 5 diets and 5 periods. Each period lasted 10 d consisted of a 5-d adaptation and a 5-d collection periods and the marker to marker method was used for fecal collection. In both experiments, a basal diet was prepared based on corn and soybean meal without phytase or inorganic P. Four additional diets were prepared in a 2 × 2 factorial treatment arrangement with 2 phytase sources (Buttiauxella spp. or Escherichia coli) and 2 feed forms (mash or pellet). Both experiments employed the same treatments but had different supplemental phytase doses (500 and 1,500 FTU/kg in Exp. 1 and 2, respectively). In Exp. 1, supplemental phytase increased standardized total tract digestibility of P (66.1 vs. 51.7%; P < 0.001) with no effects of phytase source or feed pelleting. Feed pelleting increased digestibility of DM, crude protein, and OM (P < 0.001). In Exp. 2, supplemental phytase increased standardized total tract digestibility of P (72.8 vs. 44.8%; P < 0.001) with no effects of phytase source or feed pelleting. Feed pelleting increased digestibility of DM and OM (P < 0.001). Taken together, supplemental phytase at 500 and 1,500 FTU/kg increases P digestibility regardless of phytase source or feed pelleting.

The impact of age and feeding length on phytase efficacy during the starter phase of broiler chickens

Phytase is of importance to the poultry industry because of its ability to hydrolyze phytate and release phosphorus (P) for use by poultry. However, the effect of age on phytase efficacy is not fully understood. A total of 864 day-old broiler chicks were used to investigate the effect of age and feeding length on phytase efficacy using growth performance, mineral utilization, and tibia ash as response criteria of evaluation. The experiment was arranged as a 3 × 2 × 2 factorial in a randomized complete block design with 3 diets including; a positive control (PC; 0.4% non-phytate P (nPP)), a negative control (NC; 0.2% nPP) and a NC diet supplemented with phytase at 2,000 FYT/kg; 2 ages (i.e., days 14 and 22); and 2 feeding lengths (i.e., 2 and 5 D) with 8 replicates each. Birds fed the NC had decreased (P < 0.01) body weight gain and feed efficiency compared with birds fed the PC regardless of age or feeding length. Similarly, birds fed the phytase-supplemented diet had improved (P < 0.01) performance as compared to birds fed the NC regardless of age. There were no significant differences in P utilization between birds fed for 2 to 14 D or 22 D and birds fed for 5 D to both ages. However, phytase was more efficacious at day 14 than day 22 when mineral utilization was considered because the super dose of phytase elicited greater response in birds fed the phytase supplemented diet for 2 D until day 14. In contrast, percentage tibia ash improved (P < 0.01) in birds fed phytase supplemented diet for 5 D at both ages as compared with birds fed for 2 D. In conclusion, testing phytase products, even at high doses, for 2 D during the second week in the life cycle of broiler chicks, can be recommended from the results of this study.

Evaluation of novel protease enzymes on growth performance and nutrient digestibility of poultry: enzyme dose response

Two experiments were conducted to evaluate 3 novel proteases in broilers. In experiment 1, 600 male, Cobb 500 broilers were allocated to 1 of 12 experimental diets (5 birds/pen and 10 replicates/diet). A control (C) diet was formulated to be adequate in all nutrients. Proteases 1, 2, or 3 were added to this diet at 3 doses (1x, 3x, or 9x) in a 3 × 3 factorial arrangement of treatments. The factorial was augmented with 2 treatments of phytase at 500 or 1,500 FTU/kg added to the C diet. In experiment 2, 2,050 male Ross 308 broilers were allocated to 1 of 10 experimental diets (25 birds/pen and 9 replicates/diet). A C diet was formulated to be adequate in all nutrients. Protease 1, 2, or 3 was then added to the C diet at 3 doses (1x, 2x, or 4x) in a 3 × 3 factorial arrangement of treatments plus the C. In experiment 1, birds fed phytase gained more (P < 0.05) than birds fed protease, but neither were different than birds fed the C. Supplementation of 9x dose of any protease resulted in a reduction (P < 0.05) in BWG when compared with birds fed 1x dose of protease or phytase at 500 or 1,500 FTU/kg. Feed conversion ratio was improved (P < 0.05) in birds fed phytase compared with birds fed the C diet. Nitrogen digestibility was greater (P < 0.05) in birds fed protease 1 when compared with birds fed protease 2. Birds fed the 1x dose of protease or 500 FTU/kg of phytase had a greater (P < 0.05) N digestibility than birds fed 3x dose of protease. In experiment 2, protease supplementation significantly reduced (P < 0.05) BWG when compared with birds fed the C from hatch to 35 D post-hatch. Protease supplementation did not improve broiler growth performance or N digestibility above that of a nutrient adequate control diet or a diet supplemented with 500 FTU/kg of phytase.

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 120kcal/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.

Effect of a high dose of exogenous phytase and supplementary myo-inositol on mineral solubility of broiler digesta and diets subjected to in vitro digestion assay.

This study was conducted to evaluate the effect of microbial phytase and myo-inositol supplementation in low non-phytate phosphorus (nPP) diets on pH and the solubility of minerals in an in vitro digestion procedure (IVDP) and to compare this with digesta from birds fed different diets (grower diets) compared to the in vitro test (starter diets). A total of 660 1-day-old broilers were randomly allotted into 11 dietary treatments and fed a corn-soybean-meal-based diet with recommended nPP (positive control; PC), an nPP-deficient diet (negative control; NC), NC diets supplemented with phytase (500; 1,000; 2,000; 3,000; 4,000; 5,000; and 6,000 FTU/kg), an NC diet plus 0.15% myo-inositol, and an NC diet with reduced Ca level (Ca: nPP ratio same as PC) from 1 to 23 D of age. The pH and Ca solubility of the NC diet was increased compared with the PC when subjected to IVDP (P < 0.05). P solubility in the gizzard and jejunal digesta was reduced in the NC compared with the PC diet and this was also reflected in the IVDP. Phytase addition to the NC diets linearly increased (P < 0.05) the pH value and Ca and P solubilities in both digesta and diets subjected to IVDP. Higher doses of microbial phytase increased (P < 0.05) Zn and Fe solubilities in both digesta and IVDP. Myo-inositol supplementation of the NC diet had no effect on mineral solubility, but decreased (P < 0.05) the pH of the IVDP. Lowering the Ca content of the NC diet decreased (P < 0.05) the pH of the in vitro digested diets and Ca solubility in both broiler digesta and IVDP and also increased (P < 0.05) P solubility in both the jejunal digesta and IVDP. Correlations were noted between the solubility of P in the in vitro assay and that in the gizzard and jejunal digesta, and also with bird performance, confirms the usefulness of in vitro assay.

Available Phosphorus and Calcium Reduction in the Finisher Phase and Phytase Utilization on Broilers

SUMMARY The objective of this study was to access/identify the effects of phosphorus (P) restriction as a result of non-inclusion of monocalcium phosphate on broiler's diet after 21 d of age and the use of high doses of phytase (PHY). Broilers were divided into 4 treatments: positive control (PC), with phosphate inclusion; with phytase (WPHY), a reduction of 0.15% of available P and calcium (Ca) with the inclusion of 1,000 FYT; and 2 treatments with P restriction starting at 21 d of age: Without phosphate (WoP) and without phosphate supplemented with 4,000 FYT PHY (WoP+4000 FYT). Broilers performance (WG, FI, and FCR) and bone characteristics (bone weight, mineral residue, and Ca and P ratio) were assessed at 41 d of age. In relation to performance, the exclusion of monocalcium phosphate from the diet resulted in worse WG and FCR. However, the inclusion of higher PHY dose (WoP+4000 FYT) overcame the mineral deficiency, and performance was similar to treatments that met bird's mineral requirements (PC and WPHY). The treatment with mineral restriction (WoP) had the worst results in every bone quality assessment. However, broilers of WoP+4000 FYT group had bone parameters similar to PC and WPHY. Therefore, removing phosphate in grower and finishing phases has negative impacts on broiler's performance and bone conformation, but adding high phytase dosage (4,000 FYT) overcome this damages.

Comparative effects of two phytases versus increasing the inorganic phosphorus content of the diet, on nutrient and amino acid digestibility in boilers

Comparative effects of graded doses of two phytases on growth performance, nutrient and amino acid (AA) digestibility were investigated in corn-soybean meal-based broiler diets. A negative control diet (NC) with low phosphorus (P) content (1.8, 4.4 and 2.5 g/kg retainable, total and phytate P respectively) was supplemented with four doses of a Buttiauxella sp phytase (analyzed activity of 303 to 1046 FTU/kg) or an E. coli phytase (analyzed activity of 442 to 1811 FTU/kg), and tested against three positive control diets comprising the NC + 0.6, 1.2 or 1.8 g P from monocalcium phosphate (MCP)/kg feed and increased Ca content (+0.8 g/kg). A total of 1152 male Ross 308 broilers at 5 days of age were assigned to 72 cages with 16 birds/cage and 6 cages/treatment were given free access to pelleted diets until 21 days of age. Feed intake (FI), body weight and mortality were recorded and used to calculate body weight gain (BWG) and feed conversion ratio (FCR) during 5–20 days of age. Excreta was collected on day 18–20 to determine total tract retention of nutrients. Tibias (from 4 birds pooled per cage) and ileal digesta (from all birds and pooled per cage) were sampled at 21 days of age to determine tibia ash, ileal digestibility of nutrients and AA. Compared to NC, increasing phytase dose and MCP levels produced a stepwise increase in FI, BWG and reduction in FCR. Increasing phytase dose produced curvilinear increases in BWG, ileal P digestibility, retention and tibia ash (P < 0.01) but effects were greater for Buttiauxella vs. E. coli phytase. In contrast, only Buttiauxella phytase increased the ileal digestibility of protein and total AA (+3.7% on average vs. NC at 1046 FTU/kg, P < 0.05). Linear increases in ileal digestibility of all individual AA were seen with increasing dose of Buttiauxella (P < 0.05 in all cases) and were greatest for cysteine (+ 7.9% vs. NC at 1046 FTU/kg), whereas only 2 individual AA showed linear increases in digestibility in response to increasing dose of the E. coli phytase (cysteine and proline, P < 0.05). Ileal digestibility of Na (%) was markedly increased (less negative) by phytase, especially for the Buttiauxella phytase which produced a 96% increase in ileal Na digestibility at 1046 FTU/kg vs. NC. Across treatments, ileal digestibility of AA and Na were positively correlated (P < 0.001). These results provide insight into the ‘extra-phosphoric’ effects in broilers fed corn-soybean meal-based diets and suggest that the Buttiauxella and E. coli phytase had markedly different degrees of ‘extra-phosphoric’ effects on AA digestibility per standard FTU. The data showed that the AA digestibility response to increasing phytase dose do not follow the same response curve as for digestible P, and that the response curves are specific for different phytases.

Increasing doses of phytase from Citrobacter braakii in diets with reduced inorganic phosphorus and calcium improve growth performance and lean meat of growing and finishing pigs.

The objective of this study was to evaluate the effect of increasing doses of bacterial phytase (RONOZYME HiPhos) on performance and carcass characteristics of growing and finishing pigs. The study included 120 castrated males with initial weight of 23.21 ± 1.91 kg and 68 days of age, distributed in a randomized block design with five treatments and eight replicates with three animals each. The pigs were fed five corn-soybean meal-based diets: positive control (PC), supplemented with inorganic phosphorus and calcium; negative control (NC), with 0.13% reduction in available phosphorus and 0.11% in calcium; and three NC diets supplemented with 1,000, 2,000, and 3,000 phytase units (FYT)/kg in the feed. Compared with the NC diets without phytase, diets with 1,000, 2,000, and 3,000 FYT/kg inclusion increased the daily weight gain by +12% (quadratic, p<0.05) during the growing I period; +2.9, +2.9, and +10.5% (linear, p<0.01), respectively, during the growing II period; and +4.1, +5.1, and +8.2% (linear, p<0.001), respectively, over the entire experimental period. The daily feed intake increased by 0, +2.8, and +4.3% (linear, p<0.05), respectively, considering the entire experimental period; and the final live weight increased by +3.2, +4.2, and +6.1% (linear, p<0.001), respectively. The phytase treatments did not influence feed conversion ratio, carcass weight and yield, backfat thickness, loin depth and carcass lean meat. According to the European Carcass Classification (SEUROP), however, the animals fed the PC diet and the three phytase levels had more carcasses classified as E (between 55–60% lean meat) when compared to carcasses of pigs fed the NC. Supplementing increasing levels of phytase to a corn- and soybean meal-based diet with inorganic P and Ca reduction improved daily weight gain and feed intake of growing pigs, and such effects were maintained until slaughter age.

Effects of super-dosing phytase and inositol on growth performance and blood metabolites of weaned pigs housed under commercial conditions1

A total of 2,156 weaned pigs (6.75 ± 0.11 kg BW) were used in a 42-d study to evaluate whether improvements in growth performance associated with super-dosing phytase can be explained by the complete dephosphorylation of phytate and liberation of inositol. Two phytase doses (0 and 2,500 FTU/kg) and 3 inositol concentrations (0%, 0.15%, and 0.30%) were combined to create 6 dietary treatments in a 2 × 3 factorial arrangement. Pigs were fed a 3-phase feeding program, with periods being 10, 10, and 22 d, respectively. Blood samples were collected on days 0, 21, and 42 from a subset of 48 pigs to analyze mineral and myo-inositol concentrations. During Phase 1, super-dosing phytase tended to improve ADG compared with pigs fed diets without phytase (P = 0.09). Increasing concentrations of inositol improved the efficiency of gain in pigs fed diets without phytase (1,022.1, 1,040.9, and 1,089.2 g/kg), but not diets with phytase (1,102.2, 1,087.2, and 1,076.2 g/kg), and this improvement was equivalent to that observed with super-dosing phytase in the absence of inositol (interaction, P = 0.015). During Phase 2, super-dosing phytase improved ADG (P = 0.001), resulting in heavier BW (P = 0.007). During Phase 3 and overall, inositol supplementation increased ADG and ADFI in a quadratic manner (P < 0.10), with the highest ADG and ADFI observed for pigs fed 0.15% of inositol. Super-dosing phytase increased serum Zn on day 21, but not on day 42 (interaction, P = 0.008), increased serum Cu (P = 0.01), but decreased serum Fe (P = 0.02). Plasma myo-inositol increased linearly from 66.9 to 97.1 and 113.2 nmol/mL with increasing inositol (P < 0.001). When plasma myo-inositol was analyzed within the subgroup of pigs fed diets without added inositol, super-dosing phytase increased plasma myo-inositol from 57.81 to 76.05 nmol/mL (0 and 2,500 FTU/kg, respectively; P = 0.05). Results demonstrate that exogenous inositol improved efficiency of gain in weaned pigs to the same level as that observed with super-dosing phytase, but this occurred only during the first 10 d of the nursery period. This suggests that the improvement in efficiency of growth when applying super-dosing phytase could be linked, in part, to complete dephosphorylation of phytate and liberation of myo-inositol, and that myo-inositol had a greater metabolic impact in piglets immediately after weaning. Consequently, myo-inositol may be a conditionally essential nutrient for young pigs during weaning stress, but further research is needed to prove this hypothesis.

Increasing the dosing of a Buttiauxella phytase improves phytate degradation, mineral, energy, and amino acid digestibility in weaned pigs fed a complex diet based on wheat, corn, soybean meal, barley, and rapeseed meal1.

ABSTRACTThis study evaluated the effects of increasing the dose of a 6-phytase from Buttiauxella on phytate degradation, mineral, energy, and AA digestibility in weaned pigs fed complex diets based on wheat, corn, soybean meal, barley, and rapeseed meal. A negative control (NC) diet containing no added inorganic phosphorus (P) and a reduction of 0.1% calcium (Ca) and 36 kcal/kg ME was supplemented with Buttiauxella phytase at 0, 250, 500, 1,000, or 2,000 FTU/kg diet and tested against a nutritionally adequate, positive control (PC) diet. One phytase units (FTU) is the amount of enzyme that liberates 1 micromole of inorganic phosphate per minute from a sodium phytate substrate at pH 5.5 and 37 °C. Barrows (Topigs × Pietrian; initial mean body weight 19.3 kg) were housed individually in metabolic crates and fed the test diets in mash form via 2 equal meals per day for 9 d (fed at 2.5 times the maintenance energy requirement), with 8 replicate pigs per treatment, in 2 experimental runs (total n = 48). After a 3-d adaptation period, urine and feces were collected over 5 d for measurements of apparent total tract digestibility (ATTD) and retention of nutrients. On day 9, pigs were euthanized and ileal digesta collected for measurements of apparent ileal digestibility (AID) of nutrients. Phytase improved (P < 0.05) digestibility of all measured AA except Trp (P < 0.1), and AID P, nitrogen, phytate, ATTD P, Ca versus NC. Increasing phytase dose from 0 (NC) to 2,000 FTU/kg increased AID Lys, Cys, Thr, Val, Ile, Leu, mean AA, P, N, phytate, ATTD P, N, Na, energy, ME, P retention (g/d), and reduced P excretion (g/d) in a linear or exponential manner (P < 0.05). Phytase at 2,000 FTU/kg improved AA digestibility by between +3.1 percentage points (Trp) and +8.8 percentage points (Cys) versus NC (average +6.3 percentage points) (P < 0.05). Phytase inclusion at 2,000 FTU/kg reduced P excretion (g/d) by 57% versus PC (P < 0.05). In conclusion, increasing Buttiauxella phytase in the range of 0 to 2,000 FTU/kg increased phytate degradation, improved AA and P digestibility, and reduced P excretion in weaned pigs fed complex diets.

Phytase as an alleviator of high-temperature stress in broilers fed adequate and low dietary calcium

This study aimed to investigate the effect of phytase and dietary Ca level on performance, phytate (inositol hexa-phosphate, IP6) concentration, and anti-oxidant enzyme activity in broilers exposed to cycling high environmental temperatures. A total of 2,970 day-old Cobb 400 male broilers were randomly allocated among 6 treatments, with 15 replicate pens, and 33 birds per pen. Corn-soy diets low in available phosphorus (avP, 0.15% matrix applied) were fed in 2 phases; starter (0 to 21 d) and grower (22 to 42 d). Diets were factorially arranged by 2 × 3, with adequate (0.90% starter, 0.80% grower) or low (0.60% starter, 0.50% grower) dietary Ca and phytase (0, 500, or 3,000 phytase units (FTU)/kg). Temperature was not regulated, but followed environmental changes determined by the summer season in India; 22 to 39°C in the morning and 23 to 40°C at night. At 42 d of age, supplementing either dose of phytase increased (P < 0.001) weight gain (+128 g) and feed intake (+194 g) of birds, while only 3,000 FTU/kg phytase lowered (P < 0.01) feed conversion ratio (FCR) compared to the control. Birds fed low Ca diets had poorer (P < 0.01) weight gain (-33 g) and FCR (+0.04) than birds fed adequate Ca levels, suggesting that Ca was limiting in these diets. Phytase and low dietary Ca reduced the concentration of IP esters in the gastrointestinal tract of broilers. Lower IP6, IP5, IP4, and IP3 concentrations and increased myo-inositol provision was positively correlated to anti-oxidant enzyme activity in tissues. These results indicate that phytase can be used to alleviate the negative performance traits accredited to broilers under high temperature stress, potentially by reducing the anti-nutritive effect of IP6 and improving anti-oxidant status of birds. However, caution should be taken when reducing dietary Ca levels as improvements in IP6 degradation and anti-oxidant status cannot overcome the constraints on growth by diets that do not meet the Ca requirements.

Perceptions of veterinarians on the use of nutritional supplements in the horse industry

The objective of this study was to access/identify the effects of phosphorus (P) restriction as a result of non-inclusion of monocalcium phosphate on broiler's diet after 21 d of age and the use of high doses of phytase (PHY). Broilers were divided into 4 treatments: positive control (PC), with phosphate inclusion; with phytase (WPHY), a reduction of 0.15% of available P and calcium (Ca) with the inclusion of 1,000 FYT; and 2 treatments with P restriction starting at 21 d of age: Without phosphate (WoP) and without phosphate supplemented with 4,000 FYT PHY (WoP+4000 FYT). Broilers performance (WG, FI, and FCR) and bone characteristics (bone weight, mineral residue, and Ca and P ratio) were assessed at 41 d of age. In relation to performance, the exclusion of monocalcium phosphate from the diet resulted in worse WG and FCR. However, the inclusion of higher PHY dose (WoP+4000 FYT) overcame the mineral deficiency, and performance was similar to treatments that met bird's mineral requirements (PC and WPHY). The treatment with mineral restriction (WoP) had the worst results in every bone quality assessment. However, broilers of WoP+4000 FYT group had bone parameters similar to PC and WPHY. Therefore, removing phosphate in grower and finishing phases has negative impacts on broiler's performance and bone conformation, but adding high phytase dosage (4,000 FYT) overcome this damages.

Influence of phytase enzyme on ruminal biogas production and fermentative digestion towards reducing environmental contamination.

Environmental impact of livestock production has received a considerable public scrutiny because of the adverse effects of nutrient run-offs, primarily N and P, from agricultural land harboring intensive energy livestock operations. Hence, this study was designed to determine the efficacy of dietary phytase supplementation on fermentation of a sorghum grain-based total mixed ration (TMR) using a ruminal in vitro digestion approach. Phytase was supplemented at three doses: 0 (control), 540 (P540), and 720 (P720)g/t dry matter, equivalent to 0, 2.7 × 106, and 3.6 × 106 CFU/t DM, respectively. Compared to P720 and the control, gas production was higher for P540 after 12h (P= 0.02) and 24h (P= 0.03) of fermentation suggesting a higher microbial activity in response to phytase supplementation at lower phytase levels. Correspondingly, dry matter degradability was found to have improved in P540 and P720 compared to the control by 13 and 11% after 24h of incubation (P= 0.05). For ammonia nitrogen (NH3-N), a tendency towards lower values was only observed for P540 at 24h of fermentation (P= 0.07), while minimal treatment effects were observed at other fermentation times. The concentrations of total volatile fatty acids (VFA) were higher (P< 0.05) after 48h of fermentation for P540 and P720 compared to the control (P= 0.03) by 10% and 14%, respectively. Ruminal acetate tended towards higher values in the presence of phytase after 12h of fermentation (P= 0.10), but towards lower values after 24h of fermentation (P= 0.02), irrespective of the phytase dose applied. A trend towards lower ruminal propionate levels was observed in the presence of phytase after 6h (P= 0.10) and 12h (P= 0.06) of fermentation, while no effects were found at other fermentation times. In conclusion, phytase supplementation has the potential to improve metabolic energy activity of rumen microorganisms and the use of feed constituents. Thus, phytase supplementation could help to reduce environmental contamination in areas of ruminant production.

A critical review of methods used to determine phosphorus and digestible amino acid matrices when using phytase in poultry and pig diets

SummaryPhytase is applied in animal feed based on its standard activity measured at pH 5.5, however the relative activity at pH 3 (e.g. stomach pH, the main site for the breakdown of phytate) varies among the commercial phytases, ranging from 56% (an E coli phytase) to 235% (Buttiauxella phytase). These diverse sources of phytases have varying capability for degrading phytate and, correspondingly, different P, digestible amino acid and metabolisable energy matrix values. In addition, the matrix values recommended by different phytase suppliers are not comparable, as different methodologies have been used to determine them. Phosphorus (P) and other matrix values can be determined by direct measurement of digestible P (dP) improvements by the addition of phytase above a negative control in large numbers of in vivo studies using increasing phytase doses. Alternatively, matrix values can be assessed by indirect measurement, using inorganic P (usually mono- or dicalcium sources) as a reference, typically based on tibia or metacarpal ash as a response parameter to estimate available P equivalence, either at a single or different phytase doses. When using the indirect measurement, the available P equivalence with increasing phytase doses may be calculated based on a log linear model. Although both methods are acceptable methodologies, direct measurement may under-estimate and indirect measurement may over-estimate matrix values, and a large number of in vivo studies give the best estimates of matrix values. Phytase efficacy can be influenced by phytase source, dose level, dietary composition (Ca level and Ca: P ratio). Phytase end users are encouraged to be aware of the methods used by suppliers to determine matrix values, before applying them in their feed formulations.

High doses of phytase on growth performance and apparent ileal amino acid digestibility of broilers fed diets with graded concentrations of digestible lysine.

Two experiments of the same design were conducted to determine the influence of phytase on performance and apparent ileal digestibility (AID) of amino acids in broilers fed graded concentrations of digestible lysine (dgLys). Cobb 400, male broilers were allocated to 1 of 16 diets consisting of 4 basal diets formulated at 80, 88, 96, or 104% of the Cobb 400 dgLys requirements for each feeding phase. Phytase was included in each basal diet at 0, 750, 1,500, or 3,000 phytase units (FTU)/kg. In Exp. 1, 33 birds/pen from hatch to day 42 were fed a 2-phase feeding program with 12 replicate pens/diet. In Exp. 2, there were 25 birds/pen from hatch to day 21 and 8 replicate pens/diet. Data were analyzed as a 4 × 4 factorial and means separated using orthogonal contrasts. In Exp. 1, feed intake (FI) increased (quadratic, P < 0.05) as dgLys increased in the diet. Body weight gain (BWG) increased (quadratic, P < 0.05) as dgLys concentration or phytase dose increased in the diet. As phytase dose increased in the diet, feed conversion ratio (FCR) was improved in a linear or quadratic (P < 0.05) manner depending on the dgLys concentration of the diet (dgLys × phytase, P<0.05). In Exp. 2, FI linearly (P < 0.05) increased as dgLys increased in the diet. Increasing the concentration of dgLys or phytase in the diet increased (quadratic, P < 0.05) BWG and improved (quadratic, P < 0.05) FCR. The AID of most amino acids was influenced by a dgLys × phytase interaction (P < 0.05), except threonine, valine, tryptophan, serine, cysteine, or leucine (linear or quadratic effect of phytase, P < 0.05), where phytase improved the AID in birds fed diets containing 80, 88, or 96% of the dgLys requirement, but not birds fed 104%. The predicted dgLys requirement to maximize performance, carcass, and digestible lysine intake was 97.6 to ≥ 104%. The predicted dose of phytase to maximize BWG or FCR was between 1,990 and 2,308 FTU/kg, regardless of the dgLys concentration in the diet. The predicted dose of phytase to maximize carcass weight was between 1,527 and 2,658 FTU/kg of diet and to maximize breast weight was 0 to ≥ 3,000 FTU/kg diet, depending on the dgLys concentration in the diet. In conclusion, optimal performance in the absence of phytase could be achieved at much lower levels of lysine in the presence of phytase.

High doses of phytase on growth performance and apparent ileal amino acid digestibility of broilers fed diets with graded concentrations of digestible sulfur amino acids.

Two experiments of the same design were conducted to determine the influence of phytase on performance and apparent ileal digestibility (AID) of amino acids in broilers fed graded concentrations of digestible sulfur amino acids (dgM+C). Cobb 400 male broilers were allocated to 1 of 10 diets consisting of 5 basal diets formulated at 75, 82, 89, 96, or 103% of the Cobb 400 dgM+C requirements for each feeding phase. Phytase was included in each basal diet at 0 or 2,000 FTU/kg. In experiment 1, 33 birds/pen from hatch to day 42 were fed a 2-phase feeding program with 10 replicate pens/diet. In experiment 2, there were 26 birds/pen from hatch to day 21 and 8 replicate pens/diet. Data were analyzed as a 5 × 2 factorial and means separated using orthogonal contrasts. In experiment 1, overall (hatch to day 42) feed intake (FI) decreased (linear, P < 0.05), body weight gain (BWG) increased (quadratic, P < 0.05), and feed conversion ratio (FCR) was improved (quadratic, P < 0.05) as dgM+C increased to ≥96% in the diet. Phytase increased (P < 0.05) BWG and improved (P < 0.05) FCR, regardless of the percent dgM+C in the diet. In experiment 2, overall (hatch to day 21) BWG increased (quadratic, P < 0.05), and FCR was improved (quadratic, P < 0.05) as dgM+C increased to ≥96% in the diet. Phytase increased FI (P < 0.05) and BWG (P < 0.05) and improved FCR (P < 0.05), regardless of the percent dgM+C in the diet. In the absence of phytase, the AID of all amino acids was greatest (quadratic, P < 0.05) in birds fed between 89 and 96% dgM+C. However, in the presence of phytase the AID of all amino acids was greatest (quadratic, P < 0.05) in birds fed 82% dgM+C and greater at all levels of dgM+C than birds fed diets without phytase (dgM+C × phytase, P < 0.05). In conclusion, phytase improved AID of all amino acids and improved growth performance regardless of the level of dgM+C in the diet.

Effect of phytase dose on productive performance and bone status of layers fed with graded levels of digestible lysine

Exogenous phytase could influence dietary protein availability by variation in using dose. The objective of the present study was to determine if incremental dosing of an evolved E.coli 6-phytase would lead to improvements in lysine availability through evaluating performance and bone status in Bovans White layers. A total of 182 layers were placed in individual cages and distributed to 13 treatments: a 3×4 factorial arrangement with three levels of digestible lysine (dLys - 0.67, 0.77, and 0.87 %) and four doses of phytase (0, 300, 1 200, and 4 800 FTU/kg) in 0.12 % available P (avP) diets. Additionally, one phytase-free control treatment was included with 0.25 % avP and 0.87 % dLys. Productive parameters were recorded for 25 weeks, from 39 week-old. At the end, abdominal fat deposition and the tibia were sampled; in bone was determined breaking strength and bone ash. Layers fed 1 200 FTU/kg phytase increased egg production percentage (F3,169 = 2.01, p = 0.019), abdominal fat deposition (F3,169 = 2.52, p = 0.059), bone breaking strength (F3,169 = 4.29, p = 0.006) and bone ash weight (F3,169 = 3.62, p = 0.015) compared with non-phytase inclusion. Furthermore, 1 200 FTU/kg phytase decreased incidence of broken eggs and soft-shell eggs (F3,169 = 2.9, p = 0.037). Phytase and dLys levels influenced egg mass and bone ash concentration (F12,169 = 1.86, p = 0.043). FCR and body weight loss was reduced with phytase inclusion (respectively: F12,169 = 2.43, p = 0.045, and F12,169 = 2.24, p = 0.001). Phytase-free control diet increased egg weight (F12,169 = 3.70, p &lt; 0.068), but gave greater BW loss (F12,169 = 17.79, p &lt; 0.001), less abdominal fat content (F12,169 = 5.85, p &lt; 0.017), and no effect on other variables (p &gt; 0.07). In conclusion, 1 200 FTU/kg of phytase improved productive performance and preserved body weight and bone status, without equivalence of phytase inclusion for dLys level, even with higher doses.Figure A. Response of egg marketable mass

Exogenous phytase and xylanase exhibit opposing effects on real-time gizzard pH in broiler chickens

ABSTRACT1. The current study was conducted to evaluate the influence of high phytase doses and xylanase, individually and in combination, on performance, blood inositol and real-time gastric pH in broilers fed wheat-based diets.2. In a 42-d experiment, a total of 576 male Ross 308 broiler chicks were allocated to 4 dietary treatments. Treatments consisted of a 2 × 2 factorial arrangement, with 500 or 2500 FTU/kg phytase and 0 or 16 000 BXU/kg xylanase, fed in two phases (starter 0–21; grower 21–42 d). Heidelberg pH capsules were administered to 8 birds from each treatment group, pre- and post-diet phase change, with readings captured over a 5.5-h period.3. At 21 and 42 d, birds fed 500 FTU/kg phytase without xylanase had on average 127 and 223 g lower weight gain than all other treatments, respectively (P < 0.05). At 42 d, body weight-corrected feed conversion ratio (bwcFCR) was reduced (P < 0.05) by supplementing 2500 FTU/kg phytase or xylanase, with the combination giving a 12 point reduction in bwcFCR compared to birds fed 500 FTU/kg phytase without xylanase. Inositol content of plasma was twice that of the erythrocyte (P < 0.001), with 2500 FTU/kg phytase tending to increase (P = 0.07) inositol content in both blood fractions.4. Across all treatments, capsule readings ranged from pH 0.54 to 4.84 in the gizzard of broilers. Addition of 2500 FTU/kg phytase to the grower diet reduced (P < 0.05) average gizzard pH from 2.89 to 1.69, whilst feeding xylanase increased (P < 0.001) gizzard pH from 2.04 to 2.40. In contrast, digital probe measurements showed no effect of xylanase on gizzard pH, while addition of 2500 FTU/kg phytase increased (P = 0.05) pH compared to 500 FTU/kg phytase with or without xylanase.5. These findings suggested that xylanase and high phytase doses have opposite effects on real-time gastric pH, while similarly improving performance of broilers.

The effects ofmicrobial phytases and dietary calcium and phosphorus levels on the productive performance and bone mineralization of broilers

Two trials were conducted to evaluate the effects of phytase and different levels of calcium (Ca) in an available phosphorus-limited diet (aP) on the performance, bone mineralization, and Ca and P retention of broilers. In Trial 1, 160 one-day-old male broilers were placed into 40 cages and allocated to five dietary treatments: one positive control [PC, 4.7 and 4.3 g/kg non-phytate P (NPP) and 9.0 and 8.5 g/kg Ca, from 1 to 21 days (d) and from 21 to 35 d of age, respectively] and four negative control [NC, 3.2 and 2.9 g/kg NPP and 7.0 and 6.3 g/kg Ca in starter (1–21 d) and growth (22–35 d) diet] groups comprising 4 concentrations of phytase A (FLF® 1000 FUT, 0, 250, 500 and 1000 FTU/kg). In Trial 2, 300 one-day-old broilers were placed into 60 cages and allocated to 10 dietary treatments, consisting of two NC diets (3.2 g/kg NPP), either 7.0 g/kg Ca (low Ca) or 9.0 g/kg Ca (high Ca), supplemented (0 or 500 FTU/kg) with four different phytases [OptiPhos® 5000 CT (A), Phyzyme® XP10000 TPT (B), Ronozyme® NP (C) and FLF® 1000 FUT (D)] from 1 to 14 d. In Trial 1, the PC group and the group receiving the highest dose of phytase A FLF® 1000 FUT (1000 FTU/kg) yielded significantly higher average daily gains from 1 to 21 d and higher tibia weights and ash contents than the NC, 250, and 500 FTU/kg. In Trial 2, no differences were observed in performances between animals receiving different types of phytase. Low Ca diets improved the feed efficiency from 1 to 7 d and ileal P digestibility. The interaction between Ca:aP and phytase affected (P ≤ 0.05) the feed efficiency from 1 to 7 d and ADG from 7 to 14 d. Based on this study, high levels of phytase (1000 FTU/kg) supplemented in starter (1–21 d) and growth (22–35 d) diets containing 3.2 and 2.9 g/kg NPP and 7.0 and 6.3 g/kg Ca, respectively, may be required to promote performance and bone mineralization in growing broilers. Lowering Ca levels to 7 g/kg in starting diets may exert greater effects on performance and ileal P digestibility than low levels (500 FTU/kg) of phytase.