Yueming Dersjant-Li

This study aimed at determining the effects of phytase alone and in combination with XAP at full matrix specifications on growth performance, nutrient digestibility, carcass yield, toe ash, gastrointestinal organ weight and pH, energy utilisation (AME, AMEn, and ME:GE), and the digestibility of key nutrients in the jejunum and ileum of broilers fed complex diets. Day-old mixed-sex Cobb 500 broilers (n = 384) were assigned to four dietary treatments with eight replicates of 12 birds per treatment from d 0 to 42, with energy utilisation determination from d19 to 21 and digestibility determination at d21. The treatments were as follows: a positive control (treatment 1, PC) formulated meeting nutritional requirements and three test diets reformulated with reduced nutrients and energy according to respective matrix values of the enzymes used. The enzymes supplemented are: treatment 2, a mixed enzyme (NC1 + XAP, 100 g/ton with activities of 2000 U/kg xylanase, 200 U amylase and 4000 U protease, respectively); treatment 3, a novel consensus bacterial 6-phytase variant (NC2 + PhyG) at 1000 FTU/kg; and treatment 4 (NC3 + XAP + PhyG, PhyG at 1000 FTU/kg and XAP combination). Overall, enzyme inclusion with full matrix application maintained overall weight gain, feed intake and the FCR. There were significant increases in starch, Ca, P and Na digestibility with almost all enzyme inclusions (p < 0.05). NC2 + PhyG and NC3 + XAP + PhyG reduced the feed cost/kg live gain compared to PC (p = 0.006). In conclusion, this study demonstrates that the full matrix values for phytase alone or in combination with XAP may lower the cost/kg live gain while maintaining the growth performance of broilers offered a complex diet with increased use of locally available ingredients (rapeseed and lupins).

This experiment evaluated whether a consensus bacterial 6-phytase variant (PhyG) could totally replace the effect of added trace minerals (TM; Zn, Cu, Fe, and Mn) in an all-vegetable diet, in weaned pigs. A total of 144 DanBred × Pietrain weaned pigs (28 d of age, body weight 7.0 ± 0.44 kg) were assigned to floor pens (12 pens/treatment; 4 pigs/pen; 2 females, 2 castrated males). Diets were based on corn, wheat, barley and soybean meal, fed in 2 phases (starter I: day 1 to 14 and starter II: day 14 to 42) and provided ad libitum. Treatment diets comprised: 1) a negative control (NC1) diet formulated without added TM but otherwise nutritionally adequate; 2) a positive control (PC), comprising the NC1 supplemented with Zn, Cu, Fe, and Mn at 120, 80, 96, and 80 mg/kg, respectively, and; 3) the NC1 reduced in Ca and digestible P to account for the expected contribution of PhyG which was supplemented at 1,500 phytase units (FTU)/kg during starter I and 1,000 FTU/kg during starter II (NC2+PhyG). Growth performance was monitored over 42 d, and on day 42 blood, liver and femur bone samples were collected from 1 pig/pen for TM analysis. Data were analyzed by one-way ANOVA and treatment means were separated by Tukey's HSD test. Pen was the experimental unit. Final (day 42) body weight and overall average daily gain were reduced in NC1 compared with PC (-2.04 kg/pig and -48.8 g/pig/day, respectively; P < 0.05) and increased (P < 0.05) in NC2+PhyG compared with NC, to levels not different from the PC. Zinc in bone ash at day 42 was increased in the PC compared with NC1 (+25.7 mg/kg, respectively; P < 0.05) and further increased in NC2+PhyG vs. NC1 or PC (+49.9 and +24.2 mg/kg, respectively), whereas Fe in bone was increased in NC2+PhyG vs PC (+35.4 mg/kg; P < 0.05). The results indicate that PhyG supplementation at the applied doses maintained growth performance and tissue TM concentrations at levels comparable to those achieved by the TM-supplemented diet. The findings suggest that the enzyme could replace supplemental Zn and may also support a reduction in the level of supplemental Cu, Fe and Mn in piglet diets, depending on the content of these TM in the basal diet.

Data from 8 datasets generated from 5 independent experiments that determined the effects of a consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) in growing pigs (~21 to 45 kg body weight) were combined and modeled to test the hypothesis that the phytase results in significant improvements in ileal AA digestibility. The aim was to generate accurate and robust dose-related predictions of the digestible AA contributions of the phytase. The 5 experiments were conducted in Spain, Australia, USA, and Brazil and incorporated variation in diet composition (ingredient composition, phytate-phosphorus (PP) content, limestone solubility), diet form, animal breed and sex. A total of 325 datapoints (observations) were analyzed. First, the relationship between the percentage AID of AA and log-transformed phytase dose (range 0 to 4,000 phytase units (FTU)/kg, analyzed values) was modeled by log-linear regression across all datasets without adjustment for variation in the response to the negative control (NC) diet. The model predicted that the mean AID of total AA in the NC diets was 68.6% (range 43.3% [Cys] to 81.7% [Arg]). This was increased linearly by PhyG supplementation (P < 0.05), by 3.7 percentage units when dosed at 1,000 FTU/kg and by 4.5 percentage units at 4,000 FTU/kg. Second, the percentage unit change in the AID of AA at each phytase dose from baseline (NC without added phytase) was calculated separately for each dataset and the data then combined and modeled together by log-linear regression, against analyzed and log-transformed phytase dose. By this analysis, increases were evident for the AID of all individual (and total) AA. Increases (vs. baseline) at 1,000 and 2,000 FTU/kg were greatest for Trp (+ 6.1 and + 6.8 percentage units), Thr (+ 3.4 and + 3.8 percentage units after correction for synthetic Thr), Gly (+ 7.5 and + 8.3 percentage units) and Cys (+ 5.6 and + 6.2 percentage units). In conclusion, combined data from 5 separate experiments indicate that the bacterial phytase-6 variant will improve ileal digestibility of AA if included in diets fed to growing pigs. The data will allow diet-specific AA matrix recommendations to be made in commercial feed formulations containing PhyG.

Undigested P and N are excreted and contribute to the environmental impacts of dairy farming. Degradation of phytate in the rumen has been shown to be high but variable, leading to incomplete phytate-P utilization and resultant antinutritional impacts of phytate along the gastrointestinal tract. We investigated the effect of a novel bacterial 6-phytase (PhyG) on the apparent total-tract digestibility (ATTD) and excretion of DM, phytate-P (PP), P, CP and NDF in lactating dairy cows. Forty-eight lactating Holstein-Friesian cows were assigned to 3 treatments with 16 cows per treatment in a randomized block design. Cows averaged 44.1 kg milk/d, and 124 DIM at the experiment start. Diets were fed ad libitum as a TMR that was formulated to meet nutritional requirements except for P which was fed at 92% of the recommendation. Treatments comprised a control diet (CON) and the control diet supplemented with 2,000 or 5,000 phytase units/kg DM of PhyG. The experiment lasted for 19 d including a 14 d diet adaptation period and a 5 d fecal collection period. Dry matter intake did not differ across treatments. The ATTD of PP in CON was 88.5%, indicating incomplete phytate degradation. The ATTD of ash, P and CP increased linearly, whereas the ATTD of PP and NDF increased both linearly and quadratically with increasing PhyG dose level; with PhyG at 5,000 FTU/kg, the ATTD of PP, P, CP and NDF increased by 9.2, 13.7, 4.1 and 7.5% points above CON, respectively. Fecal excretion of ash, PP, P and NDF were reduced linearly. Supplementation of PhyG also reduced excretion of PP quadratically and CP excretion tended to be reduced linearly. Body weight and milk yield did not differ across treatments, but milk protein yield tended to increase linearly with increasing PhyG dose. The addition of PhyG to the diet of lactating dairy cows improved nutrient utilization and decreased nutrient excretion. It could therefore contribute to reducing the environmental impacts of dairy production.

This experiment tested the hypothesis that supplementation of a nutrient- and energy-reduced mixed-cereal diet with phytase, xylanase and β-glucanase, over an entire wean-to-finish growth cycle, would result in growth performance outcomes that were not different from those achieved by pigs fed an unsupplemented, nutritionally-adequate diet. A total of 192 weaned pigs [DanBred × Pi, initial body weight (BW) 7.2 ± 0.4 kg] were assigned to 48 floor pens [4 pigs/pen (2 male, 2 female), 12 pens/treatment], in a completely randomized design. Diets included: 1) a nutritionally adequate wheat, corn and barley-based positive control (PC); 2) a negative control (NC) based on the PC but without added inorganic P, reduced in Ca, net energy (NE), digestible amino acids (AA) and Na, supplemented with PhyG at 1,000, 1,000, 750, 500 and 500 FTU/kg in starter I (7 to 11 kg BW), starter II (11 to 25 kg BW), grower I (25 to 55 kg BW), grower II (55 to 85 kg BW) and finisher (85 to 115 kg BW) phases, respectively (NC1 + PhyG low); 3) NC1 further reduced in Ca, digestible AA and NE, (by ≤ 0.03 percentage points, ≤ 0.01 percentage points and ≤ 9 kcal/kg, respectively) supplemented with PhyG at 2,000, 2,000, 1,000, 750 and 750 FTU/kg per phase (NC2 + PhyG high), and; 4) as 2) but further reduced in NE and digestible AA (by 26 to 33 kcal/kg and ≤ 0.01 percentage points, respectively), supplemented with 2,440 XU/kg xylanase and 304 U/kg β-glucanase (NC3 + PhyG low + XB). For the overall period, growth performance (all measures) was maintained in the enzyme-supplemented treatments to a level not different from the PC, whereas in starter II and grower I, BW was increased (+ 1.82 and + 5.11 kg/pig, respectively; P < 0.05) and gain:feed was increased (P < 0.05) in NC3 + PhyG low + XB, compared with the PC. Total estimated feed costs per kilogram BW gain (BWG) were lower (P < 0.05) in NC3 + PhyG low + XB (-0.05 € or 7.3%) and the carbon footprint of production was reduced in NC2 + PhyG high and NC3 + PhyG low + XB compared with the PC (by 128 and 145 g CO2 equivalents per kilogram of BWG, respectively, equivalent to reductions of 6.0% and 6.8%; P < 0.05). These results confirm the appropriateness of the applied energy and nutrient reductions for PhyG and PhyG with xylanase–β-glucanase in a mixed-cereal diet from wean to finish and highlight a potential feed cost saving and environmental sustainability benefit of the application.

To begin formulating broiler diets on a digestible calcium (Ca) basis, robust Ca digestibility values for ingredients and factors affecting this digestibility are needed. This study had three main objectives: (1) determine the standardized ileal digestibility (SID) of Ca and phosphorus (P) for seven plant-based feed ingredients in broilers, (2) assess the impact of phytate source on SID Ca from limestone (LS), and (3) evaluate the effect of phytase on SID Ca and P for the different ingredients. Two experiments were conducted to satisfy these objectives. In Experiment 1, a 4 × 2 × 2 factorial design was used, with four plant-based feed ingredients (corn, wheat, sorghum, and full-fat soybean meal (FFS)), two LS inclusions in the diet (absence of LS and the inclusion of LS required to achieve 0.65% Ca in the final diet), and two phytase doses (0 and 1000 FTU/kg diet). Experiment 2 utilized a 3 × 2 × 2 factorial design with three plant-based ingredients (soybean meal (SBM), rapeseed meal (RSM), and sunflower meal (SFM)), two LS inclusions in the diet (absence of LS and the inclusion of LS required to achieve 0.65% Ca in the final diet), and two phytase doses (0 and 1000 FTU/kg diet). The trial had eight replicate pens (6 broilers/replicate) per treatment. Data were analyzed using a factorial analysis in JMP Pro 16.0 with means separation performed when p < 0.05, using Tukey HSD. The SID Ca in the absence of phytase for wheat (72.9%) and FFS (69.9%) was higher (p < 0.05) than for sorghum (54.5%) and corn (46.3%). In Experiment 2, the SID Ca in the absence of phytase from SFM (61.0%) was higher (p < 0.01) than RSM (42.7%) and SBM (46.8%). The SID Ca from added LS was affected by the ingredient, with diets containing wheat and FFS resulting in the lowest (p < 0.05) SID Ca versus those containing corn and sorghum irrespective of phytase dose in Experiment 1, and the lowest (p < 0.05) for SBM and RSM vs. SFM in the absence of phytase in Experiment 2. Phytase supplementation increased (p < 0.01) SID Ca and SID P across all feed ingredients compared to non-supplemented diets. There was a two-way interaction (p < 0.01) of LS addition and ingredient on SID P in both experiments. The results of this study provide SID Ca and SID P values from the selected ingredients and show that phytate from different ingredients reacts differently with Ca from LS and should be considered when developing SID coefficients of Ca and P for use in commercial broiler feed formulation. The SID coefficients of Ca and P for the individual feed ingredients evaluated in this study will allow for the further development and transition towards dCa and dP in commercial feed formulation.

An experiment was conducted to evaluate the effects of increasing the dose of a novel consensus bacterial 6-phytase variant expressed in Trichoderma reesei (PhyG) in broilers fed complex diets highly deficient in minerals, dig AA, and energy. Diets were a nutrient-adequate control (PC); a nutrient-reduced control (NC) formulated with a reduction in available P (avP) by 0.199%, Ca by 0.21%, crude protein by 0.72–1.03%, dig Lys by 0.064–0.084%, Na by 0.047%, and ME by 87.8 kcal/kg, respectively; and NC supplemented with PhyG at 500, 1000, and 2000 FTU/kg feed. BW was decreased and FCR increased in the NC vs. PC, while the PhyG treatments were similar to the PC. Carcass yield and bone ash were also maintained with PhyG supplementation. Phytase provided economic benefit on a feed cost per kg of weight basis for 1 to 35 d; the cost reductions equated to USD 0.006, 0.016, and 0.02/kg BWG at 500, 1000, and 2000 FTU/kg. In conclusion, this trial demonstrated that supplementation with a novel consensus phytase variant in diets highly deficient in minerals, dig AA, and energy maintained growth performance and provided economic benefit, with production benefits being maximized at inclusion levels of 2000 FTU/kg.