Evaluation of the responses of broiler chickens to varying concentrations of phytate phosphorus and phytase. Ⅱ. Grower phase (day 12-23 post hatching)

Evaluation of exogenous phytase in high-phytate diets for broiler chickens and pigs

There is a gap in the understanding of the relationship between dietary phytate levels and the relative efficacy of phytase to improve amino acid (AA) digestibility in pigs and chickens. Two experiments were conducted to investigate the effect of exogenous phytase on standardized ileal digestibility (SID) of AA and the apparent ileal digestibility (AID) of P in both standard- (SP) and high-phytate (HP) diets for broilers and swine. There were either 40 cages of Cobb 500 male broilers or 10 crossbred barrows (35 kg) fitted with ileal T-cannulas. Both studies were allotted to five dietary treatments (8 replicates). Treatments consisted of four corn-soybean meal-based diets arranged in a 2 × 2 factorial of standard or high phytate and exogenous phytase at 0 or 1 000 phytase units (FYT)/kg; and one N-free diet. Birds were fed a common starter diet from d 0 to 20 and fed experimental diets from d 20 to 25. Birds were euthanized on d 25 via CO2 asphyxiation, and digesta were collected from the terminal ileum. Pigs were fed for a total of four 7-d periods, where digesta were collected on d 6 and 7 of each period. Diet and digesta samples were analyzed for DM, N, Ti, AA, and P to determine AA and P digestibility. The SID of AA was determined by correcting the AID of AA for the basal endogenous losses estimated using the N-free diet. Main effects of the diet type (standard or HP) and phytase (0 or 1 000 FYT/kg), and the interaction of diet type and phytase were evaluated. For both experiments, the HP diets produced lower SID of AA compared to the SP (P < 0.001). For broilers, there was a phytase effect (P < 0.001) for the SID of all AAs evaluated regardless of the diet type. For pigs, phytase improved (P < 0.05) the SID of Met, Lys, Cys, Glu and Ser and tended to improve (P < 0.10) Arg, Leu, Thr, and Tyr. There were no significant interactions for either experiment. For both experiments, AID of P was lower for the HP diets (P < 0.01), and phytase produced greater AID of P for both diet types (P < 0.01). These data indicate that phytase greatly improves the digestibility of P for broilers and pigs and has the ability to significantly increase the digestibility of amino acids for these animals, regardless of the dietary phytate P.

Application of enzyme matrix values for energy and nutrients to a wheat-corn-soybean meal-based broiler diet supplemented with a novel phytase, with or without a xylanase-β-glucanase, achieved a production benefit over a nutritionally adequate unsupplemented diet

The effect of applying an energy and nutrient matrix to a wheat-corn-soybean meal-based diet supplemented with a novel consensus bacterial 6-phytase variant (PhyG) and xylanase-β-glucanase on growth performance, bone mineralization, carcass weights, feed costs, and carbon footprint was evaluated. A randomized complete block design (3,300 Ross 308 mixed-sex birds; 60 pens, 12 pens per treatment) tested 5 treatments: 1) a positive control diet (PC), containing 0.92, 0.84, 0.71% Ca and 0.43, 0.38, 0.30% digestible P during 1 to 10, 11 to 21, and 22 to 32 d of age, respectively; 2) a negative control reduced in Ca, digestible P, digestible AA, ME, and Na by phase based on the PhyG dosing regimen (NC1); 3) NC1 supplemented with PhyG at 2,000, 1,500, and 1,000 FTU/kg by phase (NC1+PhyG); 4) as NC1 but additionally reduced in ME (NC2); and 5) NC2 supplemented with PhyG as in 3) plus 1,220 U/kg of xylanase and 152 U/kg of β-glucanase (NC2+PhyG+XB). Final (d 32) BW, overall (0-32 d of age) ADFI, FCR, d 10 and 32 tibia ash and carcass part weights were reduced or impaired (P < 0.05) in NC1 and NC2 vs. PC (d 32 BW -477 g/bird (23.4%) and -422 g/bird (20.7%), respectively). Growth performance (all measures, all phases) was improved and tibia ash (at 10 and 32 d of age), total carcass thigh, breast and leg weights were increased (P < 0.05) in NC1+PhyG vs. NC1, and NC2+PhyG+XB vs. NC2. Overall growth performance outcomes in NC1+PhyG and NC2+PhyG+XB were not different (P > 0.05) from the PC. Total feed cost and carbon footprint per kilogram BW gain (BWG) were reduced (P < 0.05) vs. PC in NC2+PhyG+XB [-0.052 € and -376 g CO2 eq./kg BWG, respectively] and NC1+PhyG [-0.038 € and -260 g CO2 eq./kg BWG, respectively]. The results validated the nutrient matrices in the test diets and highlighted a potential feed cost and environmental sustainability benefit which was greatest when the enzymes were applied in combination.

A Novel Bacterial 6-Phytase Improves Productive Performance, Precaecal Digestibility of Phosphorus, and Bone Mineralization in Laying Hens Fed a Corn-Soybean Meal Diet Low in Calcium and Available Phosphorus

Exogenous phytases are commonly added to low-phosphorus and low-calcium diets to improve P availability and reduce P excretion by poultry. This study investigated the effect of supplementation with a novel bacterial 6-phytase on egg production, egg quality, bone mineralization, and precaecal digestibility of P in laying hens fed corn-soybean meal-based diets. A total of 576 Hy-Line brown laying hens were used in a completely randomized block design at 25-45 weeks of age (woa). The three treatments included a positive control (PC) adequate-nutrient diet with 2840 kcal metabolizable energy/kg, 0.77% digestible lysine, 3.5% Ca, and 0.30% available P (avP); a negative control (NC) diet with 0.16% points less Ca and avP; and an NC diet supplemented with a novel bacterial 6-phytase at 300 phytase units/kg diet. Hen performance and the percentage of damaged eggs were measured every 4 weeks. Body weight, precaecal digestibility of P, and bone parameters at 45 woa were also measured. The reduction in avP and Ca in the NC diet did not compromise performance or egg quality. However, it decreased (P < 0.001) body weight, tibial dry matter, tibial ash and P content, and precaecal digestibility of P. Importantly, all these parameters were significantly improved (P < 0.001) and essentially restored to the levels measured in PC diet-fed hens upon supplementation with phytase. In summary, the present study demonstrates that the new bacterial 6-phytase could effectively counteract the negative effects of P and Ca deficiencies on body weight, bone mineralization, and P availability, thereby supporting high productivity without compromising the welfare of laying hens.

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.

Effect of Phytase Level and Form on Broiler Performance, Tibia Characteristics, and Residual Fecal Phytate Phosphorus in Broilers from 1 to 21 Days of Age

The present study evaluated the individual and combined effects of coated and uncoated phytase on broiler performance, tibia characteristics, and residual phytate phosphorus (P) in manure. Two repeated studies were conducted using 240-day-old Cobb 500 by-product male broilers per trial. For each trial, birds were assigned to four treatments with four replicate battery cages per treatment (60 birds/trt) and grown for 21 days. Treatments included: (1) negative control (NC), (2) NC + 1000 phytase units (FTU) coated phytase (C), (3) NC + 1000 FTU uncoated phytase (U), and (4) NC + 500 FTU coated + 500 FTU uncoated phytase (CU). Data were analyzed with a one-way ANOVA and means were separated using Tukey’s HSD. In the pooled data for both trials, all treatments with dietary phytase had a higher body weight (BW) and feed consumption (FC) than the NC on day 21 (p < 0.05). Similarly, a six-point reduction was observed for day 1 to 21 feed conversion (FCR) for U and CU (p < 0.05). All treatments with phytase inclusion differed from the NC in every evaluated parameter for bone mineralization (p < 0.05) and had significantly lower fecal phytate P concentrations compared to the NC (p < 0.05). Overall, bird performance was essentially unaffected by phytase form, indicating that combining phytase forms does not appear to offer any advantage to the evaluated parameters from day 1 to 21.

The Duration of the Trial Influences the Effects of Mineral Deficiency and the Effective Phytase Dose in Broilers' Diets

Two trials varying in duration (short- and long-term) were conducted to evaluate the effects of providing deficient (NC) or sufficient (PC) Ca and P levels, and different doses of a new phytase (250, 500, and 1000 FTU/kg feed), in broiler feed on growth performance, nutrient digestibility and retention, and tibia mineralization. A total of 80 and 490 male chicks (Ross) of 21 and 1 days of age were used in the short- and long-term trials, respectively. In the long-term trial, chicks fed NC diets showed a lower (p < 0.05) average daily gain and feed intake compared to chicks fed PC and a greater (p < 0.05) feed conversion ratio compared to 500 and 1000 FTU/kg feed during the starting period. Regarding the effects on minerals’ and nutrients’ coefficients of retention, animals fed NC showed a significantly higher digestibility for P than those fed the PC diet in the long-term trial. Additionally, feeding 250 to 500 FTU/kg diets increased most of the nutrients’ digestibility in the short-term but only P digestibility in the long-term trial. Tibia mineralization increased linearly with phytase addition (p < 0.05) only in the long-term trial. In conclusion, the effects of dietary mineral and phytase levels on growth performance are more noticeable in young animals. In addition, the duration of the trial is key due to a possible adaptation phenomenon of birds to low P supplementary levels.

Modeling improvements in ileal digestible amino acids by a novel consensus bacterial 6-phytase variant in broilers

Data from 13 datasets from 4 trials on the effect of a novel consensus bacterial 6-phytase variant (PhyG) on the apparent ileal digestibility (AID) of amino acids (AA) in broilers were used to model AID AA responses. The datasets were obtained from 3 trial locations (New Zealand, Australia and United States) and collectively incorporated variations in diet composition (feedstuff composition, phytate-P (PP) level, limestone solubility), feed form (mash or pellet), bird genetics (strain), and age at sampling (11-35 d of age). In total, 384 observations were analyzed. First, the relationships between AID of AA (as coefficients) and increasing phytase dose level from 0 to 4,000 FTU/kg were evaluated across all datasets using exponential curve fitting. Second, the percentage unit change in AID of AA at each phytase dose level from baseline (basal diet [BD] without phytase) was calculated separately for each dataset and the data then modeled together using exponential curve fitting. The model-predicted mean coefficient of AID of total AA in basal diets was 0.76 (range 0.56 [Cys] to 0.83 [Glu]), which was increased by PhyG to 0.80 and 0.81 at 2,000 and 4,000 FTU/kg, respectively. Exponential increases in the percentage unit improvement in AID of 18 individual and of total AA with increasing phytase dose level were evident (P < 0.05). Improvements (vs. BD) at 2,000 FTU/kg and 4,000 FTU/kg, respectively, were greatest for Cys (+9.2 and +11.0% units), Met (after deduction of synthetic Met, +8.4 and +9.0% units), and Thr (after deduction of synthetic Thr, +6.2 and +7.3% units). The data demonstrated consistent improvements in the AID of AA by the phytase. The modeling results generated from data gathered from birds sampled at different ages and from different dietary settings with correction of synthetic AA for Lys, Met, Thr, and Trp, enabled a more accurate prediction of the digestible AA contribution from the diet by this novel phytase. This will allow diet-specific AA matrix recommendations to be made in commercial feed formulations.